JP2007232230A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating device free from problems, capable of maximizing a coefficient of performance at all times even when discharge pressure and suction pressure of a single-stage or multiple-stage compressing mechanism are changed. <P>SOLUTION: This refrigerating device comprises: a refrigerating cycle constituted by successively circularly connecting the single-stage compressing mechanism 10, an oil separator 8, a condenser 3, an expansion means 4 for a cooler, and the cooler 5; an oil injection circuit successively connected between an oil outlet of the oil separator 8 and an oil inlet of the single-stage compressing mechanism 10, and composed of a first oil cooler 20 for cooling the oil separated by the oil separator 8, and an oil flow rate adjusting means 51 for adjusting a flow rate of the oil injected to the single-stage compressing mechanism 10; a discharge temperature detecting means 102 detecting a refrigerant temperature of the discharge opening of the single-stage compressing mechanism 10; and a controller 200 controlling the oil flow rate adjusting means 51 on the basis of the refrigerant temperature detected by the discharge temperature detecting means 102. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus having an oil-cooled compressor.

In a screw compressor or the like, in order to remove heat generated in the compression process, the oil separated from the discharge gas in the oil separator connected to the compressor discharge port is cooled with cooling water or the like in the oil cooler. A system (hereinafter referred to as an oil-cooled compressor) in which the cooled oil is injected into a compression mechanism via an orifice or the like (hereinafter referred to as a fixed throttle) is known.
In a conventional oil-cooled compressor, an oil-cooling circuit that supplies cooled oil to the compressor is disposed at a lower position than the oil level position of the oil recovery container, and the oil-cooled circuit is disposed at a high part of the oil-cooling circuit. The thing provided with the gas venting means is disclosed (refer patent document 1).

  In addition, for cooling the motor of a conventional refrigeration system, a cooling jacket is provided on the outer wall of the motor (hereinafter referred to as a motor cooling jacket), and cooling water is passed through the cooling flow path of the motor cooling jacket to generate motor heat. Although the method of removing was common, when cooling an electric motor with a refrigerant | coolant, since the cooling capability was consumed only for the motor heat_generation | fever, there existed a problem that the coefficient of performance of an apparatus fell. In order to solve this problem, the conventional hydraulic screw compressor has a cooling oil flowing into the motor casing, and a portion of the motor that requires cooling is immersed in the cooling oil. (Refer to Patent Document 2).

  In addition, the conventional two-stage screw compressor includes a first stage and a second stage compression mechanism having first and second stage screw rotors in a motor casing, and the oil separation and recovery device is provided from the second stage compression mechanism. The first oil supply flow path leading from the lower oil reservoir to the discharge-side bearing and shaft seal of the first-stage screw rotor 2, the bearing of the second-stage screw rotor 3, and the shaft seal; A lower oil reservoir between the first and second stage compressor mechanisms and a second oil supply passage for communicating the suction side bearing of the first stage screw rotor are provided to improve the suction capacity (Patent Document 3). reference).

Japanese Examined Patent Publication No. 06-0068278 (page 3, Fig. 1) Japanese Patent Laying-Open No. 2005-69062 (paragraphs 0010 to 0016, FIGS. 1 and 2) JP 09-268888 (paragraphs 0010 to 0014, FIG. 1)

In recent years, in the field of refrigeration and air conditioning, it has become common to change the compressor frequency using an inverter in order to improve the coefficient of performance during partial load operation.
When the inverter is operated with the compressor frequency significantly lower than the rated frequency (hereinafter referred to as low frequency operation), the amount of refrigerant sucked by the compressor is greatly reduced compared to the rated time. The calorific value is greatly reduced compared to the rated value. On the other hand, even if the frequency changes, the pressure difference between the discharge pressure and the oil injection portion does not change so much, so the amount of oil injected into the compression mechanism is almost the same as during operation at the rated frequency.
In this case, since excessive oil is injected into the compression mechanism, the viscous resistance inside the compression mechanism increases, and the electric motor input increases.
As a result, the refrigeration apparatus using the conventional oil-cooled compressor has a problem that the coefficient of performance deteriorates during low-frequency operation.

  The present invention has been made to solve the above-described problems, and always maximizes the coefficient of performance even when the discharge pressure and the suction pressure of the single-stage or multi-stage compression mechanism change. The object is to obtain a device.

A refrigeration apparatus according to the present invention includes a refrigeration cycle in which a compressor, an oil separator, a condenser, an expansion means for a cooler, and a cooler are sequentially connected in an annular manner, an oil outlet of the oil separator, and an oil injection of the compressor. An oil injection circuit comprising a first oil cooler that is sequentially connected between the inlets and cools the oil separated by the oil separator, and an oil flow rate adjusting means that adjusts the flow rate of the oil injected into the compressor. When,
Compressor discharge temperature detection means for detecting the refrigerant temperature at the discharge port of the compressor, and control means for controlling the oil flow rate adjustment means based on the refrigerant temperature detected by the compressor discharge temperature detection means. It is a thing.

