KR20180138073A - Piston for reciprocating compressor and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a piston of a reciprocating compressor and a manufacturing method thereof. According to an embodiment of the present invention, the piston comprises: a first part formed in a front portion of the piston to be slid on the inner circumferential surface of a cylinder; and a fourth part formed in a rear portion of the piston and having an external diameter identical to that of the first part. The manufacturing method of the piston comprises the following steps of: processing a plurality of second parts extending backward from the first part and having an external diameter identical to that of the first part and a third part located between the plurality of second parts and having a pin through hole into which a piston pin is inserted; processing a fifth part for forming an intermediate stepped pulley between the first part and a fourth part; and cutting the fourth part and the fifth part.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a reciprocating compressor,

An embodiment of the present invention relates to a piston of a hermetic compressor and a method of manufacturing the same.

A reciprocating compressor refers to a device for compressing a fluid by sucking and compressing a refrigerant through a reciprocating movement of the piston in a cylinder and discharging the refrigerant. The reciprocating compressor can be classified into a reciprocating compressor and a reciprocating reciprocating compressor according to the driving method of the piston. Here, the connection type reciprocating compressor compresses the refrigerant by reciprocating motion of the piston in the cylinder of the piston connected to the rotary shaft of the drive unit through the connecting rod and the piston pin. The oscillating reciprocating compressor is connected to the mover of the reciprocating motor, And the refrigerant is compressed by the reciprocating movement of the piston in the cylinder.

The connection type reciprocating compressor is disclosed in the first prior art (Korean Patent Laid-Open No. 10-2010-0085760, published on Jul. 29, 2010, titled "reciprocating compressor"). The connection type reciprocating compressor disclosed in the first related art includes a housing shell forming a sealed space, a driving unit provided in the housing shell and providing a driving force, a driving shaft connected to the rotating shaft of the driving unit, A compression unit for compressing the refrigerant by the reciprocating motion of the piston in the reciprocating motion of the piston, and a suction and discharge unit for sucking the refrigerant and discharging the compressed refrigerant through the reciprocating motion of the compression unit.

A discharge hose through which the compressed refrigerant is discharged is connected to the suction and discharge unit, and the discharge hose is coupled to a discharge pipe coupled to a shell of the compressor.

The piston reciprocates at a high speed in the cylinder. A portion of the outer circumferential surface of the piston sliding in the cylinder forms a sliding portion, and a portion to which the connecting rod and the piston pin are connected may not form the sliding portion.

The structure of such a piston is disclosed in the second prior art (Japanese Patent No. 6,048,849, issued on December 2, 2016, title of the invention: a hermetic compressor and a refrigerator). According to the piston disclosed in the second prior art, there is a problem that the area of the portion where the sliding portion is not formed (the non-hermetic portion) is relatively large, thereby increasing the mass of the piston and increasing vibration and noise during operation of the compressor.

In order to solve the above problems, it is an object of the present invention to provide a piston of a reciprocating compressor capable of reducing the mass of a reciprocating piston in a cylinder and a method of manufacturing the same.

Particularly, it is an object of the present invention to provide a piston of a reciprocating compressor and a method of manufacturing the same, which can reduce a mass of a piston by removing a portion unnecessary for a sliding action of the piston after machining the piston to form the sliding portion and the non-

A piston of a reciprocating compressor according to an embodiment of the present invention is connected to a connecting rod through a piston pin and reciprocates inside the cylinder and has a cylindrical shape.

The piston includes a first part formed on a front part of the piston and sliding on an inner circumferential surface of the cylinder, and a fourth part formed on a rear part of the piston and having an outer diameter equal to the outer diameter of the first part.

The method of manufacturing a piston includes a plurality of second parts extending rearward of the first part and having an outer diameter equal to that of the first part and a plurality of second parts located between the plurality of second parts, And machining a third part having a hole.

The manufacturing method further includes a step of machining a fifth part forming an intermediate step between the first part and the fourth part, and cutting the fourth part and the fifth part.

The fifth part includes a groove recessed from the outer circumferential surface of the piston, and may have an annular shape.

