WO2010035592A1 - Screw compressor - Google Patents

Screw compressor Download PDF

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Publication number
WO2010035592A1
WO2010035592A1 PCT/JP2009/064444 JP2009064444W WO2010035592A1 WO 2010035592 A1 WO2010035592 A1 WO 2010035592A1 JP 2009064444 W JP2009064444 W JP 2009064444W WO 2010035592 A1 WO2010035592 A1 WO 2010035592A1
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WO
WIPO (PCT)
Prior art keywords
discharge
bypass passage
casing
screw
chamber
Prior art date
Application number
PCT/JP2009/064444
Other languages
French (fr)
Japanese (ja)
Inventor
龍一郎 米本
昌幸 浦新
Original Assignee
日立アプライアンス株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日立アプライアンス株式会社 filed Critical 日立アプライアンス株式会社
Priority to EP09816009A priority Critical patent/EP2343457A1/en
Priority to CN2009801379258A priority patent/CN102165197A/en
Publication of WO2010035592A1 publication Critical patent/WO2010035592A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
    • F04C18/14—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
    • F04C18/16—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with helical teeth, e.g. chevron-shaped, screw type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
    • F04C28/24—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves
    • F04C28/26—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves using bypass channels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
    • F04C28/28—Safety arrangements; Monitoring

Definitions

  • the present invention relates to a screw compressor used for refrigeration and air conditioning, and is particularly suitable for a screw compressor whose capacity is controlled.
  • Patent Document 1 A conventional screw compressor is described in Patent Document 1. This screw compressor reduces the abnormal load on the screw rotor and the bearing member that supports it by bypassing the compressed gas to the discharge side by operating the relief valve provided on the slide valve when the discharge pressure rises abnormally Like to do.
  • IPLV period coefficient of performance
  • An object of the present invention is to obtain a screw compressor capable of preventing over-compression with a simple structure.
  • Another object of the present invention is to obtain a screw compressor capable of improving the period performance coefficient by improving the efficiency in the operating range of the low load region.
  • the present invention forms a compression chamber by a pair of screw rotors including a male rotor and a female rotor, and a casing that houses the pair of screw rotors, and the casing includes a compressed gas.
  • the casing In the screw compressor in which the discharge port for discharging the gas and the discharge chamber into which the compressed gas discharged from the discharge port flows are formed, the casing on both the male rotor side and the female rotor side in the vicinity of the discharge port.
  • a bypass passage that connects the compression chamber and the discharge chamber is provided, and a valve that opens and closes the bypass passage is provided.
  • valve for opening and closing the bypass passage may be configured to open when the pressure in the compression chamber communicating with the bypass passage is higher than the pressure in the discharge chamber.
  • bypass passage may be formed at a position communicating with the compression chamber within a set volume ratio of 1.5 to 3.0, preferably 1.5 to 2.7.
  • the present invention is particularly effective when applied to a configuration in which the screw rotor is driven by an electric motor capable of controlling the number of revolutions by an inverter.
  • a pair of screw rotors including a male rotor and a female rotor, and a casing that houses the pair of screw rotors form a compression chamber, and discharge that discharges compressed gas to the casing.
  • the compression chamber and the discharge chamber are respectively connected to the casings on both sides of the discharge port.
  • a bypass passage is provided, and a valve for opening and closing the bypass passage is provided.
  • Still another feature of the present invention is that a pair of screw rotors including a male rotor and a female rotor, a main casing that houses the pair of screw rotors, a discharge casing provided on a discharge side of the main casing, and the screw rotor
  • a motor casing containing an electric motor for driving the motor, a discharge port provided in at least one of the main casing and the discharge casing, a compression chamber formed by the pair of screw rotors and the main casing, and the discharge casing
  • a discharge chamber into which compressed gas discharged from the discharge port flows is provided in the discharge casing in the vicinity of the discharge port, and communicates the compression chamber and the discharge chamber.
  • a bypass passage and the compression communicating with the bypass passage Pressure is closed when less than the pressure of the discharge chamber is to provided a valve for opening and closing the bypass passage is configured to open when high.
  • bypass passage may be provided on both the male rotor side and the female rotor side of the discharge port formed in the casing.
  • both the male rotor side and female rotor side casings in the vicinity of the discharge port are provided with bypass passages that connect the compression chamber and the discharge chamber, respectively, and valves that open and close the bypass passage
  • valve that opens and closes the bypass passage is configured to open when the pressure in the compression chamber communicating with the bypass passage is higher than the pressure in the discharge chamber, so that overcompression can be prevented. Since the efficiency in the driving range of the area can be improved, the period coefficient of performance can be improved.
  • FIG. 2 is a cross-sectional view taken along line AA of the screw compressor shown in FIG. 1 and showing a screw rotor rotation position when a bypass passage provided in a discharge casing is opened or just after being opened.
  • FIG. 2 is a cross-sectional view taken along line AA of the screw compressor shown in FIG. 1 and shows a screw rotor rotation position when a bypass passage is fully opened or immediately after that.
  • FIG. 2 is a cross-sectional view taken along line AA of the screw compressor shown in FIG.
