WO2013005394A1

WO2013005394A1 - Sliding member

Info

Publication number: WO2013005394A1
Application number: PCT/JP2012/004161
Authority: WO
Inventors: 福原　弘之; 石田　貴規
Original assignee: パナソニック株式会社
Priority date: 2011-07-01
Filing date: 2012-06-27
Publication date: 2013-01-10
Also published as: JP6004199B2; CN103635705B; CN103635705A; JPWO2013005394A1

Abstract

It is anticipated that sliding conditions for sliding members will become harsher in the future. If sliding in a borderline lubrication state, in which maintaining adequate lubricating oil between sliding surfaces is not possible, and the oil film is ruptured and the sliding members come in contact with each other, continues for a long time, adhesion of abrasion powder and abrasive frictional wear may proceed, ultimately leading to locking due to seizure or to abnormal frictional wear. In the present invention, by appropriately setting the shape (size, depth, opening area) of recesses according to the sliding load rather than simply providing countless identical recesses on the surface of the sliding member, a highly efficient, highly reliable sliding member is provided, wherein frictional loss and wear are reduced even under harsher sliding conditions.

Description

Sliding member

The present invention relates to the surface shape of a sliding member, and in particular to a sliding surface of a sliding member mainly made of a metal material with respect to an apparatus in a compressor for a refrigeration cycle and the like.

Reducing the friction loss of the sliding member is necessary to improve the efficiency and reliability of the device. For example, in the case of a reciprocating compressor used for a refrigerator-freezer, etc., the thickness of the oil film existing between the sliding members is about 1 to 2 μm or less at the commonly used rotation speed of 1500 to 3000 rpm .
In the past, in order to reduce the friction loss of the sliding member, efforts have been made to remove asperity as much as possible by removing fine irregularities on the contacting sliding surface.
On the other hand, in order to reduce the friction loss of the sliding member, there has been proposed a technique of processing for forming a recess on the sliding surface of the smoothed sliding member. Specifically, a technique has been proposed in which an infinite number of concave portions having a substantially arc-shaped cross section are formed on the sliding surface of the sliding member (see, for example, Patent Document 1).

Hereinafter, these conventional techniques will be described using the drawings. FIG. 10 and FIG. 11 show a state in which the sliding members sliding relative to each other are opposed via an oil film (not shown) of lubricating oil.
FIG. 10 shows a state in which the sliding surfaces of the sliding member 30 facing the sliding member 32 are both smoothed.
FIG. 11 shows that the sliding surface of the opposing sliding member 30 is made smooth and the sliding surface 38 of the other sliding member 32 is provided with innumerable recesses 36. According to Patent Document 1, when lubricating oil is supplied to the contact sliding portion 34, the lubricating oil becomes oil balls in the concave portions 36 formed innumerably by surface tension, and when a load is applied, the concave portions 36 are adjacent The oil balls are connected to each other, and an oil film is formed on the entire sliding surface.

JP 7-188738 A

However, in the above-mentioned conventional compressors and the like, the output can be further increased, the rotation speed can be reduced for preventing noise and vibration, the viscosity of lubricating oil can be reduced for improving efficiency, and the efficiency can be improved On the contrary, it is assumed that the sliding condition of the sliding member will be more severe in the future.
As shown in FIG. 10, in the case where the sliding surfaces between the sliding

members

30 and 32 are smooth with each other, the lubricating oil can not be sufficiently retained in the contact sliding portion 34, so the oil film is broken and the sliding occurs. The moving

members

30, 32 may come in contact with each other. When the sliding condition in the boundary lubrication area continues for a long time between the sliding

members

30 and 32 as described above, adhesion of wear powder and abrasive wear progress, and finally, so-called locking due to seizing or abnormal wear is caused. There is everything.
Further, as shown in FIG. 11, when the innumerable recesses 36 are provided on the sliding surface 38, the friction coefficient starts to increase rapidly after a while from the start of sliding, or the coefficient of friction is large immediately after the start of sliding. It may change to a high value with fluctuations. As a result, severe wear may occur on the sliding surfaces of the sliding

members

30, 32.

