JP2008138589A - Reciprocating compressor of refrigerating circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reciprocating compressor of a refrigerating circuit capable of enhancing compression efficiency of a refrigerant, by restraining a temperature rise in the delivery refrigerant. <P>SOLUTION: This reciprocating compressor of the refrigerating circuit has a piston 32 forming a compression chamber 33 in a cylinder bore and reciprocating by receiving rotation of a main shaft 34, an intermediate pressure chamber 68 introducing a low temperature refrigerant from a gas-liquid separator 10 of the refrigerating circuit into the compression chamber 33, and an openable-closable rotary valve 78 arranged between the compression chamber 33 and the intermediate pressure chamber 68 and injecting the low temperature refrigerant into the compression chamber 33 from the intermediate pressure chamber 68 in a compression process of the refrigerant in the compression chamber 33 by being rotated by interlocking with the main shaft 34. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reciprocating compressor of a refrigeration circuit, particularly for an automotive air conditioning system.

This type of reciprocating compressor has a plurality of cylinder bores in its cylinder block, and pistons are reciprocally fitted in these cylinder bores, and the pistons form a compression chamber in the cylinder bores. Each piston sequentially reciprocates in the cylinder bore with the rotation of the main shaft, thereby executing a series of processes from suction of refrigerant to compression through discharge in each compression chamber (Patent Document 1).
JP 2001-027177

Generally, R134a is used as a refrigerant in a compressor for an air conditioning system for automobiles, and this refrigerant has a very high global warming index (GWP) of about 1300. For this reason, the compressor of Patent Document 1 uses carbon dioxide having a low global warming index as a refrigerant, and in recent years, the use of a mixed refrigerant containing CF ₃ I has also been proposed.
When the former refrigerant is compressed, its operating temperature is higher than 150 ° C. compared to R134a, and the heat load received by the compressor is large. In contrast, with the latter refrigerant, the operating temperature can be suppressed to the same level as with R134a, but the CI bond in CF ₃ I contained in the refrigerant has a low binding energy, so the refrigerant itself Easily decomposes at operating temperature.

  The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide a reciprocating compressor of a refrigeration circuit capable of suppressing an increase in refrigerant discharge temperature and enhancing refrigerant compression efficiency. There is to do.

  In order to achieve the above object, the present invention includes a piston that is reciprocally fitted in a cylinder bore, forms a compression chamber in the cylinder bore, and is capable of reciprocating in response to rotation of the main shaft. In the reciprocating compressor of the refrigeration circuit in which a series of processes from the suction of the refrigerant into the compression chamber to the discharge through the compression is performed, the compression process from the refrigeration circuit is lower than the discharge pressure of the refrigerant and into the compression chamber An intermediate pressure chamber that is supplied with a refrigerant having an intermediate pressure higher than the transient pressure of the refrigerant, a connection passage that connects the intermediate pressure chamber and the compression chamber, and a connection passage that is provided in the compression chamber. And an open / close valve that opens the connection passage when the refrigerant pressure is between the transient pressure and the intermediate pressure.

  According to the above-described reciprocating compressor, when the refrigerant is in the compression process in the compression chamber, the on-off valve is opened, and the refrigerant in the intermediate chamber has a difference between the pressure in the intermediate chamber and the transient pressure in the compression chamber. Based on this, it is injected into the compression chamber through the on-off valve. Here, since the refrigerant in the intermediate chamber is lower than the refrigerant temperature in the compression chamber, the refrigerant in the compression process in the compression chamber is cooled by being mixed with the refrigerant from the intermediate pressure chamber.

Specifically, the on-off valve is a rotary valve mechanically coupled to the main shaft (Claim 2), a rotary valve rotated by a motor independent of the main shaft (Claim 3), or an electromagnetic valve ( Claim 4).
Further, the reciprocating compressor may further include a variable capacity mechanism having a swash plate (Claim 5), and the refrigerant is carbon dioxide (Claim 6) or a compound having a CI bond. (Claim 7).

  In the reciprocating compressor of the refrigeration circuit according to claims 1 to 7, since the intermediate-pressure chamber to the low-temperature refrigerant are injected into the compression chamber in the refrigerant compression process, an increase in the temperature of the refrigerant discharged from the compressor is suppressed. In addition, the refrigerant can contain carbon dioxide or a compound having a CI bond, which greatly contributes to the prevention of global warming. Moreover, the injection of the refrigerant into the compression chamber during the compression process increases the compression efficiency of the refrigerant and greatly contributes to the improvement of the energy efficiency of the refrigeration circuit.

