JPH0932922A - Piston ring structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston ring structure capable of preventing the abrasion of a piston ring exceeding the prescribed level for avoiding the fracture thereof. SOLUTION: Gas pressure relief grooves 17 and 18 formed over the prescribed length from piston ring internal surface 1w in a radial external direction, are provided on a piston ring 1 fitted to the groove 4 of a piston 3 in such a condition as expanding due to exposure to gas pressure on the internal surface 1w as well as having the external surface 1x worn due to pressed contact with a cylinder liner 2, so that gas pressure acting on the internal surface 1w can be released when the external surface 1z is worn to the prescribed amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston ring structure used in a reciprocating air compressor or the like, and more particularly to a piston ring structure which is prevented from being worn over a certain level.

[0002]

2. Description of the Related Art FIGS. 7 and 8 show a piston ring a used in a reciprocating air compressor. As shown in the figure, the piston ring a is configured such that a ring body mounted in a ring groove d of a piston c reciprocating in a cylinder b is circumferentially divided into a large piece e and a small piece f. . The piston ring a is formed such that its thickness g is thinner than the groove width h of the ring groove d, and its mounting margin i is smaller than the groove depth j of the ring groove d.

According to this structure, when the piston c moves upward as shown by an arrow k in FIG. 8, the gas in the compression chamber above the piston c circulates between the ring a and the ring groove d, and the ring groove d. Of the large pieces e and the small pieces f, and the piston ring a is expanded. As a result, the outer peripheral surface n of the piston ring a (the large piece e and the small piece f) is pressed against the cylinder liner b, and a gas leak seal is achieved.

[0004]

However, such a seal means that the outer peripheral surface n of the ring is worn because the outer peripheral surface n of the piston ring is pressed against and slidably contacts the cylinder liner b. Since this abrasion is continuously performed during the operation of the compressor, the radial thickness p of the ring itself becomes extremely thin due to long-term operation, which may cause cutting.

Particularly, in an oil-free air compressor in which the inside of the cylinder is not lubricated with lubricating oil, although carbon or Teflon-based self-lubricating material is used for the material of the piston ring a, there is no lubricating oil. The wear of the outer peripheral surface n of the ring easily progresses, and the wear cutout of the piston ring a is a serious problem.

Once the piston ring a is cut off, not only compression leakage may occur, but also broken pieces of the piston ring a may interfere with other parts (for example, a discharge valve) and impair its function. Therefore, it is necessary to stop the compressor in an emergency and perform disassembly and repair. Therefore, it is necessary to frequently check the wear condition of the piston ring a, and the interval of regular maintenance of the compressor is shortened.

An object of the present invention, which has been devised in consideration of the above circumstances, is to provide a piston ring structure which prevents abrasion of the piston ring beyond a certain level and avoids its cutting damage.

[0008]

In order to achieve the above object, the present invention is mounted in a ring groove of a piston, receives gas pressure on an inner peripheral surface to expand its diameter, and presses an outer peripheral surface against a cylinder liner. A gas pressure that is formed in a predetermined length from the inner peripheral surface of the ring to the radial outside in order to release the gas pressure applied to the inner peripheral surface of the worn piston ring when the outer peripheral surface of the ring wears by a certain amount. It is constructed with a relief groove.

The gas pressure relief grooves may be formed on the upper and lower surfaces of the piston ring, respectively.

The groove depth of the gas pressure relief groove may be formed in a taper shape which gradually becomes shallower toward the radially outer side of the piston ring.

The groove width of the gas pressure relief groove may be formed in a taper shape which gradually narrows outward in the radial direction of the piston ring.

According to the above construction, when the outer peripheral surface of the piston ring which is in sliding contact with the cylinder liner is worn by a certain amount, the gas pressure acting on the inner peripheral surface of the ring is released through the gas pressure relief groove, so that the ring is The diameter will not be expanded any more and wear will stop.

According to the above construction, since the gas pressure relief grooves are formed on the upper and lower surfaces of the piston ring, the gas pressure acting on the inner peripheral surface of the ring is increased and decreased when the piston is raised and lowered. Each is released through the relief groove.

