JP6219971B2 - Piston ring and compressor using the same - Google Patents

Description

  The present invention relates to a piston ring and a compressor using the same, and more particularly to a compressor in which wear is reduced without reducing the performance of the piston ring.

As a background art in this technical field, there is Japanese Utility Model Publication No. 1-7888 (Patent Document 1). This publication describes a structure in which a lip structure is provided below a piston ring joint portion of a piston ring used in an oil-free fluid compressor to prevent fluid leakage at the piston ring joint portion.
In Japanese Utility Model Publication No. 59-21067 (Patent Document 2), a circumferential groove is provided on the outer peripheral surface of the piston ring in order to prevent wear of the piston ring for the internal combustion engine. A technique for balancing the surface pressure by providing a hole for guiding pressure in the groove is shown.

No. 1-7888 Japanese Utility Model Publication No.59-21067

  Patent Document 1 does not describe a structure that balances the sliding surface pressure of the piston ring, and it is a problem to reduce wear of the piston ring.

  Further, Patent Document 2 does not describe what kind of shape the joint portion of the piston ring is and how the circumferential groove is provided to the joint portion. FIG. 32 shows a configuration example of a piston ring of a general internal combustion engine. As shown in FIG. 32, a piston ring for an internal combustion engine is generally made of metal such as cast iron, and the joint shape is a straight joint 72 (FIG. 32a) or an oblique angle cut joint 73 (FIG. 32b). However, since the cylinder and the ring are the same type of metal, the difference in thermal expansion is small, and the abutment gap can be set to several tens of microns. In addition, since it is for an internal combustion engine, oil is present around the piston ring, and as a result, the leakage in the vicinity of the joint including the joint is not so large, and the shape of the joint does not affect the performance. Therefore, it is considered that details of the joint portion of the piston ring are not described. However, especially when used in an oil-free compressor, since the piston ring is made of resin, a joint width of several millimeters, that is, an internal combustion engine is used to prevent the piston ring from being stretched at the operating temperature. The piston ring joint width of the engine is several tens of times, and it is necessary to reduce leakage at the joint part. The state of the joint portion of the piston ring used in the reciprocating oilless compressor corresponding to FIG. 32 is schematically shown by a and b in FIG. As shown in FIG. 33, the joints 76 and 77 in FIG. 33 are larger than the joints 72 and 73 in FIG. Note that the same relationship applies to the step shape (step cut) joint shown in FIG. Therefore, in the case of a reciprocating oilless compressor, it is a problem to form a circumferential groove on the outer peripheral surface of the stone ring after reducing leakage at the joint portion.

  In view of the above problems, an object of the present invention is to provide a compressor in which wear is reduced without causing performance degradation due to leakage from a piston ring joint portion.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. The present invention includes a plurality of means for solving the above-described problems. For example, a cylinder, a piston, and a seal between a pressure side and a non-pressure side in the cylinder are attached to the piston. A compressor including a piston ring and generating a compressed fluid by compressing a fluid in a cylinder with a piston, wherein the piston ring overlaps with a step shape in a piston ring height direction at a joint portion thereof. A second abutment portion that overlaps with the lip shape in the radial direction of the piston ring is provided, and an end portion of the first abutment portion includes a first abutment groove that communicates an inner periphery and an outer periphery of the piston ring. The second abutting portion has a second abutting groove on the non-pressurizing side, and the end portion of the second abutting portion overlaps the lip shape so that the inner periphery and the outer periphery of the piston ring are not in communication with each other. First The circumferential groove does not communicate with the communicating mouth groove said second abutment groove and a compressor provided in the piston ring outer periphery.

  ADVANTAGE OF THE INVENTION According to this invention, the compressor which can aim at the abrasion reduction of a piston ring sliding surface can be provided, without producing a performance fall.

It is a figure which shows schematic structure of a reciprocating compressor. It is a figure which shows the cross-sectional shape by which the piston ring was mounted | worn with the conventional piston. It is a figure which shows the general joint shape (step cut) of a piston ring. It is the figure which showed the AA cross section of FIG. It is the top view and side view of the piston ring which provided the conventional lip shape. It is the piston ring perspective view which looked at FIG. 5 from the inner diameter side. It is a figure which shows a mode that the conventional lip | rip part seals. It is a figure which shows a mode that the sliding surface of the conventional piston ring outer periphery was worn out. It is the figure which showed the BB cross section of FIG. It is the figure which showed CC cross section of FIG. It is the figure which showed the DD cross section of FIG. It is a figure explaining the surface pressure balance of the conventional piston ring. It is a figure which shows the structure of the piston ring in Example 1. FIG. It is a figure explaining the surface pressure balance by the circumferential groove in Example 1. FIG. It is a figure which shows the structure of the piston ring in Example 2. FIG. It is a figure which shows the structure of the piston ring in Example 2. FIG. It is a figure which shows the structure of the piston ring in Example 3. FIG. It is a figure which shows the structure of the piston ring in Example 4. FIG. It is a figure which shows the structure of the piston ring in Example 5. FIG. It is a figure which shows the structure of the piston ring in Example 6. FIG. It is a figure which shows the structure of the piston ring in Example 7. FIG. It is a figure which shows the structure of the piston ring in Example 8. FIG. It is a figure which shows the structure of the piston ring in Example 9. FIG. It is a figure which shows the structure of the piston ring in Example 10. FIG. It is a figure which shows the structure of the piston ring in Example 10. FIG. It is a figure which shows the structure of the piston ring in Example 10. FIG. It is a figure which shows the structure of the piston ring in Example 11. FIG. It is a figure which shows the state of the piston which assembled | attached the piston ring in the cylinder in Example 12. FIG. It is a figure which shows the relative positional relationship of the two piston rings assembled | attached to the piston in Example 12. FIG. It is a fragmentary sectional view of the piston ring of FIG. It is a figure which shows the structure of the piston ring in Example 12. FIG. It is a figure which shows the structural example of the piston ring of an internal combustion engine. It is a figure which shows the structural example of the piston ring for oil-free reciprocating compressors. It is a figure which shows the structural example which processes the circumferential groove depth of the piston ring in Example 13 accurately.

