JP5598206B2 - air compressor - Google Patents

Description

  The present invention relates to a reciprocating air compressor.

  Conventionally, in a reciprocating compressor that generates compressed air by reciprocating movement of the piston in the compression chamber defined in the cylinder, it is mounted on the outer periphery of the piston to prevent leakage of compressed air to the non-compressing chamber side (back side) It is also known to have a lip ring that is in sliding contact with the inner periphery of a cylinder. The lip ring has a shape bent toward the compression chamber side, and reciprocates in a state where the outer periphery thereof is always pressed against the inner periphery of the cylinder by the pressure of the compressed air in the compression chamber. When the pressure of the compressed air in the compression chamber is high, the lip ring may turn over to the anti-compression chamber, and the performance may be deteriorated due to the compressed air leaking to the anti-compression chamber. Therefore, for example, in the reciprocating pump described in Patent Document 1, the lip ring is prevented from being turned up by forming a support portion that supports the side surface of the anti-compression chamber of the lip ring at the outer edge portion of the piston.

JP 2001-280250 A

  However, in the reciprocating pump described in Patent Document 1, since the piston is formed of a metal material such as aluminum as an integral part of the connecting rod, it is necessary to ensure that the cylinder is not in direct contact with the cylinder formed of the metal material. There must be a gap in the radial direction. For this reason, the compressed air with high pressure is deformed so that the lip ring enters the gap, and a gap is formed between the lip ring and the cylinder, which may cause leakage of the compressed air.

  This invention is made | formed in view of this problem, Comprising: It aims at providing the air compressor which can prevent the leak of compressed air.

In order to achieve the above object, an air compressor according to the present invention includes:
A cylinder,
A piston that slides within the cylinder and defines a compression chamber with the cylinder;
A bent portion that bends from the radial direction of the cylinder toward the compression chamber, a contact portion that extends from the bent portion and contacts the inner peripheral portion of the cylinder, and seals between the cylinder and the piston; A plurality of lip rings arranged to overlap each other in the sliding direction of the piston,
With
The plurality of lip rings include a first lip ring and a second lip ring disposed on a side of the first lip ring opposite to the compression chamber, and are made of a material having substantially the same coefficient of thermal expansion. And
The bent portion of the second lip ring is in contact with the bent portion of the first lip ring and has a curvature substantially equal to the curvature of the bent portion of the first lip ring;
It is characterized by that.

  Each of the plurality of lip rings may have a substantially uniform thickness.

  The first lip ring may be formed so as to be gradually thinner from the bent portion to the contact portion.

  ADVANTAGE OF THE INVENTION According to this invention, the air compressor which can prevent the leakage of compressed air can be provided.

It is a top view of the air compressor concerning the embodiment of the present invention. It is a side view of the air compressor concerning an embodiment of the present invention. It is a front view of the air compressor concerning an embodiment of the present invention. It is principal part sectional drawing of the 1st step | paragraph compression apparatus of the air compressor which concerns on embodiment of this invention. It is principal part sectional drawing of the 2nd stage | paragraph compression apparatus of the air compressor which concerns on embodiment of this invention. It is a principal part enlarged view of FIG. It is a principal part enlarged view of FIG. It is a figure for demonstrating the waist broken state of a lip ring. It is a figure which shows the modification of a 1st lip ring.

  Hereinafter, an air compressor according to an embodiment of the present invention will be described with reference to the drawings. 1 to 3 are a top view, a side view, and a front view, respectively, of the air compressor 1 according to the present embodiment. As shown in the figure, the air compressor 1 is mainly composed of a drive unit 100, an air tank unit 200, a control circuit unit 300, and a compressed air generation unit 400, which are indicated by a two-dot chain line. It is accommodated in the cover 500. The air compressor 1 includes a handle 600 for carrying.

  The drive unit 100 is composed of, for example, an electric motor or the like, and converts the rotational motion of the electric motor to the reciprocating motion of the piston of the compressed air generation unit 400 via a crankshaft (not shown), thereby causing the compressed air generation unit 400 to move. Drive. The drive circuit of the drive unit 100 is controlled by the control circuit unit 300. Further, the cooling fan 110 is provided so as to sandwich the compressed air generating unit 400 together with the driving unit 100. The cooling fan 110 is attached to the rotation shaft of the drive unit 100 and cools the compressed air generation unit 400 by ventilation.

