WO2017203642A1

WO2017203642A1 - Screw compressor and refrigeration cycle device

Info

Publication number: WO2017203642A1
Application number: PCT/JP2016/065499
Authority: WO
Inventors: 伊藤　健
Original assignee: 三菱電機株式会社
Priority date: 2016-05-25
Filing date: 2016-05-25
Publication date: 2017-11-30

Abstract

This screw compressor is provided with a casing, a screw rotor that rotates inside the casing and that has a plurality of screw grooves in the outer peripheral surface, and one gate rotor that has teeth which engage with the screw grooves of the screw rotor and that rotates along with the rotation of the screw rotor. A compression chamber is configured in a space enclosed by a part of the casing, the screw grooves, and the gate rotor, and the part of the casing has a cooling flow channel that guides a refrigerant from the exterior to the compression chamber. The cooling flow channel is enlarged in the middle of the flow channel, and a cooling part is configured where the enlarged flow channel portion is filled with the refrigerant.

Description

Screw compressor and refrigeration cycle apparatus

The present invention relates to a screw compressor and a refrigeration cycle apparatus used for a refrigerant compressor of a refrigerator, and more particularly to a screw compressor having a single gate rotor combined with the screw rotor.

The conventional screw compressor has a screw groove formed on the outer peripheral surface and is coupled to the drive shaft of the motor, two or one gate rotor engaged with the screw groove of the screw rotor, and capacity control It is comprised by the valve, the casing, etc. (for example, refer patent document 1). Hereinafter, a structure in which a compression operation is performed using one gate rotor is referred to as a mono-gate rotor structure, and a structure in which a compression operation is performed using two gate rotors is referred to as a twin gate rotor structure.

In this type of screw compressor, the discharge temperature of the refrigerant gas discharged from the compressor becomes high when the driving conditions are high and the motor speed is increased by the inverter. When the discharge temperature increases, problems such as deterioration of the refrigerant and oil and insufficient cooling of the compression unit occur. Therefore, there is a technique in which liquid refrigerant is injected into a compression chamber in the middle of compression in order to suppress an excessive increase in discharge temperature (see, for example, Patent Document 2).

Patent Document 3 discloses a two-stage screw compressor provided with two sets of a screw rotor and a gate rotor. In this two-stage screw compressor, the low-stage compression section is configured with a twin gate rotor structure, and the high-stage compression section is configured with a monogate rotor structure.

In addition to the screw rotor and the two gate rotors, the low-stage compression section includes a low-stage screw housing that rotatably surrounds the screw rotor, and the low-stage compression section includes a low-stage screw housing as a component. Housed in a corrugated casing. In addition to the screw rotor and one gate rotor, the high-stage compression section includes a high-stage screw housing section that surrounds the screw rotor in a rotatable manner, and these are partly composed of the high-stage screw housing section. Is contained in a high-stage casing. Then, the refrigerant compressed in the low-stage compression section flows into the high-stage casing, and the high-stage compression section sucks, compresses and discharges the refrigerant flowing into the high-stage casing.

Japanese Patent No. 3170882 Japanese Patent Laid-Open No. 56-117056 Japanese Patent No. 5414345

As shown in FIGS. 1 and 3 of Patent Document 1, in a screw compressor having a twin gate rotor structure, a pair of two gate rotors are arranged symmetrically with respect to the screw rotor axis of the screw rotor. The structure is symmetrical about the rotor axis. For this reason, the radial load due to the compression is offset, and the radial compressive load does not act on the screw rotor shaft in the compression stroke. However, since there are two gate rotors, there are problems that the number of parts is increased and the number of assembly steps is also large.

On the other hand, as shown in FIG. 4 of Patent Document 1, a screw compressor having a monogate rotor structure does not have a symmetric structure around the screw rotor shaft, so that the load due to compression is not offset and the screw rotor shaft Deflection occurs. For this reason, if the clearance between the outer peripheral surface of the screw rotor and the inner peripheral surface of the casing is not sufficiently secured, the outer surface of the screw rotor and the inner peripheral surface of the casing during operation due to the deflection of the screw rotor shaft due to the compressive load. There was a risk that both would come into contact with each other.

Therefore, in the monogate rotor structure, the gap between the outer peripheral surface of the screw rotor and the inner peripheral surface of the casing must be increased as compared with the twin gate rotor structure, and the leakage of compressed gas increases, resulting in poor performance. There was a problem. For this reason, it is important to suppress the expansion of the gap during operation.

By the way, when the discharge temperature of the refrigerant discharged from the screw compressor is high, the casing portion that houses the screw rotor is thermally expanded under the influence of the heat, and the outer peripheral surface of the screw rotor and the inner peripheral surface of the casing The gap between them increases, the leakage of compressed gas increases, and the performance decreases.

