JP6036902B2 - Multistage compressor - Google Patents

Description

  The present invention relates to a multistage compressor in which a low-pressure compressor and a high-pressure compressor are connected.

  In general, a multi-stage compressor is known in which the atmospheric pressure is compressed by a low-pressure compressor and then the compressed air is further compressed by a high-pressure compressor to increase the pressure to a higher pressure.

  Known pistons used in the compressor include a normal cylindrical piston employed in a reciprocating engine and a rocking piston that reciprocates while swinging in the cylinder. The operation of the cylindrical piston is stable because the piston portion moves along the axis of the cylinder, but the structure is complicated and expensive. On the other hand, the locking piston has a simple structure and is relatively inexpensive, but because the piston part swings in the cylinder, the space between the piston part and the cylinder changes and the space becomes maximum. Is larger than the space in the cylindrical piston, the lip ring provided in the piston portion must be flexible. However, if a locking piston with such a structure is used on the high-pressure side of a multistage compressor, the lip ring will deform without being able to withstand high-pressure loads, and air will leak from the space between the lip ring and the cylinder to compress it. Efficiency is reduced. Conventionally, a rocking piston is used for a low-pressure compressor, and a cylindrical piston is often used for a high-pressure compressor.

  On the other hand, the locking piston is simple in structure, so there are few failures and it is inexpensive. Therefore, an improvement has been desired so that it can be employed in a high-pressure compressor. Corresponding to this, a compressor having a structure that employs a locking piston on the high-pressure side is also known (see Patent Document 1). This is because a thick donut plate-shaped support ring made of synthetic resin is overlapped on the back side of the lip ring, and the support ring is configured to protrude slightly from the piston part to prevent excessive deformation of the lip ring. It is what.

JP 2003-222077 A

  However, the support ring can withstand high pressure, but there is no overlap between the outer diameter and the inner diameter of the cylinder, that is, the part corresponding to the change in the space between the piston and cylinder during the swinging movement of the piston There is no. The dimension of the protruding portion from which the support ring protrudes from the outer peripheral surface of the piston portion must be the amount corresponding to the intermediate space between the minimum and maximum spaces when the piston portion swings. Therefore, there is a problem that it is difficult to sufficiently prevent the lip ring from being deformed when the space is maximized.

  It is an object of the present invention to provide a multi-stage compressor that can solve the above problems and can cope with high pressure.

In order to solve the above problems, a multistage compressor according to claim 1 is a multistage compressor in which a low-pressure compressor and a high-pressure compressor are connected, and is swingable in a cylinder of the low-pressure compressor. Sealing between a locking piston disposed slidably, a rocking piston swingably and slidably disposed in a cylinder of the high- pressure compressor, and a locking piston and cylinder of the low-pressure compressor A sealing member that seals between the locking piston and the cylinder of the high-pressure compressor, and the rocking piston of the locking piston of the low-pressure compressor has a swing angle of the locking piston of the high-pressure compressor. smaller than the swing angle, the overlap amount for the inner diameter of the cylinder of the seal member of the high-pressure compressor, the inner diameter of the cylinder of the seal member of the low-pressure compressor It characterized in that it is formed to be smaller than the overlap amount.

  The invention according to claim 2 is characterized in that, in claim 1, the outer diameter of the piston portion of the locking piston of the compressor on the high pressure side is smaller than that of the locking piston of the low pressure compressor.

  The invention according to claim 3 is characterized in that, in claim 1 or 2, a lip ring is provided on the locking piston of the low-pressure compressor and the locking piston of the high-pressure compressor.

  According to the first aspect of the present invention, since the rocking angle of the locking piston of the high pressure compressor is made smaller than the rocking angle of the locking piston of the low pressure compressor, the rocking piston does not rock much at high pressure. Therefore, it can cope with high pressure.

  According to the invention of claim 2, since the outer diameter of the piston portion of the locking piston of the high pressure side compressor is made smaller than the locking piston of the low pressure compressor, the compression load on the high pressure side piston portion is low. Therefore, the multistage compression can be smoothly operated.

  According to the invention of claim 3, since the lip ring is provided on the locking piston of the low pressure compressor and the locking piston of the high pressure compressor, the lip ring seals between the piston and the cylinder. Can do.

