JPH10148178A - Reciprocating compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a load at the time of start, also the abrasion of a lip ring at the time of continuous operation, etc. SOLUTION: The lip part 22B of a lip ring 22, for sealing between an oscillation piston 9 and a cylinder 21, is formed so that an outer diameter dimension D under ordinary temperature can be reduced than the inner diameter dimension E of the cylinder 21, also the maximum outer diameter at the time of thermal expansion can be within a range of ±0.2% to the maximum inner diameter of the cylinder 21. This can reduce sliding resistance, between the inner peripheral surface and lip part 22B of the cylinder 21 at the time of starting, to reduce the load of a reciprocating compressor at the time of starting. Also even in the case where the lip ring 22 is caused at the time of continuos operation, the abrasion of the lip part 22A can be restrained, thereby prolonging the life of the lip ring 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillating piston type reciprocating compressor suitably used for compressing a fluid such as air.

[0002]

2. Description of the Related Art An oilless reciprocating compressor for compressing air or the like is generally known as a reciprocating compressor provided with a oscillating piston which reciprocates while oscillating in a cylinder.

A conventional oilless reciprocating compressor of this type will be described with reference to FIGS. 2 and 3. FIG.

In FIG. 2, reference numeral 1 denotes a cylindrical cylinder. A cylinder head 2 is provided at an upper end of the cylinder 1, and a suction chamber A and a discharge chamber B are formed in the cylinder head 2 by a partition wall 3. It is defined.

Reference numeral 4 denotes a valve plate provided between the cylinder 1 and the cylinder head 2. A gasket (not shown) is provided between the valve plate 4 and the cylinder 1 and between the valve plate 4 and the cylinder head 2. ) And the like. A compression chamber C is defined between the valve plate 4 and a swinging piston 9 described later.

Reference numeral 5 denotes a suction port provided on the valve plate 4, reference numeral 6 denotes a discharge port provided on the valve plate 4, the suction port 5 connects the suction chamber A and the compression chamber C, and the discharge port 6 The discharge chamber B communicates with the compression chamber C.

Reference numeral 7 denotes a suction valve provided on the valve plate 4 between the suction chamber A and the compression chamber C. The suction valve 7 moves the swinging piston 9 from a top dead center to a bottom dead center. The valve is sometimes opened and closed when moving from the bottom dead center to the top dead center.

Reference numeral 8 denotes a discharge valve provided on the valve plate 4 between the discharge chamber B and the compression chamber C. The discharge valve 8 moves a swing piston 9 from a bottom dead center to a top dead center. The valve is sometimes opened and closed when moving from the top dead center to the bottom dead center.

Reference numeral 9 denotes a swinging piston provided reciprocally in the cylinder 1. The swinging piston 9 is connected to an output shaft or the like (not shown) of a rotation source via a crankshaft. A connecting rod 10 and a disk-shaped retainer 11 fastened by a bolt or the like to a disk-shaped mounting flange 10A provided at one axial end of the connecting rod 10. An annular step portion 10B into which a lip ring 12 described later is fitted is provided at the center of the mounting flange 10A.

Reference numeral 12 denotes an annular lip ring for hermetically sealing the gap between the swinging piston 9 and the cylinder 1. The lip ring 12 has a self-lubricating property such as a fluororesin and the like to improve the slidability with the cylinder 1. The connecting rod 10 is formed of a resin material having excellent flexibility,
The mounting flange 10A is fitted to the annular stepped portion 10B.
And the retainer 11.

Here, as shown in FIG. 3, the lip ring 12 is located on the inner peripheral side and is attached to the mounting flange 10A and the retainer 1.
1, and a flat annular fixed portion 12 </ b> A interposed therebetween, and protrudes radially outward from the oscillating piston 9 at an outer peripheral side of the fixed portion 12 </ b> A, and has an L-shaped cross section toward the compression chamber C side. And a lip portion 12B on the outer peripheral side that is bent
2B is formed in a cup shape so as to be in sliding contact with the inner peripheral surface of the cylinder 1 over the entire circumference.