In Patent Document 2, although discharge temperature is lowered by liquid refrigerant injection, there is no mention of reduction of a gap between the screw rotor and the casing due to thermal expansion of the casing.

Also, in Patent Document 3, since the high-stage compression portion has a monogate rotor structure, the screw rotor shaft is bent due to the compression load as described above. Moreover, since the high stage compression part becomes high temperature, the high stage screw accommodating part thermally expands. For this reason, in the high-stage compression section, the gap between the outer peripheral surface of the screw rotor and the inner peripheral surface of the high-stage screw housing section has a thermal expansion of the high-stage screw housing section in addition to the deflection of the screw rotor shaft. Join and spread. Therefore, the refrigerant leaks to the higher suction side and the efficiency is lowered.

In order to improve this, in Patent Document 3, by injecting a cooled refrigerant into the space in the high-stage casing that houses the high-stage compression section, and surrounding the high-stage screw housing section as a cooling atmosphere, The high-stage screw accommodating portion is cooled from the outside. In patent document 3, the cooled refrigerant | coolant is inject | poured into the space which accommodates the whole high stage compression part instead of a compression chamber. That is, the space into which the cooled refrigerant is injected corresponds to the suction space where the refrigerant before being sucked into the compression chamber of the high-stage compression unit is located. Therefore, when this configuration is developed in a single screw compressor having a single screw rotor, the cooled refrigerant is injected into the suction space, which causes a problem of a reduction in the amount of sucked gas air.

The present invention has been made in consideration of the above-described problems. In a single-gate compressor having a monogate rotor structure, the gap between the outer peripheral surface of the screw rotor and the inner peripheral surface of the casing is caused by bending of the screw rotor shaft. An object of the present invention is to provide a screw compressor and a refrigeration cycle apparatus capable of suppressing the expansion of the gap due to the thermal expansion of the casing in a portion where the width of the casing becomes wider.

A screw compressor according to the present invention has a casing, a screw rotor that rotates in the casing and has a plurality of screw grooves on the outer peripheral surface, and teeth that engage with the screw grooves of the screw rotor. A compression rotor is formed by a space surrounded by a part of the casing, the screw groove, and the gate rotor, and a part of the casing allows the refrigerant from outside to be compressed into the compression chamber. The cooling channel forms a cooling part that is enlarged in the middle of the channel and in which the expanded channel part is filled with the refrigerant.

A refrigeration cycle apparatus according to the present invention includes the screw compressor, the condenser, the main decompression device, and the evaporator, and is branched from a refrigerant circuit in which the refrigerant circulates, and a pipe between the condenser and the main decompression device, An injection pipe connected to the cooling flow path of the screw compressor via an injection decompression device, and an injection decompression device that is provided in the injection pipe and decompresses the refrigerant that passes through the injection pipe. is there.

According to the present invention, the cooling passage is provided in a part of the casing constituting the compression chamber, that is, in a portion where the clearance between the outer peripheral surface of the screw rotor and the inner peripheral surface of the casing is widened by the deflection of the screw rotor shaft. A part of the casing is cooled by a cooling portion provided in an enlarged manner in the middle of the flow path. For this reason, increase of the clearance gap between the outer peripheral surface of a screw rotor and the internal peripheral surface of a casing can be suppressed.

1 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100 including a screw compressor 102 according to Embodiment 1 of the present invention. It is a schematic sectional drawing of the screw compressor 102 which concerns on Embodiment 1 of this invention. It is a horizontal schematic sectional drawing in the XX line of FIG. FIG. 4 is an enlarged perspective view around the screw rotor of FIG. 3. It is a figure which shows the compression principle of the screw compressor 102 which concerns on Embodiment 1 of this invention. It is the figure which expand | deployed the internal peripheral surface of the screw accommodating part 3, and the screw rotor 1 in the screw compressor 102 which concerns on Embodiment 1 of this invention. It is a refrigerant circuit figure of the refrigerating cycle device 100 provided with screw compressor 102 concerning Embodiment 2 of the present invention. It is a Ph diagram illustrating the approach. It is a refrigerant circuit figure of the refrigerating cycle device 100 provided with screw compressor 102 concerning Embodiment 3 of the present invention. It is the figure which expand | deployed the internal peripheral surface of the screw accommodating part 3, and the screw rotor 1 in the screw compressor 102 which concerns on Embodiment 3 of this invention. It is a refrigerant circuit figure of the refrigerating cycle device 100 provided with screw compressor 102 concerning Embodiment 4 of the present invention. It is a horizontal schematic sectional drawing in the XX line of FIG. 2 of the screw compressor 102 which concerns on Embodiment 4 of this invention. It is the figure which expand | deployed the internal peripheral surface of the screw accommodating part 3, and the screw rotor 1 in the screw compressor 102 which concerns on Embodiment 4 of this invention.