  • FIG. 5 is a cross-sectional view taken along line BB in FIG. 4.
  • FIG. 4 is a view showing a modification of the embodiment shown in FIGS. 3A to 3C and corresponding to FIGS. 3A to 3C.
  • FIG. 4 shows another modification of the embodiment shown in FIGS. 3A to 3C and corresponds to FIGS. 3A to 3C.
  • FIG. 4 is a view showing still another modified example of the embodiment shown in FIGS.
  • FIG. 4 is a view showing still another modified example of the embodiment shown in FIGS. 3A to 3C, and showing the vicinity of the discharge port in FIGS. 3A to 3C in an enlarged manner.
  • FIG. 4 is a view showing still another modified example of the embodiment shown in FIGS. 3A to 3C, and showing the vicinity of the discharge port in FIGS. 3A to 3C in an enlarged manner.
  • FIG. 4 is a view showing still another modified example of the embodiment shown in FIGS. 3A to 3C, and showing the vicinity of the discharge port in FIGS. 3A to 3C in an enlarged manner.
  • FIG. 4 is a view showing still another modified example of the embodiment shown in FIGS. 3A to 3C, and showing the vicinity of the discharge port in FIGS. 3A to 3C in an enlarged manner.
  • FIG. 8B is a view in which a leaf spring type valve and a valve presser are respectively provided in the bypass passage provided in the vicinity of the discharge port portion shown in FIG.
  • FIG. 10 is a cross-sectional view taken along line DD of the valve portion shown in FIG. 9.
  • FIG. 5 is a diagram showing another embodiment of the example shown in FIG. 4 and corresponding to FIG. 4.
  • FIG. 12 is a cross-sectional view of the vicinity of the valve portion as viewed from the direction of arrows CC in FIG. 11.
  • FIG. 13 shows another example of the example shown in FIGS. 11 and 12, and is a cross-sectional view of a portion corresponding to FIG.
  • FIG. 13 is a cross-sectional view of a portion corresponding to FIG. 12, showing still another example of the example shown in FIGS.
  • FIG. 15 is a cross-sectional view of the vicinity of the valve portion viewed from the direction of arrows EE in FIG. 14.
  • FIG. 15 is a sectional view of a portion corresponding to FIG. 12 or FIG. 14, showing still another example of the example shown in FIG. 11 and FIG. 12.
  • FIG. 1 is a longitudinal sectional view of a screw compressor showing Example 1 of the present invention.
  • the screw compressor shown in FIG. 1 is roughly divided into a compressor unit 17 and a motor unit 18.
  • the gas to be compressed (for example, the refrigerant flowing through the refrigeration cycle) is sucked from a suction port 20 formed in the motor casing 16 on the motor unit 18 side, and the stator 3 and the rotor 4 constituting the motor (drive motor) 22
  • the air is compressed from the suction port 9 by a compressor unit 17 including a pair of screw rotors (male rotor 2 and female rotor 2A).
  • the compressed gas is discharged from the discharge port 10 and the discharge radial port 44 to the discharge chamber 12 and then flows into the oil separator 80 to separate the oil from the compressed gas, and from the discharge port 19 to the outside of the compressor. It is designed to be discharged.
  • the compressor unit 17 includes a main casing 1 that encloses the screw rotors 2 and 2A and accommodates the roller bearing 6, a discharge casing 21 that forms the discharge chamber 12 and accommodates the roller bearing 7 and the ball bearing 8. ing.
  • the main casing 1 is also formed with a suction port 9, a discharge port 10 and a discharge radial port 44.
  • the suction port 20 and the suction port 9 form a suction flow path to the screw rotors 2 and 2A.
  • the discharge port 10, the discharge radial port 44, and the discharge chamber 12 form a discharge passage from the screw rotors 2 and 2A.
  • the screw rotor 2 includes a pair of male rotor 2 and female rotor 2A (see FIGS.
  • a compression chamber is formed by the meshed portion of the cylindrical bore and the male rotor 2 and female rotor 2A.
  • the shaft portions provided on both sides of the male rotor 2 are supported by a roller bearing 6 provided in the main casing 1, and a roller bearing 7 and a ball bearing 8 provided in the discharge casing 21.
  • the motor unit 18 includes a motor casing 16, a stator 3, a rotor 4, and the like.
  • the motor unit 18 is configured to transmit the driving force to the male rotor 2 of the compressor unit 17.
  • the stator 3 is mounted on a motor casing 16, and the rotor 4 is fixed to a shaft portion provided on the inner peripheral side of the stator 3 and on the motor portion side of the male rotor 2. With this configuration, the driving force of the motor 22 is transmitted to the male rotor 2, and the female rotor 2 ⁇ / b> A is driven by the male rotor 2.
  • the capacity adjustment with respect to the load is performed by inputting a signal from an intake pressure sensor (not shown) and a signal from a discharge pressure sensor (not shown) to a control device (not shown), and an inverter ( The number of revolutions of the motor 22 is controlled by an unillustrated) to adjust the discharge amount.