Longitudinal sectional view of a multi-stage (two-stage) compressor according to the present invention (A)-(g) is center sectional drawing of the various aspect of the lip ring which concerns on this invention, respectively (A) (b) is the form which made the rocking angle small, (c) is sectional drawing which shows the form of the rocking piston of a normal rocking angle Cross section of the main part of the high pressure locking piston Enlarged view showing a part of the locking piston of FIG. 4 (outer corner) changed (A) and (b) are central sectional views of lip rings of different forms. Sectional drawing which shows the state at the time of the maximum inclination of the rocking piston of FIG. (A) (b) is the front view which shows the other aspect of the deformation | transformation suppression part of a connecting rod, and its side view (A) (b) is the front view which shows the other aspect of the deformation | transformation suppression part of a connecting rod, and its cross-sectional view Cross section of locking piston with protective member Sectional drawing which shows other embodiment of a locking piston Perspective view of an air compressor equipped with the above multi-stage (two-stage) compressor

  FIG. 1 shows a multi-stage (two-stage) compressor. This multi-stage compressor is obtained by connecting a low-pressure compressor A and a high-pressure compressor B. The cylinders 1 and 2 of the compressors A and B have rocking pistons 3 and 4 swingable and slidable. Contained. Each of the locking pistons 3 and 4 is integrally provided with a dish-like piston portion 7 or 8 at the tip (small end portion) of the connecting rod 5 or 6, and is located at an eccentric position of the base portion (large end portion) of the connecting rod 5 or 6. The formed bearing holes 10 and 11 are supported by a crankshaft 12 disposed at the center of the apparatus main body. The crankshaft 12 is operatively connected to a rotary drive device (not shown).

  The compressors A and B compress the atmosphere taken into the low-pressure side cylinder 1 by reciprocating the locking piston 3 of the low-pressure (primary pressure) side compressor A by the rotation of the crankshaft 12 to generate a high pressure ( The secondary air is sent to the cylinder 2 of the compressor B on the side, and the compressed air is further compressed by reciprocating the piston 4 on the high pressure side to increase the pressure to a high pressure. Are sent out.

  By the way, the locking piston 4 of the high-pressure side compressor has the following structural features.

  First, the outer diameter of the piston portion 8 of the high-pressure side locking piston 4 is smaller than that of the piston portion 7 of the low-pressure side locking piston 3. This is to prevent the compressive load on the high pressure side piston portion 8 from abruptly increasing compared to the compressive load on the low pressure side piston portion 7.

  Lip rings 13 and 14 for sealing between the pistons 3 and 4 and the cylinders 1 and 2 are attached to the outer periphery of the piston portions 7 and 8 of the rocking pistons 3 and 4. The lip rings 13 and 14 are non-metallic materials composed of components such as synthetic resin and synthetic rubber, specifically polytetrafluoroethylene or modified polytetrafluoroethylene, copper or bronze alloy powder, spherical carbon or carbon fiber, and molybdenum dioxide. It is an annular member that is formed from and is continuous without any breaks.

  The lip ring 14 of the locking piston 4 of the high pressure side compressor has a seal portion (lip portion) that can be elastically deformed to the extent that it contacts the inner surface of the cylinder 2 in the high pressure region and performs a sealing action.

  Therefore, the lip ring 14 has the following structural features.

  That is, the overlap amount of the outer diameter of the lip ring 14 with respect to the inner diameter of the cylinder 2 is formed to be smaller than at least the overlap amount of the outer diameter of the lip ring 13 of the locking piston 3 on the low pressure side with respect to the inner diameter of the cylinder 1. Has been. This is because if the overlap part of the lip ring 14 is large, the elasticity is inevitably high and flexible, so that it easily deforms when subjected to a high internal pressure, and air leakage occurs from the deformed part, resulting in poor sealing. This is because there is a risk of it happening. Therefore, the overlap amount of the lip ring 14 of the locking piston 4 on the high-pressure side is set to be at least smaller than that on the low-pressure side so that it is difficult to elastically deform when subjected to high pressure.

  Further, the height (lip height) of the lip portion 15 formed on the outer periphery of the high-pressure side lip ring 14 is formed to be at least lower than the lip height of the low-pressure side lip ring 14.

  This is also because the higher the lip height, the higher the elasticity, the more easily deformed when subjected to the action of high pressure, and there is a risk of poor sealing due to air leakage. This is to facilitate the storing operation.

