JP6723237B2 - Compressor and its usage - Google Patents

Description

The present invention relates to compressors and methods of use thereof.

In Patent Document 1, a throttle passage (orifice) is provided in the piston ring in order to prevent excessive wear of the piston ring when one piston ring reaches specified wear, and compressed gas is supplied to the piston ring that has reached the wear limit. A technique is shown in which it does not work and the subsequent progression of wear is eliminated (Fig. 6, etc.).

JP-A-4-203370 JP, 2014-214672, A

In the piston ring described in Patent Document 1, a passage communicating from the upper surface to the lower surface is shown. When wear progresses in such a piston ring, the communicating passage opens or closes due to the radial movement of the piston during operation.

Therefore, in the piston ring described in Patent Document 1, leakage from the communicating flow path becomes unstable, and it is not possible to sufficiently secure the sealability of the piston ring. On the other hand, for example, when a plurality of piston rings are provided, the wear of the piston rings is biased to one piston ring, and the time until the piston ring is replaced cannot be extended.

In view of the above points, it is an object of the present invention to provide a compressor having improved sealability of a piston ring.

Another object of the present invention is to provide a method of using a compressor that can extend the time until the piston ring is replaced.

In order to solve the above problems, the present invention provides a cylinder, a piston that reciprocates between a crank chamber side and a compression chamber side in the cylinder, and compresses a fluid in the compression chamber, and the cylinder provided in the piston. A piston ring for sealing between the crank chamber side and the compression chamber side, wherein the piston ring has an upper abutment provided on the compression chamber side and a lower abutment provided on the crank chamber side; An inner peripheral side and an outer peripheral side of the piston ring communicate with each other in the upper joint, and an outer peripheral groove that communicates with the upper joint and does not communicate with the lower joint is provided on the outer periphery of the piston ring. A compressor is provided with a blocking member for blocking the upper joint and the lower joint.

In addition, the present invention in another aspect provides a cylinder, a piston that reciprocates between a crank chamber side and a compression chamber side in the cylinder, and compresses fluid in the compression chamber, and the cylinder provided in the piston. A method of using a compressor, comprising: a plurality of piston rings that seal between the crank chamber side and the compression chamber side of the compressor, wherein at least one of the plurality of piston rings has reached a limit wear. Provided is a method of using a compressor, which is characterized by continuing to use the compressor.

According to the present invention, it is possible to provide a compressor having improved piston ring sealability.

Further, according to the present invention in another aspect, it is possible to provide a compressor capable of extending the time until the piston ring is replaced and a method of using the compressor.

It is a figure which shows the structure of a step cut piston ring. It is a figure which shows the method of abutment processing of a step cut piston ring. It is a figure which shows the surface pressure balance of a step cut piston ring. It is a figure which shows the leak passage of the A section of FIG. It is a figure which shows the structure of the piston ring in Example 1 of this invention. It is a figure which shows the surface pressure balance of the piston ring in Example 1 of this invention. It is a figure which shows the structure of the abutment of the piston ring in Example 1 of this invention. It is a graph which shows the comparison of the amount of wear of the conventional piston ring and the piston ring in Example 1 of the present invention. FIG. 3 is a sectional view of a piston when two piston rings are used in Example 1 of the present invention. It is the figure which looked at the piston from the abutment side when using two piston rings in Example 1 of the present invention. It is a figure which shows the wear amount at the time of using two piston rings in Example 1 of this invention. It is a figure which shows the amount of wear when three piston rings are used in Example 2 of this invention. It is a figure which shows the structure of the abutment of the piston ring in Example 2 of this invention. It is a figure which shows the structure of a reciprocating compressor. It is a figure which shows the structure of the piston ring formed with the material with high hardness. It is a figure which shows the initial structure of the high hardness rider ring in Example 3 of this invention. FIG. 7 is a cross-sectional view showing the relationship between the initial thickness of a high-hardness rider ring and the time of critical wear in Example 3 of the present invention. It is a figure which shows the structure at the time of the limit wear of the high hardness rider ring in Example 3 of this invention when one end of the abutment contacts. It is a figure which shows the initial structure of the high hardness rider ring in Example 4 of this invention. It is a figure which shows the structure at the time of limit wear of a high hardness rider ring in Example 4 of this invention. It is a figure which shows the structure of the rider ring of high hardness in Example 5 of this invention. It is a development view of a high-hardness rider ring in Example 5 of the present invention. It is a figure which shows the structure of the rider ring of high hardness in Example 5 of this invention. It is a development view of a high-hardness rider ring in Example 5 of the present invention.

First, the structure of a reciprocating compressor and the structure of a piston ring, which are the premise of the present invention, will be described with reference to the drawings.

FIG. 14 shows a schematic structure of the reciprocating compressor. In FIG. 14, (A) is an overall configuration diagram and (B) is an enlarged view of the compressor body. When the motor 15 shown in FIG. 14 is rotationally driven, the rotational force is transmitted to the crank portion 18 provided in the crank chamber 9 of the compressor body 11 through the belt 14, and the crank portion 18 rotates.

The rotational movement of the crank portion 18 is transmitted to the connecting rod 17, and the piston 7 reciprocates in the cylinder 8. As the piston 7 reciprocates in the cylinder 8, the fluid sucked from the suction port 12 is compressed in the compression chamber 10 and discharged from the discharge port 13 toward the tank 16 to store the compressed fluid in the tank 16. The fluid compressed by the compressor body 11 may be a specific gas (nitrogen, oxygen, refrigerant) in addition to air. Further, the compressor body 11 may be one that compresses the fluid at atmospheric pressure, or may be a booster that recompresses the pressurized gas.