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

  FIG. 1 is a diagram showing a schematic structure of a reciprocating compressor. 1A is an overall configuration diagram, and FIG. 1B is an enlarged view of a compressor body. In FIG. 1, a motor 2 and a compressor body 3 are arranged on a tank 1, a compressor pulley 5 is rotated by a belt 4 attached to a motor pulley (not shown), and rotation of a crankshaft 6 is reciprocated by a connecting rod 7. After the piston 8 reciprocates, the air compressed from the suction silencer 11 flows into the tank 1 from the compressor main body discharge port 12 through a pipe (not shown). Here, the piston ring 9 attached to the piston 8 has a function of sealing between the pressure side and the non-pressure side in the cylinder. Further, since the compressor body is compressed without lubrication in the case of an oil-free reciprocating compressor, the piston ring 9 and the rider ring 10 are made of a resin such as tetrafluoroethylene resin.

  FIG. 2 is a view showing a cross-sectional shape of the piston 8 with the piston ring 9 attached thereto. In the case of an oil-free compressor, the piston ring 9 is made of ethylene tetrafluoride resin or the like, so that the ring has no elasticity unlike an oil-supplied metal ring. Therefore, a back clearance is provided on the inner diameter side of the piston ring 9, and the pressure in the cylinder Pc is guided to the back surface of the piston ring 9 from the piston ring top clearance, so that the piston ring 9 is pressed against the inner surface of the cylinder 13. The structure prevents leakage between the ring 9 and the cylinder 13 sliding surface.

  On the other hand, the piston ring 9 has an integral shape cut at the joint portion, and can be assembled to the piston by the presence of the joint portion. Moreover, the structure of the abutment portion has been devised so as not to leak from the abutment portion during compression. The most common abutment shape is the abutment portions 14 and 15 of the step shape (step cut) shown in FIG. In this case, there is no leakage passage that directly goes out from above, but the AA cross section of FIG. 3 passes through the lower part of the joint from the back as shown in FIG. 4 to form a leakage passage, and the leakage shown by the arrow in the drawing occurs. Therefore, performance degradation is a problem.

  On the other hand, as shown in FIGS. 5 and 6, there is a piston ring in which leakage is reduced by providing a lip shape at the joint portion on the lower side of the piston ring (see, for example, Patent Document 1). That is, in FIG. 5, FIG. 5 (A) shows the surface which becomes the lower side (non-pressurization side in the cylinder) when the piston ring is assembled, and also shows the shape of the joint portion on the side surface of the piston ring. FIG. 5B similarly shows a surface on the upper side (pressure side in the cylinder). Hereinafter, the upper side and the lower side indicate the pressure side or the non-pressure side in the cylinder when the piston ring is assembled to the piston. As for this piston ring, the upper abutment part has a step shape as shown in FIG. 5 (B), and the lower side has a lip shape as shown in FIG. 5 (A). FIG. 6 is a perspective view of a lip joint part which is a lower joint part and a step-shaped joint part which is an upper joint part from the lower inner diameter side. As shown in FIGS. 5 and 6, the lip abutment portion is composed of a radially inner lip 21 and an outer lip receiving portion 22 of the piston ring.

  FIG. 7 shows a state in which the lip 21 receives pressure from the inner diameter side and contacts and seals the lip receiving portion 22. FIG. 8 shows a state in which the sliding surface with the cylinder on the outer periphery of the piston ring is worn by δ and the abutment portion 25 is expanded to the limit. The piston ring outer periphery wear amount at this time is the limit wear amount δ (that is, the wear amount when the joint is separated).

  FIGS. 9 to 11 show cross sections BB to DD in FIG. 7, and a leakage passage is generated from the back surface of the piston ring from any joint portion of the piston ring with respect to the piston ring joint shown in FIG. Indicates that it is not. That is, FIG. 9 shows a BB cross section of FIG. FIG. 10 shows a CC cross section of FIG. 7 and is sealed by the lip 21 and the lip receiving portion 22. FIG. 11 shows a DD cross section of FIG. 7, which is also sealed by the lip 21 and the lip receiving portion 22.