The outer peripheral surface of the piston includes a first inclined portion extending from the front end of the fifth part to the second part and a second inclined portion extending from the rear end of the fifth part to the fourth part.

The outer diameter of the fifth part may be smaller than the outer diameter of the second part and the fourth part.

The first and second inclined portions may be inclined radially outwardly.

The outer diameter of the fifth part may be larger than the outer diameter of the third part.

Cutting the fourth part and the fifth part includes performing cutting using a cutting line extending in a radial direction at a point where the first inclined part and the fifth part meet.

When the cutting of the fourth part and the fifth part is completed, the end of the first inclined part forms the rear end of the piston.

The step of machining the second part and the third part includes the step of supporting the piston on a support and positioning it between the first and second rollers to perform centerless grinding.

The step of machining the second part and the third part includes:

Supporting the piston on a support, and positioning the piston between the first and second rollers to perform centerless grinding.

The second part may include a plurality of second parts, and the second parts may be provided on both sides of the rear part of the first part.

The first and second parts may form a sliding portion contacting the inner circumferential surface of the cylinder.

According to the above-mentioned solving means, by reducing the mass of the piston, vibration or noise that may occur during operation of the compressor can be reduced.

Particularly, since the mass of the piston is reduced, it is possible to reduce the size of the unbalanced force that may be generated in the reciprocating movement of the piston, thereby reducing wear of the piston sliding portion.

In addition, since the fifth part required for the outer surface machining of the piston can be removed (cut) after the piston is machined, the mass of the piston can be easily reduced.

In addition, by forming a cut surface in the fourth part connecting the sliding part of the piston and the fifth part, it is possible to reduce the occurrence of deformation of the piston sliding part in the cutting process.

1 is a cross-sectional view illustrating a configuration of a reciprocating compressor according to an embodiment of the present invention.
2 is a plan view showing a part of the construction of a reciprocating compressor according to an embodiment of the present invention.
3 is a cross-sectional view showing a piston disposed in a cylinder of a reciprocating compressor according to an embodiment of the present invention.
4 is a perspective view showing the configuration of a piston according to an embodiment of the present invention.
5 is a view showing a piston base material used for manufacturing a piston according to an embodiment of the present invention.
6 is a schematic view showing a state in which a piston base material according to an embodiment of the present invention is processed using a roller device.
7 and 8 are views showing a state in which a plurality of parts are formed on the outer circumferential surface of the piston by machining a piston base material according to an embodiment of the present invention.
9 is an enlarged view of the portion "A" in Fig.
FIG. 10 is a view showing a state in which a cutting process is performed on the piston in the intermediate manufacturing stage shown in FIGS. 7 and 8. FIG.
11 is a cross-sectional view taken along line I-I 'of FIG.
12 is a flow chart showing a method of manufacturing a piston according to an embodiment of the present invention.

FIG. 1 is a cross-sectional view showing the construction of a reciprocating compressor according to an embodiment of the present invention. FIG. 2 is a plan view showing a part of a reciprocating compressor according to an embodiment of the present invention. Fig. 3 is a cross-sectional view showing a piston in a cylinder of a reciprocating compressor according to the present invention.

1 to 3, a reciprocating compressor 10 according to an embodiment of the present invention includes a shell 11 having a closed space and driving parts 12 and 13 disposed inside the shell 11 . The driving units 12 and 13 include a stator 12 and a rotor 13 disposed inside the stator 12. [

In the shell 11, a suction pipe 15 for sucking the refrigerant and a discharge pipe (not shown) for discharging the compressed refrigerant may be combined. A suction muffler 20 for reducing the noise of the refrigerant sucked through the suction pipe 15 may be coupled to the suction pipe 15.

The reciprocating compressor 10 further includes a rotary shaft 15 coupled to a central portion of the rotor 13 and a cylinder block 30 supporting the upper portion of the rotary shaft 15. A lower portion of the cylinder block 30 includes a shaft support portion 32 for supporting the rotation shaft 15 and the rotation shaft 15 can be inserted into the shaft support portion 32 and rotated.