FIG. 1 schematically shows a refrigeration circuit of an automotive air conditioning system.
The refrigeration circuit includes a refrigerant circulation path 2, and a compressor 4, a condenser 6, a first expansion valve 8, a gas-liquid separator 10, a second expansion valve 12, and an evaporator 14 are sequentially inserted in the circulation path 2. ing. The compressor 4 discharges the refrigerant toward the condenser 6, and the discharged refrigerant circulates through the circulation path 2. Here, the circulation path 2 includes a high pressure region 2 _H extending from the discharge port of the compressor 4 through the condenser 6 to the first expansion valve 8, and the gas-liquid separator 10 and the second expansion valve 12 from the first expansion valve 8. And a low pressure region 2 _L that reaches the suction port of the compressor 4 through the evaporator 14. In FIG. 1, the suction port and the discharge port are denoted by reference numerals 4 a and 4 b.

FIG. 2 shows details of the compressor 4.
The compressor 4 is a variable capacity reciprocating type, and its housing 16 includes an end plate 18, a center casing 20, and a cylinder head 22 from the left side as viewed in FIG. 2, and these are integrally coupled.
The center casing 20 has a crank chamber 24 adjacent to the end plate 18 in the interior thereof, while a portion of the center casing 20 on the cylinder head 22 side is formed as a cylinder block 26.

  A compression unit 28 is disposed in the center casing 26, and the compression unit 28 includes a plurality of cylinder bores 30 formed in the cylinder block 26, and the cylinder bores 30 are spaced at equal intervals around the axis of the cylinder block 26. It is arranged and penetrates the cylinder block 26. A piston 32 is slidably fitted in each cylinder bore 30, and the piston 32 forms a compression chamber 33 in the cylinder bore 30. In FIG. 2, only one cylinder bore 30 and one piston 32 are shown.

  On the other hand, a main shaft 34 is disposed in the crank chamber 24 so as to be coaxial with the axis of the cylinder block 26, and the main shaft 34 includes an inner end rotatably supported by the cylinder block 26 via a bearing 36, and an end plate 18. It has an outer end that extends to the outside of the housing 16 via a bearing 38 and a seal unit 40. The outer end of the main shaft 34 receives a driving force from an automobile engine and can be driven to rotate.

In the crank chamber 24, a rotor 42 is attached to the main shaft 34, and the rotor 42 rotates integrally with the main shaft 34 and is rotatably supported by the end plate 18 via a thrust bearing 44.
A swash plate 46 is disposed in the crank chamber 24 so as to surround the main shaft 34, and the swash plate 46 is connected to the rotor 42 via a link 48. The link 48 allows the swash plate 46 to tilt with respect to the main shaft 34, and thereby the tilt angle of the swash plate 46 can be varied.

Further, the swash plate 46 supports a swing plate 54 via a radial bearing 50 and a thrust bearing 52, and the rotation of the swing plate 54 is blocked by a rotation blocking mechanism (not shown). Such a swing plate 54 and each of the pistons 32 described above are respectively connected to both ends of a piston rod 56, and both ends of the piston rod 56 are configured as ball joints.
As described above, when the main shaft 34 is rotated, this rotational force is converted into a reciprocating motion of the piston 32 through the rotor 42, the swash plate 46, the swing plate 54 and the piston rod 56 as is well known.

On the other hand, as is apparent from FIG. 2, a valve plate 58 is sandwiched between the cylinder block 26 and the cylinder head 22 via a gasket (not shown), and the valve plate 58 is provided for each cylinder bore 30, that is, in the compression chamber. It has a suction hole 60 and a discharge hole 62 assigned to each 33.
Between the valve plate 58 and the cylinder head 22, a suction chamber 64, a discharge chamber 66 and an intermediate pressure chamber 68 are formed independently of each other.

Here, the intermediate pressure chamber 68 is positioned at the center of the cylinder head 22, and the discharge chamber 66 and the suction chamber 64 have an annular shape that sequentially surrounds the intermediate pressure chamber 68.
Suction chamber 64 while each communicating with the suction hole 60 is connected to a low pressure area 2 _L of the circulation path 2 through the suction port 4a described above. The suction port 4a is formed in the cylinder head 22.

On the other hand, the discharge chamber 66 while respectively communicating with the discharge hole 62, is connected to the high pressure zone 2 _H of the circulation path 2 through the discharge port 4b described above, the discharge port 4b are also formed in the cylinder head 22.
The suction hole 60 and the discharge hole 62 described above can be opened and closed by a suction valve 70 and a discharge valve 72. Each of the intake valve 70 and the discharge valve 72 is a reed valve, and is arranged separately on both surfaces of the valve plate 58. Reference numeral 74 denotes a valve retainer for the discharge valve 72.