As shown in FIGS. 3 and 4, the piston 7 is provided with the piston ring 1 shown in FIG. 1 in a ring groove 19 formed in the piston 7. The piston ring 1 seals against fluid leakage from the compression chamber 10 side (pressurized side pressurized by the piston 7) to the crank chamber 9 side (non-pressurized side not pressurized by the piston 7). Note that, hereinafter, the case where the compression chamber 10 side is arranged on the upper side and the crank chamber 9 side is arranged on the lower side will be described as an example. FIG. 1 shows the structure of a step cut piston ring 1 used in a reciprocating compressor. The piston ring 1 having a step cut shape has notches 2 and 3 formed at different positions on the circumference of the compression chamber 10 side and the crank chamber 9 side from the inner side toward the outer side in the radial direction. In the joint gaps 2 and 3, the inner peripheral side and the outer peripheral side (radially inner and outer side surfaces) of the piston ring 1 communicate with each other. The piston ring 1 has a structure in which the upper joint 4 and the lower joint 5 are overlapped with each other in the gaps 2 and 3. With such a structure, for example, even in an oscillating compressor in which the piston 7 tilts as the piston reciprocates, the piston ring 1 expands and contracts to maintain the sealing property of the compression chamber 10.

FIG. 2 shows a method of processing the piston ring 1. The piston ring 1 is cut into a circular ring in which the gaps 2 and 3 are in close contact with each other by pushing it with a cutter 6 having a combination of L-shapes as shown in FIG. Thereby, the abutment gaps 2, 3, the upper abutment 4, and the lower abutment 5 are formed. Since the piston ring 1 can be processed simply by making a notch with the cutter 6, it can be processed without man-hours and cost.

FIG. 3 shows a state of surface pressure balance when the piston ring 1 is used. Since there is a gap between the ring groove 19 of the piston 7 and the piston ring 1, the pressure Pc in the compression chamber 10 acts on the back surface (side surface in the radial direction) of the piston ring 1. On the other hand, the sliding surface has a triangular pressure distribution because the upper end (the compression chamber 10 side) is Pc and the lower end (the crank chamber 9 side) is the atmosphere.

As a result, a part of the pressure on the sliding surface and the back surface is offset, and the average pressure difference between the sliding surface and the back surface in the region shown in (I) acts as the surface pressure P1.

FIG. 4 shows a cross-sectional shape of the AA part in FIG. As for the abutment of the piston ring 1, the upper abutment 4 and the lower abutment 5 are in contact with each other, and the abutment gap 2 and the abutment gap 3 are blocked. Therefore, there is no flow path that directly leaks from the upper surface to the lower surface of the piston ring 1.

However, as shown in FIG. 4, the abutment gap 3 of the piston ring 1 is open from the rear surface of the piston ring 1 to the atmosphere side (the side of the crank chamber 9), so that a leakage flow path exists, and the width of the abutment gap 3 is increased. When is large, the sealing property is a problem.

Further, when the piston ring 1 is used, since the surface pressure during sliding with the cylinder 8 is high, there has been a problem of extending the replacement life due to wear.

Here, when the piston ring according to Patent Document 1 is used, the wear is not constant, and uneven wear may occur in which wear of a part of the circumference progresses. In this case as well, the degree of opening of the passage changes depending on the location, and a stable passage cannot be formed. Therefore, even if the degree of wear is not great, the sealability of the piston ring may be deteriorated and the seal may not be sufficiently performed.

Further, when the passage is opened due to wear of the piston ring, it gradually opens. Therefore, depending on the shape of the communication hole, the amount of leakage from the opening is small and the back pressure of the piston ring is unlikely to change, so that the compressed fluid may not be able to flow sufficiently from the communication hole. As a result, for example, when a plurality of piston rings are provided, the wear of the piston rings is biased to one piston ring, and the time until the piston rings are replaced cannot be extended.

The reciprocating compressor and piston ring in each embodiment of the present invention will be described below with reference to the drawings.

FIG. 5 is a view showing the structure of the piston ring 21 of this embodiment. In FIG. 5, the piston ring 21 has a step cut shape similar to that of the piston ring 1, and the inner peripheral side and the outer peripheral side (radially inner and outer side surfaces) of the piston communicate with each other in the gaps 22 and 23, respectively. There is. An outer peripheral groove 26 is provided on the outer periphery of the piston ring 21 (sliding surface with the cylinder 8). The case where the outer peripheral groove 26 is located at the center of the height of the piston ring is shown as an example. Here, the height of the piston ring 21 means a direction perpendicular to the circumferential direction and the radial direction of the piston ring 21, and the piston ring thickness of the piston ring 21 means the radial direction.

