JP5380353B2 - Reciprocating compressor - Google Patents

Description

  The present invention relates to a reciprocating compressor in which a piston swings in a cylinder.

  The oscillating compressor disclosed in Patent Document 1 is a two-stage reciprocating compressor that compresses air compressed by a low pressure side compression unit using a high pressure side compression unit, and a piston reciprocates while oscillating in a cylinder. The air was compressed by the low pressure side compression part and the high pressure side compression part.

  In addition, the two-stage compressor disclosed in Patent Document 2 is a two-stage reciprocating compressor that compresses air compressed by the low-pressure side compression section using the high-pressure side compression section. By using a piston to which the piston body is fixed, it is formed so that the piston reciprocates while swinging (inclining) in the cylinder, and in the high pressure side compression section, the piston body swings with respect to the connecting rod tip. By using the piston, the tip of the piston is reciprocated in the cylinder without being inclined.

JP2007-32532A JP-A-11-62822

  Since the oscillating compressor of Patent Document 1 forms the piston without considering the angle of inclination of the piston in the low-pressure side or high-pressure side cylinder, it is possible to improve the sealing performance and life of the piston. There wasn't.

  In addition, the two-stage compressor disclosed in Patent Document 2 uses a piston whose piston body swings with respect to the tip of the connecting rod in the high-pressure side compression section. It was difficult to reduce the size.

  In view of the above problems, the present invention provides a low-pressure side compression part and a high-pressure side compression part piston in consideration of the angle at which the piston inclines in a cylinder, thereby providing a reciprocating piston having a compact and highly sealable piston. An object is to provide a dynamic compressor.

In order to solve the above-described problems, a reciprocating compressor according to the present invention has a low-pressure side piston and a low-pressure side cylinder, and the low-pressure side piston reciprocates while swinging in the low-pressure side cylinder. The high pressure side piston is compressed by the low pressure side compression portion by reciprocating while swinging in the high pressure side cylinder. A reciprocating compressor comprising a high-pressure side compressor that further compresses air, and a motor that drives the low-pressure side compressor and the low-pressure side compressor, and is based on a maximum inclination angle when the low-pressure side piston swings The maximum inclination angle when the high-pressure side piston swings does not increase, and the maximum clearance generated between the low-pressure side piston and the low-pressure side cylinder when the low-pressure side piston swings. It is characterized in that the serial maximum gap generated between the high pressure side piston during oscillation of the high-pressure side piston and the high pressure side cylinder are prevented from becoming large.

A reciprocating compressor according to another aspect of the present invention includes a motor having a rotation shaft, a low-pressure side cylinder, and a low-pressure side piston, and compresses air, a high-pressure side cylinder, and a high-pressure side piston. A reciprocating compressor including a high-pressure side compression unit that further compresses the air compressed by the low-pressure side compression unit, wherein the low-pressure side piston and the high-pressure side piston are each a rotating shaft of the motor. An eccentric that performs an eccentric motion with rotation; a connecting rod extending from the eccentric; and a piston body provided at a tip of the connecting rod; the eccentric amount of the low-pressure side piston with respect to the rotational axis of the motor of the motor Is r1, and r1> r2 where r2 is the amount of eccentricity of the high-pressure side piston relative to the rotational shaft of the eccentric motor. The low-pressure side piston and to form the high-pressure side piston, said at swinging of the high pressure side piston than the maximum gap generated between the low-pressure side piston during oscillation of the low-pressure side piston and the low pressure side cylinder as The maximum gap generated between the high-pressure side piston and the high-pressure side cylinder is reduced .

  ADVANTAGE OF THE INVENTION According to this invention, the two-stage reciprocating compressor provided with the piston with a compact and high sealing performance can be provided.

It is the figure which showed the low voltage | pressure side compression part and high voltage | pressure side compression part of the compressor in the Example of this invention. It is the figure which expanded the high voltage | pressure side compression part in the Example of this invention. It is the figure which showed the whole reciprocating compressor in the Example of this invention. It is the figure which showed the rocking | fluctuation motion of the piston in an Example in this invention.

  An embodiment of the present invention will be described with reference to FIGS.