  According to this invention, the compressor, the oil separator, the condenser, the expansion means for the cooler, and the cooler are sequentially connected in an annular manner, the oil outlet of the oil separator, and the oil inlet of the compressor An oil injection circuit comprising a first oil cooler for sequentially cooling the oil separated by the oil separator and an oil flow rate adjusting means for adjusting the flow rate of the oil injected into the compressor; Compressor discharge temperature detection means for detecting the refrigerant temperature at the discharge port of the compressor, and control means for controlling the oil flow rate adjustment means based on the refrigerant temperature detected by the compressor discharge temperature detection means. Therefore, the oil flow rate can be kept optimal even during low frequency operation, so that the coefficient of performance can be improved.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a refrigeration apparatus using a single-stage compressor having oil flow rate adjusting means according to Embodiment 1 of the present invention.
In FIG. 1, the refrigeration apparatus includes a single-stage compressor 10, a compressor discharge port 7 of the single-stage compressor 10, an inlet 8a of an oil separator 8, an oil separator 8, a refrigerant gas outlet 8b, a condenser 3, and an expansion for a cooler. The means 4, the cooler 5, and the suction port 6 of the single stage compressor 10 are sequentially connected in an annular manner through a refrigerant pipe to form a refrigeration cycle (the refrigerant flow circulates clockwise in the drawing).
On the other hand, the oil separator oil outlet 8c of the oil separator 8, the first oil cooler 20, the oil flow rate adjusting means (for single stage) 51, and the single stage compressor oil inlet 10a of the single stage compressor 10 are sequentially connected. An oil injection circuit is configured.

  Further, a temperature detection means 102 for detecting the refrigerant temperature at the compressor discharge port 7 of the single stage compressor 10 is provided, and the temperature detection means 102 is connected to a controller 200 for calculating an appropriate oil flow rate from the discharge temperature. Yes. Further, the controller 200 is connected to the oil flow rate adjusting means 51 and controls the oil flow rate to be an appropriate amount.

Next, the operation will be described.
First, regarding the operation of the refrigeration cycle, the refrigerant discharged from the compressor discharge port 7 of the single-stage compressor 10 is separated into high-pressure refrigerant gas and high-pressure oil by the oil separator 8. The high-pressure refrigerant gas is guided to the condenser 3, and exchanges heat with cooling water, outside air, etc. in the condenser 3 to be condensed and liquefied to become a high-pressure liquid refrigerant. After the pressure is reduced to the suction pressure by the cooler expansion means 4, the refrigerant becomes low-pressure two-phase refrigerant and flows into the cooler 5. The low-pressure two-phase refrigerant absorbs heat from the heat source and evaporates in the cooler 5, is sucked into the single-stage compressor 10 through the suction port 6 of the single-stage compressor 10, is compressed and discharged, and becomes high-temperature gas. It reaches.
On the other hand, the high-pressure oil separated by the oil separator 8 flows out from the oil separator oil outlet 8 c and flows into the first oil cooler 20. The high pressure oil that has flowed in is cooled by cooling water or the like in the oil cooler 20, and then flows into the single stage compressor 10 from the single stage compressor oil inlet 10 a via the oil flow rate adjusting means 51. The refrigerant merges with the refrigerant gas sucked from the suction port 6 of the compressor.

Next, a control method of the oil flow rate adjusting means 51 will be described.
The discharge temperature detected by the temperature detection means 102 is input to the controller 200, and the controller 200 compares the detected discharge temperature with a preset allowable temperature range. If the detected discharge temperature is higher than the allowable temperature range, cooling is insufficient and the oil flow rate is increased. If the detected discharge temperature is lower than the allowable temperature range, the cooling is excessive and the oil flow rate is reduced. Further, when the detected discharge temperature is within the allowable temperature range, the oil flow rate is maintained as it is.
Table 1 summarizes the control method of the oil flow rate adjusting means 51 described above.

  As described above, the compressor, the oil separator, the condenser, the expansion means for the cooler, and the cooler are sequentially connected in an annular manner, and between the oil outlet of the oil separator and the oil inlet of the compressor. And an oil injection circuit comprising a first oil cooler for cooling the oil separated by the oil separator and an oil flow rate adjusting means for adjusting the flow rate of the oil injected into the compressor; Compressor discharge temperature detection means for detecting the refrigerant temperature at the discharge port of the compressor, and control means for controlling the oil flow rate adjustment means based on the refrigerant temperature detected by the compressor discharge temperature detection means. Therefore, in the conventional method of injecting oil into the compression mechanism through the fixed throttle, when the frequency changes, excessive oil flows into the compression mechanism, so the coefficient of performance of the device cannot be maximized. If the frequency changes Since proper amount of oil is injected into the compression mechanism to the compression mechanism, it is possible to maximize the coefficient of performance of the device.

As shown in FIG. 2, an oil circuit solenoid valve 60 may be used as the oil flow rate adjusting means 51.
When decreasing the oil flow rate, the oil circuit solenoid valve 60 is closed, and when increasing the oil flow rate, the oil circuit solenoid valve 60 is opened.
In FIG. 2, the oil circuit electromagnetic valve 60 that adjusts the oil flow rate is configured by one electromagnetic valve, but the oil flow rate may be adjusted using a plurality of electromagnetic valves.
The oil flow rate adjusting means is not limited to the oil circuit solenoid valve, and a flow rate adjusting valve such as a ball valve may be used.

Embodiment 2
FIG. 3 is a configuration diagram of a refrigeration apparatus using a two-stage compressor having oil flow rate adjusting means according to Embodiment 2 of the present invention.
In FIG. 3, the refrigeration apparatus includes a low-stage compression mechanism 1, a high-stage compression mechanism 2, a compressor discharge port 7 of the compressor 2, an inlet 8a of an oil separator 8, an oil separator 8, a refrigerant gas outlet 8b, The condenser 3, the expansion means for cooler 4, the cooler 5, and the suction port 6 of the low-stage compression mechanism 1 are sequentially connected in an annular manner through a refrigerant pipe to constitute a refrigeration cycle.