  Since the height of the lip portion 15 of the lip ring 14 on the high-pressure side is formed lower than that on the low-pressure side, the elasticity is also low and the pressure for tensioning to the outside is high, so that it is difficult to deform even under the action of high pressure. Therefore, there is little possibility of causing a seal failure due to stress reduction or air leakage. Moreover, the operation | work which accommodates the lip ring 14 in the cylinder 2 at the time of an assembly | attachment is not difficult. The force for shrinking the lip 15 so that it can be accommodated in the cylinder 2 during the operation is ± 10 compared with that at the time of low pressure due to the relationship between the load for shrinking the lip 15 and the area of the lip 15 that contacts the inner surface of the cylinder 2. It is better to set within%.

  The lip ring 14 of the high pressure side locking piston is required to have at least the overlap amount and the lip height as described above as shown in FIG. When the pressure in the cylinder 2 on the high pressure side is sufficiently increased, such as at the time of starting, the lip portion 15 of the lip ring 14 acting in the high pressure region is not easily elastically deformed. Depending on the conditions, there is a possibility that the sealing performance cannot be exhibited. Therefore, as shown in FIG. 2 (b), the lip portion 15 of the lip ring 14 has a large seal function in the low pressure region and the lower seal portion 16 for a small diameter high pressure region that performs a seal function in the high pressure region. It is preferable that the upper seal portion 17 is integrally provided for the low pressure region of the diameter. The lower seal portion 16 is formed thick, whereas the upper seal portion 17 is thin and relatively easily deformed elastically. A step portion 18 is formed between the lower seal portion 16 and the upper seal portion 17.

  According to the above lip ring configuration, the lower seal portion 16 of the lip ring 14 acting in the high pressure region is not easily elastically deformed in the low pressure state, but the upper seal portion 17 is elastically deformed in the low pressure state and is sufficiently sealed. An effect can be secured. As described above, since the sealing performance can be exhibited even in the low pressure state, the increase in the back pressure against the lip ring 14 is reduced even in the high pressure state, the pressing force to the cylinder 2 is reduced, and the wear of the lip ring 14 is effectively prevented. can do.

  The arrangement structure of the lower seal portion 16 and the upper seal portion 17 is not limited to the above-described form. For example, as shown in FIG. 6C, a step may not be provided between the upper seal portion 17 and the lower seal portion 16, and the upper and lower seal portions 16 and 17 may be continuous. The upper seal portion 17 may be formed so as to warp outward as shown in d) so as to be easily elastically deformed. Alternatively, as shown in FIG. You may make the structure of the shape extended from the part 16 as it is.

  Further, the upper seal portion 17 is not formed continuously on the upper portion of the lower seal portion 16, but the lower seal portion 16 and the upper seal portion 17 are separately formed as shown in FIG. The portion 17 is formed so as to protrude obliquely upward from the inside closer to the center than the lower seal portion 16. The upper end of the upper seal portion 17 is formed to extend above the lower seal portion 16, and the height of the upper seal portion 17 is higher. Therefore, the upper seal portion 17 is more easily elastically deformed than the lower seal portion 16 and can cope with a low pressure. In this case, the upper seal 16 may be configured for high pressure and the lower seal 17 may be configured for low pressure as shown in FIG.

  In order to cope with the high pressure, not only the shape of the lip ring 14 but also the swing angle of the locking piston 4 of the high pressure side compressor is made smaller than the swing angle of the locking piston 3 of the low pressure side compressor. You may make it set to. The swing angle α is the stroke L of the locking piston 4, that is, the distance from the central axis P of the connecting rod 6 to the swing rotation center O1, and the distance from the swing rotation center O1 to the center O2 of the seal portion by the lip ring 14. It is determined by. In order to reduce the swing angle α, as shown in FIG. 3 (a), it is indicated by the distance from the swing rotation center O1 to the center O2 of the seal portion without changing the stroke L of the locking piston 4. The length of the connecting rod 6 may be increased, or the stroke L of the locking piston 4 may be reduced without changing the length of the connecting rod 6 as shown in FIG.

  In addition, the figure (c) is a reference figure which shows the maximum inclination state of the rocking piston 4 before making a rocking | swiveling angle small. In the figure, α0 indicates a swing angle and L0 indicates a stroke.

  Next, the configuration of the locking piston corresponding to the high pressure will be described in detail.

