JP2015155652A - Screw fluid machine and refrigeration cycle apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw fluid machine capable of suppressing a temperature increase in an injection section to enable injection of a necessary refrigerant quantity, and reducing oscillation and pipe pulsation by injecting refrigerant into an operation chamber small in pressure fluctuation.

SOLUTION: A screw fluid machine of the present invention comprises: a male rotor and a female rotor rotating while engaging with each other; a casing storing therein the male rotor and the female rotor; a plurality of operation chambers constituted by the male rotor, the female rotor, and the casing; an injection port formed in the operation chambers for injecting refrigerant into the operation chambers; and pivotal support means rotatably, pivotally supporting the male rotor and the female rotor, the operation chambers being each configured to have a constant capacity after completion to draw in the refrigerant, and the injection port being open to the operation chambers having the constant capacity after completion to draw in the refrigerant and being closed before a compression stroke of each operation chamber.

COPYRIGHT: (C)2015,JPO&INPIT

Description

  The present invention relates to a screw fluid machine and a refrigeration cycle apparatus including the screw fluid machine.

  Screw fluid machines are widely used as refrigeration and air-conditioning compressors and air compressors. Because it is a major component of heat pump equipment such as air conditioners, chillers, and refrigerators, social demands for energy saving are extremely strong, and high efficiency and high capacity are becoming increasingly important. ing.

  Non-Patent Document 1 discloses gas injection. Gas injection consists of two stages of decompression means for the refrigeration cycle, and a gas-liquid separator is provided in the middle to separate it into gas refrigerant and liquid refrigerant, and only the gas refrigerant is directly put into the cylinder in the middle of the compression stroke at intermediate pressure. This is a system provided with a guiding injection circuit. The enthalpy difference (refrigeration effect) can be increased on the evaporator side, and the cooling capacity can be increased. In addition, compared with a single-stage compression two-stage expansion cycle, an ideal injection is possible in a two-stage compression two-stage expansion cycle. In addition, the economizer system leads the condensed high-pressure liquid refrigerant to the intercooler and partially decompresses it through the expansion valve to gasify it, thereby cooling the liquid refrigerant sent to the evaporator and improving the refrigerating capacity. The gas refrigerant evaporated in the intermediate cooler is injected into the working chamber from an economizer port (port for injecting the gas refrigerant) provided in the compressor.

  Patent Document 1 provides a gas-liquid separator in the refrigeration cycle for the purpose of increasing the coefficient of performance of the refrigeration cycle (ratio of refrigeration capacity to the compressor input), and uses the gas refrigerant separated by the gas-liquid separator as a compressor. Disclosed is gas injection. If the compression ratio is higher than the design compression ratio, the gas injection port is used for gas injection for the purpose of improving the coefficient of performance, and if the compression ratio is lower than the design compression ratio, it is used as a discharge bypass port. A refrigeration cycle apparatus with reduced loss can be obtained.

  Patent Document 2 discloses a screw fluid machine that includes a screw rotor and a cylinder having an economizer port, and the economizer port communicates with the compressor before the compression chamber between the screw rotor and the cylinder is sealed. . Since the economizer port can be communicated with the compression chamber when the internal pressure of the compression chamber is low, and the amount of refrigerant ejected from the economizer port can be increased, the cooling effect by this refrigerant can be enhanced.

JP 2012-127565 A Japanese Patent No. 4140488

"Refrigerant compressor" Japan Society of Refrigeration and Air Conditioning 2013

  In conventional single-stage compression injection, whether it is a gas injection or an economizer system, the working chamber at the injection destination is in the compression stroke, so the pressure rises in the working chamber and the required amount of refrigerant is injected. Can not be. As a result, it is not possible to obtain a sufficient increase in cooling capacity and improvement in the coefficient of performance with gas injection, and with the economizer system, the saturation temperature cannot be lowered and the economizer effect (increase in refrigeration capacity) is sufficient. You can't get it. Furthermore, injecting into the working chamber having such pressure fluctuations causes problems such as vibration and piping pulsation.

