JP2007205651A - Refrigerating system and vehicular air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a freezing system capable of preventing deterioration of a cooling capacity. <P>SOLUTION: In the refrigerating system 2, a CO<SB>2</SB>refrigerant is circulated in a circulation path. In the circulation path, a compressor 18, a gas cooler 20, an expansion device 22, and an evaporator 24 are sequentially interposed in the circulation path in this order as seen from a flowing direction of the refrigerant. The expansion device is provided with an expanding part 30 expanding the refrigerant by restricting action, an oil separator part 40 separating oil for the compressor from the refrigerant, and an oil pump part 50 force feeding the separated oil to the compressor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a refrigeration system, and more particularly to a refrigeration system using a CO ₂ refrigerant and a vehicle air conditioner that employs the refrigeration system.

In recent years, a refrigeration system using a refrigerant having a small global warming potential has been developed in consideration of the global environment. An example of this type of refrigerant is natural CO ₂ (carbonic acid) gas.
However, since this CO ₂ refrigerant has a supercritical region on the high pressure side and the cycle efficiency is poor, an internal heat exchanger is provided between the gas cooler and the expansion valve, and the refrigerant and evaporator on the outlet side of the gas cooler Internal heat exchange is performed with the refrigerant on the outlet side (see, for example, Patent Document 1).
JP 2002-225549 A

By the way, this kind of compressor compresses a refrigerant | coolant, but this refrigerant | coolant normally contains lubricating oil (oil). This oil not only lubricates the sliding surfaces and bearings in the compressor, but also functions as a seal for the sliding surfaces. However, the circulation in the circulation path by the oil becomes a factor of reducing the cooling capacity of the refrigeration system.
In other words, this oil dissolves very well in the CO ₂ refrigerant on the high pressure side, but hardly dissolves on the low pressure side. Specifically, the undissolved oil on the low-pressure side sticks as a liquid to, for example, a tube wall inside the evaporator, and forms a layer unique to the oil. And if the oil circulation rate (OCR) in an evaporator becomes 0.3% or more, there exists a problem that heat transfer will deteriorate extremely. As described above, in the above-described conventional technology, there is still a problem with respect to the decrease in cooling capacity.

  This invention is made | formed in view of such a subject, and it aims at providing the refrigeration system and vehicle air conditioner which can prevent the fall of a cooling capability.

In order to achieve the above object, a refrigeration system according to claim 1 is a refrigeration system in which CO ₂ refrigerant circulates in a circulation path, and the circulation path has a compressor, a gas cooler, and an expansion in the flow direction of the refrigerant. The expansion device includes an expansion unit that expands the refrigerant by throttling, an oil separator unit that separates the compressor oil from the refrigerant, and the separated oil to the compressor. And an oil pump section for pumping.

Further, in the invention described in claim 2, the oil separator portion includes a separation plate that moves the refrigerant upward while the oil moves to the side as the rotating shaft rotates. .
Furthermore, the invention according to claim 3 is characterized in that the expansion unit includes a scroll unit having movable and fixed scrolls driven by a rotating shaft.

Furthermore, the invention according to claim 4 is characterized in that the oil pump unit includes a trochoid unit having inner and outer rotors driven by a rotating shaft.
According to a fifth aspect of the present invention, a vehicle air conditioner includes the above-described refrigeration system.

Therefore, according to the refrigeration system of the first aspect of the present invention, the CO ₂ refrigerant contains oil, which flows out of the compressor, is cooled by the gas cooler, and reaches the expansion device. The expansion device includes an expansion function of the refrigerant, an oil separation function from the refrigerant, and an oil pressure feeding function to the compressor. That is, the refrigerant in the expansion device is expanded by the expansion action of the expansion unit, and the oil is separated in the oil separator unit. This oil is always returned from the oil pump unit to the compressor. As a result, the inflow of oil to the evaporator is avoided, so that the heat exchange function is ensured and the cooling capacity of the refrigeration system using the CO ₂ refrigerant is prevented from being lowered.

