KR100202899B1 - Friction reduction cylinder structure of a compressor - Google Patents

Abstract

The present invention relates to a compressor having a friction reducing cylinder structure for improving the lubricity of a piston constituting a high pressure generating portion for compressing refrigerant in a hermetic compressor of a refrigerator having a means for sucking and discharging a refrigerant into a sealed casing.

The present invention relates to a compressor in which a high-pressure generating portion composed of a cylinder (13), a piston (14), etc. is lubricated from a shaft performing a screw pump operation; The cylinder 13 is formed with lubricating grooves 23 having a predetermined width W and height H at both sides of the inside at a predetermined interval so that the width W of the lubricating groove 23 is smaller than the width W of the piston 14); < / RTI > The piston (14) has a gradient in which the diameter (D) varies with the length (L) so that the diameter (D) increases toward the front and the airtightness is maintained as a whole.

Accordingly, the present invention improves the lubrication structure of the cylinder and the piston in the hermetic compressor of the refrigerator, thereby achieving stable lubrication to prevent deterioration of the performance of the compressor and prolong the service life.

Description

Compressor with friction reducing cylinder structure

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor, and more particularly, to a hermetic compressor of a refrigerator having a means for sucking and discharging a refrigerant in a closed casing, a friction for opening the lubrication of a piston constituting a high- To a compressor of a reduction cylinder structure.

BACKGROUND ART [0002] In a refrigerator, a compressor is a means for converting a rotational force due to electrical energy into a mechanical energy of reciprocating motion, and a refrigerant having a low boiling point passes through the compressor to a high pressure (about 12 atmospheres). The high-pressure refrigerant is cooled in the condenser to be in a liquid state. When this liquid-state refrigerant is vaporized in the cooler, one refrigeration cycle is completed.

1, the compressor 10 has a structure in which a suction pipe (not shown) and a discharge pipe (not shown) of a refrigerant are connected to the outside of the closed casing 11, and a high-pressure generating unit and a motor unit are installed inside .

The high pressure generating portion can be roughly divided into a cylinder 13, a piston 14 and a valve 15. The motor portion can be roughly divided into a stator 18 and a rotor 19. The high pressure generating portion includes a motor portion And a shaft (12).

The cylinder 13, the piston 14, the valve 15, the discharge muffler 16 and the like are formed as an integral assembly and supported on the frame 17. The frame 17 also has a floating portion 17a that rotatably supports the shaft 12 on which the rotor 10 is mounted and also serves as a sliding bearing.

In operation, the shaft 12, which is rotated by the motor, induces eccentric motion in its upper part and eccentric motion again reciprocates the piston 14 in the cylinder 13 through the connecting rod, At this time, the refrigerant is passively opened and closed by the pressure difference on both sides to move the refrigerant in one direction.

Accordingly, the refrigerant introduced through the suction pipe flows into the cylinder 13 through the suction muffler after being filled in the closed casing 11. The refrigerant compressed in the cylinder 13 passes through the discharge muffler 16, To the condenser (escape bypass).

Since the mechanical friction loss in the compressor 10 having such a construction is closely related to the compressor efficiency, it is necessary to appropriately lubricate the rotating contact portion. In particular, the cylinder 13 and the cylinder 13, which receive a concentrated load by eccentric motion of the shaft 12, A highly lubricating structure is required between the pistons 14.

The conventional compressor 10 has a structure in which the upper and lower inner grooves 12b are communicated by the outer grooves 12a in which the inner grooves 12b are formed on the upper and lower sides of the shaft 12 and the outer grooves 12a, However, a screw lubrication system in which the external grooves 12a and the internal grooves 12b induce a kind of screw pump action to lubricate them is applied.

