JP2001041161A - Non-lubricant compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-lubricant compressor which is excellent in sealing ability in the compression stroke, and permits leakage from a lower chamber of a piston to an upper chamber of the piston in the intake stroke. SOLUTION: In this non-lubricant compressor, the interior of a cylinder 1 and the interior of a crankcase are lubricant-sealed with an oil seal, and a combination gas tight ring 4 is mounted in a ring groove 3 of a piston 2. The piston 2 has an air passage 11, and the air passage 11 is formed by a hole piercing from the top of the piston 2 to the upper surface of the ring groove 3 to communicate a clearance gap between the bottom of the ring groove 3 and the inner peripheral surface of the combination gas tight ring 4 with an upper chamber of the piston 2 in the cylinder 1. The air passage is formed by a groove formed on the upper surface of the ring groove 3 extending from the outer peripheral surface of the piston 2 toward the bottom of the ring groove 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-lubricated compressor.

[0002]

2. Description of the Related Art There has been proposed a non-lubricated compressor in which the inside of a cylinder and the inside of a crankcase are sealed with an oil seal and a piston chamber in the cylinder is not lubricated (Japanese Patent Application Laid-Open No. 8-326658).

Conventionally, a non-lubricated reciprocating air compressor uses a resin single gas tight ring having a stepped opening shape. The reason is as follows.・ Made of resin to withstand use without lubrication.・ Because the resin material has a large thermal expansion coefficient, it is necessary to set a large gap between the openings. In addition, since the abrasion is large and the sealing performance tends to deteriorate, a gas tight structure is adopted.

However, the gas tight ring is
Although the sealing performance can be maintained during the overlap of the abutment, if the abrasion is performed until the overlap of the abutment disappears, the sealing performance is rapidly deteriorated, and the protruding portion of the abutment may be broken. On the other hand, in order to extend the life of the gas tight ring, attempts have been made to increase the overlap of the joints, but since the strength of the resin material is low, the joints are broken and there is a limit. For this reason, maintenance and replacement were indispensable according to the life of the gas tight ring.

[0005]

On the other hand, the present applicant proposed in Japanese Patent Application No. 10-333391 a combined gas tight ring having excellent sealing performance and durability.

This combined gas tight ring is a combination ring comprising a pair of upper and lower outer rings having an abutment, and an inner ring having an abutment and arranged on an inner peripheral side of the outer ring. A projection is formed on each inner periphery of the pair of outer rings, and the projection of the one outer ring and the projection of the other outer ring are at different angular positions from the abutment, and these projections are located at the abutment of the inner ring. It is characterized by being arranged in a gap.

However, according to this combined gas tight ring, the lower chamber of the piston in the cylinder is compressed during the suction stroke in which the piston descends. In particular, in a non-lubricated compressor in which the periphery of the piston rod is lubricated with an oil seal, the lower chamber of the piston in the cylinder is narrow, and when this part is compressed, the load is repeatedly applied to the oil seal, Have undesired effects.

It is an object of the present invention to provide a non-lubricated compressor which has excellent sealing performance in a compression stroke and permits leakage from a lower chamber of a piston to an upper chamber of a piston in a cylinder in a suction stroke.

[0009]

According to the present invention, there is provided a non-lubricated compressor in which the inside of a cylinder and the inside of a crankcase are sealed with a lubricating oil by an oil seal, and the piston reciprocates in the cylinder without lubrication. A gas tight ring is mounted in the groove, and an air passage communicating with a gap between the bottom surface of the ring groove and the inner peripheral surface of the gas tight ring and an upper chamber of the piston in the cylinder is formed in the piston. It is characterized by the following.

The air passage is formed by a hole passing through the top surface of the piston and the upper surface of the ring groove, or a groove formed on the upper surface of the ring groove from the outer peripheral surface of the piston toward the bottom surface of the ring groove.