  FIG. 4 shows a locking piston on the high-pressure side. The locking piston 4 is provided integrally with the tip of the connecting rod 6 and slides while swinging in the cylinder 2. It is provided with a ring presser 20 that is provided at the upper part and is slightly smaller in diameter than the piston main body 18, and a lip ring 14 that is provided between the piston main body 18 and the ring presser 20 and seals between the inner surface of the cylinder 2. The lip ring 14 is made of a non-metallic material such as synthetic resin or synthetic rubber.

A circular recess 21 is formed on the upper surface of the piston main body 18, whereas the ring presser 20 is circular, and a circular protrusion 22 is formed protruding at the center lower part. And the circular convex part 22 of the ring presser 20 fits inside the circular concave part 21 of the piston main body 18, and the ring presser 20 is being fixed to the upper surface of the piston main body 18 with the fixing volt | bolt 23 penetrated from upper direction. The lip ring 14 is formed in an annular shape, with the center opening 24 (see FIG. 2A) fitted to the circular convex portion 22 of the ring retainer 20, the upper ring retainer 20 and the lower piston body 18 It is sandwiched between and fixed.

  The lip ring 14 is a donut plate-like base portion 25 sandwiched between the piston main body 18 and the ring presser 20, and is formed to stand up obliquely upward from the outer peripheral end of the base portion 25. It is comprised from the lip | rip part 15 which seals between. Further, a corner portion 26 whose cross section is curved in an arc shape is formed between the base portion 25 and the lip portion 15. As shown in FIG. 5, the corner portion 26 includes an outer corner portion 27 in which both the outer surfaces of the base portion 25 and the lip portion 15 are in contact, and an inner corner portion 28 in which both the inner surfaces of the base portion 25 and the lip portion 15 are in contact. It consists of and. The following relationship exists between the curvature radius r1 of the outer corner portion 27, the curvature radius r2 of the inner corner portion 28, and the thickness t of the lip ring 14.

r1 <r2 + t
That is, the radius of curvature r1 of the outer corner portion 27 is formed smaller than the dimension obtained by adding the thickness t of the lip ring 14 to the radius of curvature r2 of the inner corner portion 28. That is, the thickness of the corner portion 26 is set to be larger than the thickness of the base portion 25 and the lip portion 15 of the lip ring 14. The radius of curvature of the outer corner portion 27 may be zero.

  Further, as shown in FIG. 6A, the shape of the corner portion is not a curve but a straight chamfered shape, and the outer corner portion 27 may be set so that the chamfering of the inner corner portion 28 is larger than the chamfering. Alternatively, as shown in FIG. 6B, the curvature of the corner portion is set to be small so that the thickness of the corner portion 26 is larger than the thickness of the base portion 25 and the lip portion 15 (the outer corner portion 27 has a smaller curvature, the inner corner portion 28). May be zero curvature).

  As a result, the stress due to the internal pressure from above the piston body 18 is reduced, deformation due to the internal pressure can be suppressed, and the space S formed between the piston body 18 of the connecting rod, the cylinder 2 and the lip ring 14 is reduced.

  Further, the outermost diameter of the lip ring 14 is larger than the inner diameter of the cylinder 2. Furthermore, the lip ring 14 is formed larger than the major axis of the ellipse on the inner surface of the cylinder 2 that is in contact with the piston body 18 when the piston body 18 is at the maximum inclination. Thus, since the lip ring 14 has a portion that overlaps the cylinder 2, the gap between the cylinder 2 and the locking piston 3 can be reliably sealed. It is formed to be smaller than the overlap amount of the lip ring 14 of the locking piston 3 on the low pressure side so that it is difficult to elastically deform when subjected to a high pressure.

  4 and 5 in which the locking piston 4 is not inclined with respect to the cylinder 2, the lower surface 30 of the base portion 25 of the lip ring 14 is at least the inner end portion 28a of the curved surface of the inner corner portion 28. Is in contact with the upper surface of the piston main body 18 in a region from the portion 29a that intersects perpendicularly to the cylinder 2 side.

  Further, the lip ring 14 is in contact with the cylinder 2 from a portion 29b where at least the extension 31a of the upper surface 31 of the base portion 25 is in contact with the inner surface of the cylinder 2 to the upper end. In addition, the outer corner part 27 of FIG. 5 is shown as what is curving rather than the outer corner part 27 of FIG.