A spring 19 is provided under the stator 12 to absorb vibrations transmitted to the stator 12 when the rotor 13 rotates. The spring 19 is coupled to the lower portion of the shell 11, and may have a plurality of springs.

The reciprocating compressor 10 is provided with an eccentric portion 16 provided at an upper portion of the rotary shaft 15 and having a central portion eccentric from the center of the rotary shaft 15 and an eccentric portion 16 disposed at an outer peripheral surface of the eccentric portion 16, (17).

The reciprocating compressor 10 further includes a connecting rod 40 coupled to the outside of the sleeve 17 and converting the rotational motion of the rotating shaft 15 into linear motion. The counterweight 16 may be provided with a counterbalance 18 for balancing parts that move within the shell 10.

The cylinder block 30 includes a cylinder 50 forming a compression chamber 55. A piston (100) provided for reciprocating movement may be disposed in the cylinder (50). The piston 100 may be coupled to the connecting rod 40.

A volume spacer 102 for reducing a dead volume formed in the discharge hole 73 may be provided in the front portion 101 of the piston 100. [ The volume spacer 102 may protrude from the center of the front portion 102 and may be inserted into the discharge hole 73 when the piston 100 moves to the top dead center.

Define the direction. The direction in which the piston 100 advances and compresses the refrigerant, that is, the right direction with reference to Fig. 1 is referred to as "forward ", and the opposite direction is defined as" rear ". The forward and rearward directions may be collectively referred to as "axial direction", and the direction perpendicular to the axial direction may be referred to as "radial direction".

The rear portion of the piston 100 is opened to form an opening 103 (see FIG. 4), and at least a part of the connecting rod 40 can be inserted into the opening 103.

The piston 100 may have a pin through-hole 105 through which the piston pin 60 is inserted. The sinker pin through-hole 105 may be formed at a position eccentrically forward from the reference center of the piston 100 in the fore-and-aft direction. The piston pin 60 may be inserted into the pin through hole 105 to connect the connecting rod 40 and the piston 100.

The reciprocating compressor 10 is provided at one side of the cylinder 50 to allow the refrigerant to be sucked into the compression chamber 55 of the cylinder 50 or to discharge the refrigerant compressed in the compression chamber 55 A valve assembly 70 may be included. The valve assembly 70 may include a suction hole 71 through which the suction refrigerant flows and a discharge hole 73 through which the discharge refrigerant flows.

The valve assembly 70 may be provided at one side thereof with a head cover 75 for separating the suction refrigerant and the discharge refrigerant. The head cover 75 may be coupled to the suction muffler 20.

An oil supply unit 82 for sucking the oil 80 stored in the bottom of the shell 10 may be installed under the rotary shaft 15. The oil 80 sucked by the oil supply unit 82 is supplied to the rotary shaft 15, the connecting rod 40, the cylinder 50, the piston 100, and the like, An oil passage 84 may be formed.

4 is a perspective view showing the configuration of a piston according to an embodiment of the present invention.

Referring to FIG. 4, the piston 100 according to the embodiment of the present invention may have a cylindrical shape. In detail, the piston 100 includes a front portion 101 that faces the compression chamber 55 of the cylinder 50 and a rear portion 106 that has an opening 103 to which the connecting rod 40 is connected.

The piston 100 may advance in the direction in which the front portion 101 compresses the compression chamber 55 or reciprocate while moving backward in the direction of expanding the compression chamber 55. A position where the piston 100 compresses the compression chamber 55 to the maximum is referred to as a top dead center (TDC), and when the piston 100 is extended to the maximum extent of the compression chamber 55 The position of the state can be called the bottom dead center (BDC). That is, the piston 100 can reciprocate between the TDC and the bottom BDC.

The volume spacer 102 is provided on the front portion 101 of the piston 100. A rod engaging portion 104 to which the connecting rod 40 is coupled is provided on the rear portion 106 of the piston 100. The piston 100 may be understood as a component extending from the front portion 101 toward the rear portion 106 in the forward and backward directions.