  A compressor according to an embodiment of the present invention will be described with reference to FIG. The compressor in the present embodiment has a crankcase 1, and a motor 3 having a shaft (rotating shaft) 2 is attached to the crankcase 1. The shaft 2 of the motor 3 is provided with a connecting rod 4A and a piston 4 on the low pressure side including a piston body 5, a connecting rod 8A and a piston body 11 via an eccentric 7 and an eccentric 13 for converting rotational motion into reciprocating motion, respectively. The high-pressure side piston 8 provided is attached. The low pressure side piston main body 5 is constituted by a retainer 5A, and the high pressure side piston main body 11 is constituted by a base 11A and a top 12A.

  The piston body 5 on the low pressure side is provided with a lip ring 6. The high pressure side piston body 11 is provided with a lip ring 9 and a piston ring 10.

  The lip ring 6 is provided with a skirt portion (lip portion) in order to increase the contact area with the cylinder 14, and is mounted in a direction in which the skirt portion faces the compression chamber on the low pressure side. Thereby, the sealing performance between the piston 4 and the cylinder 14 can be ensured.

Next, it demonstrates, referring the enlarged view of the high voltage | pressure side compression part shown in FIG.
The lip ring 6, the lip ring 9 and the piston ring 10 are formed in a substantially annular shape by a resin material excellent in wear resistance and self-lubricating property. The piston ring 10 has a substantially rectangular cross section and a constant radial width over the entire circumference. Further, the piston ring 10 is formed with an abutment portion (not shown) in the circumferential direction thereof, so that the diameter can be enlarged and reduced while maintaining the sealing performance by the abutment portion. In addition, the piston ring 10 has an inner diameter in a state where the piston ring 10 is in contact with an inner peripheral surface of a high-pressure side cylinder 17 described later when the high-pressure side piston 8 is at the top dead center position or the bottom dead center position. The diameter is larger than the minimum diameter of the piston ring groove, which is the groove in the portion where the is mounted. Thereby, the piston ring 10 can be moved in the radial direction with respect to the piston 8 on the high pressure side.

The lip ring 9 is mounted in a direction opposite to the lip ring 6 (direction in which the skirt portion faces the crankcase side). By mounting in this direction, the centers of the lip ring 9 and the piston body 11 coincide. Further, when the cylinder 17 is assembled to the crankcase 1, the lip ring 9 comes into contact with the inner wall surface of the cylinder 17 and determines the assembly position of the cylinder 17. Therefore, the centers of the cylinder 17 and the piston body 11 coincide. As a result, the piston ring 10 mounted on the piston body 11 and the cylinder 17 can be centered. Furthermore, the lip ring 9, it is possible to the piston ring 10 to prevent contact between the piston body 11 and the cylinder 17 when worn, can improve the life of the piston main body 11 and the cylinder 17. Further, by sandwiching the lip ring 9 between the base 11A and the connecting rod 8A, it is possible to prevent the compression heat generated in the cylinder 17 from being transmitted from the piston body 11 to the connecting rod 8A, and to increase the temperature of the large end portion. Can be reduced. As a result, it is possible to improve the life of the bearings provided on the outer circumferences of the eccentrics 7 and 13.

  By attaching the lip ring 6 to the low pressure side piston 4, the manufacturing cost can be reduced. Further, by installing the lip ring 9 on the high-pressure side piston 8 and mounting the piston ring 10, it is possible to improve the assembling property, the sealing property, and the wear resistance.

  A low pressure side cylinder 14, an air valve 15, a cylinder head 16 and a high pressure side cylinder 17, an air valve 18 and a cylinder head 19 are attached to the crankcase 1. The low pressure side connecting rod 4A is provided on the low pressure side. A compression chamber is formed in each cylinder by the piston 4 and the high-pressure side piston 8 provided with the high-pressure side connecting rod 8A.

  In the compressor according to the embodiment of the present invention, when the shaft 2 is rotated by driving the motor 3, the low pressure side and high pressure side pistons 4 and 8 are reciprocated in the cylinders 14 and 17 by the eccentrics 7 and 13, respectively. The low pressure side compression section including the piston 4 and the cylinder 14 on the side and the high pressure side compression section including the piston 8 and the cylinder 17 on the high pressure side are driven. The low-pressure side compression unit sucks air from the atmospheric pressure into the cylinder 14 through the cylinder head 16 and the air valve 15, compresses it, and discharges it to the high-pressure side compression unit via a pipe (not shown). Is a two-stage compression structure that sucks in the compressed air discharged by the low-pressure side compression section, further compresses it, and discharges it to the storage tank. At this time, the structure is such that the low-pressure side and the high-pressure side compression section and the piping are cooled by air by the rotation of the fan 20 attached coaxially with the shaft 2.