In the compressor 10 adopting the screw lubrication system, the freezing oil that performs a lubrication function at a predetermined height is filled in the inside of the closed case 11 and one end of the inner groove 12b is submerged in the freezing oil, The freezing oil rises due to the rotation to lubricate the bushing portion 17a and is discharged to the upper portion of the shaft 12 to be scattered toward the cylinder 13 and the piston 14 and then dropped to the sealed case 11 Reduces sliding friction resistance loss.

However, since the free oil does not penetrate into the clearance between the cylinder 13 and the piston 14 due to the high pressure formed inside the cylinder 13, an appropriate oil film can not be formed. Therefore, stable lubrication can not be performed and unstable lubrication There is a drawback that it becomes a state.

Accordingly, it is an object of the present invention to provide a compressor having a friction reducing cylinder structure capable of achieving stable lubrication by improving the lubricating structure of a high-pressure generating portion in which an oil film is not smoothly formed in a hermetic compressor of a refrigerator having means for sucking and discharging refrigerant in a sealed case The purpose is to provide.

FIG. 1 is a schematic view showing the inside of a hermetic compressor according to the present invention; FIG.

FIG. 2 is a side cross-sectional view showing the interior of the cylinder of FIG. 1;

3 is a cross-sectional view taken along line A-A of FIG. 1;

DESCRIPTION OF THE REFERENCE NUMERALS

10: compressor 11: sealed case

12: shaft 12a: outer groove

12b: inner groove 13: cylinder

14: piston 15: valve

16: discharge muffler 17: frame

17a: bushing portion 18: stator

19: rotor 23: lubrication groove

23a: upper end portion 23b: lower end portion

W / H / L / D: Width / Height / Length / Diameter

In order to achieve the above object, the present invention provides a compressor in which a high-pressure generating portion composed of a cylinder (13), a piston (14), etc. is lubricated from a shaft performing a screw pump operation; The cylinder 13 is formed with lubricating grooves 23 having a predetermined width W and height H at both sides of the inside at a predetermined interval so that the width W of the lubricating groove 23 is smaller than the width W of the piston 14); < / RTI > Wherein the lubricant piston (14) has a gradient in which the diameter (D) varies with the length (L), and the diameter (D) increases toward the front to maintain the airtightness as a whole to provide.

At this time, the lubricant groove 23 is divided into an upper end portion 23a and a lower end portion 23b, and the lubricant groove 23 is formed so that its depth is slightly deeper at the lower end portion 23b.

[Example]

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a schematic view of the interior of a hermetic compressor according to the invention, and FIG. 2 shows a side sectional view showing the interior of the cylinder of FIG.

The present invention is applied to a compressor (10) which is lubricated from a shaft (12) in which a high pressure generating portion composed of a cylinder (13), a piston (14)

As described above, in the compressor 10 adopting the screw lubrication system, the freezing oil which performs the lubrication function at a predetermined height is filled in the inside of the closed case 11 and one end of the inner groove 12b is locked in the freezing oil, The freezing oil rises due to the rotation of the piston 12 and lubricates the adhering portion 17a and is discharged to the upper portion of the shaft 12 so that the eccentric portion of the shaft 12 and the piston 14 and between the piston 14 and the cylinder 13 Even frozen oil is scattered.

Such a scattering lubricating system includes a piston 14 reciprocating linearly moving in a reciprocating linear motion at a high speed and a cylinder 13 receiving a concentrated load on both sides due to the eccentric movement of the shaft 12 to stably form an oil film by freezing oil However, when the cylinder 13 and the piston 14 are worn out due to factors such as the key friction, the compression performance of the compressor 10 is reduced, and vibration and noise are increased.

Accordingly, the present invention is intended to improve the lubrication structure of the cylinder (13) and the piston (14).

At this time, the cylinder 13 of the present invention is formed with the lubricating grooves 23 having a predetermined width W and height H at both sides of the inside thereof at predetermined intervals, and the width W of the lubricating grooves 23, (L) of the piston (14).