Also, the sliding surface of the sliding member of the compressor is such that the entire surface is not sliding under the same sliding conditions (load, lubricating oil viscosity, speed), but the sliding surfaces are in contact with each other There are mixed regions where the lubrication condition is severe and regions where the lubrication condition is not severe such that the sliding surfaces are separated by an oil film. Therefore, it is difficult to obtain a sufficient effect even if the same recess is disposed in the entire sliding surface.

The present invention has been made to solve the above-described conventional problems, and the sliding surface of the sliding member of the compressor is in a region where the lubricating state is severe due to the sliding conditions (load, lubricating oil viscosity, speed) Depending on the area that does not, the specifications of the recess, ie the size of the recess opening, the depth of the recess, and the ratio of the opening to the sliding surface of the sliding member (hereinafter referred to as the opening area ratio) are set optimally. And a recess is provided. Thereby, the sliding surface of the sliding member is made to have an area for suppressing wear and further enhancing the reliability of the sliding member, and a region for further reducing friction loss, that is, fluid viscosity loss. An object of the present invention is to provide a highly reliable and low-loss sliding member by effectively reducing friction loss and wear.

In order to solve the above-mentioned conventional problems, the sliding member of the present invention is divided into a region where lubrication is severe depending on sliding conditions and a region not having such a region on the sliding surface of the sliding member. A recess according to the specification is provided on the surface. As a result, lubricating oil is effectively exuded by surface pressure relief of the contact surface and oil accumulation to suppress wear, and decrease in the contact area reduces fluid viscosity loss, effectively resulting in friction loss and wear. It can be reduced.

According to the sliding member of the present invention, lubricating oil is effectively exuded by surface pressure relief of the sliding surface and oil accumulation to suppress wear, and decrease in the contact area reduces fluid viscosity loss, As friction loss and wear can be effectively reduced, a sliding member with a low friction coefficient and high reliability can be provided.

The perspective view schematic diagram of the sliding member in Embodiment 1 of this invention A schematic view of a friction test device for measuring friction characteristics Characteristic diagram showing the sliding state of the sliding member according to the first embodiment and the sliding member of the comparative example Transverse cross-sectional view of a reciprocating compressor using the sliding member of the present invention Transverse cross-sectional view of a rotary compressor using the sliding member of the present invention Transverse cross-sectional view of a scroll compressor using the sliding member of the present invention Top view of fixed scroll of scroll compressor using sliding member of the present invention Top view of fixed scroll of scroll compressor using sliding member of the present invention Top view of fixed scroll of scroll compressor using sliding member of the present invention A schematic cross-sectional view of a conventional smooth sliding surface A schematic cross-sectional view of a sliding surface provided with a conventional recess

DESCRIPTION OF SYMBOLS 10 Disc-like sliding member 12 Ring-like sliding member 132 Sliding member 136, 136a, 136b

Concave part

137, 137a, 137b

Flat part

138, 138a, 138b Sliding surface 150 Reciprocating compressor 170 Rotary compressor 180 Scroll compressor 188 Fixed scroll 189 Orbiting scroll 190 Thrust bearing surface 191 Inner circumferential side 192 Outer circumferential side

A first aspect of the invention has two sliding members sliding on the sliding surfaces of each other, and at least one of the sliding surfaces is provided with a plurality of dimple-shaped recesses, the shape of the recesses or the recesses By making the opening area ratio different depending on the area, lubricating oil is effectively exudeed by surface pressure relaxation of the sliding surface and oil accumulation to suppress wear, and the fluid viscosity loss is reduced by reducing the contact area. Since the friction loss and the wear can be effectively reduced, a sliding member having a low friction coefficient and high reliability can be provided.

The second invention produces the same effect as that of the first invention because the recess different depending on the region has a different shape of at least one of the opening size and the recess depth.

A third invention has a first region and a second region as the regions, and the first region has a lubrication condition that is more severe than that of the second region. Making the recess depth of the recess formed in the second region shallower than the recess depth of the recess formed in the second region, and setting the opening area ratio in the first region to the second region By making the opening area ratio smaller than in the above, it is possible to provide a sliding member having a low friction coefficient and high reliability.

According to a fourth aspect of the present invention, since the opening face of the recess is substantially circular, lubricating oil is likely to ooze out, and a sliding member having a low coefficient of friction and high reliability can be provided.