  On the other hand, the oil separator oil outlet 8c of the oil separator 8 is connected to the first oil cooler 20, and the outlet side of the first oil cooler 20 is branched into two, one of which is an oil flow rate adjusting means. The high-stage side compression mechanism 2 is connected to the high-stage side compression mechanism oil inlet 2a via the high-stage side compression mechanism 2 via the high-stage side compression mechanism 52, and the other is connected to the low-stage side compression mechanism via the oil flow rate adjusting means 53 (for low-stage). 1 is connected to a low-stage compression mechanism oil inlet 1a. The oil injection circuit is configured by the above configuration.

  Further, a temperature detecting means 102 for detecting the refrigerant temperature at the compressor discharge port 7 of the high stage side compression mechanism 2 and a temperature detecting means 101 for detecting the refrigerant temperature at the intermediate point 9 which is the discharge port of the low stage side compression mechanism 1 are provided. Provided. The temperature detection means 102 and the temperature detection means 101 are connected to a controller 200 that calculates an appropriate oil flow rate from the discharge temperature. The controller 200 is connected to the oil flow rate adjusting means (for high stage) 52 and the oil flow rate adjusting means (for low stage) 53, and controls the oil flow rate to be an appropriate amount.

  Next, the operation will be described. First, regarding the operation of the refrigeration cycle, the refrigerant discharged from the compressor discharge port 7 of the high-stage compression mechanism 2 is separated into high-pressure refrigerant gas and high-pressure oil by the oil separator 8. The high-pressure refrigerant gas is guided to the condenser 3, and exchanges heat with cooling water, outside air, etc. in the condenser 3 to be condensed and liquefied to become a high-pressure liquid refrigerant. After the pressure is reduced to the suction pressure by the cooler expansion means 4, the refrigerant becomes low-pressure two-phase refrigerant and flows into the cooler 5. The low-pressure two-phase refrigerant absorbs heat from the heat source and evaporates in the cooler 5, and is sucked into the single-stage compressor 10 from the suction port of the single-stage compressor 10, compressed and discharged into a high-temperature gas, and reaches the compressor discharge port 7. .

  On the other hand, the high-pressure oil separated by the oil separator 8 flows out from the oil separator oil outlet 8 c and flows into the first oil cooler 20. The high-pressure oil that has flowed in is cooled by cooling water or the like in the oil cooler 20 and then branched into two. One of the high-pressure oil passes through the oil flow rate adjusting means (for the high stage) 52 and from the high stage side compression mechanism oil inlet 2a. It flows into the high-stage compression mechanism 2 and the other flows through the oil flow rate adjusting means (for low-stage) 53 and flows into the low-stage compression mechanism 1 from the low-stage compression mechanism oil inlet 1a. In each compression mechanism, the oil merges with the refrigerant and flows out from the discharge port of each compression mechanism.

Next, a control method of the oil flow rate adjusting means (for high stage) 52 will be described. The temperature of the compressor discharge port 7 detected by the temperature detection means 102 is input to the controller 200, and the controller 200 compares the detected discharge temperature with a preset allowable temperature range. If the detected discharge temperature is higher than the allowable temperature range, the cooling capacity is insufficient and the oil flow rate is increased. If the detected discharge temperature is lower than the allowable temperature range, the cooling capacity is excessive and the oil flow rate is decreased. Further, when the detected discharge temperature is within the allowable temperature range, the current oil flow rate is maintained.
The control method of the oil flow rate adjusting means 52 (high stage) described above is summarized as in Table 1 shown in the first embodiment.

  Next, a control method of the oil flow rate adjusting means (for the low stage) 53 will be described. The temperature of the intermediate point 9 detected by the temperature detecting means 101 is input to the controller 200, and the controller 200 compares the detected discharge temperature with a preset allowable temperature range. If the detected discharge temperature is higher than the allowable temperature range, the cooling capacity is insufficient and the oil flow rate is increased. If the detected discharge temperature is lower than the allowable temperature range, the cooling capacity is excessive and the oil flow rate is decreased. Further, when the detected discharge temperature is within the allowable temperature range, the oil flow rate is maintained as it is.

The control method of the oil flow rate adjusting means 52 (high stage) described above is the same as that in Table 1 shown in the first embodiment.
In a general operation state, the temperature of the compressor discharge port 7 is higher than the intermediate point 9, so the oil flow rate adjusting means (for the low stage) 53 may be controlled by the temperature of the compressor discharge port 7. . In this case, it is not necessary to attach the temperature detecting means 101 to the intermediate point 9.

As described above, even if the compressor is a multistage compressor, the coefficient of performance can be improved because it can be controlled to an appropriate oil flow rate in accordance with a change in the operating state.
In addition, although the present Example showed the example of the freezing apparatus using the two-stage compression mechanism, you may implement this invention in the freezing apparatus using the compression mechanism of three or more steps.

Embodiment 3
FIG. 4 is a configuration diagram of a refrigeration apparatus using a single-stage compressor having an oil-cooled electric motor cooling jacket according to Embodiment 3 of the present invention.
4, the refrigeration apparatus includes a single-stage compressor 10, a compressor discharge port 7 of the single-stage compressor 10, an inlet 8a of an oil separator 8, an oil separator 8, a refrigerant gas outlet 8b, a condenser 3, and an expansion for a cooler. The refrigeration cycle is configured by the means 4, the cooler 5, and the suction port 6 of the single-stage compressor 10 being sequentially connected in an annular manner through the refrigerant pipe.

On the other hand, an oil separator oil outlet 8 c of the oil separator 8 is connected to the first oil cooler 20, and the outlet of the first oil cooler 20 is an oil-cooled electric motor cooling jacket provided in the single-stage compressor 10. The fixed throttle 91 is connected to the single stage compressor oil inlet 10 a via the fixed throttle 91. The oil injection circuit is configured by the above configuration.
In addition, the condenser 3 and the first oil cooler are cooled by circulating the cooling water or the like stored in the cooling tower 900 with the pump 901 through the condenser 3 and the first oil cooler.

