JP2536565Y2 - Compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a compressor with reduced wear of a piston ring.

"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. As shown in FIG. 6, it is used for a compressor and is connected to a crankshaft (not shown) provided in a crank chamber 1b via a connecting rod 2a and a piston pin 2b, and is movably provided in the cylinder 1. The compression chamber 1a is formed inside the cylinder 1 by the piston 2 thus obtained.

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 piston ring 4 and the second piston ring 5 are provided in FIG. As shown in the figure, a stepped joint (abutment) 6 is provided, and an appropriate gap is provided in the abutment 6 so that the first piston ring 4 and the second piston ring 5 can be opened. A thin plate 7 is attached to each inner peripheral surface of the first piston ring 4 and the second piston ring 5 in order to prevent leakage of fluid from the abutment 6.

It is to be noted that a rider ring made of ethylene resin is fitted on the outer periphery of the piston 2 and serves as a sliding portion of the piston 2.

[Problem to be Solved by the Invention] In the above-described conventional technology, a force as shown in FIG. 10 acts on the first piston ring 4 and the second piston ring 5.

f ₁ : Force acting on the back surface (S ₁ ) of the piston ring 4 or 5 f ₂ : Force acting on the outer peripheral surface (S ₂ ) of the piston ring 4 or 5 S ₁ : Area S on the back surface of the piston ring 4 or 5 ₂ : Area of outer peripheral surface of piston ring 4 or 5 P _C : Pressure of compression chamber 1a P _O : Pressure on crank chamber 1b side P _L : Surface pressure of outer peripheral surface of piston ring 4 or 5 H: Piston ring 4 or 5 Thickness D ₁ : outer diameter of piston ring 4 or 5 D ₂ : inner diameter of piston ring 4 or 5 P _L = f ₂ / S ₂ = (P _C −P _O ) · D ₂ / D ₁ (1) where f ₂ = (P _C −P _O ) · S ₁ = (P _C −P _O ) · (π · D ₂ · H) S ₂ = π · D ₁ · H From the above equation (1) As you can see, the compression chamber in the cylinder
1a the first piston ring 4 surface pressure P _L is increased in proportion to the pressure P _C is increased, the wear of the second piston ring 5 is increased. This wear reduces the it is sufficient to reduce the surface pressure P _L, but in order to reduce the surface pressure P _L, the first piston ring 4, necessary to increase the outer diameter of the second piston ring 5 However, there is a limit in the structure and it cannot be increased unnecessarily, and it is difficult to greatly reduce the surface pressure acting on the outer periphery of the piston ring with the conventional piston ring shape.

Therefore, it is conceivable to reduce the wear on the piston rings by increasing the number of piston rings, but it is difficult to equalize the pressure acting on each piston ring, and the pressure acts evenly on each piston ring. Otherwise, there is a problem that it is not practical such that only a specific piston ring wears quickly.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a compressor in which wear of a piston ring is reduced and durability is improved.

"Means for Solving the Problems" The present invention has the following configuration to achieve the above object. That is, a cylinder and a piston connected to a crankshaft in a crank chamber and movably provided in the cylinder to form a compression chamber in the cylinder,
The cylinder is mounted in a groove formed on the outer peripheral surface of the piston to seal by contacting the compression chamber and the crank chamber of the cylinder with the cylinder, is expandable, and has a diameter smaller than the groove bottom diameter of the groove. In a compressor comprising a piston ring having a large inner diameter, the crank chamber side wall surface of the concave groove has a conical surface inclined from the compression chamber side toward the crank chamber side as going from the outer periphery of the piston toward the center side. The piston ring is characterized in that a side surface of the crankcase of the piston ring is formed in a conical surface having the same gradient as the conical surface.

[Operation] According to the above configuration, when the piston is slid in the axial direction in the cylinder, the piston ring expands in diameter due to the differential pressure generated between the compression chamber and the crank chamber in the cylinder, and the outer circumference of the piston ring expands. Closely contact the inner surface of the cylinder, and the compression chamber and the crank chamber in the cylinder are sealed.