Embodiment 1 FIG.
FIG. 1 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100 including a screw compressor 102 according to Embodiment 1 of the present invention. Here, in FIG. 1 and the following drawings, the same reference numerals denote the same or corresponding parts, and are common to the whole text of the embodiments described below. In addition, the form of the component shown by the whole specification is an illustration to the last, and is not limited to these description. In particular, the combination of the constituent elements is not limited to the combination in each embodiment, and the constituent elements described in the other embodiments can be applied to other embodiments as appropriate. The pressure level is not particularly determined in relation to the absolute value, but is relatively determined in terms of the state and operation of the system, apparatus, and the like.

The refrigeration cycle apparatus 100 includes a refrigerant circuit in which a screw compressor 102 driven by an inverter 101, a condenser 103, a main decompression apparatus 104, and an evaporator 105 are connected in order by refrigerant piping.

The refrigeration cycle apparatus 100 further branches from between the condenser 103 and the main decompression apparatus 104 and is provided in an injection pipe 107 connected to the screw compressor 102 and an injection pipe 107 and passes through the injection pipe 107. And an injection decompression device 106 for decompressing the refrigerant.

The screw compressor 102 sucks the refrigerant and compresses the refrigerant to a high temperature and high pressure state. The screw compressor 102 is driven by supplying electric power from a power supply source (not shown) to the motor 7 via the inverter 101. The screw compressor 102 is not limited to the one driven by the inverter 101 so that the number of rotations can be varied, and may be a constant speed.

The condenser 103 cools and condenses the gas discharged from the screw compressor 102.

The main decompression device 104 decompresses and expands the mainstream refrigerant that has flowed out of the condenser 103. Here, the main pressure reducing device 104 is constituted by a temperature-sensitive expansion valve, and the opening degree is adjusted according to the outer wall temperature on the motor 7 housing side of the casing 4 of the screw compressor 102 detected by the temperature-sensitive cylinder 104a. So-called temperature automatic expansion valve. Specifically, when the outer wall temperature rises, the temperature-sensitive expansion valve is adjusted in the opening direction, and when the outer wall temperature decreases, the temperature-sensitive expansion valve is adjusted in the closing direction. Here, the main decompression device 104 is controlled based on the outer wall temperature, but the main decompression device 104 may be controlled based on the outlet temperature of the evaporator 105.

The main pressure reducing device 104 is not limited to a temperature-sensitive expansion valve, and may be an electronic expansion valve that can variably adjust the opening of a throttle by a stepping motor (not shown). In addition to the electronic expansion valve, other types may be used as long as they have a similar role, such as a mechanical expansion valve adopting a diaphragm in the pressure receiving portion, a capillary tube, or the like.

The evaporator 105 evaporates the mainstream refrigerant that has flowed out of the main decompression device 104.

The injection decompression device 106 decompresses and expands part of the refrigerant that flows out of the condenser 103 and passes through the injection pipe 107 toward the main decompression device 104. The injection decompression device 106 is here constituted by a temperature-sensitive expansion valve, and is a so-called temperature automatic expansion valve whose opening degree is adjusted according to the discharge temperature detected by the temperature-sensitive cylinder 106a. Specifically, when the discharge temperature rises, the temperature-sensitive expansion valve is adjusted in the opening direction, and when the discharge temperature decreases, the temperature-sensitive expansion valve is adjusted in the closing direction. Specifically, the injection decompression device 106 is opened when the discharge temperature exceeds the operation control upper limit, and is adjusted so that the discharge temperature is close to the operation control upper limit. The injection decompression device 106 is not limited to the temperature-sensitive expansion valve, and other types of devices may be used in the same manner as the main decompression device 104.

The refrigeration cycle apparatus 100 further includes a control device 108. The control device 108 performs control such as control of the inverter 101, the main decompression device 104, the injection decompression device 106, and the capacity control of the screw compressor 102.

The refrigerant applied to the refrigeration cycle apparatus 100 of the example of this embodiment is not limited to a specific refrigerant as long as it is a refrigerant that involves a phase change between a liquid phase and a gas phase. In consideration of the influence on the environment, it is preferable to select one having a low GWP. The refrigerant having a low GWP is, for example, R32, HFO-1123, HFO-1234yf, or a mixed refrigerant including at least one of them. Note that the refrigerant applied to the refrigeration cycle apparatus 100 may be a natural refrigerant such as carbon dioxide.

(Operation of refrigeration cycle equipment)
Next, operation | movement of the refrigerating-cycle apparatus 100 of Embodiment 1 is demonstrated.

The discharge gas discharged from the screw compressor 102 is cooled by the condenser 103. The refrigerant cooled by the condenser 103 is branched after passing through the condenser 103, and the mainstream refrigerant is decompressed by the main decompression device 104 and expanded. And the refrigerant | coolant which flowed out from the main pressure reduction apparatus 104 is heated with the evaporator 105, and becomes refrigerant gas. The refrigerant gas flowing out of the evaporator 105 is sucked into the screw compressor 102.