  The air tank unit 200 is composed of a pair of cylindrical air tanks 211 and 212 arranged in parallel. The air tanks 211 and 212 store the compressed air generated by the compressed air generation unit 400 and supplied through the discharge pipe 220. The supplied compressed air has a pressure of, for example, 3.0 to 4.2 MPa in the air tanks 211 and 212. In addition, since the air tanks 211 and 212 are connected via the communication pipes 231 and 232, the pressure inside the air tanks 211 and 212 is maintained substantially the same. The compressed air stored in the air tanks 211 and 212 is depressurized to a predetermined pressure by the pressure reducing valves 241 and 242 and then connected to the compressed air outlets (couplers) 251 and 252 (not shown). ) Through an air tool (not shown) such as a nailer. Pressure gauges 261 and 262 are attached in the vicinity of the couplers 251 and 252 so that the pressure of the compressed air taken out from the couplers 251 and 252 can be monitored.

  The control circuit unit 300 is mainly composed of a main power switch 310, a display unit 320, and a circuit board (not shown) on which switching elements and the like are arranged, and based on an operation signal from the main power switch 310 and the like. The on / off of the electric motor of the drive unit 100 is controlled. The display unit 320 displays, for example, a warning about tank pressure or overload using an LED or the like.

  The compressed air generating unit 400 generates compressed air by compressing air taken from outside. For example, as shown in FIG. 1, the first stage compressor 410, the second stage compressor 420, the crank A case 430. The first-stage compression device 410 and the second-stage compression device 420 are arranged to face each other via the crankcase 430. FIG. 4 shows a cross-sectional view of a main part of the first stage compression device 410, and FIG. 5 shows a cross-sectional view of a main part of the second stage compression device 420. The first-stage compression device 410 includes a low-pressure side cylinder 411, a low-pressure side piston 412, a low-pressure side connecting rod 413, and the like formed from a metal material such as an aluminum alloy. The low pressure side cylinder 411 and the low pressure side piston 412 define a low pressure side compression chamber 414 in which air taken in from the outside is compressed. The second-stage compression device 420 includes a high-pressure side cylinder 421, a high-pressure side piston 422, a high-pressure side connecting rod 423, and the like formed from a metal material such as an aluminum alloy. The high pressure side cylinder 421 and the high pressure side piston 422 define a high pressure side compression chamber 424 in which the compressed air discharged from the first stage compression device 410 is compressed. The low pressure side piston 412 and the high pressure side piston 422 are connected to a crankshaft (not shown) via a low pressure side connecting rod 413 and a high pressure side connecting rod 423, respectively. With this configuration, the rotational motion of the crankshaft is converted into the reciprocating motion of the low pressure side piston 412 in the low pressure side cylinder 411 and the reciprocating motion of the high pressure side piston 422 in the high pressure side cylinder 421.

  Next, the low pressure side lip ring 415 for sealing between the low pressure side cylinder 411 and the low pressure side piston 412 in the first stage compression device 410 will be described with reference to FIGS. 4 and 6. In the following description, among the sliding directions of the low-pressure side piston 412, the moving direction of the low-pressure side piston 412 during the compression process is the upward direction, and the opposite is the downward direction.

  As shown in FIG. 4, the low-pressure side lip ring 415 formed in an annular shape is formed on the upper surface of the low-pressure side connecting rod 413 with a protruding portion 412 a protruding downward in a cylindrical shape from the lower surface of the low-pressure side piston 412. Arranged. Further, the protrusion 412 a of the low pressure side piston 412 is fitted into a recess 413 a formed on the upper surface of the low pressure side connecting rod 413. The low pressure side piston 412 is fixed to the low pressure side connecting rod 413 by the bolt 416 in a state where the low pressure side lip ring 413 is sandwiched between the low pressure side piston 412 and the low pressure side connecting rod 413.

  FIG. 6 shows an enlarged view of the main part of FIG. As shown in FIG. 6, the low-pressure lip ring 415 includes a flat plate portion 415a sandwiched by the upper surfaces of the low-pressure piston 412 and the low-pressure connecting rod 413, a bent portion 415b bent upward from the flat plate portion 415a, and a bent portion 415b. And an abutting portion 415 c that abuts against the inner peripheral portion of the low-pressure side cylinder 411. With such a configuration, when the bent portion 415b receives a downward pressure due to the pressure of compressed air during the compression process, the contact portion 415c is more strongly contacted with the inner peripheral portion of the low-pressure side cylinder 411. In this way, the low pressure side lip ring 415 seals the low pressure side compression chamber 414.