A gas tight ring is a ring having a structure for preventing leakage through an abutment, and a combined gas tight ring or a single gas tight ring is used.

The combined gas tight ring has, for example, the following structure. A pair of upper and lower outer rings having an abutment, and an inner ring having an abutment and arranged on the inner peripheral side of the upper and lower outer rings, and are located on the outer peripheral surface of the inner ring in the circumferential direction and the axial direction. Are shifted to form a pair of projections, one of which is arranged in the opening gap of the upper outer ring, and the other projection is arranged in the opening gap of the lower outer ring. A pair of upper and lower outer rings having an abutment, and an inner ring having an abutment and arranged on the inner peripheral side of the upper and lower outer rings, each having a projection on each inner peripheral surface of the upper and lower outer rings. The projections of the one outer ring and the projections of the other outer ring are located at different angular positions from the abutment, and these projections are arranged in the abutment gap of the inner ring.

[0013] In the combined gas tight ring, due to the above-described structure, the abutment gaps of the upper and lower outer rings are arranged at positions shifted from each other in the circumferential direction, and the upper and lower outer rings are prevented from rotating by the inner ring. As described above, since the abutment gaps of the upper and lower outer rings do not overlap in the axial direction, a combination ring having excellent sealing properties is obtained. In addition, the combined gas tight ring has three rings integrated and has a degree of freedom in the ring groove of the piston.
Good followability to the cylinder and good sealing performance.
Further, even if the outer ring is worn and the opening gap widens, the inner gap is sealed by the inner ring, so that the ring has a long life and is excellent in durability.

In the combined gas tight ring,
The inner ring preferably has a smaller thickness in the radial direction than the outer ring for weight reduction and the like. In this case, the combined gas tight ring having the projections on the inner ring (described above) can have a larger projection height than the combined gas tight ring having the projections provided on the outer ring (described above). Therefore, when the outer ring is worn, the combined gas tight ring in which the inner ring is provided with a projection can secure a longer rotation preventing action. In addition, since the outer periphery of the outer ring requires high-precision processing for gas sealing, it is easier to provide the inner ring with projections than to provide the inner ring with projections.

Next, the operation of the piston in the compression stroke and the suction stroke will be described for a compressor using a combined gas tight ring.

In the compression stroke in which the piston rises, the opening gap of the lower outer ring is sealed with an inner ring, and the lower surface of the lower outer ring and the lower surface of the ring groove are in close contact with each other, so that they leak into the lower chamber of the piston. Never. Also,
Even if the outer peripheral surface of the outer ring is worn and the abutment gap is widened, the sealing performance at the time of compression is not impaired since the abutment gap between the upper and lower outer rings is sealed by the inner ring.

On the other hand, in the suction stroke in which the piston descends,
"Lower chamber of piston → gap between lower surface of ring groove and lower surface of lower outer ring and lower surface of inner ring → clearance between inner peripheral surface of inner ring and bottom surface of ring groove → air passage formed in piston → upper chamber of piston" Is formed, the leakage from the lower chamber of the piston to the upper chamber of the piston in the cylinder is allowed. For this reason, the pressure in the lower chamber of the piston in the cylinder does not increase.

The operation of the piston in the compression stroke and the suction stroke is the same when a single gas tight ring is used.

Therefore, in a non-lubricated compressor in which the inside of the cylinder and the inside of the crankcase are sealed with a lubricating oil with an oil seal, the pressure in the lower chamber of the piston in the cylinder can be prevented from rising during the suction stroke when the piston descends. Undesirable repetitive load is not applied to the oil seal, so that the oil seal is prevented from being adversely affected.