When the piston is operated, f ₁ : force acting on the back surface (S ₁ ′) of the piston ring 14 or 15 f ₂ : force acting on the outer peripheral surface (S ₂ ′) of the piston ring 14 or 15 f ₃ : piston ring Force f ₄ acting on the compression chamber side end surface (S ₃ ) of 14 or 15: Conical surface of piston ring 14 or 15 on crank chamber 1b side
Force S ₁ acts in the direction perpendicular to the 21 ': the area of the back surface of the piston ring 14 or 15 S _2': the area of the outer peripheral surface of the piston ring 14 or 15 S _3: the area of the compression chamber side end surface of the piston ring 14 or 15 P _C : Pressure in compression chamber 1a P _O : Pressure on crank chamber 1b side P _L ′: Surface pressure on outer peripheral surface of piston ring 14 or 15 H ₁ : Thickness on back of piston ring 14 or 15 H ₂ : Piston ring Thickness of outer periphery of 14 or 15 D ₁ : Outer diameter of piston ring 14 or 15 D ₂ : Inner diameter of piston ring 14 or 15 θ: P _L − P _L ′ = (P _C −P _O ) {D ₁ / D ₂ · (1−H ₁ / H ₂ ) + (H ₁ / H ₂ −1) (1 + D ₁ / D ₂ ) / 2} = (P _{C -P O (H 1 / H} 2 -1) (1-D 1 / D 2) / 2 .................. (4) , and the reducing the wear of the piston ring compared with the conventional piston ring Can be. That is, the crank chamber side wall surface of the concave groove of the piston is formed as a conical surface inclined from the compression chamber side to the crank chamber side as going from the outer periphery of the piston toward the center side, and the crank chamber side surface of the piston ring is
Since the conical surface is formed in the same conical surface as the conical surface, the force applied from the crankcase side wall surface of the concave groove to the side surface of the crankcase of the piston ring during compression is directed toward the center of the piston. Since the force on the cylinder side becomes weaker, the wear of the piston ring can be reduced.

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

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.

The piston 11 has a cylindrical shape whose one end (the upper end in FIG. 2) is closed, and is slidably fitted into the cylinder 1 via a rider ring 8. It is partitioned into a compression chamber 1a and a crank chamber 1b. On the outer peripheral surface of the piston 11, a piston
11 annular grooves formed at intervals in the axial direction
13,13 are formed. A first piston ring 14 and a second piston ring 15 are mounted in these concave grooves 13, 13, respectively. The first piston ring 14, the second
The piston ring 15 seals between the compression chamber 1a and the crank chamber 1b.

The recessed grooves 13, 13 are tapered rings 17, 1 attached to bolts 16 at predetermined intervals in the axial direction of the piston 11 in circumferential grooves 12 formed on the entire outer circumferential surface of the piston 11 on the compression chamber side.
7 and a wall 1 provided at the end of the piston 11 on the compression chamber 1a side.
It is formed between 8 and the compression chamber 1a side taper ring 16.

The outer diameter of the tapered ring 17 is smaller than the inner diameter of the cylinder 1, and a gap is formed between the inner surface of the cylinder and the tapered ring 17. The side surface of the crank chamber 1b of the tapered ring 17 is a surface orthogonal to the axis of the piston 11. A side surface of the compression chamber 1a of the taper ring 17 is formed as a conical surface (taper surface) 19 which is inclined from the compression chamber 1a side to the crank chamber 1b side as going from the outer periphery of the piston 11 to the center side.
The compression chamber 1a side taper ring 17 and the crank chamber side taper ring 17 are the same, and the compression chamber 1a side groove 13 and the crank chamber 1b side groove 13 have the same shape.

The first piston ring 14 and the second piston ring 15 are made of a flexible and flexible non-metallic heat-resistant elastic material such as ethylene resin, and are used as a gas seal between a cylinder and a piston of a compressor. Things. First
Since the piston ring 14 and the second piston ring 15 have the same shape, the shape of the first piston ring 14 will be described and the description of the shape of the second piston ring 15 will be omitted.