On the other hand, of the liquid refrigerant after passing through the condenser 103, the remaining refrigerant excluding the mainstream refrigerant flows into the injection pipe 107 and is decompressed by the injection decompression device 106, which will be described later provided in the casing 4. It is injected into the compression chamber through the injection flow path. The injected liquid refrigerant is mixed with the refrigerant gas being compressed and discharged from the screw compressor 102. Thus, the discharge temperature can be lowered by injecting the liquid refrigerant into the compression chamber.

(Screw compressor)
Hereinafter, the screw compressor 102 according to Embodiment 1 of the present invention will be described with reference to FIG.

FIG. 2 is a schematic cross-sectional view of the screw compressor 102 according to Embodiment 1 of the present invention. FIG. 3 is a horizontal schematic sectional view taken along line XX in FIG. The arrows in FIG. 3 indicate the direction of the refrigerant pressure. FIG. 4 is an enlarged perspective view of the periphery of the screw rotor of FIG.
The screw compressor 102 is a single screw compressor having one screw rotor 1 and has a monogate rotor structure having one gate rotor 2. The screw compressor 102 includes a single screw rotor 1, a single gate rotor 2 that engages with the screw rotor 1, a motor 7, and a casing 4 that houses these.

The screw rotor 1 is formed in a substantially cylindrical shape, and a plurality of screw grooves 11 are formed in a spiral shape on the outer peripheral portion, and is coupled to the screw rotor shaft 6. The screw rotor shaft 6 is rotatably supported by

bearings

5 a and 5 b, and the screw rotor 1 is rotationally driven by a motor 7 coupled to the screw rotor shaft 6. One end of the screw rotor 1 is a refrigerant suction side (right side in FIG. 2), and the other end is a discharge side (left side in FIG. 2).

The motor 7 has a stator 7 a and a rotor 7 b, the stator 7 a is fixed to the inner surface of the casing 4, and the rotor 7 b is coupled to one end of the screw rotor shaft 6.

The gate rotor 2 has a plurality of teeth 21 that engage with the screw grooves 11 of the screw rotor 1 formed on a gear, and is attached to the gate rotor shaft 22. The gate rotor shaft 22 is rotatably supported by

gate rotor bearings

23a and 23b. In the gate rotor 2, the plurality of teeth 21 are engaged with the screw grooves 11, and rotates as the screw rotor 1 rotates.

The casing 4 includes a screw accommodating portion 3 that forms a cylindrical space 3a (see FIG. 4) as a constituent element, and the screw rotor 1 is rotatably accommodated in the screw accommodating portion 3. And the screw accommodating part 3 which is a part of casing 4 has covered a part of outer peripheral surface of the screw rotor 1, as shown by the dotted line of below-mentioned FIG.5 and FIG.6, and the screw accommodating part 3 and screw A compression chamber 10 is formed in a space surrounded by the screw groove 11 of the screw rotor 1 and the gate rotor 2 covered with the accommodating portion 3. That is, the compression chamber 10 is partitioned and formed by the screw accommodating portion 3 that covers the outer peripheral portion of the screw rotor 1, the screw groove 11 of the screw rotor 1, and the teeth 21 of the gate rotor 2 that engage with the screw groove 11. The

Moreover, the casing 4 has a housing portion in which a gate rotor support chamber 22a in which the gate rotor 2 is housed is formed in addition to the screw accommodating portion 3. Further, the screw accommodating portion 3 of the casing 4 is formed with an injection flow path 8 that guides refrigerant from the outside, specifically, refrigerant from the refrigerant circuit to the compression chamber 10. The opening on the outside of the casing 4 of the injection flow path 8 serves as an inlet 8a to which the injection pipe 107 is connected, and the injection pipe 107 is connected thereto. Although not shown in FIG. 3, the opening on the opposite side of the injection flow path 8 is opened on the inner peripheral surface of the screw accommodating portion 3, and an injection port 8 b for injecting a refrigerant into the compression chamber 10 (see below). 6).

The injection flow path 8 is a characteristic part of the first embodiment and will be described in detail later. The casing 4 is further provided with a working fluid suction port (not shown) and a discharge port 9 (see FIG. 5 described later).

FIG. 5 is a diagram illustrating a compression principle of the screw compressor 102 according to the first embodiment of the present invention. FIG. 6 is a developed view of the inner peripheral surface of the screw accommodating portion 3 and the screw rotor 1 in the screw compressor 102 according to Embodiment 1 of the present invention.