The outer ring and the single gas tight ring in the combined gas tight ring are formed of a resin, particularly, a heat and wear resistant resin. As the heat-resistant and abrasion-resistant resin, a heat-resistant resin material having a temperature of 200 ° C. or higher is desirable, and any one of a polyimide resin, a modified polyimide resin, a polyimideamide resin, a polybenzimidazole resin, and a polytetrafluoroethylene resin is used. The heat and wear resistant resin is one or two of carbon fiber, graphite carbon, and polytetrafluoroethylene resin.
It is preferred to contain more than one species. The inner ring in the combined gas tight ring is preferably formed of a resin, but may be formed of a metal such as steel.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

3 and 4, reference numeral 1 denotes a cylinder, 2
Is a piston inserted into a bore of the cylinder 1, and a combined gas tight ring 4 is mounted in a ring groove 3 of the piston 2. The combined gas tight ring 4 is composed of a pair of upper and lower outer rings 5 and 6 made of heat and wear resistant resin, and one inner ring 7 made of heat and wear resistant resin disposed on the inner peripheral side thereof. I have.

The upper and lower outer rings 5 and 6 are rings having the same size and having an abutment, are laminated in the axial direction, and press the inner wall surface of the cylinder 1. The inner ring 7 has a radial thickness that is smaller than the radial thickness of the outer rings 5 and 6, and an axial width that is substantially the same as the stacked axial width of the upper and lower outer rings 5 and 6. 8, 9 on the surface
Are formed so as to be shifted from each other in the circumferential direction and the axial direction. The upper protrusion 8 of the inner ring 7 is formed by the upper outer ring 5 of the upper and lower outer rings 5 and 6 that are stacked.
The lower projection 9 of the inner ring 7 is arranged in the opening gap 6a of the lower outer ring 6.

Therefore, the abutment gaps 5a, 6a of the upper and lower outer rings 5, 6 are arranged at positions shifted from each other in the circumferential direction, and the upper and lower outer rings 5, 6 are prevented from rotating by the inner ring 7. As described above, since the abutment gaps 5a and 6a of the upper and lower outer rings 5 and 6 do not overlap in the axial direction, the combined gas tight ring 4 having excellent sealing performance is obtained. In addition, the combination gas tight ring 4 has three rings 5, 6, 7 integrated and has a degree of freedom in the ring groove 3 of the piston 2, so that the followability to the cylinder 1 is good and the sealing performance is good. . Even if the outer rings 5 and 6 are worn and the opening gaps 5a and 6a are enlarged, since the opening gaps 5a and 6a are sealed by the inner ring 7, the ring has a long life and is excellent in durability.

On the other hand, an air passage 11 is formed in the piston 2 so that the lower chamber 10 of the piston 2 in the cylinder 1 is not compressed during the suction stroke of the piston 2. The air passage 11 has a gap between the bottom surface of the ring groove 3 and the inner peripheral surface of the inner ring 7 and the upper chamber 1 of the piston 2 in the cylinder 1.
2 and communicate. In the first embodiment, the air passage 1
Reference numeral 1 denotes a hole formed from the top surface of the piston 2 to the upper surface of the ring groove 3. In the first embodiment, the through-hole forming the air passage 11 is a through-hole having a circular cross section, and its central axis is located at the bottom position of the ring groove 3, but may be located inside or outside the bottom surface. The air passage 11 has a plurality of, for example, 4 to 8
Individually formed.

The operation of the piston 2 in the compression stroke and the suction stroke will be described below.

As shown in FIG. 3, during the compression stroke (FIG. 3B) in which the piston 2 rises, the abutment gap 6a of the lower outer ring 6 is sealed by the inner ring 7,
The lower surface of the lower outer ring 6 and the lower surface of the ring groove 3 are in close contact with each other. Therefore, the gap between the upper surface of the upper outer ring 5 and the upper surface of the ring groove 3 and the gap between the inner peripheral surface of the inner ring 7 and the bottom surface of the ring groove 3 are compressed, but are not leaked to the lower chamber 10 of the piston 2. Absent. And outer rings 5, 6
Of the upper and lower outer rings 5, 6 by the inner ring 7 even if the outer peripheral surfaces of the
Since the abutment gaps 5a and 6a are sealed, the sealing performance during compression is not impaired.