According to the structure described above, since the groove depth of the gas pressure relief groove is tapered, the amount of gas that escapes from the inner peripheral surface of the ring through this groove is small when wear on the outer peripheral surface of the ring is small. Yes, and increases as wear progresses.

According to the structure described above, since the groove width of the gas pressure relief groove is formed in a tapered shape, the amount of gas that escapes from the inner peripheral surface of the ring through this groove is small when wear on the outer peripheral surface of the ring is small. , As the wear progresses.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the accompanying drawings.

1 and 2 show a piston ring 1 of an oil-free reciprocating air compressor. As shown in the figure, the piston ring 1 is configured by circumferentially dividing a ring body mounted in a ring groove 4 of a piston 3 which reciprocates in a cylinder 2 into a large piece 1a and a small piece 1b. . The large piece 1a and the small piece 1b are made of a self-lubricating material such as carbon or Teflon,
As shown in FIG. 3, a push rod 5 and a coil spring 6 provided inside the piston 3 are urged outward in the radial direction.

More specifically, as shown in FIG. 3, four accommodation holes 7 are formed in the ring groove 4 of the piston 3 at equal intervals in the circumferential direction, and these accommodation holes 7 are formed. The push rod 5 and the coil spring 6 are housed therein. One end of the coil spring 6 is engaged with an engaging portion 8 formed at the tip end portion of the push rod 5, and the other end is engaged with an enlarged diameter portion 9 formed at the inlet portion of the accommodation hole 7. . According to this configuration, when the push rod 5 is inserted into the accommodation hole 7, the coil spring 6 is stretched, so that the returning force causes the large piece 1a and the small piece 1b to expand in diameter through the push rod 5.

The push rod 5 is provided with a holding portion 11 that engages with the recesses 10 formed in the large piece 1a and the small piece 1b and holds these positions. The holding portion 11 of the push rod 5 has the concave portion 1 of the large piece 1a and the small piece 1b.
By engaging with 0, the large piece 1a and the small piece 1b are prevented from moving apart and moving in the ring groove 4. That is, the push rod 5 has a function as a pusher that urges the large piece 1a and the small piece 1b of the piston ring 1 in the radial expansion direction and presses them against the cylinder liner 2.
It has a function as a retainer for holding the positions of the large piece 1a and the small piece 1b.

A piston ring 1 consisting of a large piece 1a and a small piece 1b is mounted in a ring groove 4 of a piston 3 as shown in FIG. 2 (a), and is pressed against the cylinder liner 2 by the push rod 5 and held in position. It Although only one ring groove 4 is shown in the figure,
In reality, a plurality of pistons 3 are provided in the axial direction of the piston 3, and the piston rings 1 are similarly mounted in the respective grooves 4. In the piston ring 1, the thickness 1x is formed thinner than the groove width 4x of the ring groove 4, and the mounting margin 1y is formed smaller than the groove depth 4y of the ring groove 4.

According to this structure, when the piston 3 rises as shown by an arrow 12 in FIG.
The gas in the upper compression chamber circulates between the ring 1 and the ring groove 4 and enters the inside of the ring groove 4, and the gas pressure acts on the inner peripheral surfaces 1w of the large piece 1a and the small piece 1b, and the large piece 1a.
And the small piece 1b is moved radially outward, and the piston ring 1 is expanded in diameter. As a result, the outer peripheral surfaces 1z of the piston ring 1, that is, the large piece 1a and the small piece 1b are pressed against the cylinder liner 2, and a gas leak seal between the piston 3 and the cylinder liner 2 is achieved.

With such a seal, the large piece 1a and the small piece 1
Even if the outer peripheral surface 1z of b is worn as shown by an imaginary line 13 in FIG. 3, the push rod 5 urged by the coil spring 6 expands the large piece 1a and the small piece 1b in accordance with the wear, so that the large piece The surface pressure of 1a and the small piece 1b is always kept appropriate to the cylinder liner 2. Therefore, high efficiency can be maintained forever. In addition, since the joint portion 14 of the large piece 1a and the small piece 1b is formed obliquely, a gap does not occur in the joint portion 14 even if the wear progresses.