As shown in FIG. 5, when the screw rotor 1 is rotated by the motor 7 via the screw rotor shaft 6, the teeth 21 of the gate rotor 2 relatively move in the screw groove 11. As a result, in the screw groove 11, the suction stroke, the compression stroke, and the discharge stroke are set as one cycle, and this cycle is repeated. In FIG. 5, a portion surrounded by a dotted line indicates the screw accommodating portion 3 of the casing 4, and the screw groove 11 surrounded by the screw accommodating portion 3 constitutes the compression chamber 10. Here, focusing on the compression chamber 10 indicated by hatching of dots in FIG.

The refrigerant sucked from the suction port (not shown) of the casing 4 cools the motor 7 (see FIG. 2) and then flows into the screw groove 11 in the suction stroke. FIG. 5A shows the state of the compression chamber 10 immediately after the completion of the suction stroke, in other words, the compression start of the compression start. When the screw rotor 1 is driven by the motor 7 and rotated in the direction of the solid line arrow, the volume of the compression chamber 10 is reduced as shown in FIG.

When the screw rotor 1 continues to rotate, the compression chamber 10 communicates with the outside through the discharge port 9 as shown in FIG. Thereby, the high-pressure refrigerant gas compressed in the compression chamber 10 is discharged from the discharge port 9 to the outside.

Further, the liquid refrigerant decompressed by the injection decompression device 106 of the refrigerant circuit passes through the injection pipe 107 and the injection flow path 8 provided in the screw accommodating portion 3, and then serves as a coolant from the injection port 8b to the compression chamber. 10 leads. Thus, the discharge temperature is lowered by injecting the liquid refrigerant into the compression chamber 10. As described above, since the screw compressor 102 according to the first embodiment can lower the discharge temperature, it is effective when applied to the refrigeration cycle apparatus 100 that uses a refrigerant that tends to be a high temperature such as R32. Especially noticeable.

Here, when the shaft diameter of the screw rotor shaft 6 is substantially the same in the monogate rotor structure and the twin gate rotor structure, in the monogate rotor structure, the radial load due to compression is not offset as described above. The screw rotor shaft 6 is easily bent and bends toward the non-compressed portion. Further, the screw accommodating portion 3 is thermally expanded in the radial direction. For this reason, in the conventional monogate rotor structure, the clearance 12 between the screw rotor portion corresponding to the compression portion and the screw accommodation portion 3 (hereinafter referred to as the screw clearance 12), corresponding to the deflection of the screw rotor shaft 6 and the thermal expansion of the screw accommodation portion 3. (See Figure 3) expands.

Therefore, in the first embodiment, the screw accommodating portion 3 is cooled using the liquid refrigerant passing through the injection flow path 8. As a specific configuration for cooling the screw housing portion 3, the injection flow path 8 is enlarged in the middle of the flow path, and the expanded flow path portion is filled with liquid refrigerant to cool the screw housing section 3. A cooling unit 8c is provided. The injection flow path 8 constitutes the cooling flow path of the present invention.

With this configuration, when the liquid refrigerant guided from the injection pipe 107 to the injection flow path 8 is filled in the cooling unit 8c, the cooling unit 8c serves as a cooling source for cooling the screw storage unit 3, and the screw storage The thermal expansion of the part 3 can be suppressed. Specifically, the thermal expansion of the part surrounded by the dotted line 13 in FIG. 3 can be suppressed. The refrigerant flowing out of the cooling unit 8c is injected into the compression chamber 10 from the injection port 8b.

As described above, in the first embodiment, the injection flow path 8 is provided in the portion where the screw gap 12 is widened by the deflection of the screw rotor shaft 6 and the thermal expansion of the screw housing portion 3, that is, the screw housing portion 3. The cooling part 8c is provided in the middle of the flow path of the injection flow path 8. Thereby, compared with the case where the whole flow path 8 for injection is comprised with the same flow-path cross-sectional area as the inflow port 8a and the injection port 8b, the screw accommodating part 3 can be cooled intensively, and a high cooling effect is obtained. Obtainable. Therefore, the thermal expansion of the screw housing part 3 can be suppressed, and the inner diameter of the screw housing part 3 can be locally reduced. As a result, even if the screw rotor 1 is bent, the screw gap 12 during operation can be made narrower than that of the conventional monogate rotor structure, whereby leakage of compressed gas can be suppressed, and as a result, performance can be improved. Can do.

The liquid refrigerant after passing through the injection flow path 8 flows into the compression chamber 10 after the start of compression. For this reason, when the technique of the said patent document 3 is applied to the screw compressor 102, obstruction | occlusion of the suction | inhalation gas air volume does not arise. As a result, the compression efficiency can be improved. Further, the liquid refrigerant after passing through the injection flow path 8 flows into the compression chamber 10 after the start of compression, merges with the refrigerant in the compression chamber 10 and evaporates, and thus liquid compression does not occur.