On the other hand, the upper surface of the upper outer ring 5 and the upper surface of the ring groove 3 are in close contact with each other during the suction stroke in which the piston 2 descends (FIG. 3A). At this time, “the lower chamber 10 of the piston 2 → the gap between the lower surface of the ring groove 3 and the lower surface of the lower outer ring 6 and the lower surface of the inner ring 7 → the inner ring 7
Gap between the inner peripheral surface of the ring and the bottom of the ring groove 3 → air passage 11 →
Since the passage of the "upper chamber 12 of the piston 2" is formed, the leakage from the lower chamber 10 of the piston 2 to the upper chamber 12 of the piston 2 in the cylinder 1 is allowed. Therefore, the pressure in the lower chamber 10 of the piston 2 in the cylinder 1 does not increase.

Hereinafter, a non-lubricated air compressor including the piston 2 equipped with the combined gas tight ring 4 will be described with reference to FIGS.

The compressor is a non-lubricated air compressor in which a piston 2 reciprocates in a cylinder 1. A head section 20 is fixed to the upper surface of the cylinder 1, and the head section 20 is provided with an air inlet 21a and a compressed air outlet 21b. The intake port 21a and the discharge port 21b communicate with the inside of the cylinder 1 through air passages, respectively, and an intake valve and an exhaust valve are provided in each air passage.

A piston 2 is inserted into the cylinder 1, and a combined gas tight ring 4 is mounted on one ring groove 3 formed on the outer peripheral surface of the piston 2, and a seal with the inner wall 1 a of the cylinder 1 is provided. I do. One end of a piston rod 22 is fixed to the center of the bottom surface of the piston 2, and the piston 2 is configured to reciprocate in the cylinder 1 by a cross slider crank mechanism.

The cylinder 1 is fixed to the upper surface of the crankcase 24.

A crankshaft 25 is disposed in the crankcase 24 at right angles to the direction of movement of the piston 2 and both ends are rotatably supported by bearings 26 and 26A. One end of the crankshaft 25 projects outward from the crankcase 24, and is configured to be rotationally driven by a drive source (not shown).

The crankshaft 25 is connected to the crankcase 2
4 has a pair of crank arms 27, and a slider 29 is rotatably attached to a crank pin 28 connected between the pair of crank arms 27.
The slider 29 is a block having a substantially square shape when viewed in the direction of the crankshaft 25 and is divided into two parts. The slider 29 has a pin insertion hole 30 at the center and is rotatably assembled to the crankpin 28.

A slider frame 31 is arranged around the slider 29. The slider frame 31 is a horizontally long, substantially rectangular frame having a connecting portion on the upper surface when viewed in the direction of the crankshaft 25.
2 has a height substantially the same as the height of the slider 29 and a width that is longer than the width of the slider 29. A slider 29 attached to the crank pin 28 is mounted in the window hole 32 of the slider frame 31 so as to be movable in the window hole 32 in a lateral direction (a direction perpendicular to the direction of movement of the piston 2).

The slider frame 31 includes the crankcase 2
4 is supported by a pair of guide rods 33 and 34 so as to be able to reciprocate in the direction of movement of the piston 2. The pair of guide rods 33 and 34 are fixed in the crankcase 24, and are inserted through guide holes 35 and 36 formed in the longitudinal direction at both ends in the longitudinal direction of the slider frame 31 (movement direction of the piston 2). are doing. 37,38
Are bushings respectively mounted on a pair of guide holes 35 and 36 of the slider frame 31.
Support 3,34.

The piston rod 22 extending downward from the bottom surface of the piston 2
4 is fixedly connected to the center portion of the upper surface of the slider frame 31 in the crankcase 24 by passing through a through hole 39 formed in the upper wall portion 23.

