JP2016160752A - Air compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air compressor which has a piston equipped with a lip ring, and has a piston structure capable of further improving the durability of the lip ring.SOLUTION: A compressor has a lip ring 7 for sealing a part between a piston portion 51 and a cylinder 31. A piston 5 of the compressor has: a foundation portion 54 which becomes a foundation of the lip ring attached to the piston portion; a curved portion 56 formed on the outside of the foundation portion and abutting on an R portion on a lip ring bottom surface side; and a generally plane surface 57 formed on the outside of the curved portion, and generally vertical to a piston axial direction. The curved portion is formed between the foundation portion and the generally plane surface, and the generally plane surface is formed on an outer edge portion of the piston portion. The width of the generally plane surface is preferably 1/2 or more of plate thickness dimensions of the lip ring. With this characteristics, the deformation of the lip ring R portion and the biting-in of the piston portion to the lip ring can be prevented, so that the durability of the lip ring is improved.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an air compressor (air compressor) that is a device that generates compressed air.

A conventional air compressor will be described with reference to FIGS. 1 and 2.
FIG. 1 shows a portable two-stage air compressor provided with swinging pistons called “rocking pistons” on the first and second stages.
FIG. 2 is a partial cross-sectional view showing the configuration of the two-stage piston and cylinder of the air compressor of FIG.

  In this air compressor, the crankcase 1 rotatably supports a motor shaft 8, and the crankshaft 3 is fixed to the motor shaft 8. The motor shaft 8 is connected to the output shaft of the motor 9.

  The low-pressure one-stage cylinder 11 and the high-pressure two-stage cylinder 31 are each formed in a cylindrical shape and attached to the crankcase 1. Sealing members (lip rings) included in the pistons 21 and 41 are in sliding contact with the inner peripheral surfaces of the cylinders 11 and 31.

  Cylinder heads 13 and 33 are mounted on the upper portions of the cylindrical cylinders 11 and 31. In the cylinder heads 13 and 33, a suction chamber communicating with the outside via the suction port and a discharge chamber communicating with the outside via the discharge port are defined.

  The first-stage piston 21 and the second-stage piston 41 are oscillating pistons, and are provided so as to reciprocate while oscillating in the cylinders 11 and 31. Since the first-stage piston 21 and the second-stage piston 41 have substantially the same characteristics except that there is a difference in size, the following description will mainly refer to the second-stage piston 41, and The description of the piston 21 is omitted.

  The piston 41 includes a piston main body 40 extending into the cylinder 31 and a substantially disc-shaped lip ring fixing member 61 provided on the upper portion of the piston main body.

  The piston body 40 includes a connecting portion rotatably connected to the crankshaft 3, a rod-like piston rod integrated with the connecting portion, and a piston portion 42 provided integrally on the other end side of the piston rod. It has. The piston main body 40 repeats reciprocating motion while swinging with respect to the cylinder 31 as a whole in a state where the piston portion 42 is accommodated in the cylinder 31.

  The substantially disc-shaped piston portion 42 defines a compression chamber in the cylinder 31. As shown in the partial cross-sectional view of FIG. 2, on the upper surface side (side facing the compression chamber) of the piston portion 42, a circular concave portion 43 that fits with a lip ring fixing member 61, which will be described later, and a surrounding portion are raised. A flat annular base portion 44 is formed.

  The lip ring fixing member 61 is a disk-shaped member for fixing the lip ring 71 (seal member). The lip ring fixing member 61 includes a circular convex portion 62 formed so as to protrude toward the bottom surface side, and a lip ring pressing portion 63 formed around the circular convex portion 62.

  The lip ring 71 as a sealing member has an overall appearance of a substantially circular cup shape (or a substantially circular dish shape) as a whole, and a circular opening is formed at the center thereof. The lip ring 71 includes a mounting portion 72 positioned on the inner peripheral side, a lip portion 73 positioned on the outer peripheral side, and a lip ring R portion having an arcuate cross section positioned between the lip portion 73 and the mounting portion 72. 74.

