KR20150031726A - Reciprocating compressor - Google Patents

Abstract

According to the present invention, a reciprocating compressor has a gas bearing which guides a refrigerant gas of a high pressure toward a gap of a cylinder and a piston and formed on the cylinder. The reciprocating compressor has a blocking protrusion part or a blocking groove part on the outer circumferential surface of the piston or the inner circumferential surface of the cylinder in order to prevent a portion of the refrigerant gas which is introduced between the cylinder and the piston through the gas bearing from flowing into a compression space during an suction stroke of the piston. Accordingly, the reciprocating compressor reduces a loss of suction in the compression space and improves the performance of the compressor thereby.

Description

RECIPROCATING COMPRESSOR

The present invention relates to a reciprocating compressor, and more particularly to a reciprocating compressor having a gas bearing.

Generally, a reciprocating compressor is a system in which a piston linearly reciprocates in a cylinder and sucks and compresses a refrigerant to discharge the refrigerant. Reciprocating compressors can be classified into connecting type and vibrating type according to the driving method of the piston.

In the connection type reciprocating compressor, the piston is connected to the rotating shaft of the rotating motor by a connecting rod, and the refrigerant is compressed while reciprocating in the cylinder. On the other hand, a vibrating reciprocating compressor is a system in which a piston is connected to a mover of a reciprocating motor and reciprocates in a cylinder while vibrating to compress a refrigerant. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrating reciprocating compressor. In the following description, the vibrating reciprocating compressor is abbreviated as a reciprocating compressor.

The reciprocating compressor must be smoothly lubricated with the seal between the cylinder and the piston being tightly sealed so that the performance of the compressor can be improved. For this purpose, conventionally, a method of sealing and lubrication between a cylinder and a piston by supplying a lubricant such as oil between the cylinder and the piston to form an oil film is widely known. However, the method of supplying the lubricant not only requires a separate oil supply device, but also the performance of the compressor may be deteriorated due to oil shortage depending on the operating conditions. In addition, since a space for accommodating a predetermined amount of oil is required, the size of the compressor is increased, and the inlet of the oil supply device must be always locked with the oil. Therefore, the installation direction of the compressor is limited.

1 and 2, a part of the compressed gas is bypassed between the piston 1 and the cylinder 2, and the piston 1 and the cylinder 2 A gas bearing is formed between the outer circumferential surface and the outer circumferential surface. In this case, a plurality of bearing holes 2a having a small diameter are formed to penetrate through the inner circumferential surface of the cylinder 2 to inject compressed gas.

This technique does not require a separate oil supply device as compared with the oil lubrication system for supplying oil between the piston 1 and the cylinder 2, thereby simplifying the lubrication structure of the compressor, So that the performance of the compressor can be maintained consistently. Further, since there is no need for a space for accommodating oil in the casing of the compressor, the compressor can be downsized and the installation direction of the compressor can be freely designed. Reference numerals 3 and 4 denote plate springs, reference numerals 5a to 5c denote connecting bars, and numerals 6a and 6b denote links.

However, in the above-described conventional reciprocating compressor, a part of the refrigerant gas flowing between the cylinder 2 and the piston 1 flows into the compression space during the suction stroke of the piston 1, and the high pressure The suction amount of the refrigerant is reduced and the performance of the compressor is deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reciprocating compressor capable of reducing the suction loss by blocking the refrigerant sucked into the space between the cylinder and the piston into the compression space, thereby increasing the performance of the compressor.

In order to achieve the object of the present invention, A piston inserted into the cylinder and reciprocating to form a compression space, and a suction passage communicating with the compression space in a reciprocating direction; And a gas bearing in which a bearing hole is formed through the cylinder so as to support the piston with respect to the cylinder by injecting a refrigerant gas between the cylinder and the piston, wherein at least one of the inner circumferential surface of the cylinder and the outer circumferential surface of the piston A reciprocating compressor may be provided in which a blocking portion is formed to block refrigerant gas from entering the compression space.

In the reciprocating compressor according to the present invention, the blocking protrusions or the blocking grooves are formed on the outer circumferential surface of the piston, so that a part of the refrigerant gas flowing between the cylinder and the piston through the bearing hole of the gas bearing flows into the compression space during the suction stroke of the piston So that the performance of the compressor can be improved by reducing the suction loss in the compression space by preventing the increase in the volume of the compression space.