It should be noted that since the compression load is small under operating conditions where the high pressure is low, the bending of the screw rotor shaft 6 is small, and in this case, cooling of the screw accommodating portion 3 is not necessarily required. For this reason, it is not always necessary to flow the liquid refrigerant through the injection flow path 8 during operation, and liquid refrigerant is injected from the injection flow path 8 into the compression chamber 10 only under high-pressure operating conditions. May be. Specifically, for example, an on-off valve may be provided in the injection pipe 107, and for example, it may be controlled to open when the discharge temperature is higher than the set temperature and closed when the discharge temperature is lower than the set temperature.

Embodiment 2. FIG.
FIG. 7 is a refrigerant circuit diagram of the refrigeration cycle apparatus 100 including the screw compressor 102 according to Embodiment 2 of the present invention. Here, a different part from the refrigerating-cycle apparatus 100 of Embodiment 1 is demonstrated. The refrigeration cycle apparatus 100 of the second embodiment is different from the refrigeration cycle apparatus 100 of the first embodiment in the refrigerant circuit from after passing through the condenser 103 to the main decompression device 104.

As shown in FIG. 7, the refrigeration cycle apparatus 100 of the second embodiment includes an intermediate cooler 109 between the condenser 103 and the main decompression device 104. The refrigeration cycle apparatus 100 includes a refrigerant circuit in which the refrigerant circulates by connecting the screw compressor 102, the condenser 103, the high-pressure side flow path of the intercooler 109, the main decompression apparatus 104, and the evaporator 105 in order through refrigerant piping. It is composed. The refrigeration cycle apparatus 100 further branches from between the intermediate cooler 109 and the main decompressor 104 and is connected to the screw compressor 102 via the low pressure side passage of the intermediate cooler 109, and an economizer pipe. 111, an intermediate cooler decompression device 110 that is provided upstream of the low-pressure side flow path of the intermediate cooler 109 and decompresses the refrigerant that passes through the economizer pipe 111.

The intermediate cooler 109 exchanges heat between the refrigerant that flows out of the condenser 103 and flows into the high-pressure side flow path of the intermediate cooler 109, and the refrigerant that flows into the low-pressure side flow path of the intermediate cooler 109. The refrigerant flowing into the low-pressure side flow path of the intermediate cooler 109 is a refrigerant obtained by decompressing a part of the refrigerant after passing through the intermediate cooler 109 by the intermediate cooler decompression device 110. The refrigerant that has flowed into the low-pressure side of the intercooler 109 exchanges heat with the refrigerant that has flowed into the high-pressure channel, and is then injected into the screw compressor 102. On the other hand, the refrigerant that has flowed into the high-pressure channel of the intermediate cooler 109 is cooled by heat exchange with the refrigerant that has flowed into the low-pressure channel. That is, the high-pressure side refrigerant that has flowed out of the condenser 103 directly into the high-pressure side passage of the intermediate cooler 109 is supercooled by heat exchange with the refrigerant that has flowed into the low-pressure side passage. With this increase in supercooling, the refrigeration effect of the evaporator 105 increases.

Here, the intermediate cooler decompression device 110 is controlled based on the intermediate pressure superheat, approach, discharge temperature, and the like. The intercooler decompression device 110 is composed of an electronic expansion valve capable of variably adjusting the opening of the throttle by a stepping motor (not shown). The intermediate pressure superheat degree is the degree of superheat at the low pressure side channel outlet of the intermediate cooler 109. The approach corresponds to a in FIG.

FIG. 8 is a Ph diagram illustrating the approach.
As shown in FIG. 8, the approach is the difference between the refrigerant temperature at the intermediate pressure MP at the outlet of the intermediate cooler decompression device 110 and the saturation conversion temperature of the intermediate pressure MP at the outlet of the intermediate cooler decompression device 110.

(Screw compressor)
In the first embodiment, the liquid refrigerant flowing into the injection pipe 107 and decompressed by the injection decompression device 106 passes through the injection flow path 8. On the other hand, in the second embodiment, the gas refrigerant flowing out from the low-pressure side flow path of the intermediate cooler 109 in the economizer pipe 111 passes through the injection flow path 8.

The temperature of the gas refrigerant flowing into the screw compressor 102 from the economizer pipe 111 is lower than the temperature of the refrigerant discharged from the screw compressor 102 and can be used as a cooling source for the screw accommodating portion 3.

For this reason, the second embodiment can suppress the thermal expansion of the screw housing portion 3 as in the first embodiment, can locally reduce the inner diameter of the screw housing portion 3, and can suppress the leakage of the compressed gas. In addition, since the refrigeration effect is increased by having the intercooler 109, the performance can be improved as compared with the first embodiment.

Embodiment 3 FIG.
FIG. 9 is a refrigerant circuit diagram of the refrigeration cycle apparatus 100 including the screw compressor 102 according to Embodiment 3 of the present invention. In other words, the refrigeration cycle apparatus 100 according to the third embodiment corresponds to a configuration in which the first embodiment and the second embodiment are combined. Hereinafter, the parts of the third embodiment different from the refrigeration cycle apparatus 100 of the first embodiment will be described.