  When the lip ring 71 is mounted on the piston portion 42, the lip portion 73 projects outward from the outer peripheral side of the piston portion 42. When the lip portion 73 of the lip ring 71 projects in the outside in this way and is inserted into the cylinder 31 together with the piston portion 42, the outside of the lip ring 71 is elastically deformed in the diameter reducing direction, and the mounting portion 72 and the lip portion An intermediate portion with 73 is curved in an arc shape to form a lip ring R portion 74. Further, the outer peripheral surface of the lip portion 73 is in sliding contact with the inner peripheral surface of the cylinder 31.

  The lip ring 71 having the above configuration is integrated with the piston portion 42 of the piston 41 and reciprocates while swinging in the cylinder 31 when the air compressor is operated. At that time, the lip portion 73 slides in a state where the outer peripheral surface is in contact with the inner peripheral surface of the cylinder 31.

Japanese Patent Laid-Open No. 9-144666

<First problem>
In the above-described conventional air compressor, the lip ring 71 is pressed toward the direction of arrow A shown in FIG. 2B by compressed air (air pressure) in the compression chamber during operation of the air compressor. In particular, in the compression stroke in which the piston portion 42 moves up in the cylinder 31, the pressure in the compression chamber becomes high, so that the lip ring 71 is strongly pressed in the direction of arrow A and the lip portion 73 is in the inner periphery of the cylinder 31. By friction sliding with the surface, it receives frictional force in the direction of arrow A.

  Therefore, as the operation of the air compressor is continued, the lip ring 71 is pressed against the flat base portion 44 side of the piston portion 42 and elastically deformed, and the lip ring R portion 74 is eventually shown in FIG. It bends at right angles. As a result, a portion of the lip portion 73 that is close to the lip ring R portion 74 comes to be strongly pressed against the inner peripheral surface of the cylinder 31 and slides. As a result, the life of the compressor is shortened and the sliding resistance of the piston is increased, resulting in a problem that the mechanical efficiency of the compressor is lowered.

  Moreover, since a large bending load (force in the direction of arrow A) acts on the lip ring R portion 74 due to this deformation, the lip ring 71 is located in the vicinity of the lip ring R portion 74 as shown in FIG. A crack or the like may occur in the portion, thereby impairing the hermeticity of the compression chamber and causing a problem that the compression efficiency of the compressor is significantly reduced.

  A similar problem may occur in the lip ring provided in the first-stage piston.

<Second problem>
Means for solving the first problem is disclosed in Japanese Patent Application Laid-Open No. H10-228707.
In patent document 1, as shown to Fig.3 (a), while forming the acute-angle-shaped protrusion edge part 45 formed so that it may protrude upwards on the outer side of the flat base part 44, it is the upper surface of the protrusion edge part 45 It has been proposed that the side be a curved portion 46.

  That is, according to the proposal of Patent Document 1, even when the lip ring 71 is pressed from the compression chamber side by pressure or the like, the lip ring R portion 74 can be held in the arcuate curved state while being supported by the curved portion 46. The lip ring can be prevented from being excessively deformed by the pressure and the like at this time, and as a result, the lip ring can be prevented from being damaged or unevenly worn.

  However, when the structure proposed in Patent Document 1 is adopted, as shown in FIG. 3 (b), an acute-angled protruding edge 45 (a sharply pointed edge) at the outermost portion of the curved portion 46. However, it strikes the lip ring R part at an acute angle. When the lip ring R portion 74 receives a force in the direction of arrow A due to the air pressure and the frictional force with the cylinder inner peripheral surface in the compression stroke, the distal end (projecting edge 45) of the curved portion 46 is moved to the lip ring R portion 74. There arises a problem that bite cracks occur.