  As described above, the inner end portion 27a of the outer corner portion 27 is positioned at least outside the intersecting portion 29a. Similarly, the outer end portion 27b of the outer corner portion 27 is at least the upper surface extension corresponding portion 29b. Therefore, the space S formed between the piston body 18, the cylinder 2 and the lip ring 14 of the connecting rod 3 is suppressed to be small.

  Next, as shown in FIG. 3C and FIG. 7, when the rocking piston is at the maximum inclination, the space between the lip ring 14 and the cylinder 2 is reduced on the upper side. It is comprised so that the cylinder 2 may be contacted in the area | region below the part 29c which cross | intersects the outer side end part 28b at right angles.

  According to the above-described configuration, the lip ring 14 contacts the inner surface of the cylinder 2 at least in a region including the corner portion, that is, a region including a corner portion larger than the thickness of the base portion 25 and the lip portion 15 of the lip ring 14. It will be. In this way, by receiving the pressing force in the lateral direction against the cylinder 2 generated by the tilting of the locking piston 4 or the inertia due to the tilt acting on the above-mentioned region, that is, the corner side of the lip ring 14, the lip It is possible to satisfactorily suppress the portion 15 from being excessively deformed and to secure the overall strength. Even if the internal pressure of the cylinder 2 rises, the amount of wear of the lip ring 14 is reduced because the force that the lip 15 stretches outward is low. Moreover, since the overlap amount at the time of the maximum inclination is sufficiently ensured, the force applied to the outside is supplemented by the elasticity of the lip portion 15 to ensure the sealing performance.

  By the way, as shown in FIG. 7, the space D1 between the lip portion 15 of the lip ring 14 and the ring presser 20 is equal to or less than the space D2 between the upper portion of the piston body 18 and the cylinder 2 at the maximum inclination. Therefore, even when tilted to the maximum, the piston body 18 or the ring presser 20 does not directly contact the cylinder. Further, the amount of plastic deformation of the ring presser 20 can be suppressed.

  Further, as shown in FIG. 5, the upper surface 31 of the base portion 25 of the lip ring 14 has a ring presser 20 of the ring retainer 20 at a portion spaced from the inner end portion 28a of the curved surface of the inner corner portion 28 to the center side by an appropriate distance l. It is in contact with the bottom surface. A straight portion 32 is formed between the inner end portion 28 a and the contact start portion, and the straight portion 32 is configured as a separation region that does not contact the lower surface of the ring presser 20. The reason is that stress is concentrated on the corner portion 26 when the inner end portion 28a is brought into direct contact with the ring presser 20. By providing the separation region 1 in addition to the corner portion 26, stress can be dispersed and stress concentration can be prevented from occurring.

  Incidentally, a minute gap Q is formed between the inner peripheral surface of the lip portion 15 of the lip ring 14 and the outer peripheral surface of the ring presser 20. The gap Q between the lip portion 15 and the ring presser 20 is preferably set to 1 mm or less in the state of being assembled in the cylinder 2, for example, in the case of a lip ring having a diameter of 41 mm. If it exceeds 1 mm, the amount of deformation of the lip ring increases, the sliding resistance with the cylinder 2, that is, the repeated stress increases, and the amount of wear of the lip ring 14 increases.

  Further, since the rocking piston 4 swings in the cylinder 2, at least the outer peripheral surface 33 of the ring presser 20 is formed to have a substantially spherical surface shape centering on the center of the seal portion by the lip ring 14. ing. The size of the spherical surface defining the outer peripheral surface of the ring presser 20 is a spherical shape having the same size as the inner diameter of the cylinder 2 or a slightly smaller diameter. The spherical shape may be only the ring presser 20 but may be formed on the outer peripheral surface including the lip ring 14 and the piston main body 18.

  By making the surface shape substantially spherical, it is possible to effectively suppress the lip ring 14 and the ring presser 20 from being pressed against the cylinder 2 and deformed by the pressure increase generated by the inertia based on the rocking motion of the locking piston 4. , Repetitive stress can be prevented, and fatigue of the lip ring 14 can be prevented.