  The lip shape of the piston ring is such that the lip tip 21a is thinner than the lip root 21b as shown in FIG. As a result, when the outer periphery of the piston ring 9 is worn and the joint is widened, the lip tip 21a is easily deformed so that the lip tip 21a comes into contact with the lip receiving portion 22 to obtain a sealing property. .

  Next, the surface pressure balance of the piston ring will be described with reference to FIG. FIG. 12 shows the pressure balance of the piston ring when there is no conventional circumferential groove. A cylinder internal pressure Pc acts on the back surface of the piston ring 9. On the other hand, since the piston ring sliding surface has an in-cylinder pressure Pc at its upper end and atmospheric pressure at its lower end, the pressure distribution on the sliding surface is a triangular pressure distribution as shown in the figure. As a result, the average pressure P1 of the piston ring sliding surface is a value obtained by dividing the pressure in the region I by the sliding surface. In this case, P1 = Pc / 2. Therefore, if the surface pressure against the sliding surface is large, the wear of the sliding surface also increases, so how to reduce the surface pressure against the sliding surface has been a problem.

  In this way, by using a piston ring having a lip shape at the joint portion as shown in FIGS. 5 and 6, leakage from the joint portion of the piston ring can be prevented. The challenge was to reduce the pressure and reduce the wear on the sliding surface of the piston ring.

  Embodiments of the present invention for solving the above problems will be described below with reference to the drawings.

  FIG. 13 is a view showing the structure of the piston ring 30 of this embodiment. In FIG. 13, the piston ring 30 is provided with a circumferential groove 33 on the outer periphery (sliding surface with the cylinder) of the piston ring. The case where the circumferential groove 33 is located at the center of the piston ring height is shown as an example. Here, the piston ring height refers to the direction parallel to the sliding surface of the piston ring with the cylinder, and the radial direction of the piston ring is referred to as the piston ring thickness.

  The right end of the circumferential groove 33 in the drawing communicates with the upper abutment groove 34 on the upper side of the piston ring (pressure side in the cylinder) so that the piston ring back pressure or the pressure in the cylinder can be easily guided to the circumferential groove. It is configured. In addition, you may comprise so that a back surface pressure may be guide | induced by providing a hole in the circumferential groove 33. FIG. The structure in which the holes are provided in this manner is the same in the other embodiments described below. Further, the opposite end (left side in the figure) of the circumferential groove 33 is provided up to the vicinity of the lower abutment groove 35 on the lip receiving portion 32 side of the piston ring, but does not communicate with the lower abutment groove 35. . As a result, the compressed air in the cylinder is guided from the upper abutment groove 34 to the circumferential groove 33 without processing a separate communication hole from the back surface of the piston ring. On the other hand, since the opposite side of the circumferential groove 33 does not communicate with the lower abutment groove 35, it is possible to prevent the air in the circumferential groove from leaking and the performance from deteriorating.

  Next, FIG. 14 is a view for explaining the surface pressure balance by the circumferential groove 33. In FIG. 14, the cylinder internal pressure Pc is guided to the circumferential groove 33 as described above. Accordingly, the pressure above the circumferential groove 33 acts as a sliding surface pressure distribution in which Pc is constant, the lower end of the groove is Pc, and the lower end of the piston ring is the atmosphere. In this case, the pressure Pc on the upper side of the circumferential groove 33 and the back surface of the piston ring is balanced. Therefore, the value P2 obtained by dividing the pressure in the region II by the sliding surface is the sliding surface pressure of the present embodiment, and the relationship with the conventional sliding surface pressure P1 shown in FIG. 12 is P2 <P1, This embodiment can reduce the surface pressure. FIG. 14 is written so that the lower end of the circumferential groove is ½ of the height of the piston ring. In this case, it can be seen that P2 = P1 / 2 and the surface pressure can be reduced to ½.

  Here, the circumferential groove 33 is configured as a groove (rectangular shape) having a constant width in the depth direction. For this reason, even if the outer periphery of the ring is worn, the width of the circumferential groove 33 is kept constant, so that the surface pressure can be stably balanced above the circumferential groove 33.

  As described above, according to this embodiment, the piston ring is provided with a circumferential groove that avoids the joint portion, and the piston ring sliding surface is provided by balancing the surface pressure of the piston ring without causing performance degradation due to leakage at the joint portion. It becomes possible to reduce the wear of the.

  Further, as shown in FIG. 13, the shape of the joint portion of the piston ring 30 of the present embodiment is that the lip tip 31a and the lip root 31b have substantially the same dimensions, and the respective contact surfaces are configured to be substantially concentric circles. . As a result, when the outer periphery of the piston ring 30 is worn and the lower abutment groove 35 widens, the lip 31 and the lip receiving portion 32 are substantially concentric, so that the lip 31 does not have to be deformed and sealed, and the lip 31 It is only necessary to slide and move the back surface of the receiving portion 32. Since the contact is a line contact with respect to the point contact as in the conventional structure, the contact length is long, and even if the lip tip 31a is thick, the sealing performance of the joint portion is easily obtained. It has the characteristics.