  The present invention provides a screw fluid machine that enables injection of a necessary amount of refrigerant by suppressing an increase in pressure in an injection unit, and that reduces vibration and piping pulsation by injecting into a working chamber having a small pressure fluctuation. Is an issue.

  A screw fluid machine according to the present invention includes a male rotor and a female rotor that rotate while meshing with each other, a suction end face, a discharge end face, and a bore, and a casing that houses the male rotor and the female rotor, and a male rotor and a female rotor. And a plurality of working chambers configured by a casing, an injection port formed in the working chamber for injecting refrigerant into the working chamber, a suction port provided in the casing, a discharge port provided in the casing, a male And a support means for rotatably supporting the rotor and the female rotor, and constitutes a working chamber whose volume is constant after completion of refrigerant suction, and the injection port is a working chamber whose volume after completion of refrigerant suction is constant And closed before the compression stroke of the working chamber.

  According to the present invention, there is provided a screw fluid machine that enables injection of a necessary amount of refrigerant by suppressing an increase in pressure in an injection section, and that reduces vibration and piping pulsation by injecting into a working chamber having a small pressure fluctuation. can do.

Sectional drawing of the screw fluid machine in 1st Embodiment Section A cross-sectional enlarged view of FIG. B perspective view of FIG. Casing bore development Relationship diagram between the working chamber from the completion of suction to the start of compression and the injection port, suction port, and discharge port Refrigerant circuit diagram of the refrigeration cycle apparatus in the third embodiment Refrigerant circuit diagram of the refrigeration cycle apparatus in the fourth embodiment

  The screw fluid machine of the present invention includes a male rotor and a female rotor that rotate while meshing with each other, a casing that houses the male rotor and the female rotor, a suction end surface, a discharge end surface, and a bore. A casing having a male rotor, a female rotor, and a plurality of working chambers configured by the casing; an injection port formed in the working chamber for injecting refrigerant into the working chamber; and a suction port provided in the casing; A discharge port provided in the casing and a shaft supporting means for rotatably supporting the male rotor and the female rotor constitute a working chamber whose volume is constant after the refrigerant suction is completed, and the injection port is the refrigerant suction completed It opens to the working chamber where the volume afterwards becomes constant, and closes before the compression stroke of the working chamber. A working chamber whose volume is constant after completion of refrigerant suction is formed, and the injection port opens to the working chamber where the volume becomes constant after completion of refrigerant suction and closes before the compression stroke of the working chamber. Since the pressure rise can be suppressed, it becomes possible to inject the required amount of refrigerant. Gas injection can sufficiently increase the cooling capacity and improve the coefficient of performance, and the economizer system can reduce the saturation temperature. It is possible to obtain a sufficient economizer effect (improvement of refrigeration capacity). Further, since the injection is performed into the working chamber in which the pressure fluctuation is suppressed (the volume is constant), it becomes possible to reduce vibration and piping pulsation. Furthermore, since low-temperature refrigerant injection is performed between the completion of suction and the start of compression, the refrigerant temperature before the start of compression can be lowered, and the refrigerant state change in the compression stroke can be brought closer to adiabatic compression. The energy efficiency of the screw fluid machine can be improved.

  Below, the screw fluid machine which shows the 1st form for carrying out the present invention is explained using Drawings 1-5.

  First, the overall structure of the screw fluid machine showing the first embodiment will be described with reference to FIGS. FIG. 1 shows a cross-sectional view of the screw fluid machine, and FIG. 2 shows an enlarged cross-sectional view of part A in FIG. The screw fluid machine 1 is configured by housing a compression unit 2 and a drive unit 3 in a casing 4. The screw fluid machine 1 sucks the gas refrigerant sucked into the screw fluid machine 1 from the suction port 15 into the working chamber from the suction port 10 of the working chamber after passing through the motor 14. Then, the gas refrigerant is compressed and discharged from the discharge port 16 to the outside of the screw fluid machine 1 via the discharge port 11 of the working chamber. The compression unit 2 includes a male rotor 5 and a female rotor 6 that rotate while being engaged with each other by a motor 14 disposed in the drive unit 3, a casing 4 that houses the male rotor 5 and the female rotor 6, a male rotor 5, and a female rotor. There are provided shaft support means 12a, 12b, 13a, 13b for rotatably supporting the rotor 6. The tooth grooves 5a and 6a of the male rotor 5 and the female rotor 6, the bore of the casing (wall surface facing each rotor in the radial direction) 7, the suction end face 8 of the casing, and the discharge end face 9 of the casing form a plurality of working chambers. To do.