The piston 100 includes an outer circumferential surface that slides relative to the inner surface of the cylinder 50. The piston 100 includes a first part 110, a second part 130, and a third part 150 on an outer circumferential surface thereof.

The first part 110 may be in the form of a ring having a predetermined width in the front part of the outer circumferential surface of the piston 100. The outer diameter of the first part 110 may be slightly smaller than the inner diameter of the inner circumferential surface of the cylinder 50. Accordingly, the outer circumferential surface of the first part 110 forms a first gap with the inner circumferential surface of the cylinder 50.

The lubricating oil 80 is supplied to the first gap, and the compression chamber 55 can be sealed by the lubricating oil 80. The first part 110 can be slid while being in contact with the inner circumferential surface of the cylinder 50 through the lubricating oil 80. Accordingly, the first part 110 may be referred to as a "first sliding part" or a "first sliding part ".

The second part 130 may extend from the rear side of the first part 110 to the rear side. For example, the second part 130 includes an arc surface having a substantially rectangular or square shape.

The plurality of second parts 130 may be spaced apart from one another. For example, the second part 130 may be provided on two sides of the first part 110, and the second part 130 may be provided on both sides of the rear part of the first part 110.

The outer diameter of the second part 130 may be slightly smaller than the inner diameter of the inner circumferential surface of the cylinder 50. For example, the outer diameter D1 of the first part 110 and the outer diameter D1 of the second part 130 may be the same. Therefore, the outer circumferential surface of the second part 130 forms a second gap with the inner circumferential surface of the cylinder 50.

The lubricant 80 is supplied to the second gap and the second part 130 can be slid while being in contact with the inner circumferential surface of the cylinder 50 through the lubricant 80. [ Therefore, the second part 130 may be referred to as a "second sliding part" or a "second sliding part ".

The third part 150 may extend from the rear side of the first part 110 to the rear side. The pin through hole 105 may be formed through the third part 150.

The third part 150 may be understood as a part extending in the circumferential direction between the plurality of second parts 130 among the outer circumferential surfaces formed on the rear side of the first part 110. As described above, if the second part 130 is composed of two parts, the third part 150 may be composed of two parts on the outer circumferential surface between the two second parts 130.

The third part 150 may be recessed from the first part 110 or the second part 130. For example, the third part 150 may be further cut in the inner radial direction from the outer circumferential surface of the first and second parts 110 and 130. Therefore, the outer diameter D2 of the third part 150 (see FIG. 8) may be smaller than the outer diameter D1 of the first and second parts 110 and 130.

Therefore, a third gap is formed between the third part 150 and the inner circumferential surface of the cylinder 50, and the gap of the third gap may be formed to be larger than the gap of the first gap or the second gap . In this way, in the reciprocating motion of the piston 100, the third part 150 is not in contact with the inner circumferential surface of the cylinder 50 and forms a "non-sliding part" .

The rear end of the second part 130 and the rear end of the third part 150 may form the rear part 106 of the piston 100. The fourth part 170 produced in the process of manufacturing the piston 100 is cut at the last machining step so that the rear end of the second and third parts 130 and 150 forms the rear part 106 of the piston 100 do. A detailed description thereof will be given later with reference to the drawings.

FIG. 5 is a view showing a piston base material used for manufacturing a piston according to an embodiment of the present invention, FIG. 6 is a schematic view showing a state in which a piston base material according to an embodiment of the present invention is processed using a roller device 7 and 8 are views showing a state in which a plurality of parts are formed on the outer peripheral surface of the piston by machining the piston base material according to the embodiment of the present invention, And FIG. 10 is a view showing a state in which a cutting process is performed on the piston in the intermediate manufacturing stage shown in FIGS. 7 and 8, FIG. 11 is a cross-sectional view taken along line I-I ' 1 is a flow chart showing a method of manufacturing a piston according to an embodiment of the present invention.

5 to 12, the piston 100 according to the embodiment of the present invention can be manufactured by processing the piston base material 100a. Hereinafter, a method of manufacturing the piston 100 will be described.