Next, the operation will be described. The oil separator 8 separates high-pressure refrigerant gas and high-pressure oil.
The high pressure oil separated by the oil separator 8 flows into the first oil cooler 20. The high-pressure oil that has flowed in is cooled by cooling water or the like in the oil cooler 20 and then flows into the oil-cooled electric motor cooling jacket 41. The high-pressure oil cools the electric motor in the oil-cooled electric motor cooling jacket 41 and flows into the single-stage compressor 10 through the fixed throttle 91.
Note that the operation of the refrigerant is the same as the operation of the refrigerant in the first embodiment, and is therefore omitted.

  Conventionally, when the motor of the refrigeration apparatus is cooled with refrigerant or cooling water, a method of removing the motor heat by passing cooling water through the cooling channel of the motor cooling jacket on the outer wall of the motor has been common. However, as shown in FIG. 5, the structure of the motor cooling jacket is often difficult to clean the cooling water piping due to the structure, and depending on the quality of the cooling water, there is a possibility that scale adhesion or corrosion may occur on the motor cooling jacket. In particular, when cooling water is cooled by an open cooling tower, the cooling water is concentrated, and scale adhesion and corrosion are likely to occur.

Further, when the scale adheres to the motor cooling jacket, the heat transfer efficiency decreases and the motor winding temperature rises, so that the winding thermostat operates and the compressor may stop.
In addition, when corrosion occurs in the motor cooling jacket, cooling water may enter the refrigerant circuit from pinholes or the like generated by the corrosion. When the cooling water enters the refrigerant circuit, it is necessary to replace the compressor, refrigerant, and refrigerating machine oil and to clean the refrigerant circuit. However, the above operation is a heavy burden in terms of cost and man-hours.

In the present embodiment, the compressor, the oil separator, the condenser, the expansion means for the cooler and the refrigeration cycle in which the cooler is sequentially connected in an annular manner, the oil outlet of the oil separator, and the oil inlet of the compressor A first oil cooler that is sequentially connected to cool the oil separated by the oil separator, an electric motor cooling jacket provided in the electric motor of the compressor, and a flow rate of the oil injected into the compressor An oil injection circuit consisting of a fixed throttle that squeezes the oil constant, and the fluid that flows through the motor cooling jacket is oil, so scale adhesion and corrosion do not occur in the motor cooling jacket, and the oil cooler is easily cleaned Because of the possible structure, the possibility of scale adhesion and corrosion is very low compared to conventional motor cooling jackets. For this reason, the possibility that the cooling water enters the refrigerant circuit is much lower than the conventional method of cooling the electric motor with the cooling water, and the compressor and the refrigerant generated when the cooling water enters the refrigerant circuit Costs and man-hours for replacing the refrigerating machine oil can be hardly generated.
In the present embodiment, the oil that has cooled the electric motor is injected into the compression mechanism and re-pressurized, so that it is not necessary to install an oil pump.

In FIG. 4, the cooling tower 900 is used as a cooling method for cooling water, but the cooling water may be cooled by other methods such as using well water.
The cooling means of the oil cooler is not limited to water, and other means such as air may be used.
FIG. 6 shows an example in which the present invention is applied to a two-stage compressor. Even in a two-stage compressor, the present invention can provide the same effects as when applied to a single-stage compressor.
Moreover, an intermediate cooler may be added to the configuration of FIG. 6 to provide an economizer circuit.

Embodiment 4
FIG. 7 is a configuration diagram of a refrigeration apparatus using a single-stage compressor having an oil-cooled electric motor cooling jacket and a second oil cooler according to a fourth embodiment of the present invention.
In this embodiment, the second oil cooler 21 is provided between the outlet of the oil-cooled electric motor cooling jacket 41 and the fixed throttle 91 in the refrigerating apparatus shown in FIG. 4 of the third embodiment. Other configurations are the same as those of the fifth embodiment.

Next, the operation will be described. The oil separator 8 separates high-pressure refrigerant gas and high-pressure oil.
The high-pressure oil separated by the oil separator 8 flows into the first oil cooler 20, and the inflowed high-pressure oil is cooled by cooling water or the like in the oil cooler 20, and then the oil-cooled electric motor cooling jacket 41. Inflow. The high-pressure oil cools the electric motor in the oil-cooled electric motor cooling jacket 41 and flows into the second oil cooler 21. The high-pressure oil that has absorbed heat in the oil-cooled electric motor cooling jacket 41 and has risen in temperature is cooled by cooling water or the like in the second oil cooler 21 and then flows into the single-stage compressor 10 through the fixed throttle 91.
Since the operation of the refrigerant is the same as the operation of the refrigerant in the first embodiment, a description thereof will be omitted.

  In the third embodiment, since the oil having a high electric motor heat generation temperature is injected into the compression mechanism, there is a possibility that the cooling capacity by the oil is insufficient and the discharge temperature of the compressor may be overheated. Then, since the second oil cooler for cooling the oil flowing out from the motor cooling jacket is provided at the outlet of the motor cooling jacket, the high pressure oil absorbs the heat generated by the motor by the motor jacket. Since the heat is radiated to the cooling water at, the compression mechanism can be cooled using the cooled oil, and overheating of the compressor discharge temperature can be prevented.

FIG. 8 shows an example in which the present invention is applied to a two-stage compressor. Even in a two-stage compressor, the present invention can provide the same effects as when applied to a single-stage compressor.
Moreover, an intermediate cooler may be added to the configuration of FIG. 8 to provide an economizer circuit.