  In general, in the case of a single-stage compression air compressor, air is sucked from atmospheric pressure and compressed with a piston to the maximum pressure and discharged, but during compression, compression heat is generated and discharged, reducing the efficiency of the motor. Noise, vibration, etc. occur due to torque fluctuations of the motor, and the performance of the motor requires a large output and increases in size. In increasing the pressure, the discharge temperature rises due to an increase in pressure ratio (discharge absolute pressure / suction absolute pressure), and the suction efficiency decreases, making it difficult to secure the amount of discharge air. Furthermore, an increase in the discharge temperature may increase the deformation and leakage of the air valve. Further, in the compression that performs simple (intermittent) operation, moisture in the intake air may condense and increase the generation of drainage, which may cause failure.

  Therefore, for example, in the compressor in Patent Document 2, when the pressure is increased to about 1 MPa or more as an example, the low pressure side sucks air from the atmospheric pressure, and pressurizes and temporarily cools, and the high pressure side increases the pressure on the low pressure side and performs intermediate cooling. The above problem is prevented by adopting a two-stage compression structure that sucks in the air and further pressurizes and discharges the air. In particular, portable compact compressors employ a two-stage compression structure from the viewpoint of low vibration, low noise, and miniaturization (small motor size and light weight of the compression section).

  In the two-stage compression, the pressure ratio on the low-pressure side and the high-pressure side is smaller than in the case of the one-stage compression, so that the efficiency is improved and less heat is generated, and the performance degradation due to the heat generation described above can be reduced. Since fluctuations in motor torque can be reduced, low vibration and low noise can be realized.

  Next, the design of a general two-stage compressor will be described.

Here, in the two-stage compressor of Patent Document 2, in the high-pressure side and the connecting rod have employed reciprocating piston structure connected to the piston via a needle bearing, needle bearing in this embodiment of the present invention The locking piston mechanism that integrally forms the connecting rod and the piston body is eliminated, improving durability by reducing moving parts, reducing weight and noise, and reducing costs by reducing the number of parts. did.

  Further, the oscillating compressor of Patent Document 1 forms the piston without relatively considering the angle at which the piston inclines in the low pressure side and high pressure side cylinders. Therefore, in the low pressure side compression part, even if the angle of inclination of the piston is made larger than that on the high pressure side, the effect of sealing and wear is small, but the angle of inclination of the piston is made as small as possible. However, the piston has not been sufficiently reduced in size and weight. In addition, in the high-pressure side compression section, the piston tilt angle is designed not to be sufficiently small, even though the piston tilt angle is excessively large, which affects the sealing performance and wear. For this reason, it was not possible to improve the sealing performance and life of the piston.

In an embodiment of the present invention in view of the above, the low-pressure side of the piston 4 and the high pressure side of the piston 8 the connecting rod 4A, 8A and piston body 5 (11) and integrally forming a connecting rod 4A, 8A The piston main body 5 (11) is inclined together with the connecting rods 4A and 8A when the cylinder is inclined, and the piston main body 5 (11) reciprocates while swinging in the cylinders 14 and 17, and the low pressure side piston 4 And the high-pressure side piston 8 were designed in consideration of the angle at which they were inclined in the cylinders 14 and 17, respectively.

  Here, the design of the two-stage compressor in the present embodiment will be described in detail.

  The motor power on the low-pressure side and the high-pressure side, that is, the shaft power (work amount W) increases as the pressure ratio between the suction pressure and the discharge pressure increases. The shaft power in the two-stage compressor depends on the sum of the shaft power on the low pressure side and the high pressure side, and the shaft power decreases as the pressure ratio on the low pressure side and the pressure ratio on the high pressure side decrease. That is, the shaft power is minimized when the low pressure side pressure ratio and the high pressure side pressure ratio are equal. Considering the above, in this embodiment, the various dimensions (bore diameter, stroke, etc.) of the pistons 4 and 8 on the low pressure side and the high pressure side are designed with shaft power considering the maximum pressure of the compressor.