  By the way, as shown in FIG. 4, the lower surface of the circular convex portion 22 of the ring presser 20 and the upper surface of the circular concave portion 21 of the piston body 18 are in direct contact with each other inside the base portion 25 of the lip ring 14. For this reason, the interval between the ring presser 20 and the piston main body 18 is constant. Although this interval is smaller than the thickness of the base portion 25, the pressing force is constant, and the base portion 25 is not sandwiched by an excessive pressing force and is not deformed. Further, since the ring presser 20 does not float from the piston main body 18, the fixing that occurs when the lip ring 14 or the ring presser 20 is pressed against the cylinder 2 by the pressure increase generated by the inertia based on the swinging motion of the locking piston 4. The stress on the work bolt 23 is relieved, and the tightening torque can be maintained.

  Moreover, the ring presser 20 and the piston main body 18 are not limited to the form which contact | abuts directly. You may comprise so that it may contact | abut via the intermediate material (not shown) inside the base part 25 of the lip ring 14 when the pressure of a use condition acts. The intermediate material may be a metal plate, or an adhesive that hardens over time.

Further, as shown in FIG. 5, an annular protrusion 34 is formed on the lower surface of the ring presser 20 so as to press against the surface of the lip ring 14 that contacts the base portion 25. The ring retainer 20 is fastened to the piston body 18 by the fixing bolt 23 and the annular protrusion 34 of the ring retainer 20 is strongly pressed against the contact surface portion with the base portion 25 of the lip ring 14, so that the annular protrusion 34 is Therefore, the lip ring 14 is prevented from moving on the piston body 18 and the lip ring 14 is securely fixed. And it can seal favorably between a piston part and the cylinder 2. FIG.

  It is preferable that the locking piston 4 of the high-pressure side compressor has a protrusion height higher than that of the locking piston 4 of the low-pressure side compressor.

  Further, on the upper surface of the piston body 18, an annular ridge 35 that pushes up the opening edge of the circular central opening formed at the center of the base 25 of the lip ring 14 is formed on the outer peripheral edge of the circular recess 21. Is formed.

  As a result, the opening edge of the lip ring 14 is pushed up by the annular protrusion 35, so that the space between the base portion 25 and the ring presser 20 can be eliminated and the internal pressure of the upper chamber of the cylinder 2 can be reliably sealed. Does not leak into the lower chamber of the lower portion of the piston portion 8.

  Next, as shown in FIG. 3C and the like, the connecting rod is formed to be wide in the swinging direction. Further, in the direction orthogonal to the width direction of the connecting rod 6, the connecting rod is shown in FIG. As shown, a rib-shaped deformation suppressing portion 36 is formed, and the deformation suppressing portion 36 is joined to the lower surface of the piston body 18. Since the connecting rod 6 is formed wide in the swing direction, the piston body 18 is also difficult to deform in the swing direction. In addition, since the deformation suppressing portion 36 is formed on the connecting rod 6, the connecting rod 6 is strengthened in a direction orthogonal to the swinging direction, and the piston body 18 is also difficult to deform in the same direction. ing. The deformation of the piston body 18 due to the pressure is greatly different between the swing direction and the direction orthogonal thereto. For this reason, a large stress is generated in the fixing bolt 23. However, this stress can be reduced by the rib-shaped deformation suppressing portion 36.

  Further, as shown in FIGS. 8A and 8B, the deformation control unit 36 is formed wide in the swinging direction of the connecting rod 6, but the large end side is narrowed and the small end side is widened. At the same time, the deformation suppressing portion 36 may be formed on the large end side in a direction orthogonal to the width direction. Further, as shown in FIGS. 9A and 9B, the connecting rod 6 and the deformation suppressing portion 36 may be formed in a cross-shaped cross section having the same size from the large end portion to the small end portion.

  Further, as shown in FIG. 10, nonmetallic protective members 37 a and 37 b having a strength equal to or higher than that of the lip ring 14 may be provided on the outer peripheral surfaces of the piston main body 18 and the ring presser 20. The lip ring 14 may continue to be used even after the maintenance time has passed. Even in such a case, the lip ring 14 is worn and the metal piston body 18 or the ring presser 20 directly contacts the cylinder 2. If they are rubbed together, they may be scratched, resulting in a decrease in compression efficiency or failure. However, by providing the protective members 37a and 37b made of the same non-metallic material as the lip ring 14, the protective members 37a and 37b directly contact the cylinder 2 before the piston main body 18 or the ring presser 20 contacts, and the piston Since the main body 18 or the ring presser 20 does not directly rub against the inner surface of the cylinder 2, the cylinder 2 can be protected. The protective member may be provided only on one of 37a and 37b.