In a fifth invention, the sliding member according to the first to fourth inventions is a member used for a reciprocating compressor, a rotary compressor, or a scroll compressor, so that it has a low coefficient of friction and is reliable. A high compressor can be provided.

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

Embodiment 1
FIG. 1 is a schematic perspective view of the sliding surface of the sliding member according to the first embodiment of the present invention, and shows a first area A under severe lubrication conditions and a second area B under severe lubrication conditions.
The present invention relates to two sliding members in which sliding surfaces slide with each other. The sliding surface 138 of at least one of the sliding members 132 is provided with a dimple-shaped recess 136.
The sliding surface 138 comprises the sliding surface 138 a of the first area A and the sliding surface 138 b of the second area B. Here, it is assumed that the first region A has stricter lubricating conditions than the second region B.
The shapes of the recess 136a formed in the sliding surface 138a and the recess 136b formed in the sliding surface 138b are different from each other. That is, at least one of the opening size and the recess depth is different between the recess 136a and the recess 136b.
FIG. 1 shows the case where the recess 136a and the recess 136b have different opening sizes and recess depths.
The recess depth of the recess 136a formed in the first region A is shallower than the recess depth of the recess 136b formed in the second region B, and the opening dimension of the recess 136a in the first region A is The opening size of the recess 136 b in the area B of 2 is made larger.

The opening area ratio by the recess 136a in the sliding surface 138a of the first area A is different from the opening area ratio by the recess 136b in the sliding surface 138b of the second area B.
The opening area ratio is the ratio of the total area of the opening surface of the recess 136 to the area of the sliding surface 138. A part of the sliding surface 138 of the sliding member 132 is captured by a laser microscope to perform computer image processing. The opening area ratio is obtained by dividing the sum of the areas of the opening faces of the individual depressions 136 by the total area of the sliding face 138 used for image processing after separating the opening face by the depressions 136 and the flat face 137. . In addition, the average value of the opening area ratio obtained by changing a measurement location and measuring several times was made into the representative value in the conditions.
The opening area ratio in the first region A is the total area of the sliding surface 138a used for image processing, the sum of the areas of the opening surfaces of the individual recesses 136a after separating the opening surface of the recess 136a and the flat surface 137a. It can be obtained by dividing by.
The opening area ratio in the second region B is the total area of the sliding surface 138b used for image processing, the sum of the areas of the opening surfaces of the individual recesses 136b after separating the opening surface of the recess 136b and the flat surface 137b. It can be obtained by dividing by.
In FIG. 1, the opening area ratio in the first region A is smaller than the opening area ratio in the second region B.

In the first region A where the lubricating conditions are severe, dimple-like recessed portions 136a having a shallow depth are provided with a smaller opening area ratio as compared to the second region B where the lubricating conditions are not severe (for example, The diameter is about 0.2 mm, the depth is about 1 to 3 μm, the opening area ratio is about 10 to 25%). As a result, the load is received by the flat portion on the sliding surface 138 and the lubricating oil held in the recess 136 oozes out to the flat portion, thereby providing friction even under more severe sliding conditions. Loss and wear can be reduced.
On the other hand, in the second region B in which the lubricating conditions are not severe, dimple-shaped concave portions 136b having a deep depth are provided with an increase in the open area ratio as compared with the first region A in which the lubricating conditions are severe. (For example, the diameter is within 0.15 mm to 0.3 mm, the depth is about 3 to 10 μm, the opening area ratio is about 20 to 50%). As a result, the area of the smooth surface can be reduced, and the viscosity resistance of the lubricating oil decreases, and the lubricating oil held in the recess exudes to the flat portion, thereby reducing friction loss and wear. Preferably, the shape of the opening is substantially circular. This is because the lubricating oil tends to exude.