One end of the outer peripheral groove 26 communicates with a gap 22 provided on the upper side of the piston ring 21 (on the side of the compression chamber 10 of the cylinder 8 ), so that the back surface pressure on the radially inner side of the piston ring 21 or the pressure inside the cylinder 8 is maintained. It is configured so that it can be easily guided to the outer peripheral groove. The outer peripheral groove 26 may be provided with a hole so as to guide the back pressure. The structure in which the holes are provided in this manner is the same in other embodiments described later. Further, the other end of the outer peripheral groove 26 is provided up to the vicinity of the abutment gap 23 provided on the lower side of the piston ring 21 (on the side of the crank chamber 9 in the cylinder 8), but does not communicate with the abutment gap 23. As a result, the compressed air in the compression chamber 10 is guided from the upper joint 22 to the outer peripheral groove 26 without separately processing a communication hole from the rear surface of the piston ring 21. On the other hand, since the opposite side of the outer peripheral groove 26 does not communicate with the lower joint 23, it is possible to prevent the fluid in the outer peripheral groove from leaking and degrading the performance. Further, on the inner circumference of the piston ring 21, there is provided a seal ring 27 as a blocking member for blocking the inner circumference side and the outer circumference side (radially inside and outside) of the piston ring 21. The seal ring 27 is formed of a ring-shaped plate that expands and contracts to follow the piston ring 21. The seal ring 27 is in contact with the inner peripheral surface of the piston ring 21 to seal the inside in the radial direction from the gaps 22 and 23. For example, the height of the ring 21 is the same as that of the ring 21, and the inner circumference of the ring 21 is about 1.5 turns. As long as the seal ring 27 can block the gaps 22 and 23 as described with reference to FIG. 7, the material and the number of turns are arbitrary regardless of the above.

Next, FIG. 6 is a diagram for explaining the surface pressure balance of the piston ring 21. In FIG. 6, the pressure Pc in the compression chamber 10 is guided to the outer peripheral groove 26 as described above. Therefore, the pressure distribution on the sliding surface is such that the pressure above the outer peripheral groove 26 acts at a constant Pc, the lower end of the outer peripheral groove 26 is Pc, and the lower end of the piston ring 21 is the atmosphere. In this case, the pressure Pc above the outer peripheral groove 26 and the back surface of the piston ring 21 is balanced. Therefore, the pressure difference between the sliding surface and the back surface occurs only in the area shown by (II). As in the case of FIG. 4, in this embodiment as well, the average pressure difference P2 between the sliding surface and the back surface is the surface pressure of the sliding surface in this embodiment. The relationship between the surface pressure P2 of the sliding surface of this embodiment and the surface pressure P1 of the sliding surface shown in FIG. 4 is P2<P1, and the surface pressure can be reduced by this embodiment. In FIG. 6, the height of the lower end of the outer peripheral groove 26 is half the height of the piston ring 21. In this case, the upper half of the piston ring 21 has no pressure difference between the back surface side and the sliding surface side. Therefore, it is understood that P2=P1/2 and the surface pressure can be reduced to 1/2. Further, the position of the outer peripheral groove 26 is not limited to the above, but by providing it further below in the height direction of the piston ring, the region shown in (II) becomes smaller and the surface pressure of the sliding surface is reduced. It can be further reduced.

Next, FIG. 7 shows that the seal ring 27 blocks the flow path between the radially inner side and the outer side of the piston ring 21. As described above, the seal ring 27 is provided inside the piston ring 21 in the radial direction at the positions where the gaps 22 and 23 are provided, and blocks the flow passage between the radial inside and the outside of the piston ring 21 to close the piston ring 21. The sealing performance of 21 is improved. In particular, it has a stable sealing property until the piston ring 21 reaches the limit wear.

The state of wear of the piston ring 21 when the piston ring 21 in this embodiment is used will be described with reference to FIG. The broken line schematically shows the wear situation of the conventional piston ring 1, and the time until the limit wear is T0. Here, the limit wear means that the ring sliding surface is worn and the abutment gradually expands, but the initially existing upper abutment 4 (24) and lower abutment 5 (25) do not overlap, and the two abutment gaps 2 ( 22) and 3(23) overlap each other in the circumferential direction and communicate with each other, that is, the amount of wear when the leakage flow path from the top to the bottom of the joint opens. On the other hand, the surface pressure of the piston ring 21 in the present embodiment is lower than that of the conventional piston ring 1, so that the piston ring 21 is less worn and the time until the limit wear is extended to T1.

An example of extending the life by using two piston rings of this embodiment will be described with reference to FIGS. 9 and 10.

FIG. 9 shows a case where the piston 33 is provided with two piston rings 31. The first piston ring 31-1 is attached to the upper side (compression chamber 10 side) and the second piston ring 31-2 is attached to the lower side (crank chamber 9 side). The first piston ring 31-1 and the second piston ring 31-2 have step cut shapes, and the seal ring 27 is provided on the inner side in the radial direction. The same as 21. The two piston rings 31 do not have to have the same sealing property. For example, when the sealability of the first piston ring 31-1 (the amount of fluid leakage per pressure difference) is better than that of the second piston ring 31-2, the land 35 and the second piston ring 31-2 are The pressure Pm on the back surface 36 becomes close to the pressure on the crank chamber 9 side (for example, atmospheric pressure). That is, only the first piston ring 31-1 seals and compresses between the back surface 34 and the land 35, and the first piston ring 31-1 wears more than the second piston ring 31-2. When the first piston ring 31-1 is worn to the limit wear, the overlapping portion of the upper joint 37 and the lower joint 38 of the first piston ring 31-1 starts to disappear as shown in FIG. When the overlapping portion of the upper joint 37 and the lower joint 38 completely disappears, a leak flow path opens between the upper surface and the lower surface of the first piston ring 31-1. On the other hand, since the second piston ring 31-2 is less worn, the upper joint 39 and the lower joint 40 are overlapped with each other, and there is no leakage flow path opening from top to bottom.