As shown in FIG. 9, the refrigeration cycle apparatus 100 of the third embodiment further includes the intercooler 109 of the second embodiment shown in FIG. 7 in addition to the refrigeration cycle apparatus 100 of the first embodiment shown in FIG. An intermediate cooler decompression device 110 and an economizer pipe 111 are provided.

The injection decompression device 106 is adjusted based on the discharge temperature as described above, and the intermediate cooler decompression device 110 is controlled based on the intermediate pressure superheat or approach.

(Screw compressor)
In the first and second embodiments, either the liquid refrigerant from the injection pipe 107 or the gas refrigerant from the economizer pipe 111 flows into the injection flow path 8. On the other hand, in the third embodiment, the liquid refrigerant from the injection pipe 107 and the gas refrigerant from the economizer pipe 111 join and flow into the injection flow path 8. Thereafter, the refrigerant in the injection flow path 8 is guided from the injection port 8b to the compression chamber 10 (screw groove 11 in the compression stroke).

FIG. 10 is a developed view of the inner peripheral surface of the screw accommodating portion 3 and the screw rotor 1 in the screw compressor 102 according to the third embodiment of the present invention.
As described above, the refrigerant obtained by joining the liquid refrigerant from the injection pipe 107 and the gas refrigerant from the economizer pipe 111 passes through the injection flow path 8. In order to ensure the ease of flow of the refrigerant after merging, the injection port 8b of the third embodiment is configured to have a larger flow path cross-sectional area than the injection port 8b of the first embodiment.

According to the third embodiment, the same effects as those of the first and second embodiments can be obtained.

Embodiment 4 FIG.
FIG. 11 is a refrigerant circuit diagram of the refrigeration cycle apparatus 100 including the screw compressor 102 according to Embodiment 4 of the present invention. FIG. 12 is a horizontal schematic cross-sectional view of the screw compressor 102 according to the fourth embodiment of the present invention taken along line XX in FIG. FIG. 13 is a developed view of the inner peripheral surface of the screw accommodating portion 3 and the screw rotor 1 in the screw compressor 102 according to Embodiment 4 of the present invention.

Here, the control of the refrigerant circuit of the refrigeration cycle apparatus 100 and the

decompression apparatuses

106 and 110 in FIG. 11 is the same as in the third embodiment.

(Screw compressor)
In the third embodiment, the liquid refrigerant and the gas refrigerant are combined and passed through the injection flow path 8. In contrast, the injection flow path 8 of the fourth embodiment is divided into a liquid refrigerant flow path 81 through which liquid refrigerant passes and a gas refrigerant flow path 82 through which gas refrigerant passes. Are configured to pass separately.

An injection pipe 107 is connected to an inlet 81a which is an opening on the outside of the liquid refrigerant flow path 81. Thereby, the liquid refrigerant from the injection pipe 107 passes through the liquid refrigerant flow path 81. Further, an economizer pipe 111 is connected to an inflow port 82a which is an opening on the outside of the gas refrigerant channel 82. As a result, the gas refrigerant from the economizer pipe 111 passes through the gas refrigerant passage 82.

The liquid refrigerant flow path 81 and the gas refrigerant flow path 82 are provided with

cooling portions

81c and 82c, respectively. Like the cooling unit 8c of the first embodiment, the cooling

units

81c and 82c are configured to cool the screw accommodating unit 3 by enlarging the middle of the flow path and filling the expanded flow path portion with the liquid refrigerant.

In the cooling part 81c and the cooling part 82c, the cooling part 82c is formed larger as shown in FIG. In addition, as shown in FIG. 13, the injection port 81b, which is the opening on the screw rotor 1 side of the liquid refrigerant flow path 81, and the injection port 82b, which is the opening on the screw rotor 1 side of the gas refrigerant flow path 82, The injection port 82b has a larger channel cross-sectional area. The reason why the cross-sectional area of the flow path is larger on the side through which the gas refrigerant passes than on the side through which the liquid refrigerant passes is that the gas refrigerant hardly flows when the flow path is narrow. However, the side through which the liquid refrigerant passes may be enlarged to have the same size as the side through which the gas refrigerant passes.

As described above, the injection flow path 8 is divided into the liquid refrigerant flow path 81 and the gas refrigerant flow path 82, so that the flow of each of the injection port 81b and the injection port 82b is as shown in FIG. The path cross-sectional area can be made smaller than the flow path cross-sectional area of the injection port 8b of the third embodiment.

According to the fourth embodiment, the same effects as in the first to third embodiments can be obtained, and the injection flow path 8 is divided into the liquid refrigerant flow path 81 and the gas refrigerant flow path 82. The following effects can be obtained. That is, as described above, the flow path cross-sectional areas of the injection port 81b and the injection port 82b can be made smaller than the flow path cross-sectional area of the injection port 8b of the third embodiment shown in FIG.