  Further, by increasing the thickness of the lip tip 31a, the strength in the vicinity of the lip tip can be improved even when the piston ring is worn and the joint is opened as shown in FIG.

  As described above, in this embodiment, the piston ring has a lip in the radial direction of the piston ring, the first lip portion (step shape lip portion) overlapping the step shape in the piston ring height direction at the lip portion in the piston ring. A second abutment portion (lip abutment portion) that overlaps in shape is provided, and an end portion of the first abutment portion has a first abutment groove (upper abutment groove 34) that communicates in and out in the radial direction of the piston ring. The end of the second abutment portion has a second abutment groove (lower abutment groove 35) that is not communicated inside and outside in the radial direction of the piston ring by overlapping the lip shape. A circumferential groove that communicates with the groove and does not communicate with the second joint groove is provided on the outer periphery of the piston ring. In other words, the circumferential groove is configured such that one end communicates with the first abutment groove and the other end is formed up to the front of the second abutment groove. Alternatively, the circumferential groove is provided on the outer periphery of the piston ring while avoiding the second joint groove.

In addition, this embodiment includes, as a compressor, a cylinder, a piston, and a piston ring that is attached to the piston and seals between a pressure side and a non-pressure side in the cylinder. A compressor that generates a compressed fluid by compressing, wherein the piston ring has a lip shape in a radial direction of the piston ring, and a first lip portion overlapping in a step shape in the piston ring height direction at the lip portion. And the end of the first abutment portion has a first abutment groove on the pressure side where the inner periphery and the outer periphery of the piston ring communicate with each other, and the second abutment portion The end portion of the piston ring has a second abutment groove on the non-pressurizing side in which the inner periphery and the outer periphery of the piston ring are not communicated with each other by overlapping the lip shape, and communicates with the first abutment groove. Do not communicate with the abutment groove The circumferential groove has a structure provided in the piston ring outer periphery.
As a result, it is possible to provide a compressor that can reduce the wear of the sliding surface of the piston ring without deteriorating the sealing performance and can prolong the service life.

  Next, the structure of the piston ring according to the present embodiment will be described with reference to FIGS. In addition, the same code | symbol is shown to the same structure as Example 1, and the description is abbreviate | omitted.

  In the present embodiment, as shown in FIG. 15, the piston ring height direction of the circumferential groove 33 is lowered to the lower side, that is, the non-pressurizing side, and the circumference between the piston ring heights where the lower abutment groove 35 exists is circumferential. A groove 33 is formed. Accordingly, as described with reference to FIG. 14, the range in which the constant surface pressure of the pressure Pc above the circumferential groove 33 is balanced by lowering the lower end of the circumferential groove 33 increases, so that the surface pressure can be further reduced. . Further, a communication groove 36 that connects the upper abutment groove 34 and the circumferential groove 33 is provided in the upper abutment portion to further simplify the processing. As a result, since the circumferential groove 33 is provided close to the lower abutment groove 35, the surface pressure at the abutment portion can be further reduced.

  Further, when the lip strength becomes a problem, the right end of the circumferential groove may be stopped near the upper joint groove 34 as shown in FIG. Thereby, the strength of the lip portion can be ensured.

  As described above, in this embodiment, the piston ring height direction of the circumferential groove is set within the height of the lower abutment groove, and the communication groove that communicates with the circumferential groove and the upper abutment groove is further provided. It is possible to further reduce the surface pressure.

  Next, the structure of the piston ring according to the present embodiment will be described with reference to FIG. In addition, the same code | symbol is shown to the same structure as Example 1, 2, and the description is abbreviate | omitted.

  In the present embodiment, as shown in FIG. 17, the circumferential groove 33-2 is configured to lower the piston ring height direction downward to reduce the average surface pressure, as in FIG. Moreover, the circumferential groove | channel 33-1 is provided in the upper side opening part. The circumferential groove 33-1 communicates with the upper abutment groove 34, and a communication groove 37 that communicates between the circumferential grooves 33-1 and 33-2 is provided. The reason for this is that in the case of a piston ring having a high piston ring height, only the circumferential groove 33-2 has a high piston ring height above the circumferential groove 33-2, so that the pressure above the circumferential groove 33-2 is high. This is because the pressure above the circumferential groove 33-2 is kept constant by providing the circumferential groove 33-1. Therefore, even in a piston ring having a high piston ring height, the surface pressure can be effectively reduced. In addition, you may provide the hole from a circumferential groove to a piston ring back surface as a structure which guides a pressure to the circumferential groove 33-1 or the circumferential groove 33-2. In this embodiment, two circumferential grooves are used. However, a larger number of circumferential grooves may be provided to further uniform the surface pressure.