The pressure states on the back surfaces of the first piston ring 31-1 and the second piston ring 31-2 at this time will be described with reference to FIG. 9. Since the joint of the first piston ring 31-1 is open, the pressure on the back surface 34 of the first piston ring 31-1, the land 35, and the back surface 36 of the second piston ring 31-2 is Pm=Pc. As a result, the pressure difference between the upper side and the lower side of the first piston ring 31-1 is eliminated, and the first piston ring 31-1 is not worn any more. On the other hand, the second piston ring 31-2 receives the pressure of the compression chamber 10 after the first piston ring 31-1 reaches the limit wear and seals between the compression chamber 10 and the crank chamber 9, The surface pressure between No. 8 and No. 8 increases, and wear gradually occurs.

The wear condition of the two rings in this case will be described with reference to FIG.

FIG. 11 shows a case where the first piston ring 31-1 initially receives a pressure difference between the upper and lower sides. It is shown that the first piston ring 31-1 has much wear until it reaches the limit wear. When the first piston ring 31-1 reaches the limit wear in T1 time, the ring seal moves to the second piston ring 31-2, and thereafter, the first piston ring 31-1 does not wear and the second piston ring 31-1 does not wear. Only the ring 31-2 will wear. The time T2 when the second piston ring 31-2 reaches the limit wear is the life until the two piston rings are replaced.

The life when one piston ring 21 of this embodiment is used is similar to the wear of the first piston ring 31-1, so the life when one piston ring 21 is used is time T1. When two piston rings are used, even if one piston ring (first piston ring 31-1) reaches the limit wear, it is used as it is, and the life until all the piston rings reach the limit wear is from T1 to T2. Will be extended to. Further, when three piston rings 21 are provided as shown in FIG. 12, the life can be further extended.

Up to now, it was described that the first piston ring 31-1 seals first and wear progresses, but first, even if the second piston ring 31-2 receives a large surface pressure and wear progresses, The same transition and effect are produced only by changing the order of piston rings that reach the limit wear.

Another effect of using a plurality of piston rings of this embodiment will be described below.

In the piston ring of this embodiment, when the limit wear is reached, the abutment opens rapidly in the thickness direction of the ring. Therefore, the pressure difference applied to the upper surface and the lower surface can be instantaneously transferred from the first piston ring 31-1 to the second piston ring 31-2.

As a result, even if the first piston ring 31-1 is used until the limit wear, the pressure difference between the upper and lower sides of the first piston ring 31-1 and the surface pressure applied to the sliding surface are instantaneously eliminated thereafter. After the piston ring 31-1 reaches the limit wear, it does not wear.

When the piston ring is worn, the abutment gaps 22 and 23 are opened, and the upper abutment 24 is deformed by receiving the pressure from the compression chamber 10 into the abutment gap 23. At this time, the abutment of the present embodiment has a step-cut shape and the thickness in the radial direction does not become thin. Therefore, even when the upper abutment 24 is deformed to fall into the abutment gap 23, the abutment can maintain its strength until just before the abutment is opened. Further, the strength of the abutment can be further maintained by making the thickness of the upper abutment 24 larger than that of the lower abutment 25. As a result, it becomes possible to use the plurality of piston rings until they reach the limit wear, and the replacement life can be extended.

Further, when a plurality of piston rings (first piston ring 31-1 and second piston ring 31-2) are used, at least one piston ring (first piston ring 31-1) is the limit. If the remaining at least one piston ring (second piston ring 31-2) does not reach the limit wear after reaching the wear, all remaining piston rings (the second piston ring 31-2) reach the limit. The compressor can continue to be used until wear is reached. As a result, the replacement life of the piston ring can be extended as compared with replacement when any one of the piston rings has reached the limit wear.

The first piston ring 31-1 and the second piston ring 31-2 of the first embodiment are sealed by a seal ring 27. The outer peripheral surface of the seal ring 27 and the inner peripheral surfaces of the first piston ring 31-1 and the second piston ring 31-2, which are in contact with the seal ring 27, may not always have the same shape. In this case, a minute gap may occur between the outer peripheral surface of the seal ring 27 and the inner peripheral surfaces of the first piston ring 31-1 and the second piston ring 31-2, which may cause leakage therethrough. ..

Therefore, the present embodiment shows a structure in which the pressure difference applied to the upper surface and the lower surface of the piston ring is reliably transferred from the first piston ring to the second piston ring when the wear progresses while ensuring the sealing of the abutment. ..

The piston ring of this embodiment will be described with reference to FIG. 13A and 13B, the upper surface and the lower surface of the piston ring 41 are shown in reverse so that the lower surface of the piston ring 41 can be easily seen. The piston ring 41 of the present embodiment has a gap 42 on the compression chamber 10 side (upper surface) and has the same step cut shape as that of the first embodiment. On the crank chamber 9 side (lower surface), the inner peripheral side lip 45 is in contact with the outer peripheral side lip receiving surface 46 in a lip cut shape having a lip 45 in which the inner peripheral side and the outer peripheral side overlap. By doing so, the structure is such that the leakage of the compressed fluid from the abutment gaps 43 to 44 formed by making cuts on the radially outer side and the inner side of the lower surface of the piston ring 41 is reduced. The abutment gap 43 communicates with the outer peripheral side (radial direction outer side) of the piston ring 41, and the abutment gap 44 communicates with the inner peripheral side (radial direction inner side) of the piston ring 41.