Ls：所要軸動力
ηａｄ：全断熱効率

Lad：理論断熱空気動力
Qs：吸込み状態での実風量
Ps：吸込み絶対圧力
Pd：吐出し絶対圧力
κ：比熱比 Here, the shaft power of the motor on the low pressure side and the high pressure side is calculated. The required shaft power Ls and the theoretical adiabatic air power Lad are expressed by the following equations (1) and (2).

Ls: Required shaft power ηad: Total heat insulation efficiency

Lad: Theoretical adiabatic power
Qs: Actual air volume in the suction state
Ps: Absolute suction pressure
Pd: Absolute discharge pressure κ: Specific heat ratio

D：ボア径
S：ストローク
N：回転速度
ηｖ：体積効率 Here, the actual air volume Qs in the equation (2) is determined from the parameters of the members constituting the compressor and the efficiency of the compressor as in the following equation (3).

D: Bore diameter
S: Stroke
N: rotational speed ηv: volumetric efficiency

Here, as described above, when the pressure ratio between the low pressure side and the high pressure side of the two-stage compression and the difference in shaft power are reduced, the motor power (all shaft power) is reduced. Therefore, the following equations (4), (5 In this embodiment, in order to minimize the power of the motor, it is assumed that the pressure ratio between the low pressure side and the high pressure side of the two-stage compression is equal, and the pistons 4 and 8 on the low pressure side and the high pressure side are Calculate various dimensions.
L = Ls1 + Ls2 (4)
L: All shaft power
Ls1: Required shaft power on the low pressure side
Ls2: Required shaft power on the high pressure side Pm / P1 = P2 / Pm (5)
Pm: Absolute absolute pressure P1: Absolute suction pressure on the low pressure side P2: Absolute discharge pressure on the high pressure side

Qs１：低圧側における吸込み状態での実風量

Qs２：高圧側における吸込み状態での実風量 Here, from Equations (1) and (2), Ls1 and Ls2 are

Qs1: Actual air volume in the suction state on the low pressure side

Qs2: Actual air volume in the suction state on the high pressure side

Here, when the equations (6) and (7) are transformed using the constant K in consideration of the equation (5),
Ls1 = P1 ・ Qs1 × K (8)
Ls2 = Pm · Qs2 × K (9)

D１：低圧側のボア径
D２：高圧側のボア径
S１：低圧側のストローク
S２：高圧側のストローク Substituting equation (3) into equations (8) and (9),

D1: Bore diameter on the low pressure side
D2: High pressure side bore diameter
S1: Low pressure side stroke
S2: High-pressure side stroke

Since the shaft power of the motor is minimized when the pressure ratio between the low pressure side and the high pressure side and the shaft power are equal, the following equations are obtained from equations (10) and (11).

  As described above, in this embodiment, the bore diameters and the strokes of the low pressure side piston 4 and the high pressure side piston 8 are determined from the equations (12) and (13).

  Here, in Formula (12) and Formula (13), in order to obtain high-pressure compressed air, P2 needs to be sufficiently larger than P1. That is, in Expression (12), Pm needs to be sufficiently larger than P1. In this case, in order to satisfy Expression (12) (at least the values of the left side and the right side are made closer), it is necessary to make D1 sufficiently large with respect to D2 or make S1 sufficiently large with respect to S2.

  Here, the relationship between the low-pressure side bore diameter Dl and the high-pressure side bore diameter D2 will be described.

  First, it is preferable that the bore diameter Dl on the low pressure side and the bore diameter D2 on the high pressure side satisfy D1> D2. In the case of two-stage compression, since the pressure in the compression chamber on the high pressure side is higher than that on the low pressure side, the area of the piston 8 on the high pressure side is reduced, and the load received is reduced. This is because the load F of the piston 8 acting in the longitudinal direction of the connecting rod 8A is reduced, and the size of the bearing provided on the outer periphery of the eccentric 13 on the center side of the connecting rod 8A is suppressed.

  On the other hand, as described below, in consideration of the balance of the center of gravity of the product, in this embodiment of the present invention, it is necessary to prevent the bore diameter D2 on the high pressure side from becoming extremely small with respect to the bore diameter Dl on the low pressure side. .

Here, especially in the case of a portable air compressor that is carried, balance of the center of gravity of the product is important. As shown in FIG. 3, the portable air compressor is, for example, on (approximately the center of) a pair of air tanks 22. 1, the compressor main body 21 including the low-pressure side compression unit and the high-pressure side compression unit and the motor 3 are mounted, and each auxiliary component, particularly the pressure reducing valve 23 (26) and the pressure gauge 24 (27 having a large mass) ), The air take-out coupler 25 (28) is mounted so as to be symmetric with respect to the compressor main body 21, thereby providing a layout considering the balance of the center of gravity of the product.