In the reciprocating compressor constructed as described above, the reciprocating motion of the oscillating piston 9 while oscillating in the cylinder 1 causes a suction stroke in which air is sucked from the suction chamber A into the compression chamber C. The compression operation of repeating the compression process of compressing the air in the compression chamber C and discharging the compressed air to the discharge chamber B as compressed air is performed.
During this compression operation, the lip portion 12B of the lip ring 12 is always in sliding contact with the inner peripheral surface of the cylinder 1 to hermetically seal the gap between the swing piston 9 and the cylinder 1.

[0013]

By the way, according to the above-mentioned prior art, the outer diameter D of the lip ring 12 is set to be equal to the inner diameter of the cylinder 1 so that the lip portion 12B of the lip ring 12 surely slides on the inner peripheral surface of the cylinder 1. Larger than E (D>
E) The lip ring 12
The lip portion 12B comes into frictional contact with the inner peripheral surface of the cylinder 1, and there is a problem that a large load is applied to a rotation source such as a motor when the compressor is started, for example.

Further, during continuous operation of the compressor, the cylinder 1 and the lip ring 12 are brought to a high temperature state by the heat of compression and the heat of friction from the compression chamber C, and thermally expand. In this case, since the cylinder 1 is formed of a metal material such as an aluminum alloy and the lip ring 12 is formed of a resin material, the thermal expansion of the lip ring 12 is larger than that of the cylinder 1. Would.

For this reason, in the prior art, the lip ring 1
The second lip portion 12B is further expanded due to thermal expansion larger than the inner diameter of the cylinder 1, and the lip portion 12B may be worn out early, resulting in a problem that the life of the lip ring 12 is reduced.

The present invention has been made in view of the above-mentioned problems of the prior art, and can reduce the load at the time of starting, suppress the wear of the lip ring during continuous operation and the like, and extend the life of the lip ring. It is an object of the present invention to provide a reciprocating compressor that can perform pressure reduction.

[0017]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a cylinder, a piston which reciprocates while oscillating in the cylinder, and defines a compression chamber in the cylinder; The present invention is applied to a reciprocating compressor comprising an annular lip ring for sealing between a piston and the cylinder.

A feature of the structure adopted by the invention of claim 1 is that the lip ring is located on the inner peripheral side and fixed to the piston, and from the fixed portion radially outward of the piston. And an outer peripheral lip bent toward the compression chamber.The lip has an outer diameter smaller than the inner diameter of the cylinder in advance, and the cylinder operates by a pressure from the compression chamber during a compression operation. In such a manner as to be bent and deformed toward the inner peripheral surface.

According to the above configuration, the lip portion of the lip ring is slightly separated from the inner peripheral surface of the cylinder in the initial stage of starting the compressor, so that the sliding resistance of the piston with respect to the cylinder can be reduced. The load can be reduced. When the pressure in the compression chamber is increased by the compression operation, the lip of the lip ring is bent toward the inner peripheral surface of the cylinder by the pressure from the compression chamber. It can slide on the inner peripheral surface of the cylinder to seal between the piston and the cylinder.

According to a second aspect of the present invention, the lip portion of the lip ring has a maximum outer diameter during thermal expansion by a compression operation within a range of ± 0.2% with respect to a maximum inner diameter of the cylinder. In that the outer diameter is set.

According to the above configuration, even when the cylinder and the lip ring are in a high temperature state and thermally expanded during continuous operation, the maximum outer diameter of the lip of the lip ring is larger than the maximum inner diameter of the cylinder during thermal expansion. Therefore, the wear of the lip during continuous operation can be reduced.

Furthermore, the invention of claim 3 is that the lip ring is formed of a composite material containing polytetrafluoroethylene, and the cylinder is formed of an aluminum alloy.

According to the above configuration, the slidability and heat resistance of the lip ring that slides on the inner peripheral surface of the cylinder can be improved, and the wear of the lip ring during continuous operation can be further reduced.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIG.

In this embodiment, the same components as those of the above-described prior art are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, reference numeral 21 denotes a cylinder according to the present embodiment. The cylinder 21 is formed by subjecting a molded article made of an aluminum alloy to an anodic oxidation treatment, and has a coefficient of thermal expansion of 2.4 × 10 ^-5. It is. And
The cylinder 21 has an inner diameter E at room temperature of 60.0 mm.
The maximum inner diameter E 'when thermally expanded by continuous operation is 60.1 mm.