  As described above, in this embodiment, the piston ring is provided with a plurality of circumferential grooves, both ends of the pressure side circumferential groove communicate with the upper abutment groove, and the non-pressure side circumferential groove communicates with the lower abutment groove. By connecting the pressure-side circumferential groove and the non-pressure-side circumferential groove with a communication groove, or by providing a non-pressure-side circumferential groove with a hole communicating from the circumferential groove to the back surface. Even in a piston ring having a high piston ring height, the surface pressure can be effectively reduced.

  Next, the configuration of the piston ring according to the present embodiment will be described with reference to FIG. In addition, the same code | symbol is shown to the same structure as Examples 1-3, and the description is abbreviate | omitted.

  In this embodiment, as shown in FIG. 18, the depth E1 of the circumferential groove 33 is configured such that E1> δ with respect to the limit wear amount δ of the piston ring. The limit wear amount δ indicates the wear amount of the sliding surface at the limit when the sealable lip contact length shown in FIG. 8 is obtained.

  As a result, the surface pressure can be stably reduced during the life of the piston ring, and the wear of the piston ring can be reduced. Further, during maintenance, the depth of the circumferential groove 33 of the piston ring can be checked to check the wear status of the piston ring, and as a result, the maintenance time can be grasped.

  Next, the structure of the piston ring according to the present embodiment will be described with reference to FIG. In addition, the same code | symbol is shown to the same structure as Examples 1-4, and the description is abbreviate | omitted.

  In this embodiment, as shown in FIG. 19, in order to represent the position of the circumferential groove, the height above the circumferential groove 33, that is, the height from the pressure side surface of the piston ring to the pressure side end of the circumferential groove. Where h4 is the lower height, that is, the height from the non-pressure side of the piston ring to the non-pressure side end of the circumferential groove is h5, the circumferential groove position is h4> h5, that is, the circumferential groove Is lowered from the center of the piston ring height. Thereby, the region II shown in FIG. 14 is further reduced, and the surface pressure of the sliding surface can be further reduced.

  Next, the structure of the piston ring according to the present embodiment will be described with reference to FIG. In addition, the same code | symbol is shown to the same structure as Examples 1-5, and the description is abbreviate | omitted.

  In the present embodiment, as shown in FIG. 20, when the lower thickness h1 of the piston ring joint portion is smaller than the upper thickness h2 and the rigidity of the lip is small, the position of the circumferential groove 33 is set to the lip thickness. It is shifted downward according to. Therefore, in this case, h4> h5 and the surface pressure can be further reduced.

  Next, the configuration of the piston ring according to the present embodiment will be described with reference to FIG. In addition, the same code | symbol is shown to the same structure as Examples 1-6, and the description is abbreviate | omitted.

  In this embodiment, as shown in FIG. 21, the depth E1 of the circumferential groove 33 is configured to be smaller than the lip receiving portion thickness T1. As a result, the surface pressure can be reduced without breaking the groove bottom from the circumferential groove 33 and causing leakage.

  Next, the structure of the piston ring according to the present embodiment will be described with reference to FIG. In addition, the same code | symbol is shown to the same structure as Examples 1-7, and the description is abbreviate | omitted.

  In this embodiment, as shown in FIG. 22, the lip receiving portion thickness T1 is configured to be thicker than the lip thickness T2, that is, T1> T2. In this case, the groove depth E2 can be made larger than the groove depth E1 shown in FIG. That is, E2> E1, and the allowable wear amount δ can be set large. That is, there is an advantage that the replacement life of the piston ring can be extended.

  Next, the structure of the piston ring according to the present embodiment will be described with reference to FIG. In addition, the same code | symbol is shown to the same structure as Examples 1-8, and the description is abbreviate | omitted.

  In this embodiment, as shown in FIG. 23, a communication hole communicating from the circumferential groove to the back surface, that is, a communication hole 39 communicating to the groove bottom of the circumferential groove and the inside of the piston ring in the radial direction is provided. As a result, when abrasion powder is generated on the sliding surface, it can be discharged from the circumferential groove to the back surface, and the surface pressure can be reduced without clogging the circumferential groove.

  In this embodiment, a method for manufacturing a piston ring will be described.

  As a process of manufacturing the piston ring in the above-described embodiment, first, in the case of an oil-free reciprocating compressor, compression is performed without lubrication, so that a resin such as tetrafluoroethylene resin is poured into a mold and pipe Is processed into a circular ring. Next, the joint part and the lip part are processed with a cutter or the like. After that, a circumferential groove is processed in the outer peripheral portion of the ring. In other words, the circumferential groove has one end communicating with the upper abutment groove and the other end formed up to the front of the lower abutment groove, so it is necessary to process the circumferential groove based on the abutment portion. It is necessary to make a circumferential groove after part machining.

  There are mainly two processing methods for processing the circumferential groove. One is a case where both side start points of the circumferential groove are circular arcs as shown in FIG. In this processing, a T-type slotter is used as a cutter, and the slotter can be processed at a groove depth E along the outer periphery of the piston ring, where E is the thrusting depth of the slotter. In this case, the distance L1 between the lower abutment groove 35 and the end of the circumferential groove increases with wear on the outer periphery of the piston ring during operation, but there is an advantage that the machining speed is high.