  Among them, for the compressor body 21 having the largest mass, the balance of the center of gravity is also important.

  As described above, the bore diameters D1 and D2 and the strokes S1 and S2 on the low pressure side and the high pressure side are determined so as to equalize the shaft power and the pressure ratio. The two-stage compression structure of the present embodiment shown in FIG. 1 is an opposed two-cylinder, and the center of gravity balance of the compressor body 21 is low-pressure and high-pressure cylinders 14 (17) protruding from the crankcase 1, air The length and size of the valve 15 (18) and the cylinder head 16 (19) are greatly affected. Here, as described above, in order to reduce the piston load F on the high pressure side, the bore diameter D2 is generally made smaller than the bore diameter D1 on the low pressure side, but there is an extremely difference between the bore diameters D1 and D2. If provided, not only the connecting rod 4A (8A) but also the size of the cylinder 14 (17), the air valve 15 (18), and the cylinder head 16 (19) forming the compression chamber, The balance between the center of gravity of the left and right sides of the compressor body 21 is biased, and as a result, the center of gravity balance of the entire product is deteriorated. The same applies to the case where there is a difference in the length l of the connecting rod 4A (8A) on the low pressure side and the high pressure side (the length from the center of the eccentric 7 (13) to the tip (upper surface) of the piston body 5 (11)). In this case, not only the center-of-gravity balance deteriorates, but further, the longer the distance from the compressor body 21 to the cylinder head 16 (19), the cooling air from the cooling fan 20 mounted on the compressor body 21. Is difficult to reach, leading to an increase in temperature, which may cause a decrease in performance and life. Further, when the compressor main body 21 is mounted on the air tank 22, the longer cylinder head protrudes from the air tank 22, and as a result, there may be a demerit that the product outer shape becomes large.

  Therefore, from the viewpoint of product balance, it is desirable to avoid an extreme difference between the bore diameter D on the low pressure side and the high pressure side and the connecting rod length l.

  In FIG. 3, the compressor main body 21 is mounted so that the axial direction of the shaft 2 and the longitudinal direction of the air tank 22 are orthogonal to achieve both compactness and weight balance. The compressor main body 21 may be mounted so that the axial direction of the two and the longitudinal direction of the air tank 22 face the same direction. In this case, the center-of-gravity balance can be ensured by configuring the shaft 2 to be positioned between the two air tanks 22. Further, the size can be reduced by determining the dimensions so that the cylinder head does not protrude from the air tank 22.

  As described above, in order to reduce the piston load on the high pressure side, it is necessary to make the bore diameter D2 on the high pressure side smaller than the bore diameter D1 on the low pressure side. It is necessary not to make it too large. In the present embodiment, D1, D2, S1, and S2 are determined in consideration of the above.

  Here, in the equation (12), when there is no large difference between D1 and D2 and S1 <S2, Pm is not sufficiently large with respect to P1, and from equation (13), P2 is relative to P1. It doesn't get big enough. That is, high-pressure compressed air cannot be obtained. Therefore, in this embodiment of the present invention, by setting S1> S2, the center power balance between the high-pressure side and the low-pressure side is not greatly lost while the shaft powers on the low-pressure side and the high-pressure side are substantially equal, Compressed air can be obtained.

  For example, in order not to greatly reduce the balance of the center of gravity, it is preferable to set D1 to be equal to or less than twice D2. In this case, when S1 <S2, Pm is 4 times or less than P1, and sufficiently high-pressure compressed air cannot be obtained. Therefore, in order to obtain sufficiently high-pressure compressed air, S1 needs to be designed larger than S2, and S1> S2.

  Next, the swinging motion of the piston 4 (8) and the connecting rod 4A (8A) in the rocking piston mechanism will be described with reference to FIG.