Further, if the oil separator is provided not on the outlet side of the compressor but on the expansion device, the oil cooled by the gas cooler has a high oil viscosity and can be easily separated from the refrigerant. As a result, efficient oil separation is achieved.
According to the second aspect of the present invention, the high-pressure refrigerant from the gas cooler reaches the oil separator after being expanded in the expansion unit of the expansion device. In this oil separator portion, when the separation plate rotates with the rotation of the rotating shaft, the refrigerant is moved upward and simultaneously the oil is moved sideways. Since the specific enthalpy of the refrigerant flowing toward the evaporator is reduced by the separation of the refrigerant and the oil by the stirring of the rotating shaft, it contributes to the improvement of the cooling capacity of the refrigeration system.

Furthermore, according to the invention described in claim 3, the high-pressure refrigerant from the gas cooler is introduced into the scroll unit. It can be expanded by increasing its internal volume. Further, since the expansion unit is driven by the same rotation shaft as that for driving the oil separator unit, the configuration of the expansion device can be simplified.
Furthermore, according to the fourth aspect of the invention, the high-pressure refrigerant from the gas cooler reaches the oil pump section after the oil is separated from the refrigerant in the oil separator section of the expansion device. In this oil pump portion, the volume of the gap between the inner rotor and the outer rotor is reduced, and oil can be pumped toward the compressor. In addition, since the oil pump unit is also driven by the same rotation shaft as that for driving the oil separator unit, the configuration of the expansion device can be simplified.

Further, according to the vehicle air conditioner of the fifth aspect, since the CO ₂ refrigerant that is a natural refrigerant is used, it greatly contributes to the reduction of the environmental load.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of a refrigeration system 2 of an embodiment constituting a vehicle air conditioner. The refrigeration system 2 cools the interior of a passenger compartment 4 at a desired set temperature.
The refrigeration system 2 includes a refrigeration circuit 6 that circulates a CO ₂ refrigerant (hereinafter simply referred to as a refrigerant), which is a natural refrigerant, and the refrigeration circuit 6 extends from an engine room 8 including an engine 10 to a vehicle compartment 4. Installed.

  The refrigeration circuit 6 has circulation paths 11 to 14 for the refrigerant, and most of the circulation paths 11 to 14 are arranged in the engine room 8 of the vehicle, but a part of the circulation paths 11 to 14 is in the vehicle compartment 4 of the vehicle. It also extends. Specifically, a compressor (compressor) 18, a gas cooler 20, an expansion device 22, and an evaporator (evaporator) 24 are sequentially inserted in the circulation paths 11 to 14 from the upstream side. The compressor 18, the gas cooler 20, and the expansion device 22 are disposed in the engine room 8, and the evaporator 24 is disposed in the vehicle compartment 4. In FIG. 1, reference numerals 11, 12, and 13 form the forward part of the circulation path, and reference numeral 14 forms the return part of the circulation path.

The compressor 18 is operated by the driving force of the engine 10, sucks and compresses the refrigerant in the gas state, converts the refrigerant into a high-temperature and high-pressure gas state, and discharges it to the high-pressure circulation path 11. That is, the compressor 18 generates a refrigerant flow while compressing the refrigerant.
And the gas cooler 20 receives the wind from the fan and the vehicle front which are not shown in figure, and air-cools the refrigerant | coolant which flows through the inside. Further, the high-pressure refrigerant from the gas cooler 20 is introduced into the expansion device 22 via the high-pressure side circulation path 12 and supplied to the evaporator 24 via the low-pressure side circulation path 13. It becomes a low-temperature and low-pressure gas state. The downstream side of the evaporator 24 is connected to the compressor 18 via the low-pressure side circulation path 14, and the low-temperature low-pressure gas refrigerant is sucked into the compressor 18.

Here, the expansion device 22 of the present embodiment is disposed between the gas cooler 20 and the evaporator 24, that is, between the high-pressure side circulation path 12 and the low-pressure side circulation path 13, and expands the refrigerant. In addition to the function, an oil separation function for separating the oil for the compressor from the refrigerant and an oil pressure feeding function for discharging the oil separated from the refrigerant to the compressor 18 are provided.
More specifically, as shown in FIG. 2, the expansion device 22 is arranged from the top in the order of the expansion unit 30, the oil separator unit 40, and the oil pump unit 50, and extends from the expansion unit 30 to the oil pump unit 50. A rotating shaft 28 is provided.