Embodiment 5
FIG. 9 is a configuration diagram of a refrigeration apparatus using a single-stage compressor having an oil-cooled electric motor cooling jacket and oil flow rate adjusting means according to a fifth embodiment of the present invention.
In this embodiment, the oil flow rate adjusting means is provided in FIG. 4 of the third embodiment.

Next, a control method of the oil flow rate adjusting means 51 will be described.
The discharge temperature detected by the temperature detecting means 102 and the motor cooling jacket outlet oil temperature (hereinafter referred to as jacket outlet temperature) detected by the temperature detecting means 102 are input to the controller 200 and detected by the controller 200. The detected discharge temperature is compared with a preset allowable discharge temperature range, and the detected jacket outlet temperature is compared with a preset allowable jacket outlet temperature range.

When either the detected discharge temperature or jacket outlet temperature is higher than the allowable temperature range, the cooling is insufficient and the oil flow rate is increased. When either the detected discharge temperature or jacket outlet temperature is lower than the allowable temperature range, the cooling is excessive and the oil flow rate is reduced. When the detected discharge temperature and jacket outlet temperature are within the allowable temperature range, the oil flow rate is maintained as it is.
Table 2 summarizes the control method of the oil flow rate adjusting means 51 described above.

  As described above, the motor of the compressor is provided with an electric motor cooling jacket, and the electric motor cooling jacket is connected via a pipe between the first oil cooler of the high stage side oil injection circuit and the oil flow rate adjusting means, Jacket outlet temperature detecting means for detecting the temperature of the oil at the outlet of the motor cooling jacket is provided, and the control means is based on the respective temperatures detected by the compressor discharge temperature detecting means and the jacket outlet temperature detecting means. Since the oil flow rate adjusting means is controlled, the oil injection amount is reduced compared to the conventional method, the motor input is reduced, the coefficient of performance can be improved, and the motor cooling jacket is cooled with cooling water; In comparison, in this method, the cost and man-hours required for replacement of the compressor, refrigerant, and refrigerating machine oil generated when cooling water enters the refrigerant circuit can be reduced.

FIG. 10 shows an example in which the present invention is applied to a two-stage compressor. Even in a two-stage compressor, the present invention can provide the same effects as when applied to a single-stage compressor.
Further, an intermediate cooler may be added to the configuration of FIG. 10 to provide an economizer circuit.

Moreover, FIG. 11 adds the 2nd oil cooler 21 to this Embodiment. Similar to the fifth embodiment, the compressor discharge temperature can be prevented from overheating.
Further, an intermediate cooler may be added to the configuration of FIG. 11 and an economizer circuit may be provided. Even in a two-stage compressor, the present invention can provide the same effects as when applied to a single-stage compressor.
FIG. 12 is an example in which a two-stage compressor is applied to the configuration of FIG.
Further, an intermediate cooler may be added to the configuration of FIG. 12 to provide an economizer circuit.

Embodiment 6
FIG. 13 is a block diagram of a refrigeration apparatus having an oil / gas separator according to Embodiment 6 of the present invention. In the present embodiment, an oil / gas separator fixed throttle and an oil / gas separator are added to the refrigerating apparatus shown in FIG. 6 of the third embodiment.
In FIG. 13, the refrigeration apparatus includes a low-stage compression mechanism 1, a high-stage compression mechanism 2, a compressor discharge port 7 of the compressor 2, an inlet 8a of an oil separator 8, and an oil separator that is a first oil separator. 8, the refrigerant gas outlet 8b, the condenser 3, the expansion means 4 for the cooler, the cooler 5, and the suction port 6 of the low-stage compression mechanism 1 are sequentially connected in an annular manner through the refrigerant pipe to constitute a refrigeration cycle. .

On the other hand, the first oil cooler 20 is connected to the oil separator oil outlet 8 c of the oil separator 8, and the outlet of the first oil cooler 20 is connected to the oil-cooled electric motor cooling jacket 41. The outlet of the oil-cooled electric motor cooling jacket 41 is branched into two, and one pipe is connected to the high-stage compression mechanism oil injection port 2a through a fixed throttle 92 to form a high-stage oil injection circuit. ing. One pipe is connected to an oil gas separator 42 as a second oil separator via a fixed throttle 94, and an oil outlet 42c of the oil gas separator is connected to a low stage side via a fixed throttle 93. Connected to the compression mechanism oil injection port 1a, a low-stage oil injection circuit is formed.
Further, the refrigerant gas outlet 42b of the oil gas separator 42 is connected to the intermediate point 9 of the pipe between the low stage side compression mechanism 1 and the high stage side compression mechanism 2 via the electric motor chamber 40 and is connected to the refrigerant gas injection circuit. Is forming.

  Next, the operation will be described. The oil separator 8 separates the high-pressure refrigerant gas and the high-pressure oil, and the separated high-pressure oil flows into the first oil cooler 20. The high-pressure oil that has flowed in is cooled by cooling water or the like in the oil cooler 20 and then flows into the oil-cooled electric motor cooling jacket 41. The high-pressure oil cools the electric motor in the oil-cooled electric motor cooling jacket 41 and flows into the second oil cooler 21. The high-pressure oil that has absorbed heat in the oil-cooled electric motor cooling jacket 41 and has increased in temperature is cooled by the second oil cooler 21 with cooling water or the like and then branched into two.