Since the cross-sectional area of the flow path can be reduced, each of the injection port 81b and the injection port 82b can be sized so as not to straddle the adjacent compression chamber 10, and can be arranged along the inclination of the compression chamber 10. . For this reason, since it can aim at the one compression chamber 10, it can ensure the differential pressure | voltage between the pressure of the refrigerant | coolant used for injection, and the pressure in a compression chamber, and can perform injection favorably.

1 screw rotor, 2 gate rotor, 3 screw housing, 3a space, 4 casing, 5a bearing, 5b bearing, 6 screw rotor shaft, 7 motor, 7a stator, 7b rotor, 8 injection flow path, 8a inlet , 8b Injection port, 8c Cooling section, 9 Discharge port, 10 Compression chamber, 11 Screw groove, 12 Screw gap, 21 Teeth, 22 Gate rotor shaft, 22a Gate rotor support chamber, 23a Gate rotor bearing, 23b Gate rotor bearing, 81 Liquid refrigerant flow path, 81a inlet, 81b injection port, 81c cooling section, 82 gas refrigerant flow path, 82a inlet, 82b injection port, 82c cooling section, 100 refrigeration cycle apparatus, 101 inverter, 02 Screw compressor, 103 condenser, 104 main decompression device, 104a temperature sensitive cylinder, 105 evaporator, 106 injection decompression device, 106a temperature sensitive cylinder, 107 injection piping, 108 control device, 109 intermediate cooler, 110 intermediate Pressure reducer for cooler, 111 economizer piping.

Claims

A casing,
A screw rotor that rotates within the casing and has a plurality of screw grooves on the outer peripheral surface;
Having a tooth that engages with the screw groove of the screw rotor, and a single gate rotor that rotates as the screw rotor rotates,
A compression chamber is constituted by a space surrounded by a part of the casing, the screw groove and the gate rotor,
The part of the casing has a cooling channel that guides an external refrigerant to the compression chamber. The cooling channel is enlarged in the middle of the channel, and the enlarged channel portion is filled with the refrigerant. Screw compressor constituting the cooling section.
The screw compressor according to claim 1, wherein the part of the casing is a screw accommodating portion having a cylindrical space for accommodating the screw rotor.
The refrigerant is a refrigerant accompanying a phase change between a liquid phase and a gas phase,
The cooling flow path is divided into a liquid refrigerant flow path through which liquid refrigerant passes and a gas refrigerant flow path through which gas refrigerant passes, and each of the liquid refrigerant flow path and the gas refrigerant flow path is The screw compressor according to claim 1 or 2, further comprising a cooling unit.
A refrigerant circuit comprising the screw compressor, the condenser, the main decompression device and the evaporator according to claim 1 or 2, wherein the refrigerant circulates,
A pipe for injection branched from a pipe between the condenser and the main pressure reducing device and connected to the cooling flow path of the screw compressor via a pressure reducing device for injection;
A refrigeration cycle apparatus comprising: an injection decompression device that decompresses a refrigerant that is provided in the injection piping and passes through the injection piping.
A refrigerant circuit comprising the screw compressor according to claim 1 or claim 2, a condenser, a high-pressure side flow path of an intercooler, a main decompression device, and an evaporator, wherein a refrigerant circulates;
An economizer pipe branched from a pipe between the high-pressure side passage of the intermediate cooler and the main pressure reducing device and connected to the cooling passage of the screw compressor via the low-pressure side passage of the intermediate cooler When,
A refrigeration cycle apparatus comprising: a pressure reducing device for an intermediate cooler that is provided upstream of a low pressure side flow path of the intermediate cooler in the economizer pipe and depressurizes a refrigerant that passes through the economizer pipe.
A refrigerant circuit in which the screw compressor, the condenser, the high-pressure side flow path of the intercooler, the main decompression device, and the evaporator are connected in order by refrigerant piping, and the refrigerant circulates.
An injection pipe branched from a pipe between the condenser and the main decompressor, and connected to the liquid refrigerant flow path of the screw compressor via an injection decompressor;
A pressure reducing device for injection, which is provided in the pipe for injection and depressurizes a refrigerant passing through the pipe for injection;
Branches from a pipe between the high pressure side flow path of the intermediate cooler and the main pressure reducing device, and is connected to the gas refrigerant flow path of the screw compressor via the low pressure side flow path of the intermediate cooler. Economizer piping,
A refrigeration cycle apparatus comprising: a pressure reducing device for an intermediate cooler that is provided upstream of a low pressure side flow path of the intermediate cooler in the economizer pipe and depressurizes a refrigerant that passes through the economizer pipe.
The refrigeration cycle apparatus according to any one of claims 4 to 6, wherein the refrigerant includes R32.