FIG. 2 is a perspective view of a friction test device for measuring friction characteristics. The friction characteristics of the sliding member 132 in which the concave portion 136 was formed by removal processing such as laser and etching, shot processing, and plastic processing such as press were evaluated by a ring-on-disk type experimental apparatus.
A ring-shaped sliding member 12 and a disk-shaped sliding member 10 are attached to the friction test device shown in FIG. 2 as two sliding members. The ring-shaped sliding member 12 is rotated in a predetermined direction by the rotational force transmitted through the driving member 14 and the pin 16 and receives a load from above through the stationary shaft 18.
Therefore, since the disk-shaped sliding member 10 rotates while the ring-shaped sliding member 12 contacts the disk-shaped sliding member 10 with a predetermined pressure, the friction between the ring-shaped sliding member 12 and the disk-shaped sliding member 10 Will occur. A lubricating oil (not shown) is present between the two sliding

members

10 and 12. A through hole 23 is provided on the side surface of the ring-shaped sliding member 12. Lubricating oil is appropriately supplied to the inner peripheral surface of the ring-shaped sliding member 12 from the microsyringe 24 inserted into the through hole 23 on the side surface of the ring-shaped sliding member 12, and the centrifugal force due to the rotation of the disk-shaped sliding member 10. Flows into the contact sliding portion of the two sliding members. Further, a guide portion 20 provided concentrically above the disc-like sliding member 10 and the ring-like sliding member 12 bears the bearing of the stationary shaft 18. Further, the ball bearing 22 is responsible for an aligning mechanism for bringing the ring-shaped sliding member 12 and the disk-shaped sliding member 10 into contact with each other without any contact.

In addition, the experimental conditions by the said friction experiment apparatus were as follows in order to measure the friction coefficient in boundary lubrication, mixed lubrication, and fluid lubrication. The load is 6N to 110N, the speed is 0.06 to 0.6m / sec, the viscosity is 4.6 to 130mm ² / sec, the oil supply is 0.12cm ³ / min (0.03cm ³ × 4 times / Minutes).
The ring-shaped sliding member 12 was ground-finished with an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a material of FC200 (with a hardness of about HB 180) and a surface roughness of about Ra 0.2. The disc-like sliding member 10 is subjected to lapping after grinding with an outer diameter of 27 mm, a material of FC 250 (hardness: about 200) and a surface roughness of about Ra 0.2. In the contact surface of the ring-shaped sliding member 12 with the disk-shaped sliding member 10, a cross-shaped groove (not shown) is provided so that the lubricating oil sufficiently spreads over the sliding surface. The lubricating oil was supplied in the same amount in all experiments.
Furthermore, the bearing characteristics of boundary lubrication in a sliding state in which an oil film is hard to form and metal contact occurs, fluid lubrication in an oil film formed and sliding state in which metal contact is hard to occur, and mixed lubrication in its transition state. In order to obtain the values, the relative sliding speed of the ring sliding member 12 and the disk-shaped sliding member 10 and the viscosity and contact pressure of the lubricating oil were changed.

The opening area ratio is the ratio of the total area of the opening of the recess 136 to the area of the sliding surface 138 where the ring-shaped sliding member 12 and the disk-shaped sliding member 10 contact. A part of the sliding surface 138 of the sliding member was taken in by a laser microscope to perform computer image processing. The opening area ratio is obtained by dividing the sum of the opening areas of the openings of the concave portions 136 and the flat portions 137 and then dividing the sum of the opening areas of the openings of the individual concave portions 136 by the total area of the sliding surface 138 used for image processing. It has gained. In addition, the average value of the opening area ratio obtained by changing a measurement location and measuring several times was made into the representative value in the conditions.
Further, the surface roughness indicates the average value of the results measured several times with a stylus type shape measuring machine, and the depth of the recess 136 indicates the average value of the results measured several times with the laser microscope.

FIG. 3 is a characteristic view of the coefficient of friction with the form of the sliding surface in the embodiment of the present invention as a parameter, and shows the number of bearing characteristics on the x axis and the coefficient of friction on the y axis.
The bearing characteristic number is a non-dimensional number obtained by dividing the product of viscosity and speed of lubricating oil by surface pressure, and is an index of the state of lubrication. From the fluid lubrication area where the metal surface is separated by oil film as the number of bearing characteristics decreases, the oil film becomes thinner and mixed lubrication area where metal surface contact occurs, boundary lubrication where the oil film is very small and metal contact is excessive Change to the area.
FIG. 3 shows the results of the condition 1 (□), the condition 2 (Δ) and the conventional condition 3 (実施) according to the first embodiment. In condition 1, the opening diameter of the recess 136 is 0.184 mm, the opening area ratio is 16%, the surface roughness Ra of the sliding surface 138 is 0.21, and the depth of the recess 136 is 1.2 μm. Condition 2 is that the opening diameter of the recess 136 is 0.176 mm, the opening area ratio is 35%, the surface roughness Ra of the sliding surface 138 is 0.23, and the depth of the recess 136 is 9.4 μm. Condition 3 is a conventional smooth surface without concave processing, and the surface roughness of the sliding surface 138 is Ra 0.2.