  As shown in FIG. 25, by making the height h3 of the circumferential groove 33 equal to the cutter thickness h6 of the T-slotter, that is, the width of the circumferential groove is the same as the blade thickness of the cutter for grooving. By doing so, since it can be processed by a single movement, it can be processed in a shorter time.

  As shown in FIG. 26, the other one is a case where processing is performed such that the shape in the depth direction of the end of the circumferential groove 38 is perpendicular to the circumferential surface of the piston ring. This processing can be performed by an end mill that opposes the outer periphery of the piston ring. The feature of this method is that even if the outer periphery of the piston ring is worn, the distance L2 between the lower abutment groove 35 and the end of the circumferential groove does not change, and the surface pressure of the abutment portion can be stably reduced, thereby preventing wear. This is the point. This processing method has the above-mentioned characteristics, although the processing speed is slower than when a T-type slotter is used.

  Next, the configuration of this embodiment will be described with reference to FIG. 27, the shape of the piston ring is the step joint shape shown in FIG. The pressurizing side joint 15 and the non-pressurizing side joint 14 respectively communicate with the outer peripheral side from the inner peripheral side of the piston ring. The present embodiment is characterized in that a plate 40 is used as a member that blocks communication between the outer peripheral side and the inner peripheral side of the piston ring. In this embodiment, a plate 40 made of a thin steel plate or the like is assembled on the inner peripheral side along the inner peripheral surface of the piston ring. In the example of FIG. 27, the plate 40 is wound about 1.5 times, but the length is not limited thereto. In the case of the present embodiment, the presence of the plate 40 blocks the leakage path indicated by the arrow in FIG. In this configuration, by providing the circumferential groove 33 that communicates with the pressure side joint 15 and does not communicate with the non-pressure side joint 14, the back pressure of the ring can be balanced, and the surface pressure of the sliding surface can be reduced. . Needless to say, the technology up to the tenth embodiment can be applied to the circumferential groove of the piston ring.

  Note that the plate 40 is not limited to metal, and may be made of resin, rubber, or the like, as long as the joint on the non-pressurizing side does not substantially communicate with the outer peripheral side from the inner peripheral side of the ring.

  In addition, it is difficult to distinguish the upper and lower sides of the piston ring before assembling into the piston. Necessary.

  Next, the configuration of the present embodiment will be described with reference to FIGS. FIG. 29 shows the relative positional relationship between the piston rings 53 and 54 assembled to the piston 50, and the joint is incorporated with a 180 degree deviation. 30 is a cross-sectional view of the portion indicated by FF of the piston ring 53 in FIG. 28, and is a view from above the piston.

  First, the relationship among the piston 50, the cylinder 60, and the piston rings 53 and 54 in this embodiment will be described. In this embodiment, since the piston 50 is made of slidable resin so that it can slide in direct contact with a heat-resistant cylinder, the rider ring 10 shown in FIG. do not have. In this structure, the cylinder 60 and the piston 50 are configured to have a slight gap even at the temperature during operation so that the cylinder 60 and the piston 50 do not lock due to the temperature rise during operation. In this case, as shown in FIGS. 28 and 30, the load direction gap δ load during operation is extremely small, and the δ anti load that is the anti-load direction gap is large. Two piston rings 53 and 54 are provided on the upper and lower sides, and the joint of each piston ring 53 and 54 is a straight joint without having a pressure side and a non-pressure side. Further, as shown in FIG. 30, the pressure-side piston ring 53 is configured such that the joint 55 of the piston ring 53 is always positioned in the load direction by a rotation stopper 57 formed in the ring groove of the piston. . Further, the lower piston ring 54 is configured such that the abutment 56 is positioned in the counter-load direction opposite to the piston ring 53 by the rotation of the lower ring (not shown).

  In this structure, the leak passage of the joint portion has a small clearance δ load between the second land portion 51 of the piston 50 and the inner surface of the cylinder even if the joint port 55 is straight and the width of the joint portion is large as shown in the leak passage 58 of FIG. Therefore, the area of the leakage passage 58 can be configured to be very small, and leakage from the joint portion can be reduced. Similarly, in the lower ring 54, a flow passage surrounded by the gap δ anti-load between the piston skirt 52 and the inner surface of the cylinder and the joint serves as a leakage passage. The δ anti-load is larger than the δ load and δ load <δ anti-load, but the joint is located in the opposite direction, and the pressure of the piston ring 54 part is throttled by the piston ring 53, so the piston is lower than the piston ring 53 part. The leakage at the ring 54 can also be reduced.