In the structure of the present embodiment, the piston ring 41 is sealed by the lip 45, but the lip 45 may be damaged if it is used to its limit because the cross section of the abutment is small. Therefore, as shown in FIG. 13(B), when the wear of the ring progresses, even if the lip 45 and the lip receiving surface 46 of the abutment are left overlapping with each other, the lip support is opened from the back surface of the ring to the abutment gap 43. A groove 47 having a length L is provided on the surface 46.

It should be noted that the groove 47 may be provided in the lip 45, and in that case, the groove 47 does not open to the abutment gap 43 but to the abutment gap 44.

Also in the present embodiment, by providing a plurality of piston rings 41 as in the first embodiment, it is possible to transfer the pressure difference applied to the upper surface and the lower surface of the piston ring 41 when the limit wear is reached while maintaining the sealing performance, The life can be extended as in the first embodiment.

As another embodiment, if there is a margin in sealing performance, a combination of the piston ring 21 having only the step cut shape shown in FIGS. 4 and 5 and the piston ring 41 having the step cut shape and the lip cut shape shown in FIG. 13 may be used. It is possible. In this case, there is no difference in effect regardless of which ring is provided on the top, and the life can be extended. It goes without saying that the outer circumference of the piston ring 21 (41) is provided with the outer peripheral groove 26 communicating with the upper joint 24 (37, 39) to extend the life.

In the present embodiment, an example will be described in which the life and the life of the lidar ring 50 are extended by using different materials and structures for compressing dry gas. The same components as those in Embodiments 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted.

In the piston 7 of FIG. 14, the rider ring 50 is mounted in a ring groove formed on the lower side of the piston ring 1 (on the side of the crank chamber 9 in the cylinder 8).

The rider ring 50 receives the lateral pressure in the load direction at the time of compression generated between the piston 7 and the cylinder 8 when the piston 7 reciprocates. The rider ring 50 is wound around the side surface of the piston 7 in a band shape and prevents the piston 7 and the cylinder 8 from coming into contact with each other. The rider ring 50 has a ring shape with an abutment.

In this embodiment, as shown in FIG. 14, an example in which one piston ring 1 (21) is used will be described. However, as shown in FIGS. 9 and 10, a plurality of piston rings 31-1 and 31-2 are used. May be.

Here, when the atmosphere is compressed by using the piston base material piston ring and the rider ring, the PTFE transfer film is generated on the sliding surface of the mating material (cylinder), and the PTFE material slides with each other to form the piston ring and the rider ring. It is known that wear of the steel is suppressed and a long life can be achieved.

On the other hand, if an inert dry gas such as nitrogen gas is compressed with the same structure, a transfer film will not be formed on the mating (cylinder) sliding surface and abnormal wear of the piston ring and rider ring (20 to 30 times that of atmospheric compression) Cause This is because the transfer strength of the PTFE transfer film is reduced by the inert dry gas and the transfer film does not remain on the sliding surface so that the PTFE particles do not slide with each other. When compressing the nitrogen gas, the piston ring in contact with the gas in the cylinder slides in the nitrogen gas, but since the gas leaking from the piston ring flows out toward the sliding surface of the rider ring, The rider ring also slides in nitrogen gas. When compressing nitrogen gas, extending the life of not only the piston ring but also the rider ring becomes an issue.

Here, according to Patent Document 2 (JP-A-2014-214672), a phenol resin, an epoxy resin or the like containing an oxygen atom-containing functional group having high transfer strength may be provided near the PTFE-based sliding material. Have been described. That is, there is described a technique of reducing the abrasion of PTFE by using a resin transfer film having high transfer strength as a substitute for the PTFE transfer film. Specifically, a structure is shown in which a rider ring is formed of a phenol resin, an epoxy resin, or the like containing an oxygen atom-containing functional group to reduce wear of a piston ring formed of PTFE.

However, if the rider ring made of phenolic resin, epoxy resin, etc. containing an oxygen atom-containing functional group is separated from the piston ring and the transfer film is not formed sufficiently to the position where the piston ring slides, When the pressure is high and the surface pressure is high, the wear of the piston ring cannot be suppressed.

Here, if attention is paid only to the extension of the life of the piston ring and the rider ring, the piston ring and the rider ring may be formed of a phenol resin, an epoxy resin or the like containing an oxygen atom-containing functional group having high transfer strength.

However, since these resins have high hardness and low flexibility, in consideration of the assembling to the piston 7, the structure of the piston ring 48 having two abutments in the two-part structure as shown in FIG. 15 cannot be avoided. Absent. Therefore, if the abutment is straight, even if the seal ring 27 is used on the inside of the piston ring, a leak passage can be formed that passes downward from above the abutment of the piston ring 48. As a result, leakage from the abutment cannot be reduced, and performance deterioration becomes a problem.

It is also conceivable that the piston ring has a two-divided structure, and that both ends have step-cut shaped abutments as shown in FIG. In this case, however, the hardness is high unlike the PTFE-based ring (there is one abutment) having flexibility as shown in FIG. Therefore, even if the abutment is formed into a step cut shape, for example, a leak passage is generated due to a processing dimension error in the height direction of the abutment.