From FIG. 3, it was found that the bearing characteristic number was changed by changing the load, speed, and viscosity which are sliding conditions, but the coefficient of friction was on one line, and in this experiment the number of bearing characteristics and the coefficient of friction It is possible to show the relationship of As a result, the number of bearing characteristics is smaller in condition 1 (□ mark) than in the case of condition 3 (mark 従来 mark) in which both the conventional ring-shaped sliding member and the disk-shaped sliding member are smooth surfaces. The coefficient of friction is low in the area from lubrication to mixed lubrication. Further, it can be seen that the condition 2 (.DELTA. Mark) indicates that the number of bearing characteristics is large, that is, the coefficient of friction is low in the region of fluid lubrication.
From this experimental result, the coefficient of friction is lower than that of a smooth surface by selecting the dimple specifications that match the bearing characteristic number, that is, the distribution of the loading condition, in one sliding portion and arranging them on the sliding surface. In addition, it is understood that the wear state of the sliding surface 138 can be alleviated as well as suppressing the fluctuation and unstable sliding.

The present invention is applicable to various sliding members of various devices, and the material and surface properties (initial surface roughness) of the sliding member, operating conditions, supply state of lubricating oil and oiliness (viscosity and Depending on the oil type, etc., it is necessary to determine the appropriate elements of the recess 136.
As a specific example, a sliding member of a reciprocating compressor, which is one of refrigeration cycle compressors, can be mentioned. FIG. 4 shows a cross-sectional view of the reciprocating compressor.

The following is generally used as a sliding member of the present reciprocating compressor 150.
(1) The shaft main shaft 151 and the main bearing 152 have a cantilever bearing structure, so that the upper and lower ends of the main bearing 152 may come into contact with one another. Also, both materials are made of cast iron. The shaft main shaft 151 is subjected to a manganese phosphate coating treatment on its surface, and the shaft main shaft 151 is slightly lower in hardness than the main bearing 152. The sliding surface of the shaft main shaft 151 and the sliding surface of the slide bearing 152 are both finished to have a surface roughness Ra of 0.5 or less.
(2) With respect to the thrust bearing portion 153, the crankshaft is inclined within the main bearing 152 in the suction compression stroke of the refrigerant, whereby the thrust sliding surface 154 on the shaft main shaft 151 side and the outer periphery of the thrust sliding surface 155 on the main bearing 152 side One side contact may occur, and oil film pressure is less likely to occur due to planar contact. Further, the thrust sliding surface 154 on the shaft main shaft 151 side and the thrust sliding surface 155 on the main bearing 152 side are both made of cast iron, and the thrust sliding surface 154 on the main shaft side is generally subjected to a manganese phosphate coating treatment The hardness of the thrust sliding surface 154 on the shaft main shaft 151 side is slightly lower. The thrust sliding surfaces 154 and 155 are both finished to have a surface roughness Ra of 0.5 or less.
(3) With respect to the shaft eccentric shaft 156 and the connecting rod large end hole 157, a partial contact may occur at the upper and lower ends of the connecting rod large end hole 157 in the suction compression stroke of the refrigerant. The shaft eccentric shaft 156 is made of cast iron, the connecting rod 158 is made of aluminum alloy, and the surface of the shaft eccentric shaft 156 and the surface of the connecting rod large end hole 157 are both finished to have a surface roughness Ra of 0.5 or less.
(4) The piston pin 159 swings in the connecting rod small end hole 160 with respect to the piston pin 159 and the connecting rod small end hole 160, so the oil film is difficult to be formed compared to rotational movement in a fixed direction, and the sliding area is other The contact pressure is smaller and smaller than that of the sliding portion. The piston pin 159 is made of chrome steel, and the connecting rod 158 is made of aluminum alloy. The sliding surface of the piston pin 159 and the sliding surface of the connecting rod small end hole 160 are both finished to have a surface roughness Ra of 0.5 or less. The piston pin 159 is generally surface hardened or surface hardened by nitriding or the like.
(5) With respect to the piston 161 and the cylinder bore 162, the crankshaft 163 is inclined within the main bearing 152 in the suction compression stroke of the refrigerant, and the piston is inclined in the vertical direction as viewed from the side of the reciprocating compressor 150 One part may occur in a part. The piston 161 is made of sintered iron, and the surface thereof is treated with manganese phosphate. One cylinder bore 162 is made of cast iron and has a somewhat lower hardness than the piston 161. The sliding surface of the piston 161 and the sliding surface of the cylinder bore 162 are both finished to have a surface roughness Ra of 0.5 or less.