Reference numeral 22 denotes a rip ring applied to the present embodiment in place of the lip ring 12 according to the prior art. The lip ring 22 is located on the inner peripheral side like the lip ring 12 according to the prior art and is located on the mounting flange 10A. And a flat annular fixing portion 22A sandwiched between the retainer 11 and the outer peripheral side of the fixing portion 22A, protruding radially outward from the swing piston 9 and bent toward the compression chamber C. Thereby, it is composed of a cup-shaped lip portion 22 </ b> B that slides over the entire inner circumference of the cylinder 21.

The lip ring 22 is made of a fluororesin material based on PTFE (polytetrafluoroethylene), such as CF (carbon fiber), MoS ₂ (molybdenum disulfide), etc., in order to enhance the slidability and heat resistance. Are appropriately mixed to form a composite material.

However, the lip ring 2 according to the present embodiment
No. 2 shows that the outer diameter D of the lip portion 22B at room temperature is smaller than the inner diameter E of the cylinder 21 (D <E), and the maximum outer diameter D 'during thermal expansion by continuous operation is thermally expanded. It is set to be within ± 0.2% of the maximum inner diameter E 'of the cylinder 21.

The reciprocating compressor according to this embodiment has the lip ring 22 as described above, and its basic operation is not particularly different from that of the prior art.

However, in the reciprocating compressor according to the present embodiment, the outer diameter D of the lip portion 22B constituting the lip ring 22 at normal temperature is smaller than the inner diameter E of the cylinder 21 in advance. From the lip ring 22
The sliding resistance between the lip portion 22B and the inner peripheral surface of the cylinder 21 can be reduced as compared with the related art. This allows
The load at the time of starting the compressor can be reduced, and the initial wear of the lip portion 22B can be reduced.

In this case, when the swing piston 9 is in the suction stroke, a slight gap is formed between the lip portion 22B of the lip ring 22 and the inner peripheral surface of the cylinder 21. When shifting to the compression stroke,
The lip portion 22B bends and deforms toward the inner peripheral surface of the cylinder 21 by the pressure from the compression chamber C. As a result, the lip portion 22B slides on the inner peripheral surface of the cylinder 21, and the space between the swing piston 9 and the cylinder 21 is properly sealed.

Even if the cylinder 21 and the lip ring 22 become hot due to the continuous operation of the compressor and the lip ring 22 thermally expands, the maximum outer diameter D 'of the lip portion 22B during this thermal expansion is determined by the cylinder Since it is within ± 0.2% of the maximum inner diameter E 'of the lip 21, the wear of the lip 22B during thermal expansion can be reduced, and the life of the lip ring 22 can be extended.

Next, the reciprocating compressor using the above-mentioned lip ring 22 is operated continuously, and the load at start-up, the discharge air amount,
The results of a test for measuring the wear of the lip portion 22B after the continuous operation will be described with reference to Table 1 below.

First, the lip ring 22 according to the present embodiment
Are prepared, and two kinds of comparative products 1 and 2 as lip rings to be compared are prepared.

Here, in the lip ring of the embodiment 1, the outer diameter D of the lip portion at room temperature is 59.6 (mm), and the maximum outer diameter D 'of the lip portion during thermal expansion is 60.0 mm. (M
m). The outer diameter D of the lip portion at room temperature is 5
9.75 (mm), and the maximum outer diameter D 'of the lip portion during thermal expansion is 60.1 (mm). Further, the lip ring of the embodiment 3 has an outer diameter D of the lip portion at room temperature of 59.9 (mm) and a maximum outer diameter D 'of the lip portion at the time of thermal expansion of 60.2 (mm). It is formed so that it becomes.