1 is a longitudinal sectional view showing an example in which a conventional gas bearing is applied to a reciprocating compressor,
2 is a perspective view showing an example in which a conventional plate spring is applied to a reciprocating compressor,
3 is a longitudinal sectional view showing the reciprocating compressor of the present invention,
Fig. 4 is an enlarged view of the portion "A" in Fig. 3, which is a sectional view showing an embodiment of a gas bearing,
5 and 6 are a sectional view showing an example in which a piston is provided with a gas hole in the reciprocating compressor according to FIG. 2 and a sectional view taken along line II in FIG. 5,
FIGS. 7 to 9 are a longitudinal sectional view and a frontal view showing the embodiments of the piston for explaining the blocking portion in the reciprocating compressor according to FIG. 4;

Hereinafter, a reciprocating compressor according to the present invention will be described in detail with reference to an embodiment shown in the accompanying drawings.

3 is a longitudinal sectional view showing the reciprocating compressor of the present invention.

As shown, the reciprocating compressor according to the present embodiment has a suction pipe 12 connected to the internal space of the casing 10, and a discharge pipe 13 (not shown) is connected to the discharge space S2 of the discharge cover 46 ) Can be connected. A frame 20 is provided in the internal space 11 of the casing 10 and the stator 31 and the cylinder 41 of the reciprocating motor 30 are fixed to the frame 20. The cylinder 41 is provided with a reciprocating motor A resonance spring 51 for inducing a resonance motion of the piston 42 is provided on both sides of the piston 42 in the direction of movement of the piston 42. The piston 42 is connected to the piston 32 of the piston 30, (52) may be respectively installed.

A compression space S1 is formed in the cylinder 41. A suction passage F is formed in the piston 42. A suction valve 43 for opening and closing the suction passage F is provided at the end of the suction passage F And a discharge valve 44 for opening and closing the compression space S1 of the cylinder 41 may be provided on the end surface of the cylinder 41. [

In the reciprocating compressor according to the present embodiment, when the power is applied to the reciprocating motor 30, the motor 32 of the reciprocating motor 30 reciprocates with respect to the stator 31. Then, the piston 42 coupled to the mover 32 linearly reciprocates in the cylinder 41, sucks the refrigerant, compresses the refrigerant, and discharges the compressed refrigerant.

More specifically, when the piston 42 is retracted, the refrigerant in the casing 10 is sucked into the compression space S1 through the suction passage F of the piston 42. When the piston 42 advances, the suction passage F Is closed and the refrigerant in the compression space S1 is compressed. When the piston 42 further advances, the refrigerant compressed in the compression space S1 is discharged while opening the discharge valve 44 to move to the external refrigeration cycle.

Here, the reciprocating motor 30 is inserted into the stator 31 with the coil 35 inserted therein, and an air gap may be formed only on one side of the coil 35. The magnet 32 may be provided with a magnet 36 inserted in the gap of the stator 31 and reciprocating in the direction of movement of the piston.

The stator 31 includes a plurality of stator blocks 31a and a plurality of pole blocks 31b which are respectively coupled to one side of the stator block 31a and form an air gap portion 31c together with the stator blocks 31a Lt; / RTI >

The stator block 31a and the pole block 31b may be formed into a circular arc shape by axial lamination by stacking a plurality of thin stator cores. The stator block 31a is formed in the shape of a groove when projected in the axial direction, and the pole block 31b may be formed in a rectangular shape in the axial direction projection.

The mover 32 includes a magnet holder 32a formed in a cylindrical shape and a plurality of magnets 36 coupled to the outer circumferential surface of the magnet holder 32a along the circumferential direction to form a magnetic flux together with the coil 35. [ have.

The magnet holder 32a is preferably formed of a non-magnetic material to prevent flux leakage, but it is not necessary to limit the magnet holder 32a to a non-magnetic material. The outer circumferential surface of the magnet holder 32a may be formed in a circular shape so that the magnet 36 can be linearly attached and attached. A magnet mounting groove (not shown) may be formed on the outer circumferential surface of the magnet holder 32a such that the magnet 36 is inserted and supported in the direction of motion.