  The compression process will be described. When each of the rotors 5 and 6 is rotated by the motor 14, the working chamber is generated at the suction side end portion of the rotor and moves in the axial direction. Disappear. The working chamber communicates with the suction port 10 formed in the casing during expansion of the internal volume and sucks the gas refrigerant. When the working chamber volume is almost the maximum, the working chamber deviates from the outline of the suction port and the suction port is closed to complete the suction. . When the working chamber volume is subsequently reduced, compression of the gas refrigerant confined in the inside starts, the working chamber pressure rises, and when the working chamber moves in the axial direction and the compression proceeds, the working chamber moves to the discharge port 11. Open, finish compression and start dispensing.

  The configuration of the injection unit 17 will be described. The injection part 17 is composed of an injection port 17a which is a communication hole with a working chamber disposed on the wall surface of the casing bore 7 and an injection flow path 17b which is a communication path with the injection port 17a (in FIG. Only the port 17a is shown). The refrigerant supplied from the refrigeration cycle passes through the injection flow path 17b.

  Subsequently, the compression operation and the injection operation in the working chamber will be described with reference to FIGS. FIG. 3 is a perspective view of part B of FIG. 2 and only the rotor is displayed. The arrows shown in FIG. 3 indicate the rotation directions of the male rotor 5 and the female rotor 6. FIG. 4A shows a top view of FIG. FIG. 4B is a development view of the casing bore 7 and shows a plurality of working chambers 22a to 22f and 23a to 23g configured at the representative rotational positions. 3 and 4, the male rotor 5 has four teeth 20a to 20d, the female rotor 6 has six teeth 21a to 21f, and the male rotor on the suction end face 8 side of the casing. 5 shows a state in which the fifth tooth 20a is engaged with the tooth gap between the teeth 21f and 21a of the female rotor 6.

  The configuration of the working chamber will be described. The working chamber on the male rotor 5 side is formed in a tooth space between the teeth 20 a and 20 b of the male rotor 5, and is divided by the engagement of the male rotor 5 and the female rotor 6. The suction side working chamber 22b formed in the tooth gap between the teeth 20b and 20c and divided by the engagement of the male rotor 5 and the female rotor 6 and the tooth groove between the teeth 20c and 20d of the male rotor 5 are male. The suction side working chamber 22c divided by the engagement of the rotor 5 and the female rotor 6 and the discharge divided by the engagement of the male rotor 5 and the female rotor 6 are formed in the tooth gap between the teeth 20d and 20a of the male rotor 5. Side working chamber 22d, discharge side working chamber 22e formed in a tooth gap between teeth 20a, 20b of male rotor 5 and separated by engagement of male rotor 5 and female rotor 6, and teeth 20b of male rotor 5 , 20c, the male rotor 5 formed in the tooth gap A working chamber 22f of the discharge side, separated by engagement of the rotor 6, in constructed. The working chambers 22 a, 22 b and 22 c on the male rotor 5 side suck in the gas refrigerant through the suction port 10, and the working chambers 22 e and 22 f on the male rotor 5 side discharge the gas refrigerant through the discharge port 11.