The feature of this embodiment is that, as shown in FIGS. 1 and 2, when the upper and lower surfaces 15 and 16 of the large piece 1a constituting the piston ring 1 are worn on the outer peripheral surface 1z by a certain amount. In order to release the gas pressure received on the inner peripheral surface 1w, gas pressure relief grooves 17 and 18 formed in a predetermined length L from the inner peripheral surface 1w outward in the radial direction are provided. The groove length L of the gas pressure relief grooves 17, 18 acts on the inner peripheral surface 1w as shown in FIG. 2 (b) when the large piece 1a is worn to the limit as shown by the imaginary line 19 in FIG. The gas pressure is set to a length that allows it to escape downward.

That is, before the large piece 1a reaches the wear limit shown by the imaginary line 19 in FIG. 4, the lower surface 16 of the large piece 1a and the lower surface 20 of the ring groove 4 are gas pressure relief grooves as shown in FIG. 2 (a). Although it is sealed by the seal portion 21 located at the extension of 18, the gas pressure relief groove 18 is radially outward from the side surface 21 of the piston 3 when worn just before the wear limit, as shown in FIG. 2 (b). To the inner surface 1
The gas pressure acting on w is released downward.

The gas pressure relief groove 18 provided on the lower surface 16 of the large piece 1a has been described above.
A similar gas pressure relief groove 17 is also provided on the upper surface 15 of the. The gas pressure relief groove 17 is provided to allow the gas pressure that has entered the ring groove 4 from the compression chamber below the piston 3 to escape upward when the piston 3 descends.
That is, the air compressor according to the present embodiment has the piston 3
The compression chambers are provided above and below, and when the piston 3 moves upward, the gas pressure of the upper compression chamber expands the large piece 1a and the small piece 1b as described above, and when the piston 3 descends, the gas pressure of the lower compression chamber increases. The large piece 1a and the small piece 1b are expanded in diameter.

Therefore, in a compressor of the type having a compression chamber only above the piston 3, the upper surface 15 of the large piece 1a is
The gas pressure relief groove 17 is unnecessary, and only the gas pressure relief groove 18 on the lower surface 16 of the large piece 1a is sufficient. This is because it is almost meaningless to provide the gas pressure relief groove 17 on the upper surface 15 of the large piece 1a as long as there is no gas pressure flowing from below to above. Therefore, for example, when the present invention is applied to a diesel engine or a gasoline engine, the gas pressure relief groove 18 may be provided only on the lower surface 16 of the piston ring 1.

Further, in the present embodiment, the gas pressure relief grooves 17 and 18 are formed so as to be paired with the upper and lower surfaces 15 and 16 of the large piece 1a. It may be formed on the lower surfaces 15 and 16. Further, it goes without saying that the gas pressure relief grooves 17 and 18 may be provided not only on the large piece 1a as in the present embodiment but also on the small piece 1b. Further, the number of gas pressure relief grooves 17 and 18 is not limited to the number in this embodiment, and may be larger or smaller than that.

The operation of this embodiment having the above configuration will be described.

The large piece 1a and the small piece 1b mounted in the ring groove 4 of the piston 3 enter the ring groove 4 as shown in FIG. 2 (a) before reaching the wear limit shown by the imaginary line 19 in FIG. The inner peripheral surface 1w receives the above-mentioned gas pressure to expand the diameter, and the outer peripheral surface 1z is pressed against the cylinder liner 2 to seal gas leakage.

Thereafter, the large piece 1a and the small piece 1b are moved leftward in the drawing by being pushed by the gas pressure acting on the inner peripheral surface 1w as the outer peripheral surface 1z is worn. Then, when the wear reaches just before the wear limit shown by the phantom line 19 in FIG.
As shown in (b), the gas pressure relief groove 18 projects radially outward from the side surface 21 of the piston 3, and the gas pressure acting on the inner peripheral surface 1w of the large piece 1a is released downward.

That is, between the lower surface 16 of the large piece 1a and the lower surface 20 of the ring groove 4, before the large piece 1a reaches the wear limit, as shown in FIG. 2 (a), the gas pressure relief groove 18 is extended. It is sealed by the sealing portion 21 which is opened, but when it is worn just before the wear limit, it is opened by the gas pressure relief groove 18 as shown in FIG. 2 (b).