Further, the intermediate pressure chamber 68 described above is connected to the introduction path 76 via the introduction port 74, and this introduction path 76 is connected to the gas-liquid separator 10 described above (FIG. 1). The introduction path 76 guides the gas-phase refrigerant from the gas-liquid separator 10 and introduces it into the intermediate pressure chamber 68 through the introduction port 74.
On the other hand, a cylindrical rotary valve 78 is disposed between the intermediate pressure chamber 68 and the main shaft 34, and the rotary valve 78 passes through the valve plate 58 in an airtight manner and is rotatable in the cylinder block 26. It is mated. The rotary valve 78 is positioned coaxially with the main shaft 34, and one end on the main shaft 34 side is integrally coupled to the main shaft 34. Therefore, the rotary valve 78 rotates integrally with the main shaft 34.

Specifically, a drive pin 80 that fits into the rotary valve 78 protrudes from the main shaft 34, and the drive pin 80 is connected to the rotary valve 78 via a key 82. The other end of the rotary valve 78 is rotatably supported by the cylinder head 22 via a ring-shaped thrust bearing 84.
Further, an internal passage 86 is formed in the rotary valve 78, and this internal passage 86 has one end that opens to the outer peripheral surface of the rotary valve 78 and the other end that communicates with the intermediate pressure chamber 68. As is clear from FIG. 2, one end of the internal passage 86 is positioned in the vicinity of the valve plate 58.

  In the cylinder block 26, a valve hole 88 is formed as a connection passage for each compression chamber 33. These valve holes 88 have one end that opens to the corresponding compression chamber 33 and the other end that opens toward the outer peripheral surface of the rotary valve 78 at the upper end of the cylinder bore 30 on the valve plate 58 side. The other ends of these valve holes 88 are equally spaced in the circumferential direction of the rotary valve 78, and are positioned on a rotation locus formed by one end opening of the internal passage 86 when the rotary valve 78 is rotated.

Accordingly, when the rotary valve 78 is rotated together with the main shaft 34, one end opening of the internal passage 88, that is, the above-described intermediate pressure chamber 68 communicates sequentially with each compression chamber 33 through the valve hole 88. That is, the rotary valve 78 can sequentially open and close the valve holes 88 that form a pair with the compression chambers 33 as the main shaft 34 rotates.
In response to rotation of the main shaft 34 as described above, in the cylinder bore 30, when the piston 32 is sequentially reciprocated, the suction holes from the suction chamber 64 communicating with the low pressure area 2 _L of each of the compression chambers 33 in the circulation path 2 60 Then, the refrigerant is sucked through the suction valve 70, and the sucked refrigerant is compressed, and the high-pressure refrigerant is discharged from the compression chamber 33 to the discharge chamber 66 through the discharge hole 62 and the discharge valve 72. As a result, the refrigerant is supplied from the compressor 4 to the condenser 6 through the high pressure region 2 _H of the circulation path 2.

  On the other hand, since the rotary valve 78 rotates integrally with the main shaft 34, one end opening of the internal passage 86 of the rotary valve 78 is a valve that forms a pair with the compression chamber 33 in the compression process of the refrigerant in the compression chamber 33. The valve hole 88 communicates with the hole 88 and is opened for a predetermined valve opening period. Here, the communication timing and the valve opening period are set until the transient pressure of the refrigerant in the compression process in the compression chamber 33 reaches the refrigerant pressure in the intermediate pressure chamber 68 described above.

  Therefore, when the rotary valve 78 is opened during the refrigerant compression process, the refrigerant in the intermediate pressure chamber 68 is injected into the compression chamber 33 through the rotary valve 78 and the valve hole 88. Here, the gas-phase refrigerant from the gas-liquid separator 10 described above is introduced into the intermediate pressure chamber 68, and this introduced refrigerant is sufficiently lower than the discharge temperature of the refrigerant discharged from the compressor 4. Therefore, if the low-temperature refrigerant in the intermediate pressure chamber 68 is injected into the compression chamber 33, the injected low-temperature refrigerant and the high-temperature refrigerant in the compression process are mixed in the compression chamber 33 and compressed. The temperature of the compressed refrigerant in the chamber 33, that is, the temperature increase of the refrigerant discharged from the compressor 4 can be suppressed.

As a result, in order to prevent global warming, the heat load received by the compressor 4 can be greatly reduced even when carbon dioxide compressed to a high pressure or a compound containing CF ₃ I is used as the refrigerant. In addition, the CI bond in CF ₃ I is not broken down.
Moreover, since the injection of the low-temperature refrigerant into the compression chamber 33 increases the compression efficiency of the refrigerant in the compression chamber 33, a multi-effect cycle that effectively improves the energy efficiency of the refrigeration circuit can be easily realized. .