The magnets 36 may be formed in a hexahedron shape and may be attached to the outer circumferential surface of the magnet holder 32a. When the magnets 36 are attached one by one, the outer circumferential surface of the magnet 36 can be enclosed and fixed by a supporting member (not shown) such as a separate fixed ring or a tape made of a composite material.

The stator 31 is made up of a plurality of stator blocks 31a and the plurality of stator blocks 31a are arranged in the circumferential direction of the magnet holder 32a in the circumferential direction The magnets 36 are also attached to the outer circumferential surface of the magnet holder 32a at predetermined intervals along the circumferential direction so as to have an interval between the stator blocks so that the amount of magnet used can be minimized .

The magnet 36 is formed so as to be larger than the moving direction length of the gap 31c so as not to be smaller than the moving direction length of the gap 31c and to be larger than the moving direction length of the gap 31c in the initial position, It is preferable that the end is disposed inside the cavity 31c for stable reciprocating motion.

The magnets 36 may be arranged in the moving direction only one at a time, but in some cases, the magnets 36 may be arranged in plural along the moving direction. The magnet may be arranged so that the N pole and the S pole correspond to each other along the motion direction.

The above-described reciprocating motor may be formed such that the stator has one gap 31c, but it may be formed to have a gap (not shown) on both sides of the coil in the longitudinal direction. In this case as well, the mover can be formed in the same manner as in the above embodiment.

3, the resonance spring includes a first resonance spring 51 and a second resonance spring 52, which are respectively installed on both sides in the front-rear direction of the spring supporter 53 coupled to the mover 32 and the piston 42, ).

A plurality of first resonance spring 51 and second resonance spring 52 are provided and arranged along the circumferential direction, respectively. However, only one of the first resonance spring 51 and the second resonance spring 52 may be provided, and only one resonance spring may be provided.

Since the first resonance spring 51 and the second resonance spring 52 are made of the compression coil spring as described above, a side force may be generated when the resonance springs 51 and 52 perform the stretching / have. The resonance springs 51 and 52 can be arranged so as to cancel the side force or the torsion moment of the resonance springs 51 and 52. [

For example, when the first resonance spring 51 and the second resonance spring 52 are arranged alternately in two in the circumferential direction, the first resonance spring 51 and the second resonance spring 52 have their ends The piston 42 is wound in the counterclockwise direction at the same position with respect to the center of the piston 42 and the same resonance springs located in the diagonal directions are wound around each other so that the pitching and torsional moments can be generated in opposite directions They can be arranged symmetrically with respect to each other.

The first resonance spring 51 and the second resonance spring 52 may be arranged so as to symmetrically align the end points of the respective resonance springs so that lateral tensions and torsion moments may be generated in opposite directions along the circumferential direction .

Here, the frame or the spring supporter 53 to which the ends of the first resonance spring 51 and the second resonance spring 52 are fixed is provided with a spring fixing protrusion 531 (not shown) so that the resonance springs 51 and 52 can be press- ) 532 are preferably formed, respectively, because it is possible to prevent rotation of the resonance spring.

The first resonance spring 51 and the second resonance spring 52 may be provided in the same number or in different numbers. However, the first resonance spring 51 and the second resonance spring 52 may be provided so as to have the same elastic force, respectively.

In the case where the resonance springs 51 and 52 formed of compression coil springs are applied as described above, the piston 42 may be distorted in its straightness due to the characteristics of the compression coil spring. A plurality of first resonance springs 51 and second resonance springs 52 are arranged so as to be wound in opposite directions to each other so that the lateral tensions and torsional moments generated by the respective resonance springs 51 and 52 are diagonally It is possible to maintain the straightness of the piston 42 and to prevent the surfaces contacting the resonance springs 51 and 52 from being worn out.

In addition, since the resonance springs 51 and 52 apply compression coil springs having small longitudinal deformations without restraining the lateral direction of the pistons 42, the compressors can be installed not only vertically but also horizontally, It is not necessary to connect the piston 42 and the piston 42 by separate connecting bars or links, thereby reducing the material cost and the number of assembling steps.