On the other hand, if the piston ring is made of PTFE, since it has flexibility, even if a gap due to a processing dimension error in the height direction occurs at the abutment, the abutment is flexibly deformed by the pressure and fills the gap, so that no leak passage is formed.

Therefore, when compressing nitrogen gas, there is a problem with the structure and material of the piston ring and the rider ring, which have less leakage and good compression performance and can extend the life of the piston ring and the rider ring.

The present embodiment proposes structures and materials of the piston ring 21 and the rider ring 50 that solve the above problems. In this embodiment, the piston ring 21 is made of a PTFE material and the rider ring 50 is made of a material harder than the piston ring 21.

FIG. 16 shows an example of a rider ring 50 made of a material harder than PTFE, such as phenol resin or epoxy resin containing an oxygen atom-containing functional group.

FIG. 16A shows a plan view (upper stage) and a side view (lower stage) in a state where the two abutment gaps a in the initial state of the rider ring 50 are even. Further, FIG. 16B shows the relationship between the initial thickness of the rider ring 50 and the limit wear amount when assembled to the piston 7.

The rider ring 50 of this embodiment has a two-part structure in which a cylinder is divided into two parts. The rider ring 50 is for the purpose of maintaining the posture of the piston and preventing the contact between the piston 7 and the cylinder 8 under the condition of receiving the lateral pressure during the operation of the compressor, and is not for the purpose of sealing the compressed gas. Therefore, even if the joint is straight, there is no functional problem.

As a result, the rider ring 50 is a transfer film having a high transfer strength, which is obtained from material properties such as phenol resin and epoxy resin containing an oxygen atom-containing functional group, and wear can be reduced, and long life can be obtained. On the other hand, since the piston ring 21 is made of a PTFE-based material with the structure in which the surface pressure is reduced as shown in the first embodiment, a long life can be obtained without relying on the material due to the above-mentioned effect. In addition, since it is made of a flexible PTFE-based resin and has a single abutment, it is flexible, and leakage due to dimensional errors in the abutment is reduced, and a high-performance compressor having excellent sealing properties can be obtained.

According to the present embodiment, the rider ring 50 is made of a material such as phenol resin or epoxy resin containing an oxygen atom-containing functional group, and the piston ring 21 is a PTFE ring having the structure shown in the first and second embodiments. As a result, it is possible to obtain a high-performance compressor that is excellent in the life of the piston ring 21 and the rider ring 50 and in the sealing property.

It should be noted that the rider ring 50 may be made of a PTFE-based material by reducing the surface pressure with the structure shown in the first embodiment like the piston ring 21. However, since the rider ring 50 has a structure that mechanically receives the lateral pressure of the cylinder 8, it cannot be designed in consideration of the same surface pressure balance as that of the piston ring 1 described in the first embodiment. Therefore, for example, when the surface pressure is set to 1/2, the area needs to be doubled. Therefore, the rider ring 50 becomes large, the piston 7 and the cylinder 8 that receives the sliding movement of the piston 7 also become large, and as a result, the compressor becomes very large. Therefore, the cost is increased and the vibration of the compressor is increased (since the piston 7 becomes larger, the reciprocating inertial force is increased and the vibration due to the unbalance force is increased). Thus, using a material such as a phenol resin or an epoxy resin containing an oxygen atom-containing functional group is a comprehensively superior compressor.

Further, the combination of materials having these effects is as follows in terms of hardness (Shore hardness (D)). The piston ring 21 (PTFE ring) has flexibility and preferably has a hardness of 40 or less in order to maintain the sealing performance. The rider ring 50 is preferably thin and has a hardness of 55 or more in order to have strength.

On the other hand, when the hardness of the piston ring 21 is 40 or more, the flexibility is lacking, the leakage of the abutment increases, and it becomes difficult to open the integrated ring having a single abutment and mount it on the piston 7. Further, when the hardness of the rider ring 50 is 55 or less, wear and increase in strength cause a problem such as cracking during assembly.

In this embodiment, the structure of the two-divided rider ring 50 will be described. The same components as those in Embodiment 1-3 are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, as shown in FIG. 14, an example in which one piston ring 1 (21) is used will be described. However, as shown in FIGS. 9 and 10, a plurality of piston rings 31-1 and 31-2 are used. May be.

In the rider ring 50 shown in FIG. 16A, when the contact surface with the cylinder 8 (the outer peripheral surface of the rider ring 50) is worn during operation, the abutment gradually expands. FIG. 17 shows the rider ring 50 when the rider ring 50 is worn to the limit wear amount, one of the two abutments contacts, and the other abutment opens. Further, the rider ring 50 has a two-part structure, and when one of the abutments comes into contact, the gap of the other abutment becomes the maximum. At this time, a gap between the contacting abutment and the opposite abutment is defined as a′ (FIG. 17). Let δ (shown in FIG. 16B) be the limit wear amount of the rider ring 50 that must be replaced before the contact between the piston 7 and the cylinder 8 begins. In addition, the initial abutment gap when the two abutment gaps have the same size is a (shown in FIG. 16A), and the total of the two abutment gaps is A. At this time, 2×a=A holds. The gap a'at the abutment on the opposite side to the abutment contacted at the time of limit wear is a'=A+2×δ×π (1)
Becomes

The limit wear amount δ of the rider ring 50 is smaller than the difference between the radial thickness of the rider ring 50 and the depth of the groove of the piston 7 in which the rider ring 50 is mounted.