  On the other hand, the crank chamber 24 described above is connected to both the suction chamber 64 and the discharge chamber 66 via a connection passage (not shown) that penetrates the valve plate 58 and the cylinder block 26, and the crank chamber 24 and the suction chamber 64. Is connected to the connecting passage connecting the crank chamber 24 and the discharge chamber 66, and an electromagnetic control valve is inserted into the connecting passage connecting the crank chamber 24 and the discharge chamber 66. This electromagnetic control valve controls the amount of high-pressure refrigerant flowing from the discharge chamber 66 into the crank chamber 24 and adjusts the pressure in the crank chamber 24.

  As is well known, the inclination angle of the swash plate 46 in the crank chamber 24 is maintained at an angle that balances the compression reaction force from each piston 32 and the pressure in the crank chamber 24 applied to the back surface of the swash plate 46, that is, the back pressure. Therefore, by adjusting the pressure (back pressure) in the crank chamber 24, the inclination angle of the swash plate 46, that is, the stroke of each piston 32 is adjusted, and as a result, the refrigerant discharge amount of the compressor 4 is variable. Will be.

Here, even if the stroke of the piston 32 is varied, the valve opening timing and the valve opening period of the rotary valve 78 with respect to each compression chamber 33 do not change, so that the refrigerant discharge pressure of the compressor 4 and the refrigerant pressure of the intermediate pressure chamber 68 This relationship is maintained substantially constant, and the low temperature refrigerant can be stably injected into the compression chamber 33 during the refrigerant compression process.
The present invention is not limited to the above-described embodiment, and various modifications can be made.

  For example, FIG. 3 shows a rotary valve 78 that is rotated independently of the main shaft 34. In this case, the rotary valve 78 is coaxially connected to the output shaft 92 of the electric motor 90, and the electric motor 90 is attached to the outer surface of the cylinder head 22. Normally, the electric motor 90 rotates the rotary valve 78 in synchronization with the rotation of the main shaft 34, but the valve opening timing (communication timing) and valve opening period of the rotary valve 78 can be adjusted as necessary.

FIG. 4 shows a modification in which an electromagnetic on-off valve 94 is used in place of the rotary valve 78. The electromagnetic on-off valve 94 is assigned to each compression chamber 33 and exhibits the same function as the rotary valve 78 described above.
Furthermore, the reciprocating compressor of the present invention may be of a fixed capacity type, and its drive source can also use an electric motor instead of the engine. Further, the type of reciprocating motion is not limited to the illustrated swing plate type, but may be a swash plate type or other axial piston type.

It is the schematic which showed the structure of the freezing circuit. It is sectional drawing which showed the detail of the compressor of FIG. It is the figure which showed the rotary valve of the modification. It is the figure which showed the electromagnetic on-off valve used instead of a rotary valve.

Explanation of symbols

2 Circulation path 10 Gas-liquid separator 16 Housing 24 Crank chamber 30 Cylinder bore 32 Piston 34 Main shaft 33 Compression chamber 46 Swash plate 68 Intermediate pressure chamber 70 Suction valve 72 Discharge valve 74 Introduction port 76 Introduction path 78 Rotary valve (open / close valve)
86 Internal passage (connection passage)
88 Valve hole (connection passage)
90 Electric motor 94 Electromagnetic on-off valve

Claims (7)

A piston that is reciprocally fitted in a cylinder bore to form a compression chamber in the cylinder bore and that can be reciprocated by the rotation of the main shaft, and that sucks refrigerant into the compression chamber by the reciprocating motion of the piston. In a reciprocating compressor of a refrigeration circuit in which a series of processes from compression to discharge is performed,
An intermediate pressure chamber that receives a supply of refrigerant having an intermediate pressure that is lower than the refrigerant discharge pressure and higher than the transient pressure of the refrigerant that is in the compression process in the compression chamber;
A connection passage connecting the intermediate pressure chamber and the compression chamber;
An opening / closing valve provided in the connection passage and opening the connection passage when the pressure of the refrigerant in the compression chamber is between the transient pressure and the intermediate pressure in the compression process of the refrigerant; A reciprocating compressor for a refrigeration circuit.   The reciprocating compressor of the refrigeration circuit according to claim 1, wherein the on-off valve is a rotary valve mechanically coupled to the main shaft.   The reciprocating compressor for a refrigeration circuit according to claim 1, wherein the on-off valve is a rotary valve that is rotated by a motor independent of the main shaft.   The reciprocating compressor of the refrigeration circuit according to claim 1, wherein the on-off valve is a solenoid valve.   The reciprocating compressor for a refrigeration circuit according to any one of claims 1 to 4, further comprising a variable capacity mechanism having a swash plate.   The reciprocating compressor for a refrigeration circuit according to any one of claims 1 to 5, wherein the refrigerant is carbon dioxide.   The reciprocating compressor for a refrigeration circuit according to any one of claims 1 to 5, wherein the refrigerant contains a compound having a C-I bond.

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