  The working chamber on the female rotor 6 side is formed in a tooth gap between the teeth 21 a and 21 b of the female rotor 6, and is divided by the engagement of the male rotor 5 and the female rotor 6. The suction-side working chamber 23b formed in the tooth gap between the teeth 21b and 21c and divided by the engagement of the male rotor 5 and the female rotor 6 and the tooth gap between the teeth 21c and 21d of the female rotor 5 are formed. The working chamber 23c on the suction side, the working chamber 23d formed in the tooth groove between the teeth 21d and 21e of the female rotor 6, and the male rotor 5 formed in the tooth groove between the teeth 21e and 21f of the female rotor 6 and The discharge-side operation chamber 23e partitioned by the engagement of the female rotor 6 and the tooth-side groove between the teeth 21f and 21a of the female rotor 6 and the discharge-side operation partitioned by the engagement of the male rotor 5 and the female rotor 6 Tooth space between the chamber 23f and the teeth 21a, 21b of the female rotor 2 It is formed composed of the working chamber 23g of the separated discharge side meshing of the male rotor 5 and a female rotor 6. The working chambers 23 a, 23 b and 23 c on the female rotor 6 side suck in the gas refrigerant through the suction port 10, and the working chambers 23 f and 23 g on the female rotor 6 side discharge the gas refrigerant through the discharge port 11.

  Next, the relationship between the working chamber and the injection port 17a from the completion of suction to the start of compression and the relationship between the suction port 10 and the discharge port 11 will be described with reference to FIG. Note that m1 to m5 and f1 to f5 shown in FIG. 5 are the same as those in FIG. The suction port 10 includes a suction port 10a on the male rotor 5 side, a suction port 10b on the female rotor 6 side, and a suction port 10c on the discharge end face side. The discharge port 11 includes a discharge port 11a on the male rotor 5 side and a discharge port 11b on the female rotor 6 side. The working chamber 30 which is the working chamber on the side of the male rotor 5 and has completed the suction constitutes the working chamber only by the suction side end surface 8, the discharge side end surface 9 and the tooth groove of the male rotor 5 of the casing. Until the end portion 32 reaches m5 and f5 at which discharge starts, the volume is constant and it does not communicate with other working chambers or suction ports. The working chamber 31a, which is the working chamber on the female rotor 6 side and has completed the suction, constitutes the working chamber only by the suction side end surface 8, the discharge side end surface 9 and the tooth groove of the female rotor 6 of the casing, Until the chamber end 33a reaches m5 and f5 at which discharge starts, the volume is constant and the chamber does not communicate with other working chambers or suction ports. A female rotor side working chamber 31b when the working chamber end 33a reaches m5 and f5 at which discharge starts and the working chamber end 33b is shown is 31b. According to this configuration, the working chambers 31a and 31b after completion of the suction on the female side remain the same volume even when the working chamber moves as the motor rotates, and the operation chambers are operated after the suction on the female side is completed. The chambers 31a and 31b can constitute the non-polymerization section 34 without overlapping. By disposing the injection port 17a in the non-polymerization section 34, it is possible to perform injection into the female rotor 6 side working chamber having a constant volume from the completion of suction to the start of compression.

  In the configuration shown in FIG. 5, since it is only necessary to perform the injection only on the female rotor 6 side, the male rotor 5 side working chamber after the suction is completed has a non-removal like a working chamber on the female rotor 5 side. Although the superposition | polymerization area 34 is not comprised, you may comprise as needed. As can be seen from FIG. 5, when the number of teeth of the male rotor 5 is small, the non-polymerization section corresponding to the non-polymerization section 34 of the working chamber on the female rotor 6 side is set between the completion of suction and before the start of compression. It is difficult to provide in the working chamber on the rotor 5 side, and there is an advantage that it is easier to configure the non-overlapping section only in the working chamber on the female rotor 6 side as in the present embodiment. In the case where the non-polymerization section is provided only in the working chamber on the female rotor 6 side and the non-polymerization section is not provided in the working chamber on the male rotor 5 side, the male rotor 5 is moved after the working chamber on the male rotor 5 side completes the suction. What is necessary is just to comprise so that the working chamber by the side of the male rotor 5 may start a compression stroke with the rotation angle below the male rotor rotation angle equivalent to these 2 teeth.