<Object of the present invention>
In view of the above-described problems of the prior art, an object of the present invention is an air compressor having a piston provided with a sealing member such as a lip ring, and having a piston structure capable of improving the durability of the sealing member. It is in providing the air compressor provided.

The above purpose is
A compressor including a seal member that seals between a piston portion and a cylinder,
A base part to be a base of a seal member attached to the piston part;
A curved portion formed on the outside of the base portion and contacting the R portion (curved portion) on the bottom surface side of the seal member;
A substantially flat surface formed in a direction substantially perpendicular to the piston axial direction, formed outside the curved portion;
Achieved by a compressor comprising a piston having

  In the compressor, the curved portion is formed between the base portion and the substantially flat surface, and the substantially flat surface is formed at an outer edge portion of the piston portion.

  The width of the substantially flat surface is preferably 1/2 or more of the plate thickness of the seal member.

  According to the air compressor of the present invention, it is possible to prevent the deformation of the R portion on the bottom surface side of the seal member and the generation of cracks due to the biting of the piston portion into the seal member. As a result, the seal member attached to the piston can be prevented. Durability can be improved.

It is a figure which shows a two-stage type air compressor. 2 (a) is a partial cross-sectional view showing a piston structure in a conventional air compressor, and FIG. 2 (b) is an enlarged view showing a state of deformation of a seal member (lip ring) during operation of the air compressor. It is sectional drawing. FIG. 3 (a) is a partial cross-sectional view showing a piston structure in the air compressor disclosed in Patent Document 1, and FIG. 3 (b) shows a deformation of the seal member (lip ring) during operation of the air compressor. It is an expanded sectional view which shows the mode. FIG. 4A is a partial cross-sectional view illustrating the piston structure in the air compressor of the present invention, and FIG. 4B is an enlarged view showing the state of the seal member (lip ring) during operation of the air compressor. It is sectional drawing. It is a figure which shows the size of the principal part of the piston and seal member (lip ring) used in the Example.

(Configuration of air compressor)
Hereinafter, based on FIG. 4, embodiment of this invention is described.
In the following description, the embodiment of the present invention will be described by taking a portable two-stage air compressor provided with swinging pistons called “rocking pistons” on the first and second stages as a specific example. To do.
2 and 3 are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

The partial cross-sectional view of FIG. 4 shows the configuration of the cylinder 31 on the second stage side (high pressure side), the piston portion 41, and the lip ring 7 (seal member) of the two-stage compressor.
In addition, since the structure of the 1st stage (low voltage | pressure side) is the same as that of FIG. 4, illustration and description are abbreviate | omitted.

  As shown in FIG. 4, the air compressor of the present embodiment includes a piston portion 51 provided on the front end side of the piston 5 that reciprocates while swinging in the cylinder 31, and a lip attached to the upper surface side of the piston portion. A ring fixing member 6 (retainer) and a lip ring 7 as a seal member for sealing between the piston portion 51 and the inner peripheral surface of the cylinder 31 are provided.

  The piston 5 (high-pressure piston) is an oscillating piston as in the related art described in relation to FIG.

  The piston 5 includes a piston body extending into the cylinder 31 and a lip ring fixing member 6 (retainer) provided at the upper portion of the piston body, as in the prior art shown in FIG. Yes.

  As in the prior art shown in FIG. 1, the piston body of the piston 5 includes a connecting portion rotatably connected to the crankshaft, a rod-shaped piston rod integral with the connecting portion, and the other end of the piston rod. The piston part 51 provided integrally is comprised. The piston main body repeats reciprocating motion while swinging with respect to the cylinder 31 as a whole in a state where the piston portion 51 is accommodated in the cylinder 31.

  The piston portion 51 on the front end side of the piston main body is formed in a substantially disk-like appearance, and defines a compression chamber in the cylinder 31.

  On the upper surface side of the piston portion 51 (the side facing the compression chamber), a circular concave portion 53, a base portion 54, a curved portion 56, and a substantially flat surface 57 are formed.