The piston base material 100a is formed into a cylindrical shape. The opening 105 and the rod coupling part 104 may be formed on the piston base material 100a through casting or internal processing.

The apparatus for machining the outer circumferential surface of the piston 100 includes a roller device 200, 300 and a support table 400.

In detail, the piston base material 110a may be supported on a support base 400 and positioned between the first and second rollers 200 and 300 to perform centerless grinding. In the course of performing the centerless grinding, the first part 110, the second part 130, the third part 150, the fourth part 170, and the fifth part 180 May be formed.

The first part 110 having the largest diameter and the second part 130 and the fourth part 170 may be first formed on the outer peripheral surface of the piston base material 100a. The fifth part 180 having a smaller diameter than the first, second and fourth parts 110, 130 and 170 is then machined. Finally, the third part 150 having the smallest diameter among the pistons 100 is machined .

The outer circumferential surface of the piston base material 100a can be processed in the process of rotating using the roller devices 200 and 300. The roller device (200, 300) includes a first roller (200) and a second roller (300).

The first and second rollers 200 and 300 are spaced apart from each other and the piston base material 100a may be positioned between the first and second rollers 200 and 300. The outer peripheral surface of the piston base material 100a can be cut or surface-treated while the first and second rollers 200 and 300 are rotated.

The first roller 200 includes a grinding wheel for machining the piston base material 100a. The second roller 300 includes an adjusting wheel for adjusting the machining position of the piston base material 100a. For example, the first roller 200 and the second roller 300 rotate in a clockwise direction, and the piston base material 100a can be rotated while being rotated counterclockwise.

On the lower side of the piston base material 100a, a support base 400 for supporting the base piston material 100a may be provided. When the piston base material 100a is processed using the first and second rollers 200 and 300, the front and rear portions of the base material 100a need to be stably supported.

If the movement of the piston base material 100a occurs, there is a problem that the machining precision is lowered. In order to prevent such a problem, the outer diameter of the front portion and the rear portion of the piston base material 100a may be formed to be the same and stably supported on the support base 400. [

7, the front portion of the outer circumferential surface of the piston base material 100a may be processed to form the first part 110 during the processing of the piston base material 100a. The rear part of the outer circumferential surface is processed to form a fourth part 170 having an outer diameter equal to the outer diameter of the first part 110. [

The piston base material 100a may be processed by the first and second rollers 200 and 300 while the first part 110 and the fourth part 170 are supported. That is, it can be understood that the fourth part 170 forms a supporting outer peripheral surface necessary for machining the most important sliding parts of the piston 100, that is, the first part 110 and the second part 130 .

Meanwhile, in the process of machining the outer circumferential surface of the piston base material 100a, a fifth part 180 may be formed which is recessed from the outer circumferential surface of the base material 100a. The fifth part 180 is understood as an "intermediate step" in which the piston base material 100a is formed on the outer circumferential surface, and the fifth part 180 is an annular shape located between the second part 130 and the fourth part 170 Lt; / RTI >

Particularly, the fifth part 180 defines a rear end of the second part 130. When the unnecessary part of the piston base material 100a is removed, Can be machined so as not to cause deformation of the first part (110) and the second part (130). The rear part of the plurality of third parts 150 may be connected to each other by the fifth part 180.

The outer diameter of the fifth part 180 may be smaller than the outer diameter D1 of the first and second parts 110 and 130 and may be greater than the outer diameter D2 of the third part 150.

A first inclined portion 181 extending from the front end of the fifth part 180 to the second part 130 and a second inclined part 182 extending from the front end of the fifth part 180 to the second part 130 are formed on the outer circumferential surface of the base material 100a of the piston 100a, And a second inclined portion 183 extending from the rear end of the fifth part 180 to the fourth part 170. [ Since the outer diameter of the fifth part 180 is smaller than the outer diameter of the second and fourth parts 130 and 170, the first and second inclined parts 181 and 183 may extend in a radially outwardly inclined manner (S11 and S12 ).