  The low-pressure lip ring 415 is made of, for example, a fluororesin such as PTFE (Polytetrafluoroethylene). Thereby, friction with the inner peripheral part of the low pressure side cylinder 411 can be made small, and slidability can be improved.

  Next, the 1st lip ring 425 and the 2nd lip ring 426 which seal between the high pressure side cylinder 421 and the high pressure side piston 422 in the 2nd stage | paragraph compression apparatus 420 are demonstrated using FIG. 5, FIG. In the following description, among the sliding directions of the high-pressure side piston 422, the moving direction of the high-pressure side piston 422 during the compression process is the upward direction, and the opposite is the downward direction.

  As shown in FIG. 5, the first lip ring 425 and the second lip ring 426 that are formed in an annular shape are overlapped with each other and inserted through a protrusion 422 a that protrudes downward in a cylindrical shape from the lower surface of the high-pressure side piston 422. . The upper surface of the high-pressure side connecting rod 423 is formed with a protruding portion 423a with which the lower surface of the protruding portion 422a of the high-pressure side piston 422 abuts. Further, a step portion 423b in which the second lip ring 426 is disposed is formed on the outside of the protruding portion 423a of the high-pressure side connecting rod 423. Then, in a state where the first lip ring 425 and the second lip ring 426 are sandwiched between the high pressure side piston 422 and the high pressure side connecting rod 423, the high pressure side piston 422 is fixed to the high pressure side connecting rod 423 by the bolt 427.

  FIG. 7 is an enlarged view of a main part of FIG. The first lip ring 425 includes a flat plate portion 425a sandwiched between the second lip ring 426 and the high pressure side piston 422, a bent portion 425b bent upward from the flat plate portion 425a, and a high pressure side cylinder 421 extending from the bent portion 425b. It is comprised integrally from the contact part 425c contact | abutted with the inner peripheral part. With such a configuration, when the bent portion 425b receives a downward pressure due to the pressure of compressed air during the compression process, the contact portion 425c is more strongly contacted with the inner peripheral portion of the high-pressure side cylinder 421. In this way, the first lip ring 425 seals the high pressure side compression chamber 424 in the same manner as the low pressure side lip ring 415.

  The first lip ring 425 is formed of a fluororesin such as PTFE, for example. Thereby, friction with the inner peripheral part of the high pressure side cylinder 421 can be reduced, and slidability can be improved.

  The second lip ring 426 is disposed below the flat portion 425a and the bent portion 425b of the first lip ring 425, and the first lip ring 425 (particularly, the deformation of the first lip ring 425 due to downward pressure is suppressed). The bent portion 425b) is supported.

  Specifically, as shown in FIG. 7, the second lip ring 426 includes a flat plate portion 426a sandwiched between the first lip ring 426 and the high pressure side connecting rod 423, and a bent portion 426b bent upward from the flat plate portion 426a. And an abutting portion 426c that is formed at the outer edge of the bent portion 426b and abuts against the inner peripheral portion of the high-pressure side cylinder 421. The upper surface of the bent portion 426a has a curvature substantially equal to the lower surface of the bent portion 425b of the first lip ring 425. As a result, the bent portion 426b of the second lip ring 426 contacts the bent portion 425b of the first lip ring 425 without any gap, so that the second lip ring 426 causes the bent portion 425b of the first lip ring 425 to press downward. Can be favorably supported.

  The outer diameters of the first lip ring 425 and the second lip ring 426 are the same as those on the high pressure side in the state before assembly (the first lip ring 425 and the second lip ring 426 are not placed in the high pressure side cylinder 421). It is larger than the inner diameter of the cylinder 421. Thereby, in the assembled state, the first lip ring 425 and the second lip ring 426 abut against the abutting portions 425c and 426c against the inner peripheral portion of the high-pressure side cylinder 421 in the outer diameter direction. . Therefore, when the high pressure side piston 422 swings, the first lip ring 425 and the second lip ring 426 come into contact with the inner peripheral portion of the high pressure side cylinder 421 to prevent air leakage from the high pressure side compression chamber 424.