  First, the expansion unit 30 includes a cylindrical case 31, and a scroll unit 32 is accommodated in the case 31, as shown in FIG. The scroll unit 32 includes a fixed scroll 33 and a movable scroll 36, and each of the scrolls 33 and 36 has a spiral wrap. Further, an introduction port 35 connected to the circulation path 12 is formed at the center position of the substrate 34 of the fixed scroll 33 so as to penetrate the substrate 34, and a pressure chamber 37 formed by the cooperation of the spiral wrap is opposed. Yes. The pressure chamber 37 moves from the center side of the spiral wrap toward the outer peripheral side in the radial direction along with the turning motion of the movable scroll 36 with respect to the fixed scroll 33, and at this time, the volume of the pressure chamber 37 is increased.

  In order to achieve the orbiting movement of the movable scroll 36, the back side of the movable scroll 36 is rotatably supported by an eccentric bush (not shown), and the eccentric bush is connected to the rotary shaft 28. A counterweight and a rotation preventing mechanism are provided on the back side of the movable scroll 36. In addition, a lead-out port 38 is formed through the peripheral wall of the case 31 and is connected to a refrigerant and oil delivery passage 39.

  Next, the oil separator portion 40 is located below the expansion portion 30 and includes a long tubular housing 41. An inlet 42 connected to the delivery passage 39 is formed at the lower end surface of the housing 41, and a refrigerant outlet 44 connected to the circulation path 13 is formed at the upper end portion of the housing 41. An oil outlet 45 is formed on the upper end side of the peripheral wall of the housing 41, and the oil outlet 45 is connected to the oil communication passage 46.

  A rotation shaft 28 is rotatably disposed in the housing 41, and a plurality of separation plates 43 are disposed on the outer peripheral edge of the rotation shaft 28. Specifically, the separation plate 43 is formed in a fork shape that is reduced in diameter upward, and has a shape that is divided in half in the radial direction. Further, the separation plates 43 are alternately arranged along the axial direction of the rotary shaft 28, and are configured so that refrigerant and oil can be placed on the upper side of each plate.

  Subsequently, the oil pump unit 50 is located above the oil separator unit 40, more specifically, between the expansion unit 30 and the oil separator unit 40, and includes a cylindrical case 51, which is shown in FIG. As shown in b), a trochoid unit 52 is accommodated in the case 51. The trochoid unit 52 includes an inner rotor 53 and an outer rotor 54, and the rotors 53, 54 rotate with the rotation of the rotating shaft 28. A gap 56 is formed between the inner rotor 53 and the outer rotor 54. The volume of the gap 56 varies depending on the position of the inner rotor 53 with respect to the outer rotor 54, and the suction port 55 is reduced in the peripheral wall of the case 51 at a position where the volume of the gap 56 begins to increase once the volume is once increased. A discharge port 57 is formed at each position.

  In order to make the volume of the gap 56 variable, the centers of the rotors 53 and 54 are eccentric to each other, the inner peripheral side of the inner rotor 53 is fitted to the rotary shaft 28, and the inner rotor 53 is integrated with the rotary shaft 28. It is configured to be rotatable. In addition, teeth that mesh with the outer rotor 54 are provided on the outer peripheral side of the inner rotor 53. On the other hand, teeth are also provided on the inner peripheral side of the outer rotor 54, but the number of teeth is one more than the number of teeth of the inner rotor 53. The outer peripheral side of the outer rotor 54 is loosely fitted in the case 51, and when the inner rotor 53 rotates as the rotary shaft 28 rotates, the outer rotor 54 also rotates in the same direction as the rotation direction of the inner rotor 53.