On the other hand, in the above-described reciprocating compressor, since the oil is not supplied between the cylinder 41 and the piston 42, the frictional loss between the cylinder 41 and the piston 42 must be reduced to improve the performance of the compressor have. To this end, a gas bearing is known in which a portion of the compressed gas is bypassed between the inner circumferential surface of the cylinder 41 and the outer circumferential surface of the piston 42 to lubricate between the cylinder 41 and the piston 42 by the gas force.

Fig. 4 is an enlarged view of the portion "A" in Fig. 3, and is a sectional view showing an embodiment of a gas bearing.

3 and 4, the gas bearing 100 includes a gas pocket 110 formed to a predetermined depth on the inner peripheral surface of the frame 20, and a gas pocket 110 communicating with the gas pocket 110, And a plurality of rows of bearing holes 120 formed through the inner circumferential surface. Here, the row of the bearing holes 120 refers to bearing holes formed at the same length in the longitudinal direction at the end of the cylinder 41, i.e., formed on the same circumference.

The gas pockets 110 may be annularly formed on the entire inner circumferential surface of the frame 20, but may be formed in a plurality of predetermined intervals along the circumferential direction of the frame 20, as the case may be.

A gas guide (not shown) for guiding a part of the compressed gas discharged from the compression space into the discharge space S2 to the gas bearing 100 in the discharge space may be connected to the inlet of the gas pocket 110. [

Here, the gas pocket 110 may be formed between the frame 20 and the cylinder 41, but in some cases it may be formed in the longitudinal direction of the cylinder at the end face of the cylinder 41. In this case, Since the gas pocket 110 is formed to be in direct communication with the discharge space S2 of the discharge cover 46, no separate gas guide is needed, which simplifies the assembly process and reduces manufacturing costs.

In this embodiment, although the piston is formed longer than the cylinder and the self weight of the piston is increased, the resonance spring is provided with the compression coil spring, which may cause deflection of the piston due to the characteristics of the compression coil spring, Friction loss or abrasion may occur between the cylinders. In particular, when the piston is supported by supplying gas without supplying oil between the cylinder and the piston, it is necessary to arrange the bearing holes appropriately to prevent the piston from sagging, thereby preventing friction loss or wear between the cylinder and the piston .

For example, the bearing holes 120 penetrating the inner circumferential surface of the cylinder 41 may be formed at regular intervals over the entire area in the longitudinal direction of the piston 42. That is, when the length of the piston 42 is longer than the length of the cylinder 41 and the reciprocating motion is performed in the lateral direction, the position of the bearing hole 120 for injecting the gas between the cylinder 41 and the piston 42, S1 as well as the rear region of the piston 42 as well as the front region and central region of the piston 42 adjacent to the piston. Accordingly, the gas bearing 100 can stably support the piston 41, and friction loss or wear between the cylinder 41 and the piston 42 can be prevented from occurring in advance.

Particularly, when the compression coil spring is applied to the resonance springs 51 and 52 for inducing the resonance motion of the piston 42, due to the characteristics of the compression coil spring, the lateral strain is large and the deflection of the piston may increase. However, 120 are uniformly formed over the entire area along the longitudinal direction of the piston, the piston 42 smoothly reciprocates without being sagged to effectively prevent friction loss and wear between the cylinder 41 and the piston 42 .

On the other hand, in the reciprocating compressor according to the present embodiment, the total cross-sectional area of the bearing hole disposed in the lower half of the cylinder is formed larger than the total cross-sectional area of the bearing hole disposed in the upper half, so that deflection of the piston can be prevented, It is possible to prevent the friction loss and wear of the motor.

To this end, the number of the bearing holes located in the lower half of the bearing holes 120 is greater than the number of the bearing holes located in the upper half, or the cross-sectional area of the bearing holes located in the lower half is larger than the cross- Can be largely formed. The bearing holes are formed so that the number of the bearing holes increases from the uppermost point to the lowermost point of the cylinder 41 or the sectional area increases, thereby enhancing the lower bearing force of the gas bearing.