As shown in FIG. 4, the piston 4 (8) and the connecting rod 4A (8A) are connected to the connecting rod 4A (8A) while the connecting rod 4A (8A) is moving toward the top dead center and the bottom dead center in the suction and discharge processes. ) is obliquely against the central axis of the cylinder 14 (17) by the eccentricity of the eccentric 7 (13).

l：連接棒長さ
ｒ：偏心量（＝ストロークＳ／２） The maximum inclination angle when the piston 4 (8) swings with respect to the cylinder 14 (17) will be described. Here, at the time the piston 4 (8) swings cylinder 14 (17) within the maximum angle at which the longitudinal axis is inclined connecting rods 4A against the cylinder center axis (8A), or against the cylinder center axis When the inclination angle θ is the maximum angle at which the upper surface of the piston attached to the upper side of the imaginary plane perpendicular to the connecting rod and the connecting rod is inclined, the inclination angle θ is calculated by the following equation (1 4 ). The length (the length from the center of the eccentric 7 (13) to the tip (upper surface) of the piston body 5 (11)) l and the eccentric amount r of the eccentric 7 (13) with respect to the shaft 2 of the motor 3 are determined.

l: Connecting rod length r: Eccentricity (= stroke S / 2)

  Here, as described above, since S1> S2, when the eccentric amount on the low pressure side is r1 and the eccentric amount on the high pressure side is r2, r1> r2, and the low pressure side compression unit and the high pressure side compression unit are In order to stabilize the center of gravity of the compressor provided, the connecting rod length l1 on the low pressure side and the connecting rod length l2 on the high pressure side are substantially equal, and the relationship r1 / l1> r2 / l2 is established. Therefore, from equation (14), when the maximum inclination angle on the low pressure side is θ1 and the maximum inclination angle on the high pressure side is θ2, the relationship θ1> θ2 is established.

  From the above, regarding the balance of the center of gravity of the compressor body described above, the inclination angle θ is made as small as possible while taking into account the difference in the bore diameter D between the low pressure side and the high pressure side and the difference in the connecting rod length l. In order to prevent the maximum inclination angle θ1 from becoming smaller than the maximum inclination angle θ2 on the high pressure side, the bore diameter D and stroke S (= 2 × eccentric amount r) on the low pressure side and the high pressure side and the length of the connecting rod are calculated according to the above-described formula. By determining l, it is possible to prevent performance degradation due to leakage of compressed air, and to prevent performance degradation particularly on the high pressure side. Furthermore, by making the balance of the center of gravity of the compressor main body uniform, it is possible to obtain high-pressure compressed air while preventing deterioration of the center of gravity balance of the product and uneven cooling.

  Here, an effect obtained by designing the maximum inclination angle θ2 of the high pressure side piston 8 with respect to the high pressure side cylinder 17 to be larger than the maximum inclination angle θ1 of the low pressure side piston 4 with respect to the low pressure side cylinder 14 will be described. .

  In this embodiment, the piston body 5 of the low pressure side piston 4 is provided with a lip ring 6 that is flexible and has high followability with respect to the change in the gap with the cylinder 14. Performance degradation due to leakage of compressed air from the air. On the other hand, the piston body 11 of the high-pressure side piston 8 is equipped with a piston ring 10 that requires rigidity because of high pressure and temperature. The piston ring 10 is inferior to the lip ring 6 in conformity to the gap change, and is likely to deteriorate in performance due to leakage of compressed air. Therefore, the high pressure side is compressed considering the angle at which the piston 8 is inclined with respect to the cylinder 17. It was necessary to prevent the effects of air leakage.

Way to the suction and discharge concatenated in step rods 4A (8A) is the top dead center and bottom dead center, the connecting rod 4A (8A) is against the central axis of the cylinder 14 (17) by the eccentricity of the eccentric 7 (13) It becomes diagonal. At this time, the shape of the contact surface between the lip ring 6 (piston ring 10) and the cylinder 14 (17) is an elliptical shape whose major axis is the swing direction (left-right direction in FIG. 4) (viewed from above the central axis of the cylinder). Therefore, it is easy to create a gap between the swing direction side 6A (9A) of the lip ring 6 (piston ring 10) and the cylinder 14 (17). Leakage from the gap could cause performance degradation.

  Here, in the present embodiment, as described above, since the maximum inclination angle θ2 on the high pressure side is designed not to be larger than the maximum inclination angle θ1 on the low pressure side, the maximum gap generated between the piston 4 and the cylinder 14 on the low pressure side. It was possible to prevent the maximum gap T2 generated between the piston 8 and the cylinder 17 on the high pressure side from T1 from becoming large. Thereby, it is possible to prevent the deterioration of performance due to the leakage of compressed air, particularly in the high pressure side compression section.

