JP2955353B2 - air compressor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an air compressor in which wear of a piston ring is limited.

"Conventional technology" As a conventional technology for a piston seal structure, the
What is found in the publication 7888 is known.

This type of technology is based on a so-called two-stage oilless system in which air at a target pressure is generated at a pressure lower than the target at a first stage cylinder and at a desired pressure at a second stage cylinder. Used in an air compressor, as shown in FIG. 12, it is connected to a crankshaft (not shown) provided in a crank chamber 1b via a connecting rod 2a and a piston pin 2b so as to be movable in the cylinder 1. A compression chamber 1a is formed inside the cylinder 1 by the provided piston 2.

A plurality of annular grooves 3 are formed in the outer circumferential surface of the piston 2 at intervals in the axial direction of the piston 2 to seal between the compression chamber 1a and the crank chamber 1b of the cylinder 1. The first piston ring 4 and the second piston ring 5 are mounted, and the first piston ring 4 and the second piston ring 5 are mounted.
This seals between the compression chamber 1a and the crank chamber 1b. And the first during operation
In order to absorb the effects of thermal expansion of the piston ring 4 and the second piston ring 5 and wear of the first piston ring 4 and the second piston ring 5, the first and second piston rings 4 and 5 are joined. ), And an appropriate gap is provided at the joint. Reference numeral 6 denotes the piston 2
Is a rider ring made of an ethylene resin, which is fitted on the outer periphery of the piston 2 and serves as a sliding portion of the piston 2.

However, in the conventional air compressor, even if the first piston ring 4 and the second piston ring 5 reach the wear limit, the first piston ring 4 and the second piston ring 4 Because there is no means to limit the wear of the piston ring 5,
The wear of the first piston ring 4 and the second piston ring 5 progresses, and as a result, the first piston ring 4 or the second piston ring 5 comes off the groove 3 and breaks, thereby damaging the inner wall of the cylinder. There was a risk of failure.

The same is true not only for the first piston ring 4 and the second piston ring 5 but also when a large number of piston rings are mounted on the piston 2. If one piston ring reaches the wear limit, the air compressor may be damaged as described above. Therefore, all the piston rings attached to the piston 2 must be replaced, and the piston 2 must be replaced. If even one of the many piston rings has reached the wear limit, all piston rings will be replaced even if the other piston rings have not reached the wear limit. However, there is a problem that the piston ring which has not reached the limit cannot be used effectively.

The present invention has been made in view of the above circumstances, and when the piston ring has reached the wear limit, the fluid in the compression chamber has escaped through the throttle passage formed in the piston or the piston ring to reach the wear limit. It is an object of the present invention to provide an air compressor that can limit the progress of wear of a piston ring, prevent damage to the air compressor, and improve durability.

"Means for Solving the Problems" The present invention has the following configuration to achieve the above object. That is, between a cylinder, a piston connected to a crankshaft provided in a crank chamber, and movably provided inside the cylinder to form a compression chamber in the cylinder, and between the compression chamber and the crank chamber of the cylinder. A space formed between the outer peripheral surface of the piston and the inner wall of the cylinder is formed in the compression chamber by being mounted on a concave groove formed in the outer peripheral surface of the piston at an axial interval so as to seal the piston. In an air compressor comprising a plurality of piston rings defined in a side space and a crankcase side space, only in a state where the piston rings have reached a wear limit,
A throttle passage for communicating the compression chamber side space and the crank chamber side space defined by the piston ring is provided on the crank ring side wall of the piston ring or the concave groove of the piston.

Between the space defined between the outer peripheral surface of the piston, at least one piston ring and the inner wall of the cylinder, and the crank chamber, at least one of the plurality of piston rings in the compression step has a wear limit. There is provided a throttle passage which communicates only in the reached state.

[Operation] According to the above configuration, in the compression step, when the piston is slid toward the compression chamber in the cylinder, the diameter of the piston ring increases due to a differential pressure generated between the compression chamber and the crank chamber in the cylinder. And its outer periphery is in close contact with the inner wall of the cylinder,
The compression chamber and the crank chamber in the cylinder are sealed.

Further, in this case, when at least one of the plurality of piston rings reaches the wear limit, the fluid in the compression chamber side space defined between the outer peripheral surface of the piston and at least one of the piston rings and the inner periphery of the cylinder is formed. Flows through the throttle passage into the crank chamber side space, so that the force for pressing the piston ring, which has reached the wear limit, against the cylinder inner wall due to the differential pressure generated between the compression chamber side space and the crank chamber side space hardly works. The wear of the piston ring which has reached the wear limit hardly progresses. This prevents disengagement of the piston ring from the piston and failure of the air compressor due to the piston ring, and when multiple piston rings are mounted on the piston, all piston rings remain intact until they reach the wear limit. , And the durability of the air compressor is improved as compared with the conventional case.