  One of the oil branched at the outlet of the oil-cooled electric motor cooling jacket 41 flows into the oil gas separator 42 through the fixed throttle 94. When passing through the fixed throttle 94, the pressure is reduced to an intermediate pressure. When the pressure is reduced to the intermediate pressure, the refrigerant contained in the oil flashes and becomes a two-phase flow and flows into the oil gas separator 42. The two-phase fluid is separated into oil and refrigerant gas in the oil / gas separator 42, and the refrigerant gas flows into the electric motor chamber 40. The refrigerant gas that has cooled the motor winding in the motor chamber 40 flows into the higher stage compression mechanism 2 from the intermediate point 9. The oil separated in the oil / gas separator 42 flows into the low-stage compression mechanism 1 through a fixed throttle (for low-stage) 93.

The other of the oil branched by the oil-cooled electric motor cooling jacket 41 flows into the high-stage compression mechanism oil inlet 2a through a fixed throttle (for high-stage) 92.
Since the operation of the refrigerant is the same as the operation of the refrigerant in the second embodiment, a description thereof will be omitted.

  As described above, a refrigeration cycle in which a low-stage compressor, a high-stage compressor, a first oil separator, a condenser, an expansion means for a cooler, and a cooler are sequentially connected in an annular manner, and the first oil A first oil cooler that is sequentially connected between an oil outlet of the separator and an oil inlet of the high-stage compressor, and that cools the oil separated by the first oil separator; High-stage oil injection comprising a compressor and a motor cooling jacket provided in the electric motor of the high-stage compressor, and a first fixed throttle that restricts the flow rate of the oil injected into the high-stage compressor constant. A circuit and a branch from the outlet of the motor cooling jacket of the high stage side oil injection circuit to the oil injection port of the low stage side compressor, and the oil flow rate from the motor cooling jacket is constant. A second fixed throttle that squeezes to a second fixed oil that separates oil from the second fixed throttle A low-stage oil injection circuit comprising a third fixed throttle for uniformly reducing a flow rate of oil separated by the separator and the second oil separator and injected into the low-stage compressor; and the second oil A refrigerant gas injection circuit for passing the refrigerant gas separated by the separator through the interior of the electric motor and injecting the refrigerant gas into a pipe between the low-stage compressor pressure and the low-high stage compressor pressure, The cooling capacity is improved and the coefficient of performance can be improved.

  In the present embodiment, the oil injected into the low-stage compression mechanism 1 is decompressed to an intermediate pressure, and the refrigerant concentration in oil is reduced. When the refrigerant concentration in the oil injected into the low-stage compression mechanism 1 decreases, the flash gas generated when the oil is depressurized to a low pressure decreases, and the flash gas is sucked into the low-stage compression mechanism 1. Since the decrease in the amount of refrigerant sucked from the cooler is reduced and the amount of refrigerant sucked is increased by the amount of reduction of the flash gas, the cooling capacity can be improved and the coefficient of performance can be improved.

Further, in addition to cooling from the motor cooling jacket 41, the motor winding is directly cooled by the refrigerant gas, so that it is possible to cool the motor winding more efficiently than when cooling only from the motor cooling jacket 41, The motor winding and the motor rotor can be made compact.
Therefore, when the motor winding becomes compact, the amount of copper wire used is reduced, and the motor price can be reduced.

Further, when the motor rotor becomes more compact and the diameter of the motor rotor is reduced, the centrifugal force acting on the motor rotor is reduced, and the effect of improving the maximum allowable motor speed is obtained. The allowable rotation speed of the compression mechanism is often defined by the allowable rotation speed of the electric motor. In such a case, if the allowable rotation speed of the electric motor is improved, the allowable rotation speed of the compression mechanism is improved.
In addition, when controlling the rotational speed of the compression mechanism using a frequency control device such as an inverter, if the allowable rotational speed of the compression mechanism is improved, even if the same compression mechanism is used, the compressor is sucked by the increased rotational speed. The volume can be improved and the cooling capacity can be improved.

In addition, although this Embodiment showed the example of the freezing apparatus using a two-stage compression mechanism, you may implement this invention in the freezing apparatus using the compression mechanism of three or more steps.
FIG. 14 shows an oil flow rate adjusting means (high stage) instead of a fixed throttle (for high stage) 92, a fixed throttle (for low stage) 93, and a fixed throttle (for oil gas separator) 94 in the refrigeration apparatus of FIG. 52), oil flow rate adjusting means (for low stage) 53, oil flow rate adjusting means (for oil gas separator) 54, and temperature detecting means for detecting the refrigerant temperature at the compressor discharge port 7 of the high stage side compression mechanism 2. 102, the temperature detection means 101 for detecting the refrigerant temperature at the intermediate point 9 which is the discharge port of the low-stage compression mechanism 1, and the detected temperature of the jacket outlet temperature detection means 120 for detecting the temperature of the oil at the outlet of the motor cooling jacket 41. Based on each, the controller 200 controls the oil flow rate adjusting means (for high stage) 52, the oil flow rate adjusting means (for low stage) 53, and the oil flow rate adjusting means (for oil gas separator) 54, respectively.

In the case of FIG. 14, in addition to the effects of the seventh embodiment, the coefficient of performance due to being able to operate with an appropriate oil injection amount can be improved.
FIG. 14 shows an oil flow rate adjusting means (high stage) instead of a fixed throttle (for high stage) 92, a fixed throttle (for low stage) 93, and a fixed throttle (for oil gas separator) 94 in the refrigeration apparatus of FIG. 52), oil flow rate adjusting means (for low stage) 53, oil flow rate adjusting means (for oil gas separator) 54, but either one or 2 of oil flow rate adjusting means is changed to a fixed throttle. May be. That is, at least one of the fixed throttle (for high stage) 92, the fixed throttle (for low stage) 93, and the fixed throttle (for oil gas separator) 94 may be replaced with the oil adjusting means.