  The effect of this embodiment will be described. Because the working chamber at the injection destination is a male and female independent chamber after the suction is completed and before compression starts, and the volume is constant, it is sufficient that the pressure fluctuation in the injection working chamber and the pressure itself are high. It becomes possible to solve the problem that a large injection flow rate cannot be flowed. Further, in the case of injection only into the working chamber on the female rotor side, the working chamber on the male rotor side is in the compression start stroke even if the female working chamber and the male working chamber enter the compression stroke and start to engage again. Since the suction is completed before entering, the refrigerant injected into the female working chamber does not escape to the suction space via the male working chamber, which can reduce the energy efficiency of the screw fluid machine. Absent. In addition, since the pressure fluctuation in the injection destination working chamber is small, vibration and piping pulsation can be reduced, and reliability can be improved. Furthermore, since the low-temperature refrigerant injection is performed between the completion of suction and the start of compression, the refrigerant temperature before the start of compression can be lowered, and the change in refrigerant state in the compression stroke can be brought closer to adiabatic compression. Therefore, the energy efficiency of the screw fluid machine can be improved.

  A screw fluid machine showing a second embodiment for carrying out the present invention will be described. Only differences from the first embodiment will be described.

  If the number of teeth M of the male rotor is 4 and the number of teeth F of the female rotor is 6 (F−M = 2), as shown in FIG. It is possible to provide a section having a constant volume between them and to provide the injection port 17a in the non-polymerization section 34. On the other hand, when the number of teeth M of the male rotor remains 4 and the number of teeth F of the female rotor is set to 5 (F−M = 1), the working chambers on the female side overlap after completion of suction. Even if not, the non-polymerization section cannot be secured sufficiently, so that the injection port cannot be provided, or a sufficient injection port area cannot be secured. Therefore, in order to construct a working chamber in which the volume is constant in the section from the completion of suction to before the start of compression, and in which an injection port can be provided, the number of teeth M of the male rotor and the female rotor It is desirable that the number of teeth F has a relationship of “F−M ≧ 2 (Equation 1)”. If it is the screw fluid machine which has the relation of Numerical formula 1, the same effect as a 1st embodiment can be acquired.

  A refrigeration cycle apparatus showing a third embodiment for carrying out the present invention will be described with reference to FIG. The present embodiment relates to a refrigeration cycle apparatus using the screw fluid machine shown in the first and second embodiments.

  The refrigeration cycle apparatus uses the screw fluid machine shown in the first and second embodiments as the compressor 40. The condenser 41 for condensing the gas refrigerant discharged from the discharge port 40b of the compressor 40, the expansion means 42 for the liquid refrigerant flowing out from the condenser 41, and the refrigerant expanded by the expansion means 42 are evaporated to form a gas refrigerant. The main flow path 48 is configured by sequentially connecting the evaporator 43 that supplies the gas refrigerant to the suction port 40a of the compressor 40. Furthermore, a sub-flow channel 47 branched from the main flow channel 48 between the condenser 41 and the expansion means 42 and connected to the injection port 40c of the compressor 40, and an intermediate heat exchange expansion means 44 and The intermediate heat exchanger 45 for exchanging heat between the refrigerant on the outlet side of the expansion means for intermediate heat exchange 44 and the refrigerant in the main flow path 48, and the flow rate disposed between the intermediate heat exchanger 45 and the injection port of the compressor 40 Adjusting means 46. In FIG. 6, the suction port 40 a and the injection port 40 c of the compressor 40 are schematically illustrated at the same position, but as described in the first and second embodiments, the positional relationship and structure Is different.