  Further, the first lip ring 425 is thinner than the second lip ring 426. As a result, the second lip ring 426 is more flexible than the first lip ring 425. Therefore, when the high pressure side piston 422 swings, the contact portion 425c of the first lip ring 425 is easily brought into close contact with the inner peripheral portion of the high pressure side cylinder 421 due to the pressure of the compressed air, so that air leakage can be more reliably performed. Can be prevented. However, the thickness of the 1st lip ring 425 and the 2nd lip ring 426 is not restricted to this, You may determine suitably according to the raw material and shape, and the pressure of the air to compress.

  The thicknesses of the first lip ring 425 and the second lip ring 426 are substantially uniform from the flat plate portions 425a and 426a to the contact portions 425c and 426c, respectively. Thereby, the 1st lip ring 425 and the 2nd lip ring 426 can be easily manufactured by press molding from the plate-like material of fluororesin as mentioned above.

  Further, the height of the second lip ring 426, that is, the height from the lower surface contacting the stepped portion 423b of the high pressure side connecting rod 423 to the uppermost end is determined so that the first lip ring 425 contacts the inner peripheral portion of the high pressure side cylinder 421. It is high enough to maintain. This is because the height of the second lip ring 426 is higher than this, and the bent portion 426b is bent toward the high-pressure side compression chamber 424 with the same curvature as the lower surface of the bent portion 425b of the first lip ring 425. This is because the contact portion 425c of the first lip ring 425 and the inner peripheral portion of the high-pressure side cylinder 421 are not in contact with each other, causing air leakage.

  The second lip ring 426 is made of, for example, a fluororesin such as PTFE. Thereby, friction with the inner peripheral part of the high pressure side cylinder 421 can be reduced, and slidability can be improved. The second lip ring 426 is preferably made of a material having a thermal expansion coefficient substantially equal to that of the first lip ring 425. As a result, even if the second lip ring 426 and the first lip ring 425 expand due to heat absorbed during the compression process, the second lip ring 426 expands at a substantially equal rate, so the second lip ring 426 is bent by the first lip ring 425. The portion 425b can continue to be supported at the bent portion 426b. Further, the second lip ring 426 has such a rigidity that it can suppress buckling deformation such as hip folding of the first lip ring 425 and can prevent contact between the high pressure side piston 422 and the high pressure side cylinder 421. Further, the second lip ring 426 has such flexibility that the high pressure side cylinder 421 is not damaged by contact with the inner peripheral portion of the high pressure side cylinder 421.

  The operation in the compressed air generation unit 400 configured as described above will be described. First, the first stage compression device 410 compresses the external air (atmospheric pressure) sucked into the low pressure side compression chamber 414 via the inside of the crankcase 430, and compresses the second stage via the first stage piping. Compressed air is supplied to the device 420. The second stage compression device 420 compresses the compressed air supplied from the first stage compression device 410 to an allowable maximum pressure of, for example, 3.0 to 4.5 MPa in the high pressure side compression chamber 424, and passes through the discharge pipe 220. Then, compressed air is supplied to the air tanks 211 and 212.

  Next, operations of the first lip ring 425 and the second lip ring 426 according to the present embodiment will be described.

  First, the operation when a high pressure is applied to a conventional lip ring that is not supported by the second lip ring 426 such as the low pressure side lip ring 415 will be described using the configuration of the low pressure side compression device 410. In the compression process, when a low pressure such as 0.5 to 1.5 MPa is applied to the low pressure side lip ring 415, the low pressure side lip ring 415 resists the pressure and suppresses the downward deformation. The compression chamber 414 can continue to be sealed. However, when a high pressure of, for example, 3.0 to 4.5 MPa is applied, the low pressure side lip ring 415 is buckled and deformed as shown in FIG. 8 due to the frictional force between the high pressure and the low pressure side cylinder 411. Become. As a result, a gap is formed between the low-pressure side cylinder 411 and the low-pressure side lip ring 415, and the compressed air leaks, so that the compression ratio decreases.

  Next, the operation when high pressure is applied to the first lip ring 425 supported by the second lip ring 426 in the high-pressure side compression device 420 will be described. As shown in FIG. 7, the first lip ring 425 is supported by a second lip ring 426 disposed below at a bent portion 425b. Therefore, even if a high pressure is applied downward to the first lip ring 425 during the compression process, the first lip ring 425 does not fall in the waist as shown in FIG. 8 and contacts the high pressure side cylinder 421 at the contact portion 425c. You can continue. Therefore, the first lip ring 425 can continue to seal the high-pressure side compression chamber 424.