However, the piston 2 in the cylinder 1
The chamber is in a non-lubricated oil state. That is, the oil seal 41 is attached to the annular concave portion 40 formed around the through hole 39 on the upper surface of the upper wall portion 23 of the crankcase 24, and the inner periphery of the oil seal 41 contacts the outer periphery of the piston rod 22. Sealed and crankcase 2
4 is prevented from being supplied to the piston 2 chamber in the cylinder 1. Therefore, the combined gas tight ring 4 slides on the cylinder inner wall 1a without lubrication.

The operation will be described below.

When the crankshaft 25 is rotationally driven by a driving source (not shown), the slider 29 mounted on the crankpin 28 moves in a circular orbit around the center of the crankshaft 25. At this time, as the slider 29 moves along the circular orbit, the slider 29 moves in the window hole 32 of the slider frame 31, and accordingly, the slider frame 31 moves up and down (in the movement direction of the piston 2) by a sine straight line. Do exercise.

As a result, the piston 2 reciprocates in the cylinder 1 via the piston rod 22 which is connected and fixed to the slider frame 31, and when the piston 2 descends, air flows from the suction port 21a through the intake passage to the cylinder 1 Inhaled into.

At this time, as described above, "the lower chamber 10 of the piston 2 → the gap between the lower surface of the ring groove 3 and the lower surface of the lower outer ring 6 and the lower surface of the inner ring 7 → the inner peripheral surface of the inner ring 7 Clearance between the bottom of the ring groove 3 and the air passage 11
→ Since the passage of the "upper chamber 12 of the piston 2" is formed,
In the cylinder 1, leakage from the lower chamber 10 of the piston 2 to the upper chamber 12 of the piston 2 is allowed, and the pressure of the lower chamber 10 of the piston 2 in the cylinder 1 does not increase. Therefore, an increase in the pressure of the lower chamber 10 of the piston 2 in the cylinder 1 can be prevented, so that an undesired repetitive load is not applied to the oil seal 41 and the oil seal 41 can be prevented from being adversely affected.

Next, the air in the cylinder 1 is compressed by the rise of the piston 2, and the compressed air is discharged from the discharge port 21b through the discharge passage.

At this time, the abutment gap 6a of the lower outer ring 6 is sealed by the inner ring 7, and the lower surface of the lower outer ring 6 and the lower surface of the ring groove 3 are in close contact with each other. There is no leakage into the side room 10.

Next, another embodiment 2 of the present invention will be described with reference to the drawings.

The second embodiment is the same as the first embodiment except for the structure of the air passage 11 in the first embodiment.

In the second embodiment, as shown in FIG. 5, the gap between the bottom surface of the ring groove 3 and the inner peripheral surface of the inner ring 7 and the upper chamber 12 of the piston 2 in the cylinder 1 are formed. Unlike the first embodiment, the communicating air passage 11 is formed on the upper surface of the ring groove 3. That is,
The air passage 11 formed in the piston 2 is formed on the upper surface of the ring groove 3 of the piston 2 from the outer peripheral surface of the piston 2 to the ring groove 3.
Are formed by straight grooves having a semicircular cross-section extending to the bottom surface of. A plurality of, for example, 4 to 8 air passages 11 are formed in the piston 2 at intervals in the circumferential direction.

The operation of the piston 2 in the compression stroke and the suction stroke is the same as in the first embodiment.