  The effect of this embodiment will be described. By providing the intermediate heat exchange expansion means 44 and the intermediate heat exchanger 45 in the sub-channel 47, the liquid refrigerant flowing through the sub-channel 47 is decompressed and gasified, and the main channel 48 that has passed through the condenser 41. The high-pressure liquid refrigerant can be cooled and the refrigerating capacity can be improved. Here, the screw fluid machine shown in the first and second embodiments is used for the compressor 40. Accordingly, since the working chamber communicating with the injection port 40c is after completion of suction and before compression starts and has a constant volume, the pressure in the working chamber becomes equal and low pressure corresponding to the suction pressure. Compared to the case where there is pressure fluctuation as in the conventional working chamber pressure and the pressure is higher during compression, the pressure reduction width in the sub-channel 47 can be secured larger, so that the refrigerating capacity is ensured. It becomes possible to improve. In addition, since the injection into the working chamber without pressure fluctuation can be performed, problems of vibration and piping pulsation can be reduced. It should be noted that depending on the usage situation, the flow rate adjusting means 46 provided between the intermediate heat exchanger 45 and the injection port 40c of the compressor 40 can be used to adjust the injection amount to cope with various operating situations. An injection effect can be obtained.

  A refrigeration cycle apparatus showing a fourth embodiment for carrying out the present invention will be described with reference to FIG. The present embodiment relates to a refrigeration cycle apparatus using the screw fluid machine shown in the first and second embodiments.

  The main flow path 58 of the refrigeration cycle apparatus is the same as that in the third embodiment, and the screw fluid machine shown in the first and second embodiments is used for the compressor 50. The condenser 51 that condenses the gas refrigerant discharged from the discharge port 50b of the compressor 50, the expansion means 52 for the liquid refrigerant that has flowed out of the condenser 51, and the refrigerant expanded in the expansion means 52 is evaporated to form a gas refrigerant. The main flow path 58 is configured by sequentially connecting the evaporator 53 that supplies the gas refrigerant to the suction port 50 a of the compressor 50. Further, a gas-liquid separator pre-expansion means 54 and a gas-liquid separator 55 are disposed between the condenser 51 and the expansion means 52 to separate the refrigerant into gas-liquid, and the liquid refrigerant in the gas-liquid separator 55 is The sub-flow channel 57 that flows out to the expansion means 52 of the main flow channel 58 and connects the gas refrigerant in the gas-liquid separator 55 to the injection port 50 c of the compressor 50, and the sub-flow channel 57 is compressed with the gas-liquid separator 55. Flow rate adjusting means 56 disposed between the injection ports of the machine 50. In FIG. 7, the suction port 50a and the injection port 50c of the compressor 50 are schematically illustrated at the same position, but as described in the first and second embodiments, the positional relationship and structure Is different.

  The effect of this embodiment will be described. The gas-liquid separator 55 separates the gas refrigerant and the liquid refrigerant, the gas refrigerant is injected into the working chamber of the compressor 50 via the sub-flow path 57, and the liquid refrigerant is returned to the main flow path 58, so that the refrigerating capacity Can be increased and the coefficient of performance can be improved. Here, since the screw fluid machine shown in the first and second embodiments is used for the compressor 50, the working chamber communicated with the injection port 50c is after the completion of suction, before the start of compression, and at a constant volume. For this reason, the working chamber pressure is equal to a low pressure corresponding to the suction pressure. Compared to the case where the pressure fluctuates as in the conventional working chamber pressure and is a high pressure in the middle of compression, it is possible to ensure a large pressure reduction range in the gas-liquid separator 55. Since the injection can be performed into a working chamber without any problems, vibration and piping pulsation problems can be reduced. Depending on the use situation, the flow rate adjusting means 56 provided between the gas-liquid separator 55 and the injection port 50c of the compressor 50 can be used to adjust the injection amount to cope with various operating situations. An injection effect can be obtained.