The rider ring 50 is uniformly worn by rotating in the groove during operation of the compressor. However, when one abutment is in contact and the other abutment is completely open (no overlap), the abutment open position (abutment a′) and the load direction of piston 7 (piston 7 crank part). If the directions of the rotational force of 18 act), the piston 7 will enter the position where the abutment is opened. If the piston 7 gets into the position where the abutment is opened, the rider ring 50 will stop under load and will not move. As a result, partial wear occurs without uniform wear, and the life of contact between the piston 7 and the cylinder 8 is shortened.

FIGS. 18A and 18B show the structure of the rider ring 50 in which the opposite abutment is not completely opened even when one of the abutments comes into contact, separately for the initial stage and the limit wear. FIG. 18A shows a plan view and a side view of the initial rider ring 50, and FIG. 18B shows a plan view and a side view of the rider ring 50 at the time of limit wear. The initial rider ring 50 shown in FIG. 18A is in a state where the two gap openings are a. The rider ring 50 at the time of critical wear shown in FIG. 18B is opened so that one abutment (view C) contacts and the other abutment (view D) forms a gap a′.

In the rider ring 50 shown in FIGS. 18A and 18B, even if one of the abutments is brought into contact with each other at the time of limit wear, a vertical gap that is continuous in the vertical direction does not occur at the abutment on the opposite side. As a result, even if the opposite side of the contacting abutment matches the load direction of the compressor, the piston 7 does not enter the abutment gap of the rider ring 50, and the movement of the rider ring 50 in the rotational direction does not stop.

To obtain this state, the circumferential length of the step portion (the maximum length of the portion where the upper and lower abutments overlap) with respect to the abutment gap a′ on the opposite side to the contacted abutment B (in FIG. 18B) The length shown in the side view in the direction of the arrow D) must be long.

That is, by constructing the circumferential length B of the step portion of the abutment of the rider ring so as to satisfy the following equation (2), no vertical gap is created at the abutment.

B>A+2×δ×π (2)
As a result, uniform wear occurs during use of the rider ring 50, and it is possible to prevent irregular reduction in life.

In this embodiment, a structure will be described in which the rider ring 50 divided into two parts can be smoothly used even when the wear is limited. The same components as those in the first to fourth embodiments are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, as shown in FIG. 14, an example in which one piston ring 1 (21) is used will be described. However, as shown in FIGS. 9 and 10, a plurality of piston rings 31-1 and 31-2 are used. May be.

The present embodiment relates to a structure in which a vertical gap cannot be formed even when one of the two abutments is in contact and the other abutment is opened, and the rider ring 50 does not stop in the rotational direction.

This structure and effect will be described with reference to FIGS. 19A and 19B.

The abutment of the rider ring 52 of FIG. 19A is inclined with respect to the axial direction (the direction in which the piston 7 reciprocates), and is provided so as to intersect with each other when seen through from the side. FIG. 19B is a developed view of this rider ring.

On the other hand, the shape of the rider ring 53 that does not intersect when seen through from the side is FIG. 20A, and the developed view is FIG. 20B.

In any of the structures, when the circumferential length of the inclined portion of the abutment (the maximum length of the portion where the upper abutment and the lower abutment overlap) B is the dimension represented by the formula (2) shown in Example 4, the limit wear Even when there is no vertical gap.

However, when the rider ring 53 shown in FIGS. 20A and 20B contacts at the joint of the two-divided rider ring 53 during driving, the two joints have the same direction (the direction of the arrow shown in the vertical direction in FIG. 20B). Force acts on. For example, one of the two-divided structures has two abutment gaps in both upward directions, and the other of the two-divided structures has two abutment gaps in both of which downward force acts. Therefore, it is pressed in the ring groove of the piston 7 and becomes difficult to move in the rotational direction. On the other hand, in the case of the rider ring 52 of FIGS. 19A and 19B, a force in the opposite direction (the direction of the arrow shown in the vertical direction in FIG. 19B) acts on the two joints. For example, one of the two-divided structures has two abutment gaps in the upward and downward directions, and the other of the two-divided structures has two abutment gaps in the downward and upward directions. Therefore, it is possible to prevent the piston 7 from being pressed in the ring groove, and prevent it from becoming difficult to move in the rotation direction in the ring groove. As a result, uniform wear occurs during use of the rider ring 52, and it is possible to prevent irregular reduction in life.

1 piston ring 7 piston 8 cylinder 9 crank chamber 10 compression chamber 11 compressor body 15 motor 16 tank 21 piston ring 22 abutment gap 23 abutment gap 24 upper abutment 25 lower abutment 26 outer peripheral groove 27 seal ring 31-1 first piston Ring 31-2 Second piston ring 33 Pistons 34, 36 Rear surface 35 Land 37 First upper abutment 38 First lower abutment 39 Second upper abutment 40 Second lower abutment 41 Piston ring 42 Abutment gap 45 Lip 46 Lip receiving portion 47 Groove 48 Piston rings 50, 51, 52, 53 made of a hard material Rider ring made of a hard material

Claims (16)