Embodiments Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 5 for an oilless air compressor.

In this embodiment, the same parts as those of the conventional example are denoted by the same reference numerals, and the description of some of them will be omitted.

In this embodiment, when at least one of the piston rings reaches the wear limit, the fluid in the space defined between the outer peripheral surface of the piston, the at least one piston ring, and the inner wall surface of the cylinder passes through the throttle passage. Flows into the crankcase, and the pressure that presses the piston ring, which has reached the wear limit, against the inner wall of the cylinder hardly works due to the differential pressure generated between the compression chamber and the crankcase. I try to make it hardly progress.

In FIGS. 1 to 4, reference numeral 4 denotes a first piston ring, and reference numeral 5 denotes a second piston ring. The first piston ring 4 and the second piston ring 5 are made of a non-metallic heat-resistant elastic material such as ethylene resin, which is flexible and highly adaptable, and seals a gas between a cylinder and a piston of an air compressor or the like. Is used as Each of the first piston ring 4 and the second piston ring 5 has a rectangular cross-section having an abutment in which one portion of the ring is cut away and a gap is formed between both ends of the cut portion of the ring.

The piston 2 has a cylindrical shape whose one end (the upper end in FIG. 3) is closed. The piston 2 is slidably fitted into the cylinder 1 via a rider ring 6. It is partitioned into a compression chamber 1a and a crank chamber 1b.

First annular grooves 3 are formed on the outer peripheral surface of the piston 2 at intervals in the axial direction of the piston 2.
The piston ring 4 and the second piston ring 5 are fitted.

In the outer peripheral wall of the piston 2, the first piston ring 4 reaches the wear limit in the compression stroke at one position on the side wall 3a on the crank chamber 1b side of the side wall of the concave groove 3 in which the first piston ring 4 is fitted. In the state shown in FIG. 1, a pressure adjusting passage communicating between a space 12 defined between the outer peripheral surface of the piston 2, the first piston ring 4 and the inner wall surface 1 c of the cylinder 1, and the crank chamber 1 b is provided. A throttle passage (orifice) 11 is formed.

Further, on the outer peripheral wall of the piston 2, a side wall 3 b on the side of the crank chamber 1 b of the side wall of the concave groove 3 in which the second piston ring 5 is fitted.
In the state shown in FIG. 4 in which the second piston ring 5 has reached the wear limit in the compression stroke, there is a gap between the outer peripheral surface of the piston 2 and the second piston ring 5 and the inner wall surface 1c of the cylinder 1. A pressure adjustment throttle passage (orifice) 14 is formed to communicate between the space 13 formed and the crank chamber 1b.

Next, the operation of the air compressor having the above configuration will be described. A drive source (not shown) of the air compressor is driven to rotate a crankshaft (not shown). Then, the piston 2 slides vertically (substantially in the axial direction of the piston 2) in FIG. 1 via the connecting rod 2a and the piston pin 2b.

Here, as shown in FIG. 2, the first piston ring 4,
The case where both the second piston rings 5 have not reached the wear limit will be described. In this case, during the compression stroke in which the piston 2 moves from the bottom dead center to the top dead center in the cylinder 1, the first piston ring 4 applies the compressed gas pressure of the compression chamber 1 a to the inner wall surface 1 c of the cylinder 1. It acts as a force 15a for pressing the ring 4 and acts as a force 15b for pressing the first piston ring 4 on the side wall 3a. Therefore, the first piston ring 4 is located on the inner wall surface of the cylinder.
1c and the side wall 3a are pressed to seal between the cylinder 1 and the piston 2 and also seal the orifice 11.

At this time, as shown in FIG. 2, the pressure of the compressed gas which has not been completely sealed by the first piston ring 4 and leaked from the space 12 into the space 13 is applied to the second piston ring 5 as shown in FIG. And acts as a force 16b for pressing the second piston ring 5 against the side wall 3b.
Therefore, the second piston ring 5 is pressed against the cylinder inner wall surface 1c and the side wall 3a to seal the gap between the cylinder 1 and the piston 2 and seal the orifice 14. In addition, the first
When the piston ring 4 and the second piston ring 5 have not reached the wear limit, the pressing force 15a> the pressing force 16a, and the pressing force 15b> the pressing force 16b.
It is.

Next, by operating the piston 2, the first piston ring
4, the case where the second piston ring 5 has worn and the first piston ring 4 has reached the wear limit and the second piston ring 5 has not reached the wear limit as shown in FIG. 1 will be described. In this case, in the compression stroke in which the piston 2 moves from the bottom dead center to the top dead center in the cylinder 1,
As shown in the figure, the orifice 11 is the first piston ring 4
, It is not sealed and is in an open state. Then, the compressed gas in the space 12 flows into the space 13 through the orifice 11.
Therefore, there is almost no force for pressing the first piston ring 4 against the inner wall surface 1c of the cylinder 1, and the wear of the first piston ring 4 further hardly progresses.