  The circular concave portion 53 of the piston portion 51 is formed at the center of the upper surface side of the piston portion 51 and is concavo-convexly fitted to the lip ring fixing member 6.

  The flat annular base portion 54 is formed so as to rise to the outside of the circular concave portion 53 and functions as a base of the lip ring 7 (seal member) attached to the piston portion 51.

  The curved portion 56 is formed outside the base portion 54, and comes into contact with and comes into close contact with the curved lip ring R portion 74 (R portion on the bottom surface side of the seal member).

  The substantially flat surface 57 is formed outside the curved portion 56 and is formed to be substantially perpendicular to the piston axial direction. That is, the substantially flat surface 57 is formed in a direction substantially orthogonal to the piston axial direction. The substantially flat surface 57 is not necessarily limited to a flat surface in a strict sense, and may be a slightly inclined surface or a slightly curved surface.

  The curved portion 56 of the piston portion 51 described above is formed between the base portion 54 and the substantially flat surface 57, and the substantially flat surface 57 is formed at the outer edge portion of the piston portion 51. That is, the circular recessed part 53, the base part 54, the curved part 56, and the substantially flat surface 57 are formed on the upper surface side of the piston part 51 so as to be adjacent to each other. Further, the circular concave portion 53, the base portion 54, the curved portion 56, and the substantially flat surface 57 are each formed in an annular shape and are concentrically formed on the upper surface side of the piston portion 51. A circular concave portion 53 is formed at the center on the upper surface side of the piston portion 51, and further, a base portion 54, a curved portion 56, and a substantially flat surface 57 are formed in order toward the outer side.

  The lip ring fixing member 6 (retainer) is a member for positioning a lip ring 7 which will be described later, and is formed in a substantially disk-like appearance. The lip ring fixing member 6 includes a circular convex portion 62 formed so as to protrude toward the bottom surface side, and a lip ring pressing portion 63 formed around the circular convex portion 62. The lip ring fixing member 6 is screwed to the piston portion 51 in a state where the circular convex portion 62 is engaged with the circular concave portion 53 of the piston portion 51.

  As shown in FIG. 4, the lip ring 7, which is an example of a seal member, is configured by a substantially ring-shaped member that is curved in a substantially U-shaped cross section. The lip ring 7 is made of, for example, a known material excellent in self-lubricity and flexibility, for example, a resin material such as a fluororesin or a composite material based on the fluororesin. The lip ring 7 can be produced by bending a plate-like member, for example, but the production method of the lip ring is not particularly limited, and may be produced by, for example, cutting or molding.

  The lip ring 7 as a whole has a substantially circular cup-like (or substantially circular dish-like) appearance, and a circular opening is formed at the center of the bottom thereof. The outer diameter of the lip ring 7 is larger than the piston portion 51 and larger than the inner diameter of the cylinder 31. Therefore, as shown in FIG. 4, in a state where the piston portion 51 is housed in the cylinder 31, the lip ring 7 is elastically deformed in the direction of diameter reduction, and the outer peripheral surface of the lip ring 7 is a clearance over the entire circumference with respect to the cylinder inner peripheral surface. There is always sliding contact.

  The lip ring 7 is positioned between the mounting portion 72 located on the inner peripheral side, the lip portion 73 positioned on the outer peripheral side and in sliding contact with the inner peripheral surface of the cylinder, and between the lip portion 73 and the mounting portion 72. An arcuate lip ring R portion 74 (curved portion) is included.

  The mounting portion 72 of the lip ring 7 is sandwiched between the base portion 54 of the piston portion 51 and the pressing portion 63 of the lip ring fixing member 6. That is, the mounting portion 72 of the lip ring 7 is placed on the base portion 54, and in this state, the mounting portion 72 is fixed while being sandwiched between the base portion 54 of the piston and the pressing portion 63 of the fixing member. Yes. In this state, the lip ring R portion 74 is in close contact with the piston-side curved portion 56, and the outer peripheral surface of the lip portion 73 comes into sliding contact with the inner peripheral surface of the cylinder 31. Yes.