That is, as shown in FIG. 5, in the compression stroke in which the piston 2 rises (FIG. 5B), the abutment gap 6a of the lower outer ring 6 is sealed by the inner ring 7, Since the lower surface of the lower outer ring 6 and the lower surface of the ring groove 3 are in close contact with each other, they do not leak into the lower chamber 10 of the piston 2. Even if the outer peripheral surfaces of the outer rings 5 and 6 are worn and the abutment gaps 5a and 6a are enlarged, the abutment gaps 5a and 6a of the upper and lower outer rings 5 and 6 are sealed by the inner ring 7. The sealing performance during compression is not impaired. Further, in the suction stroke in which the piston 2 descends ((a) in FIG. 5), “the lower chamber 10 of the piston 2 → the gap between the lower surface of the ring groove 3 and the lower surface of the lower outer ring 6 and the lower surface of the inner ring 7 → Since a gap is formed between the inner peripheral surface of the inner ring 7 and the bottom surface of the ring groove 3 → the air passage 11 → the upper chamber 12 of the piston 2, the lower chamber 10 of the piston 2 moves from the lower chamber 10 of the piston 2 in the cylinder 1. Leakage into the upper chamber 12 is allowed. Therefore, the pressure in the lower chamber 10 of the piston 2 in the cylinder 1 does not increase.

Therefore, as described in the first embodiment, in the non-lubricated air compressor in which the periphery of the piston rod 22 is sealed with the oil seal 41 by lubricating oil, an undesirable repetitive load is not applied to the oil seal 41.
An adverse effect on the oil seal 41 can be avoided.

The combination gas tight ring 4 is not limited to the combination ring having the above-mentioned structure, and for example, a combination ring having the following structure is used.

As shown in FIG. 6, the combined gas tight ring 4 is composed of a pair of upper and lower outer rings 5 and 6 made of heat-resistant and abrasion-resistant resin and one of the outer rings arranged on the inner peripheral side thereof. And an inner ring 7 made of heat-resistant and wear-resistant resin.

The upper and lower outer rings 5, 6 are rings having the same size and having an abutment, and are laminated in the axial direction. A projection 1 is provided on each inner peripheral surface of the upper and lower outer rings 5, 6.
The projections 13 of the one outer ring 5 and the projections 14 of the other outer ring 6 are at different angular positions from the abutment, and these projections 13 and 14 are located at the abutment gap of the inner ring 7. 7a. The inner ring 7 has a radial thickness that is smaller than the radial thickness of the outer rings 5 and 6 and an axial width that is substantially the same as the stacked axial width of the upper and lower outer rings 5 and 6.

Therefore, the abutment gaps 5a and 6a of the upper and lower outer rings 5 and 6 are arranged at positions shifted from each other in the circumferential direction, and the upper and lower outer rings 5 and 6 are prevented from rotating by the inner ring 7. As described above, since the abutment gaps 5a and 6a of the upper and lower outer rings 5 and 6 do not overlap in the axial direction, the combined gas tight ring 4 having excellent sealing performance is obtained. In addition, the combined gas tight ring 4 has three rings 5, 6, 7 integrated with each other and has a degree of freedom in the ring groove of the piston, so that the followability to the cylinder is good and the sealing performance is good. Also, the outer ring 5,
Even if the gap 6 is worn and the gaps 5a, 6a are enlarged, the gaps 5a, 6a are sealed by the inner ring 7, so that the ring has a long life and is excellent in durability.

Further, a single gas tight ring can be used in place of the combined gas tight ring 4.
An example of a single gas tight ring is shown below.

The abutment shape of the single gas tight ring 15 has a gas tight shape as shown in FIG. That is, a cutout 17 that is open to the outer peripheral surface, the lower surface, and the end face 16A of the opening is formed at one end of the opening, and the cross-sectional shape of the notch 17 is formed in a substantially rectangular shape. At the other end of the abutment, the abutment end face 16B
A protruding end 18 is formed to be inserted into the notch 17 at one end of the abutment, and the cross-sectional shape of the protruding end 18 is formed to have substantially the same size and shape as the notch 17. At the other end, the inner peripheral side is slightly cut away. Therefore, in the use state, the double end face 16
A and 16B are mounted in the ring groove of the piston with a slight gap. There is also a slight gap between the end surface of the protruding end portion 18 and the opposing surface of the notch 17. When the abutment shape is configured as a gas tight shape as described above,
Even if the outer peripheral surface of the gas tight ring is slightly worn, the abutment does not open.