When the machining and surface treatment of the first part 110 and the second part 130 as the "sliding part" are completed and the machining of the third part 150 as the non- And the fifth part 180 may be removed. The fourth part 170 and the fifth part 180 do not function as a sliding part of the piston 100 and can be removed as an unnecessary part for increasing the mass of the piston 100 (cutting step).

10, the fifth part 180 and the fourth part 170 may be cut and removed. As described above, the fifth part 180 is a part formed in the processing of the piston base material 100a before the cutting process, and may function as a guide groove for forming a cut surface.

When cutting is performed using the cutting tool on the basis of the fifth part 180, it is possible to prevent the stress generated in the cutting step from acting on the first and second parts 110 and 130 . As a result, the deformation of the first and second parts 110 and 130 may be reduced.

For example, the cutting line CL for cutting the fourth and fifth parts 170 and 180 may be formed to extend in the radial direction at a point where the first inclined part 181 and the fifth part 180 meet have. Therefore, after performing the cutting process, the rear end of the first inclined portion 181 forms the rear end portion of the piston base material 100a.

When the cutting process is completed, the manufacture of the piston 100 is completed, and the piston 100 has a structure as shown in FIG. The rear end of the piston 100 forms a cut surface 188 (S13).

Since the fourth part 170 and the fifth part 180, which are necessary for the machining accuracy and machining efficiency but are not necessary for the function of the piston 100, can be removed in the process of processing the piston, Thereby reducing the mass of the battery 100.

10: reciprocating compressor 15: rotary shaft
40: connecting rod 50: cylinder
60: Piston pin 100: Piston
102: volume spacer 105: pin through hole
110: first part 130: second part
150: third part 170: fourth part
180: fifth part 181: first inclined part
183: second inclined portion 200: first roller
300: second roller 400: support

Claims (12)

CLAIMS 1. A method of manufacturing a piston connected to a connecting rod via a piston pin to reciprocate within a cylinder and having a cylindrical shape,
The piston includes a first part formed on a front portion of the piston and sliding on an inner circumferential surface of the cylinder and a fourth part formed on a rear portion of the piston and having an outer diameter equal to the outer diameter of the first portion,
A plurality of second parts extending rearward of the first part and having an outer diameter equal to the outer diameter of the first part, and a third part having a pin through-hole interposed between the plurality of second parts and into which the piston pin is inserted, Processing step;
Machining a fifth part forming an intermediate step between the first part and the fourth part; And
And cutting the fourth part and the fifth part. ≪ Desc / Clms Page number 19 > The method according to claim 1,
In the fifth part,
And a groove recessed from an outer circumferential surface of the piston. 3. The method of claim 2,
Wherein the fifth part is a ring-shaped piston. The method of claim 3,
On the outer peripheral surface of the piston,
A first inclined portion extending from a front end of the fifth part to the second part; And
And a second ramp extending from the rear end of the fifth part to the fourth part. 5. The method of claim 4,
The outer diameter of the fifth part is smaller than the outer diameter of the second part and the fourth part,
Wherein the first and second slopes extend obliquely outwardly in the radial direction. 6. The method of claim 5,
Wherein the outer diameter of the fifth part is larger than the outer diameter of the third part. 5. The method of claim 4,
And cutting the fourth part and the fifth part,
And performing cutting using a cutting line extending in a radial direction at a point where the first inclined portion and the fifth portion meet. 8. The method of claim 7,
When the cutting of the fourth part and the fifth part is completed,
Wherein an end of the first ramp defines a rear end of the piston. The method according to claim 1,
The step of machining the second part and the third part includes:
And supporting the piston on a support and positioning the piston between the first and second rollers to perform centerless grinding. The method according to claim 1,
Wherein the plurality of second parts are provided on both sides of the rear surface of the first part, the second parts being spaced apart from each other. The method according to claim 1,
Wherein the first and second parts form a sliding portion contacting the inner circumferential surface of the cylinder. A piston of a reciprocating compressor manufactured by the manufacturing method according to any one of claims 1 to 11.

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