In the combination of the above sliding members, the present invention is considered to be effective for all possible sliding parts. That is, in a boundary lubrication area and a part where sliding in a mixed lubrication area (sliding members contact and slide) is assumed (discrimination is possible by observing the surface condition after driving) The recess area has a small opening area and a shallow recess depth, and the opening area is large and the recess depth is large in the fluid lubrication area (the area where sliding is assumed to be separated by the oil film of the sliding member) It is considered extremely effective to arrange a deep recess. That is, an appropriate opening area ratio, surface roughness, or the like corresponding to the operating rotational speed, surface pressure, actual use viscosity, etc., of the sliding members facing each other with respect to parts that easily come into contact with one another or parts that have relatively high surface pressure. The lubrication condition can be improved by providing the recess having the and the depth. In addition, the sliding member corresponding to the fluid lubrication region is provided with a recess having an opening area ratio, surface roughness, and depth corresponding to the operating rotational speed, surface pressure, actual use viscosity, etc. A shear force can be reduced, and a reciprocating compressor 150 with high efficiency and high reliability can be realized.

Another specific example is a sliding member of a rotary compressor which is one of refrigeration cycle compressors. FIG. 5 shows a cross-sectional view of the rotary compressor.

The following is generally used as a sliding member of the current rotary compressor 170.
(1) With respect to the shaft main shaft 171 and the main bearing 172, and the shaft subshaft 173 and the subbearing 174, one end contact of the end of the main bearing 172 and the subbearing 174 is likely to occur. The shaft main shaft 171 and the shaft sub-shaft 173 are integrally formed and made of cast iron, and the sliding surface of the shaft main shaft 171 and the sliding surface of the shaft sub-shaft 173 are treated with a manganese phosphate coating. One main bearing 172 and the secondary bearing 174 are made of sintered iron and have lower hardness than the shaft main shaft 171 and the shaft secondary shaft 173. The sliding surface of the main bearing 172 and the sliding surface of the sub bearing 174 are both finished to have a surface roughness Ra of 0.5 or less.
(2) Since the vane side surface 175 and the cylinder vane groove 176 reciprocate, it is difficult for oil film pressure to be generated. The vane side surface 175 is made of alloy steel, and the cylinder vane groove 176 is made of cast iron. The vane side surface 175 is finished to a surface roughness Ra of 0.5 or less, and the cylinder vane groove 176 is finished to Ra1 or less.
(3) The surface pressure of the vane tip 177 and the roller 178 becomes extremely high due to the line contact sliding. The vane tip 177 is made of alloy steel, and the sliding surface (tip) is hardened by forming a ceramic film by PVD or CVD. One roller 178 is made of cast iron. The sliding surface of the vane tip 177 and the sliding surface of the roller 178 are both finished to have a surface roughness Ra of 0.5 or less.

In the combination of the above sliding members, the present invention is considered to be effective for all possible sliding parts. That is, in a boundary lubrication area and a part where sliding in a mixed lubrication area (sliding members contact and slide) is assumed (discrimination is possible by observing the surface condition after driving) The recess area has a small opening area and a shallow recess depth, and the opening area is large and the recess depth is large in the fluid lubrication area (the area where sliding is assumed to be separated by the oil film of the sliding member) It is considered extremely effective to arrange a deep recess. That is, the appropriate opening area ratio, the surface roughness, and the depth corresponding to the operating rotation speed, the surface pressure, the actual use viscosity, etc., on the opposite sliding member, with respect to the parts that easily come into contact The lubrication can be improved by providing the recess having the taper. In addition, the sliding member corresponding to the fluid lubrication region is provided with a recess having an opening area ratio, surface roughness, and depth corresponding to the operating rotational speed, surface pressure, actual use viscosity, etc. A shear force can be reduced, and a rotary compressor 170 with high efficiency and high reliability can be realized.