  Thus, with this structure, it is possible to form a small leak passage constituted by the piston rings 53 and 54 and the piston 50, and thus to constitute a compressor with little leakage. FIG. 31 shows a circumferential groove 33 communicating with the straight abutment portion 55 of the piston ring constructed as described above. In the case of the piston 50 and the piston rings 53 and 54 configured as described above, since there is very little leakage even if there is a leakage flow path that directly leads to the non-pressurization side, the circumference communicating with the joint of each ring By forming the groove, it is possible to balance the back pressure of the piston rings 53 and 54 and reduce the surface pressure of the sliding surface without increasing leakage from the joint portion.

  FIG. 32 shows examples of piston rings used in the internal combustion engine by 70 and 71, and the joint shape is shown by joints 72 and 73. This ring can be used for a compressor as long as leakage at the joint is acceptable. FIG. 33 shows that the joints 76 and 77 have large joint gaps with respect to the ring shown in FIG. 32 so that the joint part does not stretch due to thermal expansion when used in an oil-free compressor. . Needless to say, if this embodiment is applied to these joint shapes, leakage and sliding surface pressure can be reduced.

  FIG. 31 shows an example in which the circumferential groove 33 communicated with both sides of the abutment 55 of the pressure side piston ring 53 is described, but it goes without saying that the same effect can be obtained even if only one side is communicated.

  Also, when the discharge pressure of the compressor is small, or in the case of a compressor in which the suction side pressure is introduced into the crankcase and the back pressure is applied to the piston, the pressure difference between the pressure side of the ring and the non-pressure side And the leakage at the abutment portion is reduced, and the need to position the ring abutment portion in the load direction is reduced. In this case, since the leakage at the joint is small without the ring detent 57 shown in FIG. 30, the back pressure of the ring can be balanced only by providing a circumferential groove in the piston ring that is rotatably provided. The sliding surface pressure can be reduced.

  It is also possible to provide a plurality of rings having a structure in which a circumferential groove is provided in a piston ring having a detent, and each ring can be configured to gradually reduce the ring back pressure. Furthermore, it is also possible to provide a plurality of rings having a structure in which a circumferential groove is provided in a ring that does not have a detent, and each ring can be configured to gradually reduce the ring back pressure.

  In the present embodiment, a method for processing a circumferential groove with high accuracy will be described. The circumferential groove depth is an important dimension that determines the allowable wear amount of the ring. If the depth varies, and if the outer circumference of the ring wears out and there is no groove in the shallow part, the pressure on the pressure side of the ring is introduced into the groove in the range where the groove does not communicate with the joint. In this range, the back pressure balance cannot be achieved, and as a result, the sliding surface pressure rises and the wear of this portion increases.

  Therefore, it is important to process the groove depth with high accuracy, and a method of processing with high accuracy will be described with reference to FIG. In FIG. 34, the receiving jig 80 is finished with the ring receiving portion 81 having a cylinder size and ensuring roundness. The ring 30 is set so that 81 is inserted into the receiving surface of the receiving jig 80 and the tensioning jig 82 is used to push the ring 30 uniformly from the inside.

  As a result, the outer periphery of the ring 30 is in a state in which roundness is ensured by the cylinder inner diameter dimension. On the other hand, the cutter 83 is accurately positioned with respect to the ring receiving surface 81. Therefore, by determining the locus of the cutter 83 with respect to the center of the receiving surface 81, the depth E of the circumferential groove 33 can be processed with high accuracy from the outer periphery of the ring, and partial increase in wear can be prevented. It becomes.

  In FIG. 34, the cutter is shown as an example of a T-type slotter, but it is also possible to process with an end mill or the like using a similar jig.

  Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is also possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  In addition, the present invention is not limited to an oil-free reciprocating compressor whose piston ring is made of a resin material such as ethylene tetrafluoride resin, but also for a general purpose compressor that directly sucks air and for boosting the pressure of primary pressure It can also be used with compressors (booster compressors). Further, the gas to be compressed is not limited to air, but can be applied to a gas compressor for compressing a gas other than air, such as nitrogen gas.

DESCRIPTION OF SYMBOLS 1 ... Tank, 2 ... Motor, 3 ... Compressor body, 4 ... Belt, 5 ... Compressor pulley, 6 ... Crankshaft, 7 ... Connecting rod, 8 ... Piston, 9 ... Piston ring, 10 ... Rider ring, 11 ... Suction silencer, 12 ... discharge port, 13 ... cylinder, 14, 15, 25 ... abutment part, 21, 31 ... lip, 21a, 31a ... lip tip, 22, 32 ... lip receiving part, 33, 38 ... circumferential groove, 34 ... upper joint groove, 35 ... lower joint groove, 36, 37 ... communication groove, 39 ... communication hole, 40 ... plate, 50 ... piston, 51 ... second land of piston, 52 ... piston skirt, 53 ... pressure side (Upper) piston ring, 54 ... Lower piston ring, 55 ... Upper piston ring joint, 56 ... Lower piston ring joint, 57 ... Non-rotating ring provided on the piston, 58 ... 60, cylinder, 70, 71 ... piston ring for internal combustion engine, 74, 75 ... piston ring for oilless reciprocating compressor, 72, 76 ... straight cut joint, 73, 77 ... angle cut joint, 80 ... Receiving jig, 81 ... Ring receiving surface of receiving jig, 82 ... Tension jig, 83 ... Cutter, δ ... Limit wear amount, E, E1, E2 ... Circumferential groove depth, L1, L2 ... Lower joint groove And the circumferential groove end, Pc: cylinder internal pressure, P1, P2: sliding surface pressure, h1, h2, h4, h5: piston ring height, h3: circumferential groove width, h6: cutter tooth thickness, T1 ... Lip receiving part thickness, T2 ... Lip thickness