The pressure of the compressed gas flowing into the space 13 through the orifice 11 is applied to the second piston ring 5 by the inner wall surface of the cylinder 1.
1c acts as a force 16a for pressing the second piston ring 5, and also acts as a force 16b for pressing the second piston ring 5 on the side wall 3b. As a result, the second piston ring 5 seals between the inner wall surface 1c of the cylinder 1 and the piston 2, and the second piston ring 5 separates the compression chamber 1a and the crank chamber.
1b and seal.

Therefore, even after the first piston ring 4 reaches the wear limit, the seal between the inner wall surface 1c of the piston 2 and the cylinder 1 is kept by the second piston ring 5 until the second piston ring 5 reaches the wear limit. And the durability is improved as compared with the conventional air compressor. Further, the first piston ring 4 and the second piston ring 5 do not come off from the piston 2.

Next, by operating the piston 2, the first piston ring
4, the second piston ring 5 is worn, and as shown in FIG. 4, the first piston ring 4 has not reached the wear limit,
The case where the second piston ring 5 has reached the wear limit will be described.

In this case, in the compression stroke in which the piston 2 moves from the bottom dead center to the top dead center in the cylinder 1, the orifice 11 is sealed by the first piston ring 4 and the orifice 14 is closed as shown in FIG. Since the first piston ring 4 is in an open state not sealed by the two piston rings 5, the compressed gas pressure in the compression chamber 1a is applied to the cylinder 1
15a for pressing the first piston ring 4 against the inner wall surface 1c
And acts as a force 15b for pressing the first piston ring 4 against the side wall 3a. Therefore,
The first piston ring 4 is pressed against the cylinder inner wall surface 1c and the side wall 3a to seal between the cylinder 1 and the piston 2 and seal the orifice 11.

At this time, as shown in FIG. 4, the pressure of the compressed gas leaked from the space 12 into the space 13 through the second piston ring 5 through the orifice 14 without being completely sealed by the first piston ring 4 passes through the orifice 14, as shown in FIG. Flow into 1b. For this reason,
The force that presses the second piston ring 5 against the inner wall surface 1c of the cylinder 1 is almost eliminated, and the further progress of wear of the second piston ring 5 is almost eliminated.

Therefore, even after the second piston ring 5 reaches the wear limit, the seal between the piston 2 and the inner wall surface 1c of the cylinder 1 is maintained by the first piston ring 4 until the first piston ring 4 reaches the wear limit. And the durability is improved as compared with the conventional air compressor.

Further, the first piston ring 4 and the second piston ring 5 do not come off from the piston 2.

FIG. 5 is a characteristic diagram showing a relationship between the operation time of the air compressor and the amount of wear of the piston ring, in which a broken line shows a wear characteristic diagram of the piston ring of the conventional air compressor. The wear limit of the piston ring of the conventional air compressor is indicated by the wear after the piston ring of the conventional air compressor exceeds the wear limit, and the solid line indicates the wear first in the air compressor of the present embodiment. The wear characteristic diagram of the piston ring that has reached the limit is shown, and the dashed line shows the wear characteristic diagram of the piston ring that has reached the wear limit later in the air compressor of the present embodiment, and t is the conventional air compressor. The time required for replacement of the piston ring is indicated, and T indicates the time required for replacement of the piston ring of the air compressor of the present embodiment.

As shown in FIG. 5, in this embodiment, the action of the orifice opened by the piston ring which has reached the wear limit first causes the compressed gas force to act on the piston ring which has reached the wear limit first. The piston ring no longer works and the subsequent wear progresses, and conventionally all the piston rings had to be replaced here.However, in the present embodiment, the remaining piston ring which has reached the wear limit is not removed, so the remaining This indicates that the operation can be continued further until the piston ring reaches the wear limit, so that the durability of the air compressor can be improved.

When the first piston ring 4 reaches the wear limit first in the single-stage air compressor, the space above the second piston ring 5 becomes the clearance volume, so that the performance of the air compressor slightly decreases. In a multi-stage air compressor, the effect of the clearance volume on the performance of the air compressor is small, so that the performance of the air compressor hardly decreases (first embodiment).

In the first embodiment, the orifices 11 and 14 are provided in the piston 2. However, the present invention is not limited to this, and the orifices 21a are provided in the first piston ring 21 and the second piston ring 22 as shown in FIG. The orifice 22a may be provided, and in this case, the same effect as in the first embodiment can be obtained (second embodiment).