As shown in FIG. 3, the first piston ring 14 has a trapezoidal cross section having a joint 20 in which one portion of the ring is cut out stepwise and a gap is formed between both ends of the cut portion of the ring. It can be expanded. The side surface of the crank chamber 1b when the first piston ring 14 is mounted in the concave groove 13 is formed as a conical surface (taper surface) 21 having the same gradient as the conical surface 19 contacting the conical surface 19 of the concave groove 13. Also, the first piston ring 14
The inner circumference (rear surface) of the first piston ring is the same as the conventional piston ring.
A thin plate 22 for preventing fluid from leaking from an abutment 20 of the piston ring 14 is mounted.

In addition, the first piston ring 14 attached to each groove 13,
Each conical surface 21 of the second piston ring 15 is a conical surface of each groove 13.
19 slidably in contact with the wall of the first piston ring 14 mounted in the groove 13 and the wall 18.
Compression chamber side and compression chamber side taper ring of piston ring 15
17 are provided with the same interval.

Next, the operation of the compressor having the above configuration will be described. A drive source (not shown) of the compressor is driven to rotate a crankshaft (not shown). Then, the piston 11 slides vertically (substantially in the axial direction of the piston 11) in FIG. 2 via the connecting rod 2a and the piston pin 2b.

Here, f ₁ : force acting on the back surface (S ₁ ′) of the piston ring 14 or 15 f ₂ : force acting on the outer peripheral surface (S ₂ ′) of the piston ring 14 or 15 f ₃ : piston ring 14 or 15 force f ₄ acts on the compression chamber side end face (S _3): conical surface of the crank chamber 1b side of the piston rings 14 or 15
Force S ₁ acts in the direction perpendicular to the 21 ': the area of the back surface of the piston ring 14 or 15 S _2': the area of the outer peripheral surface of the piston ring 14 or 15 S _3: the area of the compression chamber side end surface of the piston ring 14 or 15 P _C : Pressure in compression chamber 1a P _O : Pressure on crank chamber 1b side P _L ′: Surface pressure on outer peripheral surface of piston ring 14 or 15 H ₁ : Thickness on back of piston ring 14 or 15 H ₂ : Piston ring Thickness of the outer circumference of 14 or 15 D ₁ : Outer diameter of piston ring 14 or 15 D ₂ : Inner diameter of piston ring 14 or 15 θ: f ₃ = f assuming the taper inclination angle of conical surface 21 of piston ring 14 or 15 ₄ · cos θ f ₂ = f ₁ −f ₄ · sin θ Therefore, f ₂ = f ₁ −f ₃ • tan θ …… (2) Also, S ₁ ′ = π · D ₁ · H ₁ S ₂ ′ = π · D _{2 · H 2 S 3 = π (} D 2 2 -D 1 2) / 4 f 1 = S 1 '· (P C -P O) f 3 = S 3 · (P C -P O) Thus P _L' = _{f 2 / S 2 '= (} P C -P O) {D 1 / D 2 · H 1 / H 2 - (D ^{_{2 2 -D 1 2) / D}} 2 · Tanθ / (4 · H 2)} Further, FIG. 4 from the _{H 1 = H 2 + (D} 2 -D 1) / 2 · Tanθ Therefore (D ₂ -D ₁ ) · Tan θ = (H ₁ −H ₂ ) · 2P _L ′ = (P _C −P _O ) ｛D ₁ / D ₂ · H ₁ / H ₂ − (H ₁ / H ₂ −1) (1 + D ₁ / D ₂ ) / 2｝ (3) Therefore, from equations (1) and (3), P _L −P _L ′ = (P _C −P _O ) ｛D ₁ / D ₂ · (1−H ₁ / H _{2 ) + (H 1 / H 2} -1) (1 + D 1 / D 2) / 2} = (P C -P O) (H 1 / H 2 -1) (1-D 1 / D 2) / 2 ... ... (4) and (P _C −P _O )> 0 (H ₁ / H ₂ −1)> 0 (1−D ₁ / D ₂ ) / 2> 0. From the expression 4), the conventional first and second piston rings 4,5
Compared with the surface pressure PL acting on the outer circumference of the first and second embodiments.
It can be seen that the surface pressure PL 'acting on the outer peripheral surfaces of the piston rings 14, 15 is reduced.