Therefore, thereafter, the large piece 1a will have its inner peripheral surface 1
The gas pressure acting on w prevents the cylinder liner 2 from being pressed against the liner 2 and prevents further wear. Therefore, according to the present embodiment, unlike the conventional case, the piston ring 1 is not worn endlessly, that is, until it is cut, and the piston ring 1 can be reliably prevented from being cut. Therefore, the reliability of the compressor is improved.

Even if the top ring (the ring closest to the upper surface of the piston 3) becomes free in this way, the compression is retained by the second ring (not shown) at the next stage, so that the efficiency hardly decreases. Similarly, even if the second ring becomes free, the compression is retained by the third ring. Therefore, the total life of the compressor can be extended, and the intervals of regular maintenance can be extended.

Even if the gas pressure relief grooves 17 and 18 are opened and the piston ring 1 becomes free, the diameter of the ring 1 is expanded by the coil spring 6 and the push rod 5 shown in FIG. Although it is pressed, the pressing force is extremely weak, and therefore the piston ring 1 is hardly worn by this.

Another embodiment of the present invention is shown in FIGS. 5 (a) (b) (C).
Shown in

As shown, these alternative embodiments include:
Groove depths 17a, 18 of the gas pressure relief grooves 17, 18
The configuration is similar to that of the previous embodiment, except that a is formed in a tapered shape that gradually becomes shallower toward the radially outer side of the piston ring 1. Specifically, the bottom surfaces 17b and 18b of these gas pressure relief grooves 17 and 18 are linearly inclined in FIG. 5 (a) and concavely curved in FIG. 5 (b). The one in FIG. 5 (C) is inclined in a convex curve.

According to this structure, the piston ring 1
The inner peripheral surface 1w as the outer peripheral surface 1z wears.
Is moved to the left in the figure by the gas pressure acting on the inner wall surface, and finally the gas pressure relief grooves 17 and 18 are opened, and the inner peripheral surface 1w
The gas pressure that acts on the gas pressure relief groove is released, but initially the shallow portions of the gas pressure relief grooves 17 and 18 of the groove depths 17a and 18a are opened, so the amount of gas escape is small, and thereafter wear progresses. Therefore, the escape amount of gas gradually increases.

According to such a piston ring 1, the gas pressure that has entered the ring groove 4 is partly the groove depth 17a, 18 of the relief groove 17, 18 when wear is small.
It escapes from the shallow portion of b, and the rest acts on the inner peripheral surface 1w to expand the diameter of the piston ring 1. Then, as the wear increases, the ratio becomes reversed. in this way,
By releasing part of the gas pressure and using the rest for diameter expansion,
The sealability between the piston 3 and the cylinder liner 2 is improved. Further, finally, since the deep portions of the groove depths 17a, 18a of the gas pressure relief grooves 17, 18 are opened, the piston ring 1 can be surely made free.

Another embodiment is shown in FIG.

As shown in the figure, in this embodiment, the groove widths 17c and 18c of the gas pressure relief grooves 17 and 18 are formed in a taper shape which gradually narrows outward in the radial direction of the piston ring 1. The configuration is the same as that of the first embodiment except that.

According to this structure, the gas pressure relief groove 1
Since the groove widths 17c and 18c of 7 and 18 are formed in a tapered shape, the amount of gas that escapes from the ring inner peripheral surface 1w through these grooves 17 and 18 is small when the ring outer peripheral surface 1z is less worn. Will increase as the progresses.
Therefore, the same effect as that of the embodiment shown in FIG. 5 is obtained. Further, by combining the embodiments of FIGS. 5 and 6, the groove widths 17c and 18c of the gas pressure relief grooves 17 and 18 are combined.
The groove depths 17a and 18a may both be tapered.

As the prior art related to the present invention,
A device shown in FIG. 9 is known (Japanese Patent Laid-Open No. 4-203370, etc.). This technique forms a gas pressure relief hole 53 in a land portion 52 of a piston 51 forming a ring groove 50,
When the piston ring 54 is worn by a certain amount, the gas pressure acting on the ring inner peripheral surface 55 is released from the relief hole 53.