  In this embodiment, since the piston ring 10 having higher rigidity than the lip ring is mounted on the high-pressure side piston main body 11, it is difficult for performance degradation due to wear to occur.

  Moreover, although the present Example demonstrated the case where the lip ring 6 was provided in the low pressure side piston main body 5, it may replace with a lip ring and may provide a piston ring similarly to the high pressure side. In this case, the followability to the gap is reduced in the low pressure side compression part, but the pressure in the compression chamber is lower than that in the high pressure side compression part, so it is adopted by measures such as increasing the followability by reducing the thickness of the piston ring. Is possible. When the piston ring is provided in the low-pressure side piston main body 5, it is possible to prevent the performance of the low-pressure side compression portion from being deteriorated due to wear of the piston 4.

  Furthermore, the embodiment in which the lip ring 9 and the piston ring 10 are employed in the high pressure side piston body 11 has been described. However, when performance degradation due to wear does not become a problem, the piston ring is similar to the low pressure side piston body 5. Instead of 10, only the lip ring may be provided in the direction facing the compression chamber on the high pressure side. Moreover, it is good also as a structure used together with the lip ring 9. FIG. In this case, further weight reduction and cost reduction of the high-pressure side piston 8 can be realized.

  Further, the pressure in the compression chamber is such that the gas load F acting in the direction of the connecting rod central axis from the upper surface of the piston (when the piston body 5 (11) is up and the connecting rod 4A (8A) is down) and its lateral component When f is generated and the lip ring 6 (9) is pressed against the cylinder 14 (17), the wear of the surface of the lip ring 6 (9) or the cylinder 14 (17) is advanced, which may cause a decrease in performance. . In particular, since the gas load F is large in the high-pressure side compression portion, it is necessary to reduce the wear of the surfaces of the lip ring 9, the piston ring 10 and the cylinder 17 in the high-pressure side compression portion, and to prevent performance degradation.

  The lateral component f of the gas load F increases as the tilt angle θ, which is the angle at which the piston 4 (8) tilts with respect to the cylinder 14 (17), increases. In the present embodiment, as described above, since the maximum inclination angle θ2 on the high pressure side does not become larger than the maximum inclination angle θ1 on the low pressure side, the surface wear of the lip ring 9, piston ring 10 and cylinder 17 is particularly problematic. These wears can be reduced in the high-pressure side compression section, and the occurrence of performance degradation can be prevented.

  As described above, in this embodiment, the low-pressure side piston 4 and the high-pressure side piston 8 are configured according to the above-described dimensional relationship, so that the inclination angle θ is made as small as possible and the high-pressure side is higher than the maximum inclination angle θ1 on the low-pressure side. In order not to increase the maximum inclination angle θ2, the bore diameter D and stroke S (= 2 × eccentricity r) on the low-pressure side and the high-pressure side determined by the above formulas (1) to (14), and the length of the connecting rod By determining l, it is possible to prevent performance degradation due to leakage of compressed air, and to prevent performance degradation particularly on the high pressure side.

  The embodiments described so far are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention is not limitedly interpreted by these. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

1 ... Crankcase 2 ... Shaft (Rotating shaft)
3 ... Motor 4 ... Piston (low pressure side)
4A ... Connecting rod (low pressure side)
5. Piston body (low pressure side)
5A ... Retainer 6 ... Lip ring (low pressure side)
7 ... eccentric (low pressure side)
8 ... Piston (high pressure side)
8A ... Connecting rod (high pressure side)
9 ... Lip ring (high pressure side)
10 ... Piston ring 11 ... Piston body (high pressure side)
11A ... Base 12 ... Top 13 ... Eccentric (high pressure side)
14 ... Cylinder (low pressure side)
15 ... Air valve (low pressure side)
16 ... Cylinder head (low pressure side)
17 ... Cylinder (high pressure side)
18 ... Air valve (high pressure side)
19 ... Cylinder head (high pressure side)
20 ... Cooling fan 21 ... Air tank 22 ... Compressor body 23 ... Pressure reducing valve (low pressure side)
24 ... Pressure gauge (low pressure side)
25 ... Coupler (low pressure side)
26 ... Pressure reducing valve (high pressure side)
27 ... Pressure gauge (high pressure side)
28 ... Coupler (high pressure side)

Claims (14)