  In this case, when the fixed throttle (for the high stage) 92 is replaced with the oil flow rate adjusting means (for the high stage) 52, the temperature detection means 102 for detecting the refrigerant temperature at the compressor discharge port 7 of the high stage side compression mechanism 2. When the fixed throttle (for the low stage) 93 is replaced with the flow rate adjusting means (for the low stage) 53, the temperature detecting means 101 that detects the refrigerant temperature at the intermediate point 9 that is the discharge port of the low stage side compression mechanism 1, When the oil flow rate adjusting means (for oil and gas separator) 54 is replaced with the fixed throttle (for oil and gas separator) 94, detection by the jacket outlet temperature detecting means 120 for detecting the temperature of the oil at the outlet of the motor cooling jacket 41 is detected. The controller 200 controls the oil flow rate adjusting means (for high stage) 52, the oil flow rate adjusting means (for low stage) 53, and the oil flow rate adjusting means (for oil gas separator) 54 based on each temperature.

Embodiment 7
FIG. 15 is a configuration diagram of a refrigeration apparatus having an oil / gas separator and a second oil cooler according to Embodiment 7 of the present invention. The present embodiment is a configuration diagram of a refrigeration apparatus in which a second oil cooler 21 is added to the refrigeration apparatus shown in FIG. 13 of the sixth embodiment.
The differences between the oil circuits of FIG. 15 and FIG. 13 are shown below.

The outlet of the first oil cooler 20 is connected to the second oil cooler 21 via an oil-cooled electric motor cooling jacket 41. The outlet of the second oil cooler 21 is branched into two, one of which is connected to the oil gas separator 42 via a fixed throttle 94. The refrigerant gas outlet 42 b of the oil / gas separator is connected to the intermediate point 9 via the electric motor chamber 40. The oil outlet 42 c of the oil / gas separator is connected to the low-stage compression mechanism oil inlet 1 a via a fixed throttle 93.
The other pipe branched at the outlet of the second oil cooler 21 is connected to the high-stage compression mechanism oil inlet 2a via a fixed throttle 92.

Next, the operation will be described. The high-pressure oil that has flowed into the oil-cooled electric motor cooling jacket 41 cools the electric motor within the oil-cooled electric motor cooling jacket 41 and flows into the second oil cooler 21. The high-pressure oil that has absorbed heat in the oil-cooled electric motor cooling jacket 41 and has increased in temperature is cooled by the second oil cooler 21 with cooling water or the like and then branched into two. One of the oil branched at the outlet of the second oil cooler 21 flows into the oil gas separator 42 through the fixed throttle 94. The other of the oil branched off at the outlet of the second oil cooler 21 flows into the high stage side compression mechanism oil injection port 2a through a fixed throttle (for high stage) 92.
Since the operation of the refrigerant is the same as the operation of the refrigerant in the second embodiment, a description thereof will be omitted.

As described above, since the second oil cooler that cools the oil flowing out from the motor cooling jacket is provided at the outlet of the motor cooling jacket, the cooling capacity can be further improved and the coefficient of performance can be further improved.
In addition, although this Embodiment showed the example of the freezing apparatus using a two-stage compression mechanism, you may implement this invention in the freezing apparatus using the compression mechanism of three or more steps.
FIG. 16 shows an oil flow rate adjusting means (high stage) instead of a fixed throttle (for high stage) 92, a fixed throttle (for low stage) 93, and a fixed throttle (for oil gas separator) 94 in the refrigeration apparatus of FIG. ) 52, oil flow rate adjusting means (for low stage) 53, and oil flow rate adjusting means (for oil gas separator) 54.

In the case of FIG. 16, in addition to the effects of the seventh embodiment, the coefficient of performance can be improved by being able to operate with an appropriate oil injection amount.
FIG. 16 shows an oil flow rate adjusting means (high stage) instead of a fixed throttle (for high stage) 92, a fixed throttle (for low stage) 93, and a fixed throttle (for oil gas separator) 94 in the refrigeration apparatus of FIG. 52), oil flow rate adjusting means (for low stage) 53, oil flow rate adjusting means (for oil gas separator) 54, but either one or 2 of oil flow rate adjusting means is changed to a fixed throttle. May be.