However, in this technique, since the relief hole 53 is provided in the piston 51, the relief timing cannot be adjusted. On the other hand, according to the present invention, since the relief grooves 17, 18 are provided in the piston ring 1 which is a consumable item, a plurality of types of piston rings 1 provided with the relief grooves 17, 18 having different lengths are prepared in advance. If so, the relief time can be easily changed by exchanging them at the time of periodic maintenance of the compressor.

Further, when the material and hardness of the piston rings 1 and 54 are changed at the time of maintenance and the critical wear amount is changed, the prior art cannot provide any measure because the relief hole 53 is provided on the piston 51 side. According to the invention, the relief groove 1 provided in the piston ring 1
It can be easily dealt with by changing the lengths of 7 and 18 according to the material thereof.

Further, in the prior art, when the relief hole 53 is opened, the gas pressure directly acts on the piston ring 56 of the next stage, which tends to adversely affect the piston ring 56 of the next stage. On the other hand, according to the present invention, when the relief groove 18 is opened as shown in FIG. 2 (b), the gas pressure goes around the piston ring 1 and the groove 1
It flows through 8 to the next stage side. For this reason, after the labyrinth effect is exerted and interfered, the labyrinth effect is exerted on the piston ring of the next stage, and no adverse effect occurs.

Further, in the prior art, since it is necessary to form the relief hole 53 in the land portion 52 that is engaged in the unevenness of the piston 51, it is extremely difficult to process it.
In the present invention, the relief groove 17, on the surface of the piston ring 1,
Since it is sufficient to form 18, it can be easily processed.

[0047]

As described above, according to the piston ring structure of the present invention, the following effects can be exhibited.

(1) It is possible to prevent the piston ring from being worn to a certain degree or more, and to prevent the cut from occurring.

(2) Therefore, the life is extended and the reliability is improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a piston ring structure showing an embodiment of the present invention.

FIG. 2 is a diagram showing an operation of the piston ring,
(a) shows the state before the wear limit and (b) shows the state just before the wear limit.

FIG. 3 is a sectional view of a piston to which the piston ring is attached.

FIG. 4 is a diagram showing a wear limit of the piston ring.

FIG. 5 is a diagram showing another embodiment of the present invention.

FIG. 6 is a view showing still another embodiment.

FIG. 7 is a perspective view showing a piston ring structure according to a conventional example.

FIG. 8 is a diagram showing how the piston ring is pressed against a cylinder liner by gas pressure.

FIG. 9 is a side sectional view of a piston showing a related technique.

[Explanation of symbols]

 1 piston ring 1w inner peripheral surface 1z outer peripheral surface 2 cylinder liner 3 piston 4 ring groove 15 piston ring upper surface 16 piston ring lower surface 17 gas pressure relief groove 17a groove depth 17c groove width 18 gas pressure relief groove 18a groove depth 18c groove width L predetermined length

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasufumi Nehashi 3934 Inatomi, Tatsuno-cho, Kamiina, Nagano Prefecture Ishikawajima General-purpose machinery Co., Ltd. Tatsuno Factory

Claims (4)

[Claims] 1. A piston ring, which is mounted in a ring groove of a piston, receives gas pressure on its inner peripheral surface to expand its diameter, and whose outer peripheral surface is pressed against a cylinder liner and wears, and the outer peripheral surface of the ring wears by a certain amount. A piston ring structure characterized in that a gas pressure relief groove formed in a predetermined length from the inner peripheral surface of the ring outward in the radial direction is provided in order to release the gas pressure received on the inner peripheral surface when the above is performed. 2. The piston ring structure according to claim 1, wherein the gas pressure relief grooves are formed on the upper and lower surfaces of the piston ring, respectively. 3. The piston ring structure according to claim 1, wherein the groove depth of the gas pressure relief groove is formed in a taper shape that gradually becomes shallower outward in the radial direction of the piston ring. 4. The piston ring structure according to claim 1, wherein a groove width of the gas pressure relief groove is formed in a taper shape that gradually narrows outward in a radial direction of the piston ring.