  As described above, in the air compressor 1 according to the present embodiment, the second lip ring 426 is disposed below the bent portion 425b of the first lip ring 425, thereby reducing the pressure in the downward direction during the compression process. The deformation of the first lip ring 425 can be suppressed, the leakage of compressed air from the gap formed by the deformation of the first lip ring can be prevented, and the high-pressure side compression chamber 424 can be satisfactorily sealed.

  In the present embodiment, the bent portion 426b of the second lip ring 426 has a curvature substantially equal to that of the bent portion 425b of the high-pressure side lip ring 425. Therefore, the bent portion 425b of the first lip ring 425 and the second lip ring 426 are provided. And the bent portion 426b abut against each other without a gap. Therefore, the second lip ring 426 can favorably support the bent portion 425 of the first lip ring 425 against the downward pressure.

  In the present embodiment, the first lip ring 425 and the second lip ring 426 are made of materials having substantially the same thermal expansion coefficient. With such a configuration, even if the first lip ring 425 and the second lip ring 426 expand due to heat absorbed during the compression process, the first lip ring 425 and the second lip ring 426 expand at a substantially equal rate. The state where the bent portion 426b of the lip ring 426 is in contact with no gap is maintained. Therefore, the second lip ring 426 can favorably support the first lip ring 425.

  In addition, this invention is not limited to said embodiment, A various deformation | transformation and application are possible. For example, in the above embodiment, the high pressure side compression chamber 424 is sealed by two lip rings, that is, the first lip ring 425 and the second lip ring 426. However, the number of lip rings is not limited to this. The greater the number of lip rings, the more reliably the high pressure side compression chamber 424 can be sealed. Further, the number of lip rings may be determined according to the pressure of air to be compressed.

  In the above embodiment, the first lip ring 425 and the second lip ring 426 have a substantially uniform thickness from the flat plate portions 425a and 426a to the contact portions 425c and 426c. However, the shape of the first lip ring and the second lip ring is not limited to this. For example, as shown in FIG. 9, the first lip ring 427 is formed so as to have a substantially uniform thickness from the flat plate portion 427a to the bent portion 427b, and gradually becomes thinner from the bent portion 427b to the contact portion 427c. May be. As described above, the bent portion 427b has a thickness that does not buckle when supported by the second lip ring 426, and the abutting portion 427c is formed thin so that the inner peripheral portion of the high-pressure side cylinder 421 is formed. The high pressure side compression chamber 424 can be sealed more reliably.

DESCRIPTION OF SYMBOLS 1 Air compressor 100 Drive part 110 Cooling fan 200 Air tank part 211,212 Air tank 220 Discharge pipe 231,232 Communication pipe 241,242 Pressure reducing valve 251,252 Compressed air take-out port (coupler)
261, 262 Pressure gauge 300 Control circuit section 310 Main power switch 320 Display section 400 Compressed air generating section 410 First stage compression device 411 Low pressure side cylinder 412 Low pressure side piston 412a Protruding section 413 Low pressure side connecting rod 413a Recessed section 414 Low pressure side compression chamber 415 Low pressure side lip ring 416 Bolt 420 Second stage compression device 421 High pressure side cylinder 422 High pressure side piston 422a Protruding portion 423 High pressure side connecting rod 423a Protruding portion 423b Stepped portion 424 High pressure side compression chambers 425, 427 First lip ring 425a, 427a Flat plate portion 425b, 427b Bent part 425c, 427c Abutting part 426 Second lip ring 426a Flat plate part 426b Bending part 426c Abutting part 427 Bolt 500 Main body cover 600 Handle

Claims (3)

A cylinder,
A piston that slides within the cylinder and defines a compression chamber with the cylinder;
A bent portion that bends from the radial direction of the cylinder toward the compression chamber, a contact portion that extends from the bent portion and contacts the inner peripheral portion of the cylinder, and seals between the cylinder and the piston; A plurality of lip rings arranged to overlap each other in the sliding direction of the piston,
With
The plurality of lip rings include a first lip ring and a second lip ring disposed on a side of the first lip ring opposite to the compression chamber, and are made of a material having substantially the same coefficient of thermal expansion. And
The bent portion of the second lip ring is in contact with the bent portion of the first lip ring and has a curvature substantially equal to the curvature of the bent portion of the first lip ring;
An air compressor characterized by that. Each of the plurality of lip rings has a substantially uniform thickness.
The air compressor according to claim 1 . The first lip ring is formed so as to become gradually thinner from the bent portion to the contact portion.
The air compressor according to claim 1 .

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