  FIG. 11 shows another embodiment of a locking piston for high pressure, and this locking piston 4 has the same basic configuration as that described above, but is provided integrally with the tip of the connecting rod 6 to provide the cylinder 2 A dish-shaped piston main body 18a that slides while swinging inside, a liner presser 20a that is provided at the top of the piston main body 18 and has a slightly smaller diameter than the piston main body 18a, and between the piston main body 18a and the liner presser 20a. A liner 38 that is provided and constitutes a seal portion that seals between the inner surface of the cylinder 2 and a piston ring 39 provided on the outer periphery of the liner presser 20a are provided. The piston main body 18a and the liner presser 20a are members corresponding to the aforementioned piston main body 18 and the ring presser 20, respectively. Moreover, the attachment mode of the liner presser 20a and the piston main body 18a is the same as that of the ring presser 20 and the piston main body 18 of the above-mentioned form.

  The outer peripheral surface 40 of the liner 38 is formed to have a substantially spherical surface shape having a diameter that is the same as or slightly smaller than the inner diameter of the cylinder 2. This spherical shape effectively suppresses deformation of the liner 38 and the liner presser 20a due to the pressing force when the liner 38 and the liner presser 20a are pressed against the cylinder 2 due to the pressure increase generated by the inertia based on the swinging motion of the locking piston 4. In addition, repeated stress can be prevented and fatigue of the liner 38 can be prevented.

  Further, the piston ring 39 is not continuous, and a part thereof is cut, and is housed in a housing groove 42 formed on the outer periphery of the ring presser 20 with play. For this reason, the piston ring 39 can expand and contract in the radial direction in the storage groove 42. Therefore, when the piston main body 18a and the liner presser 20a are subjected to back pressure, the piston ring 39 is expanded outward, so that the line seal can be maintained by the liner 38 even if the piston main body 18a and the liner presser 20a are inclined. it can. In addition, since a sufficient thickness can be obtained, the dimensional tolerance is greatly reduced.

  The liner 38 and the piston ring 39 are also made of a non-metallic material similar to the protective member 37. The peripheral surface of the piston ring 39 is also a substantially spherical surface.

  FIG. 12 shows an air compressor equipped with the above-described multistage compressor, 43 is a motor, and 44 is a multistage compressor. The air compressed by the low pressure side compressor 47 is supplied to the high pressure side compressor 46 via the air hose 45, and this compressed air is further compressed by the high pressure side compressor 46, and is supplied to the air tank 49 via the air hose 48. It is configured to be stored. A printed circuit board 50 to which motor control components are attached is disposed at the bottom of the air compressor. A control device 52 is disposed below the printed circuit board 50, and both side portions are bent upward. This bent portion 51 has a function of promoting heat dissipation by preventing warpage of the entire substrate and ensuring strength and by the flow of air from the cooling fan 53 on the inside of both sides. Although not shown, the bottom surface of the printed circuit board 50 is potted.

1, 2 Cylinder 3, 4 Locking piston 6, 7 Connecting rod 14 Lip ring 15 Lip portion 24 Base portion 20 Ring presser 27 Outer corner portion 28 Inner corner portion

Claims (3)

A multi-stage compressor in which a low-pressure compressor and a high-pressure compressor are connected,
A rocking piston disposed slidably and slidably in a cylinder of the low pressure compressor;
A rocking piston disposed slidably and slidably in a cylinder of the high pressure compressor;
A seal member that seals between a locking piston and a cylinder of the low-pressure compressor;
A sealing member that seals between a locking piston and a cylinder of the high-pressure compressor;
With
The swing angle of the locking piston of the high pressure compressor is smaller than the swing angle of the locking piston of the low pressure compressor ,
The multistage , wherein the amount of overlap of the seal member of the high-pressure compressor with respect to the inner diameter of the cylinder is smaller than the amount of overlap of the seal member of the low-pressure compressor with respect to the inner diameter of the cylinder. Compressor.   The multistage compressor according to claim 1, wherein an outer diameter of a piston portion of a locking piston of a high-pressure side compressor is made smaller than a locking piston of the low-pressure compressor.   The multistage compressor according to claim 1 or 2, wherein a lip ring is provided on a locking piston of the low-pressure compressor and a locking piston of the high-pressure compressor.

Images