The suction port 55 described above is connected to the oil communication passage 46, and the discharge port 57 is connected to the oil discharge passage 15. In the oil discharge passage 15, the evaporator 24 is bypassed to connect the expansion device 22 and the compressor 18, and the oil separated by the oil separator unit 40 is directed from the oil pump unit 50 to the compressor 18. It has been returned.
According to the refrigeration system 2 described above, the refrigerant is compressed from the evaporator 24 with the operation of the compressor 18. That is, due to the adiabatic compression action of the compressor 18, the specific enthalpy and the pressure increase and change from point A to point B in FIG. 4. Then, a refrigerant in a high-temperature and high-pressure gas state containing oil is supplied to the gas cooler 20 through the circulation path 11.

Subsequently, the refrigerant is cooled in the gas cooler 20. That is, the specific enthalpy is reduced by the cooling action of the gas cooler 20, and the pressure is changed from point B to point C in FIG. Then, it is supplied to the expansion device 22 via the circulation path 12. In the state of the high pressure side that changes from point B to point C, the oil is very well dissolved in the refrigerant.
Next, the refrigerant from the circulation path 12 undergoes expansion due to the throttle action of the expansion unit 30. That is, the rotating shaft 28 is rotated by a pressure difference between the inlet 35 and the outlet 38 in the case 31, and the refrigerant expanded in the pressure chamber 37 passes through the delivery passage 39 to the oil separator 40. It is introduced from. In the state of the low pressure side due to the expansion, the oil is hardly dissolved in the refrigerant, so that the oil can be efficiently separated from the refrigerant.

  Specifically, the refrigerant including the oil placed on the separation plate 43 of the oil separator unit 40 moves the refrigerant having a small specific gravity toward the upper side of the housing 41 with the rotation of the rotating shaft 28, while the specific gravity. The large oil is moved toward the peripheral wall of the housing 41 by centrifugal force. By separating the refrigerant and oil by gas-liquid separation by stirring in the oil separator section 40, the specific enthalpy toward the evaporator 24 is reduced, and the enthalpy difference is enlarged. That is, the refrigerant in the vicinity of the refrigerant outlet port 44 decreases in its specific enthalpy and decreases in pressure and changes from point C to point D in the figure.

  Then, the refrigerant is jetted into the evaporator 24 through the circulation path 13, and the air around the evaporator 24 is cooled by the heat of vaporization of the refrigerant. Next, the cooling air is sent into the passenger compartment 4 to cool the passenger compartment 4. Thereafter, the refrigerant in the evaporator 24 returns to the compressor 18 through the circulation path 14, is compressed again by the compressor 18, and circulates in the circulation paths 11 to 14 as described above.

  On the other hand, the oil separated from the refrigerant is introduced into the oil pump unit 50 from the oil outlet 45 through the oil communication passage 46. The oil that has reached the suction port 55 is sucked into the gap 56 in such an arrangement that the rotors 53 and 54 increase the volume of the gap 56 as the rotary shaft 28 rotates, and then the rotor in which the volume of the gap 56 is reduced. Compressed by the arrangement of 53 and 54 and discharged toward the discharge port 57. The oil is always returned to the compressor 18 through the oil discharge passage 15 and the circulation passage 14.

As described above, according to the present invention, the CO ₂ refrigerant contains oil, and this oil flows out of the compressor 18, is cooled by the gas cooler 20, and reaches the expansion device 22. The expansion device 22 has an oil separation function from the refrigerant and an oil pressure feeding function to the compressor 18 in addition to the refrigerant expansion function. That is, the refrigerant in the expansion device 22 is expanded by the squeezing action of the expansion unit 30 and the oil is separated by the oil separator unit 40. This oil is always returned from the oil pump unit 40 to the compressor 18 via an oil discharge passage 15 separate from the circulation path 13. As a result, the inflow of oil into the evaporator 24 is avoided, so that the oil circulation rate in the evaporator 24 is reduced, the heat exchange function is ensured, and the deterioration of the cooling capacity of the refrigeration system using the CO ₂ refrigerant is avoided. Is done.