On the other hand, the lip ring of the comparative product 1 corresponds to, for example, the above-described lip ring 12 according to the prior art, and the outer diameter D of the lip portion at room temperature is equal to that of the cylinder 21.
60.5 (mm), which is larger than the inner diameter dimension E of the cylinder 21, and the maximum outer diameter D 'of the lip portion during thermal expansion becomes + 1.3% with respect to the maximum inner diameter E' of the cylinder 21 to 60.9 (mm). )
It is formed so that it becomes.

The outer diameter D of the lip at room temperature is equal to the inner diameter E of the cylinder 21 at room temperature.
Although it is smaller than 59.3 (mm), the maximum outer diameter D 'of the lip portion during thermal expansion is -9.7% with respect to the maximum inner diameter E' of the cylinder 21 (59.7 (mm)). It is formed so that it becomes.

When the above-mentioned five types of rip rings are used for a reciprocating compressor of 0.4 kW and the reciprocating compressor is continuously operated at a discharge pressure of 0.7 MPa, the current value at the time of startup is: The amount of change in the discharge air and the amount of wear of each lip after 1000 hours of continuous operation were measured. The temperature rise of the cylinder 21 during the continuous operation is 75 deg.

[0040]

[Table 1]

Here, regarding the current value at the time of starting the reciprocating compressor, when the rip ring of the comparative product 1 corresponding to the lip ring 12 according to the prior art is used, the current value at the time of starting is 125%. In contrast, when the rip rings of the products 1, 2, and 3 corresponding to the lip ring 22 according to the present embodiment are used, the current values at the time of starting are reduced to 95%, 100%, and 101%, respectively. doing.

From these results, in the lip rings of the products 1, 2, and 3, the outer diameter D of the lip portion at room temperature is smaller than the inner diameter E of the cylinder 21 at room temperature. It was confirmed that the sliding resistance between the compressors was reduced and the load at the time of starting the reciprocating compressor could be reduced.

Next, looking at the wear amount of the lip after 1000 hours of continuous operation, the wear amount of the lip ring of the comparative product 1 was 400 μm,
The wear amount of a few lip rings was 81 μm,
It is reduced to 90 μm and 96 μm.

From these results, in the lip rings of the first, second, and third embodiments, even if the thermal expansion is caused by the continuous operation, the maximum outer diameter D 'of the lip portion at this time is set to the cylinder 21.
Is set within the range of ± 0.2% with respect to the maximum inner diameter E ′, it is possible to suppress an increase in frictional force with the inner peripheral surface of the cylinder 21 and confirm that wear can be reduced. Was done.

Looking at the amount of change in the discharge air,
When the rip rings of the second and third embodiments are used, there is no change in the discharge air amount when the rip ring of the first comparison product is used. On the other hand, the discharge air amount when the rip ring of the comparative example 1 is used is reduced by 3% with respect to the discharge air amount when the rip ring of the comparative product 1 is used.

From these results, it was confirmed that the lip rings of Examples 2 and 3 can maintain the same discharge performance as the reciprocating compressor having the lip ring 12 according to the prior art. Further, in the reciprocating compressor having the lip ring of the first embodiment, the discharge air amount is reduced by 3% as compared with the reciprocating compressor according to the prior art. You can think.

In the reciprocating compressor using the lip ring of the comparative product 2, the current value at the time of starting is reduced to 90%, and the wear amount of the lip ring after continuous operation for 1000 hours is reduced to 79 μm. However, it was confirmed that the discharge air amount was reduced to 11%.

As described above, a plurality of types of lip rings having different outer diameters D of the lip portion were formed, and the above-described test was repeated using the lip rings. As a result, the maximum outer diameter of the lip portion during thermal expansion was determined. A lip ring 2 in which D 'is within ± 0.2% of the maximum inner diameter E' of the cylinder 21.
It has been confirmed that the use of No. 2 can reduce the load at the time of starting and greatly reduce the wear of the lip portion while maintaining the same discharge performance as the conventional reciprocating compressor.