Claims (16)

A compressor that includes a cylinder, a piston, and a piston ring that is attached to the piston and seals between a pressurized side and a non-pressurized side in the cylinder, and compresses the fluid in the cylinder with the piston to generate a compressed fluid. Because
The piston ring has a first joint portion provided on the pressure side and a second joint portion provided on the non-pressurization side, and a first joint groove is provided between the first joint portions. Formed, a second abutment groove is formed between the second abutment portions, the inner periphery side and the outer periphery side are not communicated with each other in the second abutment portion, and the first abutment groove communicates with the first abutment groove. A compressor characterized in that a circumferential groove that does not communicate with the second joint groove is provided on the outer periphery of the piston ring. The compressor according to claim 1,
The compressor is characterized in that the first joint portion has a step shape in which the inner peripheral side and the outer peripheral side communicate with each other, and the second joint portion has a lip shape in which the inner peripheral side and the outer peripheral side overlap. The compressor according to claim 1,
The piston ring has a piston ring height direction of the circumferential groove within the height of the second joint portion,
A compressor further comprising a communication groove communicating with the circumferential groove and the first joint groove. The compressor according to claim 1,
The piston ring is provided with a plurality of circumferential grooves, both ends of the circumferential groove on the pressure side in the cylinder communicate with the first abutment groove, and the circumferential groove on the non-pressure side in the cylinder Do not communicate with the second abutment groove,
A compressor characterized in that the pressure-side circumferential groove and the non-pressure-side circumferential groove are connected by a communication groove, or a hole that communicates from the circumferential groove to the back surface is provided in the non-pressure-side circumferential groove. The compressor according to claim 1,
A compressor characterized in that the circumferential depth of the circumferential groove is formed so as to be perpendicular to the outer peripheral surface of the piston ring. The compressor according to claim 1,
The compressor is characterized in that the circumferential groove depth E ₁ is configured such that E ₁ > δ with respect to the limit wear amount δ of the piston ring. The compressor according to claim 1,
The height from the pressure side surface of the piston ring to the pressure side end of the circumferential groove is h ₄ , and the height from the non-pressure side surface of the piston ring to the non-pressure side end of the circumferential groove is h ₅ The compressor is characterized in that the circumferential groove is provided at a position where h ₄ > h ₅ . The compressor according to claim 1,
The second abutment portion includes a radially inner lip portion and an outer lip receiving portion of the piston ring, and the thickness of the lip receiving portion is greater than the thickness of the lip portion. Compressor. The compressor according to claim 1,
A compressor characterized in that the circumferential groove has the same width as the blade thickness of a cutter for groove processing. The compressor according to claim 1,
The compressor, wherein the piston ring is provided with a communication hole that communicates with a groove bottom of the circumferential groove and a radially inner side of the piston ring. The compressor according to claim 8, wherein
A compressor characterized in that the thickness from the tip of the lip portion to the base is substantially the same, and the contact surface with the lip receiving portion is substantially concentric. The compressor according to claim 1,
A compressor provided with a member for blocking communication between an outer peripheral side and an inner peripheral side of the piston ring. The compressor according to claim 12, wherein
The compressor characterized in that the first joint part and the second joint part have a step shape in which an inner peripheral side and an outer peripheral side communicate with each other. The compressor according to claim 1,
The compressor according to claim 1, wherein the circumferential groove has a rectangular shape. Providing a first abutment on the pressure side of the piston ring and a second abutment on the non-pressure side of the piston ring;
A first joint groove is formed between the first joint parts, a second joint groove is formed between the second joint parts,
An inner circumferential side and an outer circumferential side are not communicated with each other at the second joint portion, and a circumferential groove that communicates with the first joint groove and does not communicate with the second joint groove is provided on the outer periphery of the piston ring .
The piston ring is characterized in that the first abutting portion has a step shape in which an inner peripheral side and an outer peripheral side communicate with each other, and the second abutting portion has a lip shape in which the inner peripheral side and the outer peripheral side overlap . Providing a first abutment on the pressure side of the piston ring and a second abutment on the non-pressure side of the piston ring;
A first joint groove is formed between the first joint parts, a second joint groove is formed between the second joint parts,
An inner circumferential side and an outer circumferential side are not communicated with each other at the second joint portion, and a circumferential groove that communicates with the first joint groove and does not communicate with the second joint groove is provided on the outer periphery of the piston ring.
One end of the circumferential groove communicates with the first abutment groove, and the other end is formed up to the front of the second abutment groove .

Images