  The piston 51 and the lip ring fixing member 6 are fixed by screws. Therefore, the lip ring 7 is held in a state of being fixed on the piston portion 51 by the lip ring fixing member 6.

  When the substantially circular dish-shaped lip ring 7 is mounted on the piston portion 51, the lip portion 73 projects outward from the outer peripheral side of the piston portion 51. When the lip portion 73 of the lip ring 7 projects outward in this manner and is inserted into the cylinder 31 together with the piston portion 51, the outer side of the lip ring 7 is elastically deformed in the direction of diameter reduction and the outer periphery of the lip portion 73. The surface is slidably contacted with the inner peripheral surface of the cylinder 31 over the entire circumference without gaps. In this state, an annular gap 75 is formed between the inner peripheral surface of the lip portion 73 and the outer peripheral surface of the lip ring fixing member 6.

  The lip ring 7 configured as described above is reciprocated while swinging in the cylinder 31 together with the piston portion 51 when the air compressor is operated. At that time, the outer peripheral surface of the lip portion 73 is slid in a state in which the outer peripheral surface of the lip portion 73 is always in contact with the entire inner peripheral surface of the cylinder 31 without any gap, thereby sealing between the piston portion 51 and the inner peripheral surface of the cylinder 31 In addition, the airtightness of the compression chamber that becomes high pressure is maintained. That is, the space between the piston portion 51 and the cylinder 31 is hermetically sealed by the lip ring 7, and the compressed air in the compression chamber above the piston portion 51 is prevented from leaking from the gap between the piston portion outer periphery and the cylinder. .

(Operation during operation of the air compressor)
The air compressor of this embodiment having the above-described configuration operates as follows during its operation.

  When the motor of the air compressor is driven, the piston connected to the motor shaft reciprocates as in the prior art. During this reciprocating motion, the entire piston repeats rocking with respect to the cylinder. At that time, a flexible lip ring mounted on the upper surface side of the piston body is always in sliding contact with the inner peripheral surface of the cylinder.

  The piston repeats a suction stroke for sucking air from the suction chamber into the compression chamber and a compression stroke for compressing the air in the compression chamber and discharging it to the discharge chamber to generate compressed air. The air compressed in the first stage cylinder is sent to the second stage through the discharge chamber of the cylinder head, and is further compressed in the second stage cylinder. The high-pressure compressed air generated by the two-stage cylinder is discharged through the discharge chamber of the cylinder head and stored in an external air tank. The compressed air stored in the air tank is used for nailing machines and the like.

  In the process of repeating the reciprocating motion (suction stroke, discharge stroke) of the piston as described above, the piston portion 51 swings (tilts) with respect to the cylinder 31. Therefore, although the gap dimension between the piston part 51 and the inner peripheral surface of the cylinder 31 changes, the lip part 7 is elastic to the inner peripheral surface of the cylinder 31 with the lip ring R curved in the lip ring R part 74. Therefore, the space between the piston portion 51 and the inner peripheral surface of the cylinder 31 can always be sealed.

  That is, even when the piston portion 51 is inclined with respect to the cylinder 31 and the gap dimension between the piston portion 51 and the inner peripheral surface of the cylinder 31 is increased, the elastically deformed lip portion 73 is expanded by the restoration of the original shape. The outer peripheral surface expands in the radial direction and is brought into sliding contact with the inner peripheral surface of the cylinder 31. Therefore, even if the piston portion 51 of the piston swings with respect to the cylinder 31, the lip ring 7 can always seal between the two.

The embodiment of the present invention has been described above by taking the two-stage air compressor as a specific example.
In the above description, the configuration and operation of the two-stage piston of the two-stage compressor have been described as a representative example, but the same applies to the first-stage piston.