The gas guide grooves 125 may be formed at the entrance of the bearing holes 120 to guide the compressed gas introduced into the gas pocket 110 into the respective bearing holes 120 and to serve as a kind of buffer . The gas guide grooves 125 may be formed in an annular shape so that the bearing holes of each row are communicated with each other. A plurality of the gas guide grooves 125 may be formed at regular intervals along the circumferential direction. However, it is preferable that the gas guide grooves 125 are formed at regular intervals along the circumferential direction so that the gas guide grooves 125 are individually provided for each of the bearing holes 120, because the compression gas can be balanced and the strength of the cylinder can be compensated.

On the other hand, if the diameter of the bearing hole is small or a small amount of foreign matter adheres to the bearing hole, the refrigerant gas in the gas pocket may not flow smoothly into the bearing space between the cylinder and the piston. In view of this, a gas passage hole can be formed in the piston. Thereby, the pressure of the bearing space can be lowered so that the refrigerant gas in the gas pocket 110 can smoothly flow into the bearing space through the bearing hole.

5 and 6 are a cross-sectional view showing an example in which a piston is provided with a gas hole in the reciprocating compressor according to FIG. 2 and a cross-sectional view taken along the line "I-I" in FIG.

5, the gas holes 130 may be formed at regular intervals along the circumferential direction and may be formed so as to be collinear with the bearing holes 120 in the reciprocating direction. However, In order to keep the distance between the holes 120 as far as possible, it may be preferable that the gas hole 130 and the bearing hole 120 are formed so as to be positioned on different lines in the reciprocating direction. 6, the gas hole 130 is formed in the bearing hole 120 so that the gas hole 130 is positioned between the circumferential direction of the bearing hole 120 at the longitudinal end face of the cylinder 41 and the piston 42, And may be formed on a line different from the radial direction.

On the other hand, when the gas bearing is applied as in the present embodiment, a high-pressure refrigerant gas flows into the space between the cylinder and the piston, but a part of the refrigerant gas flows into the compression space due to the pressure difference during the suction stroke of the piston, Thereby increasing the enemy, thereby preventing the fresh refrigerant gas from being sucked into the compression space, resulting in a suction loss of the compressor.

In view of this, in the present embodiment, a blocking portion may be formed on the outer circumferential surface of the piston or the inner circumferential surface of the cylinder to prevent the refrigerant gas between the cylinder and the piston from being introduced into the compression space.

FIGS. 7 to 9 are a vertical sectional view and a frontal view showing the embodiments of the piston for explaining the blocking portion in the reciprocating compressor according to FIG. 4;

7, the blocking portion 140 may include an annular blocking protrusion 141 protruding toward the inner circumferential surface of the cylinder 41 on the outer circumferential surface of the front end of the piston 42. As shown in FIG. In this case, if the height and width of the blocking protrusion 141 are too large, the friction loss with the cylinder 41 may increase, or may interfere with the bearing hole 123 of the gas bearing to interfere with the inflow of the gas. Conversely, The height and width of the blocking protrusion 141 should preferably be properly set.

8, a plurality of embossed grooves 141a are formed on the outer circumferential surface of the blocking protrusion 141 so that refrigerant gas is introduced into the embossed grooves 141a to double the sealing effect or to enter the embossed grooves 141a The bearing effect may be doubled by the refrigerant gas. Also, although not shown in the figure, one or a plurality of annular grooves may be formed in the blocking protrusions 141 at regular intervals. In this case, an effect similar to that of the embossing groove described above can be exhibited.

9, the cut-off portion may be formed by an annular cut-off groove portion 142 which is recessed by a predetermined depth on the outer circumferential surface of the periphery of the front end of the piston 42. [ In this case, only one blocking trench 142 may be formed, but a plurality of blocking trenches 142 may be formed at regular intervals. Thereby, the refrigerant gas directed to the compression space S1 is expanded into the cutoff groove portion 142, and the pressure is reduced, and leakage to the compression space can be suppressed.

When the shut-off protrusion 141 or the cut-off groove 142 is formed on the outer circumferential surface of the piston 42 as described above, the high pressure (high pressure) which flows into the space between the cylinder 41 and the piston 42 through the bearing hole 123 of the gas bearing, It is possible to prevent a part of the refrigerant gas from flowing into the compression space S1 during the suction stroke of the piston. As a result, it is possible to prevent the displacement of the compression space S1 from being raised, thereby improving the compressor performance while reducing the suction loss in the compression space S1.