The results of measuring the pressure in the lower chamber of the piston in the cylinder are shown below.

The measurement was performed for the following four types of compressors. A compressor in which an air passage is not formed in a piston (Comparative Example 1) A compressor in which an air passage (through hole) is formed in a piston (Embodiment 1) A compressor in which an air passage (groove) is formed in a piston ( Embodiment 2) Compressor with cutout formed in combination gas tight ring (Comparative Example 2)

Of the above, a compressor (Comparative Example 2) in which a cut is formed in the combined gas tight ring will be described. The combination gas tight ring is a combination gas tight ring of the type in which projections 13 and 14 are formed on the inner peripheral surfaces of the outer rings 5 and 6, respectively, of the two types of combination gas tight rings described above. A notch 19 is formed in the inner ring 7 so that the lower chamber of the piston in the cylinder is not compressed during the suction stroke (see FIG. 8). The notch 19 is for the upper outer ring 5.
The inner ring 7 is formed from the inner circumference to the outer circumference on the upper surface of the inner ring 7 portion facing the opening gap 5a.

Therefore, in the suction stroke in which the piston descends, "the lower chamber of the piston → the gap between the lower surface of the ring groove and the lower surface of the lower outer ring 6 and the lower surface of the inner ring 7 → the inner peripheral surface of the inner ring 7 and the ring The gap between the bottom of the groove → the gap between the notch 19 formed on the upper surface of the inner ring 7 and the upper surface of the ring groove → the gap 5a between the upper outer ring 5 →
The passage of the "upper chamber of the piston" is formed, so that leakage from the lower chamber of the piston to the upper chamber of the piston is allowed in the cylinder. For this reason, similarly to the compressors of the first and second embodiments, the pressure in the lower chamber of the piston in the cylinder does not increase.

The piston rings mounted on the pistons of the other three compressors (Comparative Example 1, Embodiment 1, and Embodiment 2) are the outer ring 5 of the two types of combined gas tight rings described above. , 6 is a combined gas tight ring 4 having projections 13, 14 formed on the respective inner peripheral surfaces thereof.

As is clear from the measurement results shown in FIG.
In the compressor having no air passage formed in the piston (Comparative Example 1), the pressure in the lower chamber of the piston in the cylinder increases during the suction stroke of the piston. On the other hand, in the compressors according to the first and second embodiments and the compressor in which the cut is formed in the combined gas tight ring (Comparative Example 2), the pressure in the lower chamber of the piston in the cylinder increases the suction stroke of the piston. At a low pressure.

[0063]

As described above, the non-lubricated compressor of the present invention has excellent sealing performance during the compression stroke, and also has excellent durability if the combined gas tight ring is used for the piston ring.
In the suction stroke, leakage from the lower chamber of the piston to the upper chamber of the piston is allowed in the cylinder, so in a non-lubricated compressor sealed with a lubricating oil with an oil seal,
Since the pressure in the lower chamber of the piston in the cylinder does not increase during the suction stroke of the piston, it is possible to prevent the oil seal from being adversely affected.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a compressor showing one embodiment of the present invention.

FIG. 2 is a side sectional view showing a part of the compressor.

3A is a longitudinal sectional view of a piston portion during a suction stroke, and FIG. 3B is a longitudinal sectional view of the piston portion during a compression stroke.

4A is a perspective view of an upper outer ring, FIG. 4B is a perspective view of an inner ring, FIG. 4C is a perspective view of a lower outer ring, and FIG. 4D is a plan view of a combined gas tight ring. .

5A is a longitudinal sectional view of a piston portion during a suction stroke, and FIG. 5B is a longitudinal sectional view of the piston portion during a compression stroke.

6A is a perspective view of an upper outer ring, FIG. 6B is a perspective view of an inner ring, FIG. 6C is a perspective view of a lower outer ring, and FIG. 6D is a plan view of a combined gas tight ring. .