If the oil separator 40 is provided not on the outlet side of the compressor 18 but on the expansion device 22, the oil cooled by the gas cooler 20 has a high oil viscosity and can be easily separated from the refrigerant. As a result, efficient oil separation is achieved.
Further, in the expansion unit 30, the high-pressure refrigerant from the gas cooler 20 is introduced into the pressure chamber 37 located at the center of the substrate 34. Thereafter, the pressure chamber 37 moves toward the outer peripheral side of the substrate 34 along the spiral wraps of the scrolls 33, 36, and at that time, the pressure chamber 37 can be expanded by increasing the volume of the pressure chamber 37.

The high-pressure refrigerant from the gas cooler 20 is expanded in the expansion unit 30 and then reaches the oil separator unit 40. In the oil separator section 40, when the separation plate 43 rotates with the rotation of the rotary shaft 28, the CO ₂ refrigerant having a small specific gravity is moved upward and simultaneously the oil having a large specific gravity is moved sideways. Since the specific enthalpy of the refrigerant flowing toward the evaporator 24 is reduced by the separation of the refrigerant and the oil by the stirring of the rotating shaft 28, the cooling capacity of the refrigeration system is improved.

Furthermore, the oil separated by the oil separator unit 40 reaches the oil pump unit 50. In the oil pump unit 50, the volume of the gap 56 between the inner rotor 53 and the outer rotor 54 is reduced, and oil can be pumped toward the compressor 18.
Moreover, the oil separator unit 40 and the oil pump unit 50 are operated by a differential pressure when the refrigerant expands in the expansion unit 30. Further, the above-described expansion unit 30, the oil separator unit 40, and the oil pump unit 50 are Since it drives by the same rotating shaft 28, the structure of the expansion apparatus 22 is simplified and it contributes to the reliability improvement of an expansion apparatus.

Further, by using the CO ₂ refrigerant is a natural refrigerant in an air conditioning system for vehicles, greatly contributes to reducing environmental impact.
The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the expansion unit of the present invention is not limited to the scroll type, and the oil pump unit is not necessarily limited to the trochoid type.

Further, in the above embodiment, an example embodied in a vehicle air conditioner is shown, but the refrigeration system of the present invention is a CO ₂ like a commercial air conditioner, a home heat pipe, a water heater, a heater, etc. Applicable to all refrigeration and air conditioning cycles using refrigerants.

1 is a schematic configuration diagram of a refrigeration system according to an embodiment of the present invention. It is a schematic block diagram of the expansion apparatus in the refrigeration system of FIG. (A) is an expansion part by the aa arrow directional cross-sectional view of FIG. 2, (b) is a figure explaining the oil pump part by the bb arrow directional cross-sectional view of the same figure. FIG. _{2 is} a schematic Mollier diagram of a CO ₂ refrigerant in the refrigeration system of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Refrigerating system 6 Refrigeration circuit 11, 12, 13, 14 Circulation path 18 Compressor 20 Gas cooler 22 Expansion device 24 Evaporator 28 Rotating shaft 30 Expander part 32 Scroll unit 33 Fixed scroll 36 Movable scroll 40 Oil separator part 43 Separation plate 50 Oil Pump unit 52 Trochoid unit 53 Inner rotor 54 Outer rotor

Claims (5)

CO ₂ refrigerant is a refrigeration system that circulates through the circulation path,
In the circulation path, a compressor, a gas cooler, an expansion device, and an evaporator are sequentially inserted in the refrigerant flow direction,
The expansion device includes an expansion unit that expands the refrigerant by a throttling action, an oil separator unit that separates oil for the compressor from the refrigerant, and an oil pump unit that pumps the separated oil to the compressor. A refrigeration system comprising:   2. The refrigeration according to claim 1, wherein the oil separator portion includes a separation plate that moves the refrigerant upward while the oil moves sideward as the rotation shaft rotates. system.   The refrigeration system according to claim 2, wherein the expansion unit includes a scroll unit having movable and fixed scrolls driven by the rotating shaft.   The refrigeration system according to claim 2 or 3, wherein the oil pump unit includes a trochoid unit having inner and outer rotors driven by the rotating shaft.   A vehicle air conditioner comprising the refrigeration system according to any one of claims 1 to 4.

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