As described above, according to the present embodiment, the first piston ring
14, Cylinder 1, Piston 11 by 2nd piston ring 15
The first piston ring
14. Wear of the second piston ring 15 can be reduced as compared with the conventional piston ring.

According to the present invention, f ₁ : force acting on the back surface (S ₁ ′) of the piston ring f ₂ : force acting on the outer peripheral surface (S ₂ ′) of the piston ring f ₃ : force of the piston ring Force acting on the compression chamber side end surface (S ₃ ) f ₄ : Force acting in a direction perpendicular to the conical surface of the piston ring on the crank chamber side S ₁ ′: Area behind the piston ring S ₂ ′: Outer peripheral surface of the piston ring Area S ₃ : Area of the end face of the piston ring on the compression chamber side P _C : Pressure of the compression chamber P _O : Pressure on the crank chamber side P _L ′: Surface pressure on the outer peripheral surface of the piston ring H ₁ : Thickness on the back surface of the piston ring Depth H ₂ : Outer thickness of piston ring D ₁ : Outer diameter of piston ring D ₂ : Inner diameter of piston ring θ: Taper inclination angle of conical surface of piston ring P _L −P _L ′ = (P _{C -P O) {D 1 / D} 2 · (1-H 1 / H 2) + (H 1 / H 2 -1) (1 + D 1 _{D 2) / 2} = (} P C -P O) (H 1 / H 2 -1) (1-D 1 / D 2) / 2 , and the present invention than the surface pressure acting on the outer periphery of a conventional piston ring The surface pressure acting on the outer circumference of the piston ring can be reduced, the wear of the piston ring of the present invention can be reduced as compared with the conventional piston ring, and the durability of the compressor can be improved. it can. That is,
The crank chamber side wall surface of the concave groove of the piston is formed as a conical surface inclined from the compression chamber side to the crank chamber side as going from the outer periphery of the piston toward the center side, and the crank chamber side surface of the piston ring is the same as the conical surface. Since the slope is formed in a conical surface, the force applied from the side wall surface of the crank chamber of the concave groove to the side surface of the crank chamber of the piston ring during compression is directed toward the center of the piston. Therefore, the wear of the piston ring can be reduced.

[Brief description of the drawings]

1 to 5 show a first embodiment of the present invention. FIG. 1 is an enlarged detailed sectional view of an I-circle portion in FIG. 2, and FIG. 2 is a view showing a cylinder, a piston and a piston ring. FIG. 3 is a schematic perspective view of a first or second piston ring, FIG. 4 is a cross-sectional view of a main part for describing a force acting on the piston ring, and FIG. 5 is a piston ring. 6 to 10 show an example of a conventional compressor. FIG. 6 is a side sectional view of a main part, and FIG. 7 is a piston. FIG. 8 is a side view showing an assembled state of a ring and a rider ring to a piston, FIG. 8 is a perspective view of a first piston ring or a second piston ring, FIG. Fig. 10 is for explaining the force acting on the piston ring. It is sectional drawing. 1 ... Cylinder, 1a ... Compression chamber, 1b ... Crank chamber, 11
…… Piston, 13 …… Recessed groove, 14 …… First piston ring, 15 …… Second piston ring, 17 …… Taper ring,
19 ... conical surface (tapered surface), 20 ... joint, 21 ... conical surface (tapered surface).

Claims (1)

(57) [Scope of request for utility model registration] A cylinder, a piston connected to a crankshaft in the crank chamber, and movably provided in the cylinder to form a compression chamber in the cylinder, and a piston between the compression chamber and the crank chamber of the cylinder. A compressor comprising a piston ring mounted in a groove formed on the outer peripheral surface of the piston for sealing by contacting the cylinder, the piston ring being expandable and having an inner diameter larger than the groove bottom diameter of the groove. In the crank chamber side wall surface of the concave groove is formed as a conical surface inclined from the compression chamber side to the crank chamber side as going from the outer periphery of the piston toward the center side, and the crank chamber side surface of the piston ring is A compressor characterized by being formed in a conical surface having the same gradient as the conical surface.