7 to 9, the blocking protrusion 141 or the blocking groove 142 is formed on the outer circumferential surface of the piston 42. However, the blocking protrusion 141 or the blocking groove 142 may be formed in the same shape on the inner circumferential surface of the cylinder 41 . Even in this case, the above-described embodiment and its operation effect can be greatly reduced.

In the case where the gas bearing is applied as in the present embodiment, when the foreign matter mixed with the refrigerant flows into the gas bearing, the foreign matter blocks the bearing hole which is the fine hole and prevents the refrigerant gas from flowing smoothly between the cylinder and the piston have. Particularly, when the refrigerant is mixed with the oil and flows into the gas bearing, the foreign matter tightly closes the bearing hole due to the viscosity of the oil, thereby preventing the inflow of the refrigerant gas and increasing the wear or friction loss between the cylinder and the piston. Therefore, blocking the inflow of oil or foreign matter into the gas bearing may be important for enhancing the reliability of the compressor.

In view of this, the cross-sectional area of the bearing hole can be made small so as to prevent foreign matter from flowing into the bearing hole. However, if the cross-sectional area of the bearing hole is too small, there is a possibility that the bearing hole is clogged by foreign matter, which may be undesirable. On the other hand, the cross-sectional area of the bearing hole can be increased to prevent the bearing hole from being clogged by foreign matter, but a large amount of refrigerant gas may be introduced into the gas bearing, thereby increasing the compression loss and decreasing the compressor efficiency.

Therefore, in this embodiment, as shown in FIG. 4, the size of the bearing hole 123 is appropriately increased, but the flow path resistance portion 300 is provided at the inlet side thereof to block oil or foreign matter from flowing into the bearing hole 123 At the same time, the performance of the compressor can be improved by restricting the inflow of the compressed gas. The flow path resistance portion 300 may be formed by winding a thin wire such as a fabric or a wire several times around the gas guide groove 125, inserting a porous material, inserting a block at a certain distance from the gas guide groove, And a gas dispersion groove is formed in the gas diffusion layer. Thereby, the oil can be prevented from flowing into the bearing hole, or the refrigerant can be prevented from being excessively introduced into the bearing hole.

On the other hand, in the above-described embodiments, even when the cylinder is inserted into the stator of the reciprocating motor, or when the reciprocating motor is mechanically coupled with the compression unit including the cylinder at a predetermined interval, Can be applied. A detailed description thereof will be omitted.

In the above-described embodiments, the piston is configured to reciprocate so that a resonance spring is provided on both sides of the piston in the direction of movement of the piston. In some cases, the cylinder is configured to reciprocate, May be installed. Even in this case, the positions of the bearing holes can be arranged as in the above-described embodiments. A detailed description thereof will be omitted.

20: Frame 30: reciprocating motor
31: stator 32:
41: cylinder 42: piston
51, 52: resonance spring 100: gas bearing
110: gas pocket 120: bearing hole
130: Gas cylinder hole 140:
141: blocking protrusion 141a: embossed groove
142:

Claims (5)

A cylinder having a compression space;
A piston inserted into the cylinder and reciprocating to form a compression space, and a suction passage communicating with the compression space in a reciprocating direction; And
And a gas bearing through which a bearing hole is formed in the cylinder so as to support the piston with respect to the cylinder by injecting a refrigerant gas between the cylinder and the piston,
Wherein at least one of an inner circumferential surface of the cylinder and an outer circumferential surface of the piston is provided with a blocking portion so as to block refrigerant gas from entering the compression space. The method according to claim 1,
Wherein the blocking portion is formed in a shape of a protrusion having a predetermined height along a circumferential direction of the cylinder or a circumferential direction of the piston. 3. The method of claim 2,
Wherein at least one groove is further formed in the blocking portion. The method according to claim 1,
Wherein the blocking portion is formed in a groove shape having a predetermined depth along a circumferential direction of the cylinder or a circumferential direction of the piston. The method according to claim 1,
Wherein the blocking portion is formed at a position closer to the compression space than the bearing hole closest to the compression space.

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