Furthermore, as another specific example, there is a sliding member of a scroll compressor which is one of compressors for a refrigeration cycle. FIG. 6 shows a cross-sectional view of the scroll compressor.

The following is generally used as a sliding member of the present scroll compressor 180.
(1) The shaft main shaft 181 and the main bearing 182, the shaft eccentric shaft 183 and the eccentric bearing 184, and the shaft sub shaft 185 and the sub bearing 186 are structurally at the upper and lower ends of the main bearing 182, the eccentric bearing 184 and the sub bearing 186 Hit is easy to happen. The shaft main shaft 181, the shaft eccentric shaft 183, and the shaft countershaft 185 are all made of surface hardened alloy steel. The one main bearing 182, the eccentric bearing 184, and the sub bearing 186 are all composites of resin and carbon with the metal back metal. The sliding surface of the shaft main shaft 181, the sliding surface of the shaft eccentric shaft 183, and the sliding surface of the shaft countershaft 186 are all finished to have a surface roughness Ra of 0.5 or less.
(2) The oil film pressure of the thrust bearing surface 190 formed between the fixed scroll 188 and the orbiting scroll 189 pressed against the fixed scroll 188 by the compressed gas from the main bearing 182 side is relatively flat due to flat contact. It is hard to occur. Further, since the outer peripheral portion is a low pressure and the inner peripheral portion is a high pressure, which is characteristic of the scroll compressor, the thrust bearing surface 190 is a sliding surface on which the load is easily changed. The fixed scroll 188 is made of cast iron, and the orbiting scroll 189 is made of aluminum alloy. The sliding surface of the fixed scroll 188 and the sliding surface of the orbiting scroll 189 are both finished to have a surface roughness Ra of 0.5 or less.

In the combination of the above sliding members, the present invention is considered to be effective for all possible sliding parts. That is, in a boundary lubrication area and a part where sliding in a mixed lubrication area (sliding members contact and slide) is assumed (discrimination is possible by observing the surface condition after driving) The recess area has a small opening area and a shallow recess depth, and the opening area is large and the recess depth is large in the fluid lubrication area (the area where sliding is assumed to be separated by the oil film of the sliding member) It is considered extremely effective to arrange a deep recess. That is, an appropriate open area ratio, surface roughness, and depth corresponding to the operating rotational speed, surface pressure, actual use viscosity, etc., of the sliding members facing each other with respect to a portion that easily comes into contact or an area where lubrication is severe. The lubrication can be improved by providing the recess having the taper. In addition, the sliding member corresponding to the fluid lubrication region is provided with a recess having an opening area ratio, surface roughness, and depth corresponding to the operating rotational speed, surface pressure, actual use viscosity, etc. The shear force can be reduced, and high efficiency and high reliability of the scroll compressor 180 having high efficiency and high reliability can be realized.

From the observation of the thrust bearing surface 190 of the fixed scroll 188 after the operation of FIG. 7, the region of boundary lubrication and mixed lubrication where the oil film is thin and metal contact is occurring is the inner peripheral side 191 of the involute as shown in FIG. The area of fluid lubrication where oil film is likely to occur and metal contact is not likely to occur (is not occurring) is the outer peripheral side 192 of the involute shown in FIG.

Specifically, in the area of boundary lubrication and mixed lubrication, the oil film is thin and metal contact occurs. Accordingly, in the area of boundary lubrication and mixed lubrication, it is possible to observe specular wear because the roughness (convex portion) is worn and the powder generated by the wear causes scratches. The powder generated by this abrasion scrapes the mating material and adheres to the mating material, and if the coagulated powder is pulled away at a stretch, a large scratch will occur. In the case of mirror surface wear, the accumulation of oil is eliminated and the oil film is less likely to be formed, so that adhesion is likely to occur. Finally, a large scratch is generated, wear progresses, and the reliability of the sliding member is greatly impaired. In the case of a fixed cast iron scroll and a movable scroll made of aluminum alloy, when the powder generated by the wear of the aluminum alloy adhering to the cast iron was torn off, a large scratch might have occurred. In the area of fluid lubrication, the oil film is thick and metal contact is not generated, so no sliding marks are formed. That is, it is an initial surface state with remaining processing marks, and the surface roughness is also in the initial state. From these points of view, by carefully observing the surface of the compressor part after operation, fluid lubrication and a part where sliding in a boundary lubrication and mixed lubrication area (sliding members contact and slide) is assumed A region (sliding member slides in a state of being separated by an oil film) can be separated from the assumed portion, and it is necessary to select a recess specification according to each lubrication state.