(Excellent effect achieved by air compressor)
According to the above-described air compressor of this embodiment, the base portion 54 and the curved portion 56 are formed in the piston portion 51 of the piston that reciprocates in the cylinder. Further, a substantially flat surface 57 in a direction substantially perpendicular to the piston axial direction is formed at a position adjacent to the outside of the curved portion 56. The lip ring 7 including the lip portion 73 and the attachment portion 72 is sandwiched between the piston portion 51 and the lip ring fixing member 6 in a state where the attachment portion 72 is placed on the base portion 54. In this fixed state, the bottom surface side of the lip ring R portion 74 is in contact with the curved portion 56 on the piston side, and the lip portion 73 is in sliding contact with the inner peripheral surface of the cylinder 31 (in a state of being elastically deformed in the reduced diameter direction). It is like that.

  By configuring as described above, even when the lip ring R portion 74 receives a force in the direction of the arrow A as shown in FIG. 4 (b) due to the air pressure in the compression stroke and the frictional force with the cylinder inner periphery, Since the bottom surface side of the lip ring R portion 74 is in contact with the curved portion 56 on the piston side, the deformation as shown in FIG. 2B described in <First Problem> of the prior art can be prevented.

  Further, in the present invention, a substantially flat surface 57 is formed at an outer adjacent position (an outer edge portion on the upper surface side of the piston portion) of the curved portion 56 on the piston side. Therefore, even if the lower portion of the lip ring R portion 74 is brought into contact with the substantially flat surface 57 outside the curved portion 56 by the force in the arrow A direction, the force in the arrow A direction can be received by the substantially flat surface 57. As a result, the stress acting on the lip ring 7 is dispersed (not concentrated on one point in a cross-sectional view), and moved to the lip ring side as shown in FIG. It is possible to prevent the sharp corners from being bitten.

  As a result of preventing the deformation of the lip ring R portion 74 and the occurrence of cracks due to the biting of the piston portion 51 into the lip ring 7, the excellent effect of improving the durability of the lip ring 7 can be obtained. Achieved.

(Other embodiments)
In the above-described embodiment, a two-stage air compressor has been described as an example of the present invention. However, the present invention can also be applied to a single-stage air compressor or a three-stage or more air compressor. .

  In the above-described embodiment, the oscillating piston called “rocking piston” is illustrated as an application target of the seal member. However, the application range of the present invention is not necessarily limited to the oscillating piston (rocking piston). It is also possible to apply to other pistons that can be equipped with a sealing member such as a lip ring.

  Next, specific examples of the present invention will be described.

  An experiment for confirming the durability of the lip ring was performed using a two-stage air compressor as shown in FIG.

  Specifically, an experiment was conducted by incorporating the above-described piston and lip ring structure on the two-stage side of a two-stage compression reciprocating compressor having a maximum ultimate pressure of 4.5 MPa. In this experiment, the compressor was operated with the pressure kept constant at 4 MPa.

The durability of the lip ring was determined by the following method.
(1) At the initial stage of the assembly of the compressor, the compressor was operated from atmospheric pressure, and the time taken to increase the pressure to the maximum ultimate pressure of 4.5 MPa was measured, and this was used as the reference time.
(2) Test time until the time required for operating the compressor from atmospheric pressure and increasing the pressure to the maximum pressure of 4.5 MPa is increased to 10% or more of the initial assembly time (reference time) That is, the operation time was measured.

  In this experiment, the following four types of pistons (Comparative Example 1, Comparative Example 2, Example 1, Example 2) having different structures were used. The lip ring attached to the piston was of the same type and size in all comparative examples and examples.

(Comparative Example 1)
The piston of the comparative example 1 had the structure of the prior art shown in FIG. That is, as shown in FIG. 2, a piston was used in which only a flat base portion was formed outside the circular recess and no curved portion was formed.