It is a block diagram of the freezing apparatus using the oil-cooled single stage compressor which has the oil flow volume adjustment means in Embodiment 1 of this invention. It is a block diagram of the freezing apparatus which has an oil flow volume adjustment means by the solenoid valve in Embodiment 1 of this invention. It is a block diagram of the freezing apparatus using the oil-cooled two-stage compressor which has the oil flow volume adjustment means in Embodiment 2 of this invention. It is a block diagram of the freezing apparatus using the oil-cooled single stage compressor which has the oil-cooled electric motor cooling jacket in Embodiment 3 of this invention. It is a structural diagram of a water-cooled electric motor jacket. It is a block diagram of the freezing apparatus using the oil-cooled two-stage compressor which has an oil-cooled electric motor cooling jacket in Embodiment 3 of this invention. It is a block diagram of the freezing apparatus which has a 2nd oil cooler using the oil-cooled single stage compressor which has an oil-cooled electric motor cooling jacket in Embodiment 4 of this invention. It is a block diagram of the freezing apparatus using the oil-cooled two-stage compressor which has a 2nd oil cooler in Embodiment 4 of this invention. It is a block diagram of the freezing apparatus using the oil-cooling type single stage compressor which has the oil-cooling type motor cooling jacket and oil flow rate adjustment means in Embodiment 5 of this invention. It is a block diagram of the freezing apparatus using the oil-cooled two-stage compressor which has the oil-cooled electric motor cooling jacket and oil flow rate adjustment means in Embodiment 5 of this invention. It is a block diagram of the freezing apparatus using the oil-cooled single stage compressor which has a 2nd oil cooler in Embodiment 5 of this invention. It is a block diagram of the freezing apparatus using the oil-cooled two-stage compressor which has a 2nd oil cooler in Embodiment 5 of this invention. It is a block diagram of the freezing apparatus using the oil-cooled two-stage compressor which has the oil gas separator in Embodiment 6 of this invention. It is a block diagram of the freezing apparatus using the oil-cooled two-stage compressor which has the oil gas separator and oil flow rate adjustment means in Embodiment 6 of this invention. It is a block diagram of the freezing apparatus using the oil-cooled two-stage compressor which has the oil gas separator and 2nd oil cooler in Embodiment 7 of this invention. It is a block diagram of the freezing apparatus using the oil-cooled two-stage compressor which has an oil-gas separator, the 2nd oil cooler, and an oil flow rate adjustment means in Embodiment 7 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Low stage side compression mechanism, 1a Low stage compression mechanism oil inlet, 2 High stage side compression mechanism, 2a High stage side compression mechanism oil inlet, 3 Condenser, 4 Expansion means for cooler, 5 Cooler, 7 Compressor Discharge port, 8 oil separator, 8c oil separator oil outlet, 9 midpoint, 10 single stage compressor, 10a compressor oil inlet, 20 oil cooler, 40 motor room, 41 oil cooled motor cooling jacket, 42 oil Gas separator, 51, 52 Oil flow rate adjustment means, 91-94 Fixed throttle, 101, 102 Temperature detection means, 200 Controller.

Claims (8)

A refrigeration cycle in which a compressor, an oil separator, a condenser, an expansion means for a cooler, and a cooler are sequentially connected in an annular manner;
A first oil cooler that is sequentially connected between an oil outlet of the oil separator and an oil inlet of the compressor, and cools the oil separated by the oil separator, and the oil that is injected into the compressor An oil injection circuit comprising an oil flow rate adjusting means for adjusting the flow rate of
Compressor discharge temperature detection means for detecting the refrigerant temperature at the discharge port of the compressor;
Control means for controlling the oil flow rate adjusting means based on the refrigerant temperature detected by the compressor discharge temperature detecting means;
A refrigeration apparatus comprising: The motor of the compressor is provided with a motor cooling jacket,
2. The refrigeration apparatus according to claim 1, wherein the motor cooling jacket is connected between the first oil cooler of the oil injection circuit and the oil flow rate adjusting means via a pipe. Jacket outlet temperature detecting means for detecting the temperature of the oil at the outlet of the motor cooling jacket;
The refrigeration according to claim 1 or 2, wherein the control means controls the oil flow rate adjusting means based on respective temperatures detected by the compressor discharge temperature detecting means and the jacket outlet temperature detecting means. apparatus. A refrigeration cycle in which a compressor, an oil separator, a condenser, an expansion means for a cooler, and a cooler are sequentially connected in an annular manner;
A first oil cooler that is sequentially connected between an oil outlet of the oil separator and an oil inlet of the compressor and that cools the oil separated by the oil separator, and is provided in an electric motor of the compressor An oil injection circuit comprising an electric motor cooling jacket and a fixed throttle that uniformly throttles the flow rate of the oil injected into the compressor;
A refrigeration apparatus comprising:   The refrigeration apparatus according to claim 1, wherein the compressor is a multistage compressor. A refrigeration cycle in which a low-stage compression mechanism, a high-stage compression mechanism, a first oil separator, a condenser, an expansion means for a cooler, and a cooler are sequentially connected in an annular manner;
A first oil cooler that is sequentially connected between an oil outlet of the first oil separator and an oil inlet of the high-stage compression mechanism and that cools the oil separated by the first oil separator; A high-stage side comprising a motor cooling jacket provided in an electric motor of the low-stage side compression mechanism and the high-stage side compression mechanism, and a first fixed throttle that restricts the flow rate of the oil injected into the high-stage side mechanism to be constant. An oil injection circuit;
The oil is sequentially connected from the outlet of the motor cooling jacket of the high stage side oil injection circuit to the oil inlet of the low stage side compression mechanism, and the flow rate of the oil from the motor cooling jacket is reduced to a constant level. 2 fixed throttle, a second oil separator that separates oil from the second fixed throttle, and a flow rate of oil that is separated by the second oil separator and injected into the low-stage compression mechanism is constant. A low-stage oil injection circuit consisting of a third fixed throttle for throttle;
A refrigerant gas injection circuit that causes the gas of the refrigerant separated by the second oil separator to pass through the interior of the electric motor and inject it into a pipe between the low-stage compression mechanism and the high-stage compression mechanism;
A refrigeration apparatus comprising:   When at least one of the first, second, and third fixed throttles is replaced with an oil adjusting means, and the first fixed throttle is replaced, the refrigerant temperature at the discharge port of the high-stage compression mechanism, When the second fixed throttle is changed, the refrigerant temperature between the low-stage compression mechanism and the high-stage compression mechanism, and when the second fixed throttle is changed, the oil at the outlet of the motor cooling jacket is changed. 7. The refrigeration apparatus according to claim 6, further comprising control means for controlling the oil adjusting means based on the temperature of the oil. The refrigeration apparatus according to any one of claims 2 to 7, further comprising a second oil cooler that cools the oil flowing out of the motor cooling jacket at an outlet of the motor cooling jacket.

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