On the inner peripheral side 191 of the thrust bearing surface 190 of this fixed scroll 188, the diameter 0.184 × depth 1.2 μm depth × opening area ratio 16 having the effect of reducing the friction coefficient in the mixed lubrication region from the boundary lubrication in FIG. % Of a substantially circular dimple was processed. On the outer peripheral side 192 of the thrust bearing surface 190, a substantially circular dimple having a diameter of 0.176 × 9.4 μm in depth × 35% of open area ratio having the effect of reducing the friction coefficient in the fluid lubrication region in FIG. 3 is processed did. As a result of confirming by the simulated operation and the actual device operation in the refrigerant atmosphere, the efficiency improvement of about 0.5 to 1% was recognized. In addition, after operation, the degree of abrasion on the inner circumferential side 191 is lighter than in the state without dimples, and it can be said that the lubricity is also improved, and the reliability is improved.
In addition, it is considered that the dimples are also effective in capturing the powder generated by the wear, as the minute powder generated by the wear is confirmed from the observation in the concave portion after the operation.
As described above, by providing appropriate dimples according to the load state of the sliding surface, it is possible to realize a scroll compressor having high performance and reliability.

According to the sliding member of the present invention, the sliding member has two sliding members on which the sliding surfaces slide with each other, and at least one of the sliding surfaces has a smaller opening area and a recessed portion in a region where the lubrication condition is relatively severe. A shallow recess is provided. As a result, the load is received by the flat portion on the sliding surface, and the lubricating oil held in the concave portion exudes to the flat portion, so that friction loss and the like can be obtained even under more severe sliding conditions. Wear can be reduced.
On the other hand, in the region where the lubrication condition is not so severe, the opening area is large and the recess depth is deep. As a result, the area of the smooth surface can be reduced, and friction loss and wear can be reduced by the viscosity resistance of the lubricating oil becoming low and the lubricating oil held in the concave part permeating out to the flat part. The friction loss and the wear can be reduced more than the sliding member provided with.

That is, rather than simply providing a large number of the same recesses on the sliding surface of the sliding member, depending on the sliding condition (load, lubricating oil viscosity, speed), the specification of the recess depending on the area where lubrication is severe and not That is, the recess is disposed by optimally setting the size of the recess opening, the depth of the recess, and the ratio of the opening to the sliding surface of the sliding member. Thus, the sliding surface of the sliding member has an area for suppressing wear and further enhancing reliability, and an area for further reducing friction loss, that is, fluid viscosity loss, and the friction is effectively reduced. Loss and wear can be reduced, and a reliable sliding member can be provided.

The present invention is applicable to various devices in which the sliding member is used, ie, various devices in various technical fields including compressors for refrigeration cycles.

Claims

It has two sliding members that slide on each other's sliding surface, and at least one of the sliding surfaces is provided with a plurality of dimple-shaped recesses, and the shape of the recesses or the opening area ratio by the recesses is a region Sliding member characterized in that it differs.
The sliding member according to claim 1, wherein the recess different depending on the region has a shape different from at least one of an opening size and a recess depth.
The area includes a first area and a second area,
In the case where the first region is under stricter lubrication conditions than the second region,
Making the recess depth of the recess formed in the first region shallower than the recess depth of the recess formed in the second region,
The sliding member according to claim 1 or 2, wherein the opening area ratio in the first region is smaller than the opening area ratio in the second region.
The sliding member according to any one of claims 1 to 3, wherein the opening surface of the recess is substantially circular.
The said sliding member is a member used for a reciprocating compressor, a rotary compressor, or a scroll compressor, The sliding member in any one of the Claims 1-4 characterized by the above-mentioned.