A cylinder,
A piston that reciprocates between the crank chamber side and the compression chamber side in the cylinder to compress the gas in the compression chamber,
A piston ring provided in the piston for sealing between the crank chamber side and the compression chamber side in the cylinder,
The piston ring has an upper abutment provided on the compression chamber side and a lower abutment provided on the crank chamber side at different positions in the circumferential direction,
There is an outer peripheral groove on the outer periphery of the piston ring,
One end of the outer circumferential groove is connected to the circumferential gap of the upper abutment, and the other end of the outer circumferential groove is in the circumferential gap of the upper abutment and in the circumferential direction of the lower abutment. A compressor characterized by not being connected to a gap. In the piston ring,
A first communication portion in which the outer peripheral side and the inner peripheral side of the piston ring communicate with each other in the upper joint,
There is a second communication portion in which the outer peripheral side and the inner peripheral side of the piston ring communicate with each other in the lower joint,
The compressor further includes a blocking member that is disposed on an inner peripheral side of the piston ring and blocks communication in the first communication part and blocks communication in the second communication part. The compressor according to Item 1. The compressor according to claim 1, comprising a plurality of the piston rings. The compressor according to claim 1, wherein the lower abutment has a structure in which an inner peripheral surface and an outer peripheral surface of the piston ring overlap each other. Of the plurality of piston rings, in the one lower abutment,
The outer peripheral side and the inner peripheral side of the piston ring communicate with each other, and the inner peripheral surface and the outer peripheral surface of the piston ring overlap each other at the lower joint of the other side. Compressor. The compressor according to claim 3, wherein the compressor continues to be used even after one of the plurality of piston rings reaches a limit wear. The compressor according to claim 2, wherein the blocking member is a ring-shaped plate that contacts an inner peripheral surface of the piston ring. The compressor according to claim 1, further comprising a rider ring that prevents contact between the piston and the cylinder, the rider ring being formed of a material harder than the piston ring. 9. The compressor according to claim 8, wherein the Shore hardness of the piston ring is 40 or less, and the Shore hardness of the rider ring is 55 or more. The compressor according to claim 8, wherein the rider ring has a plurality of abutments and is divided into a plurality of parts by the plurality of abutments. The compressor according to claim 8, wherein the piston ring is made of PTFE as a base material, and the rider ring is a phenol resin or an epoxy resin containing an oxygen atom-containing functional group. A cylinder,
A piston that reciprocates between the crank chamber side and the compression chamber side in the cylinder to compress the gas in the compression chamber,
A piston ring provided in the piston for sealing between the crank chamber side and the compression chamber side in the cylinder,
The piston ring has an upper abutment provided on the compression chamber side and a lower abutment provided on the crank chamber side at different positions in the circumferential direction,
There is an outer peripheral groove on the outer circumference of the piston ring, which communicates with the circumferential gap of the upper joint, and does not communicate with the circumferential gap of the lower joint.
A compressor having a structure in which an inner peripheral surface and an outer peripheral surface of the piston ring are overlapped with each other in the lower abutment, and a groove is provided in a portion where the inner peripheral surface and the outer peripheral surface are overlapped with each other. A cylinder,
A piston that reciprocates between the crank chamber side and the compression chamber side in the cylinder to compress the gas in the compression chamber,
A piston ring provided on the piston for sealing between the crank chamber side and the compression chamber side in the cylinder; and a rider ring for preventing contact between the piston and the cylinder,
The piston ring has an upper abutment provided on the compression chamber side and a lower abutment provided on the crank chamber side at different positions in the circumferential direction,
There is an outer peripheral groove on the outer circumference of the piston ring, which communicates with the circumferential gap of the upper joint, and does not communicate with the circumferential gap of the lower joint.
The rider ring is a harder material than the piston ring,
The rider ring has a plurality of abutments, and is divided into a plurality by the plurality of abutments,
The compressor is characterized in that when the sum of the dimensions of the gaps of the plurality of the abutment of the rider ring is A, the circumferential length of the abutment is B, and the limit wear amount is δ, B>A+2Xδ+π. A cylinder,
A piston that reciprocates between the crank chamber side and the compression chamber side in the cylinder to compress the gas in the compression chamber,
A piston ring provided on the piston for sealing between the crank chamber side and the compression chamber side in the cylinder; and a rider ring for preventing contact between the piston and the cylinder,
The piston ring has an upper abutment provided on the compression chamber side and a lower abutment provided on the crank chamber side at different positions in the circumferential direction,
There is an outer peripheral groove on the outer circumference of the piston ring, which communicates with the circumferential gap of the upper joint, and does not communicate with the circumferential gap of the lower joint.
The rider ring is a harder material than the piston ring,
The rider ring has a plurality of abutments, and is divided into a plurality by the plurality of abutments,
A compressor characterized in that a plurality of the abutments formed in the rider ring are inclined with respect to an axial direction. The compressor according to claim 14, wherein the plurality of abutments formed in the rider ring intersect each other when viewed from a side surface. A cylinder,
A piston capable of reciprocating between the crank chamber side and the compression chamber side in the cylinder, and capable of compressing the gas in the compression chamber,
A piston ring provided in the piston for sealing between the crank chamber side and the compression chamber side in the cylinder,
The piston ring has an upper abutment on the compression chamber side and a lower abutment on the crank chamber side at different positions in the circumferential direction,
There is an outer peripheral groove on the outer periphery of the piston ring that communicates with the circumferential gap of the upper joint and does not communicate with the circumferential gap of the lower joint, and the height of the lower end of the outer peripheral groove is the height of the piston ring. A compressor characterized in that it is located at or below the center of the sea.

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