1. ・ Screw fluid machinery
2 ・ ・ Compression part
3.Drive unit
4.Case
5 ・ ・ Male Rotor
6 .. Female rotor
7 .. Bore of casing
8 .. Suction end face of casing
9 ・ ・ Discharge end face of casing
10, 10a, 10b, 10c ... Suction port
11, 11a, 11b ... Discharge port
12a, 12b .. Male rotor shaft support means
13a, 13b .. Means for supporting female rotor
14. ・ Motor
15.Suction port
16. ・ Discharge port,
17 ・ ・ Injection
17a ・ Injection port
17b ・ ・ Injection flow path
20a ~ 20d ・ ・ Tooth of male rotor
21a to 21f ... Female rotor teeth
22a-22f .. Male rotor working chamber
23a to 23g .. Female rotor working chamber
30 .. Completed suction chamber for male rotor
31a, 31b .. Female rotor suction completion working chamber
32 .. End of working chamber of female rotor
33a, 33b .. working chamber end of female rotor
40, 50 ・ ・ Compressor
41, 51 ... Condenser
42, 52 .. Expansion means
43, 53 ... Evaporator
46, 56 .. Flow rate adjustment means
47, 57 ...
48, 58 ... Main flow path
44 ・ ・ Expansion means for intermediate heat exchange
45 ・ ・ Intermediate heat exchanger
54 .. Expansion means before gas-liquid separator
55 ・ ・ Gas-liquid separator

Claims (7)

A male rotor and a female rotor rotating while meshing with each other;
A casing having a suction end face, a discharge end face, and a bore, and housing the male rotor and the female rotor;
A plurality of working chambers configured by the male rotor, the female rotor, and the casing;
An injection port formed in the working chamber and for injecting refrigerant into the working chamber;
A suction port provided in the casing;
A discharge port provided in the casing;
Shaft support means for rotatably supporting the male rotor and the female rotor;
With
Constituting the working chamber having a constant volume after completion of refrigerant suction;
The injection port is a screw fluid machine that opens to the working chamber where the volume after completion of refrigerant suction is constant and closes before the compression stroke of the working chamber.   In Claim 1, the working chamber whose volume becomes constant after completion of refrigerant suction is the male rotor, the bore, the suction end face, and the discharge end face, or the female rotor, the bore, the suction end face, and A screw fluid machine formed by the discharge end face.   3. The screw fluid machine according to claim 2, wherein the injection port is disposed only in the working chamber formed by the female rotor, the bore, the suction end surface, and the discharge end surface.   4. The male rotor rotation angle according to claim 3, wherein the working chamber formed by the female rotor, the bore, the suction end face, and the discharge end face is equivalent to two teeth of the male rotor after completion of refrigerant suction. Screw fluid machine that starts the compression stroke at the following rotation angles.   5. The screw fluid machine according to claim 1, wherein the number M of teeth of the male rotor and the number of teeth F of the female rotor are in a relationship of F−M ≧ 2. A screw fluid machine according to any of claims 1 to 5,
A condenser for condensing gas refrigerant discharged from the screw fluid machine;
Expansion means for expanding the refrigerant flowing out of the condenser;
An evaporator that is expanded by the expansion means to evaporate the refrigerant;
A main flow path sequentially connected,
A sub-flow path branched from the main flow path between the condenser and the expansion means and connected to the injection port of the screw fluid machine;
An intermediate heat exchange expansion means that is disposed in the subflow path and expands the refrigerant flowing through the subflow path;
An intermediate heat exchanger for exchanging heat between the refrigerant flowing through the main channel on the outlet side of the condenser and the refrigerant flowing through the sub-channel on the outlet side of the expansion means for intermediate heat exchange;
A refrigeration cycle apparatus comprising: A screw fluid machine according to any of claims 1 to 5,
A condenser for condensing gas refrigerant discharged from the screw fluid machine;
Expansion means for expanding the refrigerant flowing out of the condenser;
An evaporator for evaporating the refrigerant expanded by the expansion means;
A main flow path sequentially connected,
A gas-liquid separator pre-expansion means that is disposed between the condenser and the expansion means and expands the refrigerant; and a gas-liquid separator;
A sub-flow path branched from the main circuit in the gas-liquid separator and connected to the injection port of the screw fluid machine;
With
The liquid refrigerant separated by the gas-liquid separator flows into the expansion means via the main flow path,
The refrigeration cycle apparatus in which the gas refrigerant separated by the gas-liquid separator flows into the injection port of the screw fluid machine via the sub-flow path.