The width W of the lubricant groove 23 is too large, that is, when the width W of the lubricant groove 23 is larger than the width W of the piston 14, the lubricant groove 23 is formed on both side surfaces subjected to concentrated load by the eccentric movement of the shaft 12. However, If the length L is exceeded, the clearance between the cylinder 13 and the piston 14 is broken and the compression pressure is lowered.

Generally, machining of the oil grooves such as the lubricating grooves 23 is used in the case of completely lubrication of the oil quickly and uniformly, or in the case of preventing heat adhesion at a place where complete lubrication is difficult. These oil grooves essentially reduce the film forming force so that the sum of the widths W does not exceed 50-60% of the total length of the cylinder 13.

In this respect, machining into a semicircular shape in which the height H is higher on both sides than the center of the lubricating groove 23 is one way to make it easier to move the freezing oil forward and backward while reducing the formation area of the lubricating groove 23 .

In addition, the piston 14 of the present invention has a gradient in which the diameter D along the length L is changed so that the diameter D increases toward the front, thereby maintaining the airtightness as a whole.

The front of the piston 14 is given a plus tolerance so as to approximate the dimension of the interference fit and the rear of the piston 14 is more tolerant to the diameter D of the piston 14, A method of managing the tolerance is selected such that the dimension is closer to the dimension of the looser fitting.

This reduces the airtightness due to the lubricating grooves 23 of the cylinder 13 by the front portion of the piston 14 and the fluidity of reaching the freezing oil to the lubricating grooves 23 is reduced by the rear portion of the piston 14 .

3 is a cross-sectional view taken along line A-A of FIG.

The lubrication groove 23 of the present invention is divided into an upper end 23a and a lower end 23b so that the depth of the lower end 23b is slightly deeper.

It is preferable that the lower end portion 23b is slightly deeper in order to retain the freezing oil reaching the lubricating groove 23 through the shaft 12 but the lower end portion 23b is formed to have an appropriate depth so that the oil film can be formed.

1 to 3, there are an allowable surface pressure, an allowable pressure rate coefficient, a minimum oil film thickness, and the like as important design criteria for stable lubrication. The permissible surface pressure is determined by the material of the cylinder 13 and the piston 14 Strength, fatigue limit should not be exceeded. This permissible surface pressure affects other design criteria such as the allowable pressure rate coefficient, which is related to the service life of the cylinder 13 and the piston 14, such as controlling the frictional heat, the adherence to heat, the wear and the like. Of course, increases vibration and noise.

However, since the lubricating grooves 23 are formed in the compressor of the friction reducing cylinder structure of the present invention, the surface pressure is dispersed without being concentrated, so that the surface pressure is reduced to prevent the performance and the service life of the sliding portion.

The lubrication groove 23 has a function of allowing the freezing oil dissolved in the refrigerant sucked into the cylinder 13 to be compressed by the piston 14 to be released.

As described above, the compressor of the friction reducing cylinder structure of the present invention improves the lubrication structure of the cylinder and the piston in the hermetic compressor of the refrigerator having the means for sucking and discharging the refrigerant into the closed casing, It is possible to prevent deterioration and extend the service life.

Although the present invention has been shown and described with respect to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as set forth in the following claims Those skilled in the art will readily know what is known in the art.

Claims (2)

A high pressure generating part composed of a cylinder (13), a piston (14) and the like is lubricated from a shaft which performs a screw pump operation; The cylinder 13 is formed with lubricating grooves 23 having a predetermined width W and height H at both sides of the inside at a predetermined interval so that the width W of the lubricating groove 23 is smaller than the width W of the piston 14); < / RTI > Wherein the piston (14) has a gradient in which the diameter (D) varies with the length (L), and the diameter (D) increases toward the front, thereby maintaining the airtightness as a whole. The friction damper according to claim 1, wherein the lubricant groove (23) is divided into an upper end portion (23a) and a lower end portion (23b) so that the depth of the lower end portion (23b) Structure of compressor.