Thus, according to the reciprocating compressor of the present embodiment, the outer diameter D of the lip constituting the lip ring 22 at room temperature is made smaller than the inner diameter E of the cylinder 21 in advance. In addition, the sliding resistance between the inner peripheral surface of the cylinder 21 and the lip portion 22B at the time of starting can be reduced, and the load at the time of starting the reciprocating compressor can be reduced. In this case, when the swing piston 9 is in the suction stroke, a slight gap is formed between the lip portion 22B of the lip ring 22 and the inner peripheral surface of the cylinder 21, but the swing piston 9 is in the compression stroke. When you migrate,
Since the lip portion 22B is bent and deformed toward the inner peripheral surface of the cylinder 21 by the pressure from the compression chamber C and slides on the inner peripheral surface of the cylinder 21, the space between the swing piston 9 and the cylinder 21 is properly sealed. Thus, the same discharge performance as the conventional reciprocating compressor can be maintained.

Then, the continuous operation of the reciprocating compressor brings the cylinder 21 and the lip ring 22 into a high temperature state,
Even when the lip ring 22 undergoes thermal expansion, the maximum outer diameter D 'of the lip portion 22B during this thermal expansion is set to be within ± 0.2% of the maximum inner diameter E' of the cylinder 21. With the setting, the frictional force generated between the lip portion 22B of the lip ring 22 and the inner peripheral surface of the cylinder 21 during thermal expansion can be reduced. Accordingly, wear of the lip portion 22B during thermal expansion can be suppressed, and the life of the lip ring 22 can be extended.

[0051]

As described above in detail, according to the first aspect of the present invention, the outer diameter of the lip portion provided on the lip ring is formed smaller than the inner diameter of the cylinder in advance, and during the compression operation, the lip is removed from the compression chamber of the cylinder. Since the lip portion bends and deforms toward the inner peripheral surface of the cylinder due to the pressure, the sliding resistance between the lip ring and the inner peripheral surface of the cylinder can be reduced.
Thereby, the load at the time of starting the reciprocating compressor can be reduced, and the initial wear of the lip portion can be reduced. In this case, the lip portion comes into sliding contact with the inner peripheral surface of the cylinder during the compression operation, so that the space between the piston and the cylinder can be properly sealed.

According to the second aspect of the present invention, the lip portion of the lip ring is set so that the maximum outer diameter during thermal expansion is within ± 0.2% of the maximum inner diameter of the cylinder. Therefore, even if the cylinder and the lip ring are in a high temperature state during continuous operation and the lip ring is thermally expanded,
The frictional force generated between the lip and the inner peripheral surface of the cylinder can be reduced. Thereby, the wear of the lip portion at the time of thermal expansion can be suppressed, and the life of the lip ring can be extended.

Further, according to the third aspect of the present invention, since the lip ring is formed of a composite material containing polytetrafluoroethylene, the slidability and heat resistance of the lip ring at high temperatures during continuous operation are improved. Therefore, the life of the lip ring can be further extended.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a reciprocating compressor according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a main part of a conventional reciprocating compressor.

FIG. 3 is a longitudinal sectional view showing a state in which a swing piston and a lip ring in FIG. 2 are removed from a cylinder.

[Explanation of symbols]

 9 Oscillating piston 21 Cylinder 22 Rip ring 22A Fixed part 22B Rip part D Rip ring outer diameter dimension E Cylinder inner diameter dimension

Claims (3)

[Claims] 1. A cylinder, a piston reciprocating while oscillating in the cylinder, and defining a compression chamber in the cylinder, and an annular lip ring sealing between the piston and the cylinder. In the reciprocating compressor, the lip ring is located on an inner peripheral side and is fixed to the piston, and an outer periphery that projects radially outward of the piston from the fixed portion and is bent toward the compression chamber. The lip portion is formed such that its outer diameter is smaller than the inner diameter of the cylinder in advance, and is bent and deformed toward the inner peripheral surface of the cylinder by a pressure from the compression chamber during a compression operation. Reciprocating compressor. 2. The lip portion of the lip ring has an outer diameter dimension such that the maximum outer diameter during thermal expansion due to a compression operation is within a range of ± 0.2% with respect to the maximum inner diameter of the cylinder. The reciprocating compressor according to claim 1, comprising: 3. The reciprocating compressor according to claim 1, wherein the lip ring is formed of a composite material containing polytetrafluoroethylene, and the cylinder is formed of an aluminum alloy.