A low pressure side piston and a low pressure side cylinder, and the low pressure side piston compresses air by reciprocating while swinging in the low pressure side cylinder; and
A high-pressure side compression unit that has a high-pressure side piston and a high-pressure side cylinder, and further compresses the air compressed by the low-pressure side compression unit by reciprocating while the high-pressure side piston swings in the high-pressure side cylinder When,
A reciprocating compressor including the low pressure side compression unit and a motor that drives the high pressure side compression unit,
The maximum inclination angle when the high pressure side piston swings is not larger than the maximum inclination angle when the low pressure side piston swings, and the low pressure side piston and the low pressure side cylinder are A reciprocating compressor characterized in that a maximum gap generated between the high-pressure side piston and the high-pressure side cylinder does not become larger than a maximum gap generated between the high-pressure side piston and the high-pressure side piston . The low-pressure side piston and the high-pressure side piston are respectively connected to a rotating shaft of the motor, and include an eccentric that performs a rotational motion, a piston body that compresses air in a cylinder, a connecting rod that connects the eccentric and the piston body. with reciprocating compressor according to claim 1, characterized in that the piston body is fixed to the connecting rod. The reciprocating compressor according to claim 2 , wherein the piston main body swings in accordance with the eccentric rotational movement. The reciprocating compressor according to any one of claims 1 to 3 , wherein a bore diameter of the high pressure side piston is not made larger than a bore diameter of the low pressure side piston. 5. The reciprocating compressor according to claim 4 , wherein a length from the eccentric center to the tip of the low-pressure side piston is substantially equal to a length from the eccentric center to the tip of the high-pressure side piston. 6. The rippling provided in the piston body for compressing air in said low pressure side cylinder of the low-pressure side piston, in any one of claims 1 to 5, characterized by providing a piston ring on the piston body of the high pressure side piston The reciprocating compressor described. The piston ring provided on the piston body for compressing air in said low pressure side cylinder of the low-pressure side piston, in any one of claims 1 to 5, characterized by providing a piston ring on the piston body of the high pressure side piston The reciprocating compressor described. A motor having a rotating shaft;
A low pressure side compression section that includes a low pressure side cylinder and a low pressure side piston, and compresses air;
A reciprocating same compressor comprising a high pressure side cylinder and a high pressure side piston, and comprising a high pressure side compression part for further compressing the air compressed by the low pressure side compression part,
The low-pressure side piston and the high-pressure side piston each include an eccentric that performs an eccentric motion as the rotation shaft of the motor rotates, a connecting rod that extends from the eccentric, and a piston body that is provided at the tip of the connecting rod. ,
When the eccentric amount of the low-pressure side piston with respect to the rotational axis of the motor is r1, and the eccentricity amount of the high-pressure side piston with respect to the rotational axis of the motor is r2, the r1> r2 is satisfied. The high-pressure side piston forms a low-pressure side piston and the high-pressure side piston, and the high-pressure side piston moves more than the maximum gap generated between the low-pressure side piston and the low-pressure side cylinder when the low-pressure side piston swings. And a reciprocating compressor characterized in that a maximum gap generated between the high pressure side cylinder and the high pressure side cylinder is reduced . The reciprocating compressor according to claim 8, wherein the low pressure side piston and the high pressure side piston have the piston main body fixed to the connecting rod. The reciprocating compressor according to claim 8 , wherein the piston body reciprocates while swinging in the high pressure side cylinder and the low pressure side cylinder with the eccentric eccentric motion. The reciprocating compressor according to any one of claims 8 to 10 , wherein a bore diameter of the high pressure side piston is made smaller than a bore diameter of the low pressure side piston. The length from the eccentric center of the low pressure side piston to the tip of the piston body of the low pressure side piston is 11, and the length from the eccentric center of the high pressure side piston to the tip of the piston body of the high pressure side piston is The reciprocating compressor according to claim 8 , wherein the low-pressure side piston and the high-pressure side piston are formed so that r1 / l1> r2 / l2 when l2. The lip ring is attached to the piston body in the low-pressure piston, reciprocating compressor according to any one of claims 8 to 1 2, characterized in that for mounting the piston ring on the piston body of the high pressure side piston . The piston ring is attached to the piston body in the low-pressure piston, reciprocating compressor according to any one of claims 8 to 1 2, characterized in that for mounting the piston ring on the piston body of the high pressure side piston .

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