7A and 7B show a single gas tight ring, wherein FIG. 7A is a plan view, FIG. 7B is a front view, and FIG. 7C is an enlarged perspective view of an abutment portion.

8A is a perspective view of an upper outer ring, FIG. 8B is a perspective view of an inner ring, FIG. 8C is a perspective view of a lower outer ring, and FIG. 8D is a plan view of a combined gas tight ring. .

FIG. 9 is a graph showing a result of measuring a pressure in a lower chamber of a piston in a cylinder.

[Explanation of symbols]

1 ··· cylinder, 1a ··· cylinder inner wall, 2 ··· piston, 3 ··· ring groove, 4 ··· combination gas tight ring,
5,6 ... outer ring, 5a, 6a ... aperture gap,
7. Inner ring, 7a ... Aperture gap, 8, 9, 1
3, 14, projection, 10 piston lower chamber, 11
Air passage, 12 · · · piston upper chamber, 15 · · · single gas tight ring, 16A, 16B · · · end face, 17 ·
・ Cut, 18 ・ ・ Projecting end, 19 ・ ・ Cut, 2
0 head part, 21a suction port, 21b discharge port, 22 piston rod, 23 upper wall part, 24
・ Crankcase, 25 ・ ・ Crankshaft, 26,
26A bearing, 27 crank arm, 28 crank pin, 29 slider, 30 pin insertion hole,
31 ··· Slider frame, 32 ·· Window holes, 33, 34
..Guide rods, 35,36. · Guide holes, 37,38.
・ Bushings, 39 ・ ・ Through hole, 40 ・ ・ Circular recess, 41 ・
·Oil seal.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kento Sakurai 1-9-9 Yaesu, Chuo-ku, Tokyo Imperial Piston Ring Co., Ltd. F term (reference) 3H003 AA02 AB07 AC01 BC03 CB03 CB08 CE04 3J044 AA14 CB21

Claims (6)

[Claims] In a non-lubricated compressor in which the inside of a cylinder and the inside of a crankcase are sealed with a lubricating oil by an oil seal, and a piston reciprocates in a cylinder without lubrication, a gas tight ring is mounted in a ring groove of the piston. Wherein an air passage communicating with a gap between the bottom surface of the ring groove and the inner peripheral surface of the gas tight ring and an upper chamber of the piston in the cylinder is formed in the piston. Machine. 2. The non-lubricated compressor according to claim 1, wherein the air passage is a hole penetrating a piston top surface and a ring groove upper surface. 3. The non-lubricated compressor according to claim 1, wherein the air passage is a groove formed on an upper surface of the ring groove from an outer peripheral surface of the piston toward a bottom surface of the ring groove. 4. The gas tight ring is a combined gas tight ring, and the combined gas tight ring has a pair of upper and lower outer rings having an abutment and an inner peripheral side of the upper and lower outer rings having an abutment. The inner ring is arranged, and a pair of protrusions are formed on the outer peripheral surface of the inner ring by shifting the position in the circumferential direction and the axial direction,
4. The non-contact device according to claim 1, wherein one of the protrusions is disposed in a gap between the upper outer rings and the other protrusion is disposed in a gap between the lower outer rings. Lubrication compressor. 5. The gas tight ring is a combined gas tight ring, and the combined gas tight ring has a pair of upper and lower outer rings having an abutment and an inner peripheral side of the upper and lower outer rings having an abutment. The upper and lower outer rings each have a projection formed on the inner peripheral surface thereof, and the projection of the one outer ring and the projection of the other outer ring are at different angular positions from the abutment. Wherein the projections are arranged in the abutment gap of the inner ring.
4. The non-lubricated compressor according to 2 or 3. 6. The non-lubricated compressor according to claim 1, wherein the gas tight ring is a single gas tight ring having a stepped opening shape.