(Comparative Example 2)
The piston of Comparative Example 2 had the prior art structure shown in FIG. That is, as shown in FIG. 3, an acute-angled protruding edge formed so as to protrude upward is formed on the outer edge of the biston part, and a piston having a curved part between the base part and the protruding edge is provided. used.

Example 1
The piston of Example 1 was provided with a base part and a curved part as shown in FIG. 4, and further provided with a substantially flat surface in a direction perpendicular to the piston axial direction at the tip of the curved part. The width of the substantially plane was set to 1/2 or less of the lip ring plate thickness dimension. The dimensions of the piston part of Example 1 and the main part of the lip ring used in the experiment were as shown in FIG.

(Example 2)
The piston of Example 2 was provided with a base portion and a bending portion as shown in FIG. 4, and further provided with a substantially flat surface in a direction perpendicular to the piston axial direction at the tip of the bending portion. The width of the substantially flat surface was set to 1/2 or more of the lip ring plate thickness. The dimensions of the main part of the piston part and lip ring of Example 2 used in the experiment were as shown in FIG.

(Experimental result)
The pistons of the comparative examples and examples were individually attached to the two-stage compressor, and the above-described experiment was performed for each comparative example and each example.
The experimental results are shown in Table 1.

As shown in Table 1,
In the case of Comparative Example 1, the operation time required until the time taken to increase the pressure to the maximum ultimate pressure of 4.5 MPa was increased to 10% or more was 406 hours.
In the case of Comparative Example 2, it was 798 hours.
In the case of Example 1, it was 1131 hours.
In the case of Example 2, it was 1283 hours.

  Therefore, the endurance time of the lip ring (maximum pressure reached 4.5 MPa) is higher in the compressor having the piston of the example (the present invention) than in the compressor having the piston of the comparative example (prior art). It was found that the test time until the time taken to increase the time increased to 10% or more with respect to the initial time was improved. That is, it was confirmed that the durability of the lip ring (seal member) was improved by applying the piston structure of the present invention.

  In addition, it was found that the durability time of the lip ring was further improved in Example 2 than in Example 1. In other words, it is confirmed that the durability of the lip ring (seal member) attached to the piston part is further improved by expanding the width of the substantially flat surface on the piston side to be 1/2 or more of the lip ring plate thickness. did it.

DESCRIPTION OF SYMBOLS 1 Crankcase 3 Crankshaft 5 Two-stage high-pressure oscillating piston (oscillating second piston)
6 Lip ring fixing member 7 Lip ring (substantially ring-shaped seal member)
8 Motor shaft 9 Motor 11 Low-pressure one-stage cylinder 13 Cylinder head 21 One-stage low-pressure oscillating piston (oscillating first piston)
31 High-pressure two-stage cylinder 33 Cylinder head 40 Piston body 41 Two-stage high-pressure oscillating piston (oscillating second piston)
42 Piston part 43 Circular concave part 44 Base part 45 Projection edge part 46 Curved part 51 Piston part 53 Circular concave part 54 Base part 56 Curved part 57 Rough plane 61 Lip ring fixing member 62 Circular convex part 63 Lip ring pressing part 71 Lip ring (substantially Ring-shaped seal member)
72 Mounting portion 73 Lip portion 74 Lip ring R portion 75 Clearance

Claims (3)

A compressor including a seal member that seals between a piston portion and a cylinder,
A base part to be a base of a seal member attached to the piston part;
A curved portion formed on the outside of the base portion and contacting the R portion on the bottom surface side of the seal member;
A substantially flat surface formed in a direction substantially perpendicular to the piston axial direction, formed outside the curved portion;
A compressor comprising a piston having The curved portion is formed between the base portion and the substantially flat surface,
The substantially flat surface is formed at an outer edge portion of the piston portion.
The compressor according to claim 1.   3. The compressor according to claim 1, wherein a width of the substantially flat surface is ½ or more of a plate thickness of the seal member.