In the first embodiment and the second embodiment, the example in which the two piston rings of the first piston ring 4 and the second piston ring 5 are provided on the outer periphery of the piston 2 has been described. Instead, as shown in FIG. 7, another piston ring 31 may be attached to the piston 2 and a number of piston rings may be provided on the outer periphery of the piston 2. In this case, since the air compressor can be operated until all the piston rings reach the wear limit, the durability of the air compressor can be further increased as compared with the above embodiments. 3c is a side wall (third embodiment).

In the first embodiment, the orifice 11 or the orifice 14 is provided on the side wall of the concave groove 3 of the piston 2, and in the second embodiment, the orifices 21a and 22a are provided in the first piston ring 21 and the second piston ring 22, respectively. However, the present invention is not limited to this, and as shown in FIGS.
Restriction passages 41a, 42a formed of grooves may be provided on the outer periphery of the side walls 41, 42 (fourth embodiment). Further, as shown in FIG. 10, grooves are formed on the inner peripheral surface of each piston ring 51. A throttle passage 51a may be provided (fifth embodiment). Further, as shown in FIG. 11, a throttle passage 61a formed of a groove may be provided on the side of the crank chamber 1b of each piston ring 61 mounted on the piston 2. Good (sixth embodiment).

According to the present invention, in the compression step, when at least one of the plurality of piston rings reaches a wear limit, a gap is formed between the outer peripheral surface of the piston, at least one piston ring, and the inner wall of the cylinder. Since the formed fluid in the compression chamber side space can flow into the crank chamber side space through the throttle passage, the wear limit has been reached due to the differential pressure generated between the compression chamber side space and the crank chamber side space. The force for pressing the piston ring against the inner wall of the cylinder can be hardly exerted, so that excessive wear of the piston ring can be prevented.

Further, by preventing the piston ring from being excessively worn, it is possible to prevent the piston ring from coming off from the piston and to prevent the air compressor from malfunctioning due to the piston ring.

Also, when a plurality of piston rings are mounted on the piston, all the piston rings can be operated in the same state until they reach the wear limit, and as a result, the durability of the air compressor can be improved as compared with the conventional case.

In addition, when the piston ring has not reached the wear limit, the communication between the compression-side space defined by the piston ring and the crankcase-side space is kept in an interrupted state, so that high compression efficiency can be maintained.

[Brief description of the drawings]

1 to 5 show a first embodiment of the present invention. FIG. 1 is a side sectional view of a main part showing a state when a first piston ring has reached a wear limit, and FIG. FIG. 3 is a side sectional view of a main part for explaining a force applied to the piston ring in a compression stroke. FIG. 3 is a side cross sectional view of the main part. FIG. 4 shows a state when the second piston ring reaches a wear limit. FIG. 5 is a characteristic diagram showing the relationship between the operating time of the air compressor and the amount of wear of the piston ring. FIG. 6 is a side sectional view of the essential part showing a second embodiment of the present invention. FIG. 7 is a side sectional view of a main part showing a third embodiment of the present invention. FIGS. 8 and 9 show a fourth embodiment of the present invention. FIG. 9 is a side sectional view of a main part, FIG. 10 is a perspective view of a part of a piston ring showing a fifth embodiment of the present invention, and FIG. 11 is a piston showing a sixth embodiment of the present invention. Partial perspective view of a ton ring, twelfth
FIG. 1 is a side sectional view of a main part of a conventional air compressor. 1 ... Cylinder, 1a ... Compression chamber, 1b ... Crank chamber, 1c
... inner wall surface, 2 ... piston, 3 ... groove, 3a, 3b, 3c ...
... side wall, 4,21 ... first piston ring, 5,22 ... second piston ring, 11,14,21a, 22a, 32 ... throttle passage (orifice), 41a, 42a, 51a, 61a ... throttle Passages, 31,51,61 ……
piston ring.

Continued on the front page (72) Inventor Naoki Kadoya 1116 Koizono, Ayase-shi, Kanagawa Prefecture Tokiko Corporation Sagami Plant (72) Inventor Hiroshi Terada 1116 Koizono, Ayase-shi, Kanagawa Prefecture Tokiko Corporation Sagami Plant (56) Reference Literature Japanese Utility Model 52-4010 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F04B 39/00 107

Claims (1)

(57) [Claims] 1. A cylinder, a piston connected to a crankshaft provided in a crank chamber, and movably provided inside the cylinder to form a compression chamber in the cylinder, a compression chamber of the cylinder, and a crank chamber. To seal the gap between the outer peripheral surface of the piston and the inner wall of the cylinder by being mounted in a concave groove formed at an interval in the axial direction of the piston on the outer peripheral surface of the piston. An air compressor including a plurality of piston rings defined in a compression chamber side space and a crank chamber side space, wherein the compression defined by the piston ring is performed only when the piston ring has reached a wear limit. A throttle passage communicating between the chamber side space and the crank chamber side space is provided in the crank chamber side wall of the piston ring or the concave groove of the piston. Features air compressor.