  • a bypass passage (the male bypass passage 50 shown in FIGS. 3A to 3C and the bypass passage communicating the discharge chamber 21 with the discharge casing 21 forming the compression chamber).
  • a valve 110 for opening and closing the bypass passage, and the pressure in the compression chamber is adjusted by the bypass passages 50 and 51 and the valve 110.
  • FIG. 2 is a diagram showing the relationship between the volume V and the pressure P in an arbitrary compression chamber of the screw rotor 2, 2A shown in FIG.
  • LP represents the suction pressure
  • HP2 represents the discharge pressure during full load operation
  • HP1 represents the discharge pressure during unload operation.
  • the operation cycle is a1-b1-c1-d1.
  • the operation cycle when the bypass passages 50 and 51 that connect the compression chamber and the discharge chamber and the valve 110 are not provided is a1-b1-g3.
  • -F1-d1 and e1-b1-g3 is an overcompressed area where it was compressed unnecessarily.
  • the operation cycle can be set to a1-e1-f1-d1, and therefore, unnecessary overcompression can be prevented.
  • n Polytropic index determined for each refrigerant VT: Suction volume (maximum rotor volume) It is.
  • the bypass passages 50 and 51 may be provided so as to communicate with the compression chamber at the rotation angle.
  • 3A to 3C are cross-sectional views (discharge port portion) taken along line AA of the screw compressor shown in FIG.
  • the male compression chamber 30a is formed by the male casing bore 40a and the male rotor 2
  • the female compression chamber 30b is formed by the female casing bore 40b and the female rotor 2A.
  • the male compression chamber 30a and the female compression chamber 30b are also communicated with each other.
  • FIG. 3A shows the screw rotor rotation position when the bypass passage 50 provided in the discharge casing 21 is opened or just after it is opened.
  • the male bypass passage 50 may be provided so as to be in contact with the reverse surface tangent 120 of the male rotor 2 at the determined rotation angle.
  • the female bypass passage 51 may be provided so as to be in contact with the reverse surface tangent 123 of the female rotor at the determined rotation angle.
  • the size of the holes of the bypass passages 50 and 51 is set to be equal to or smaller than the minimum tooth thickness of the male rotor and the female rotor so that adjacent compression chambers do not communicate with each other.
  • FIG. 3B shows the screw rotor rotation position when the bypass passages 50 and 51 are fully opened or just after that.
  • the compressed gas continues to be bypassed to the discharge chamber 12 by the over-compressed gas from the bypass passages 50 and 51 until the discharge from the male discharge port 42 and the female discharge port 43 is started. .
  • FIG. 3C shows the screw rotor rotation position when the gas to be compressed in the compression chambers 30a and 30b starts to be discharged from the male side discharge port 42 and the female side discharge port 43 provided in the discharge casing 21 to the discharge chamber 12. .
  • FIG. 4 is a cross-sectional view of the valve 110 provided in the male bypass passage 50 of the screw compressor shown in FIG. Since the pressure of the discharge chamber 12 acts through the discharge passage 100 in the valve passage 115 shown in the figure, when the pressure in the bypass passage 50 becomes higher than the pressure in the valve passage 115, the valve 110 is pushed up by the pressure difference. The compressed gas in the compression chamber 30a is discharged to the discharge chamber 12 through the valve passage 115.
  • the female bypass passage 51 is configured in the same manner.
  • FIG. 5 is a cross-sectional view taken along line BB in FIG.
  • a spring force is always applied to the valve 110 by a spring 112 in a direction to close the valve 110.
  • the valve 110 is opened, The over-compressed gas in the compression chamber 30 a flows out into the discharge chamber 12.
  • 111 is an oil hole
  • 113 is a flange that holds the valve 110, and this flange 113 is attached to the discharge casing 21 via a screw 114.
  • FIGS. 6A to 6B show a modification of the embodiment shown in FIGS. 3A to 3B and correspond to FIGS. 3A to 3C.
  • the male-side bypass passage 50 is first opened to bypass and discharge the overcompressed gas in the compression chamber 30a to the discharge chamber, and the female-side bypass hole 51 is opened after a delay. The compressed gas is discharged into the discharge chamber.
  • FIG. 6A by setting the male-side bypass passage 50 and the female-side bypass passage 51 at positions that overlap and open by a certain interval, it is possible to prevent over-compression continuously over a wide range. it can.
  • the bypass passages 50 and 51 are installed so as to be shifted so that the opening sections do not overlap, and the bypass passage may be set in this way.
  • FIGS. 7A to 7B show still another modification of the embodiment shown in FIGS. 3A to 3C, and are enlarged views showing the vicinity of the discharge port 10 in FIGS. 3A to 3C.
  • the bypass passage 50 when the bypass passage 50 is installed only on the male side, and the tooth thickness of the female rotor is thin and the female bypass passage cannot be installed large, the bypass passage is provided only on the male side. It is good to make it.
  • a bypass passage and a valve are not required on the female side, and the cost can be reduced.
  • the bypass passage 51 may be provided only on the female side without providing the bypass passage on the male side.
  • it is also effective to provide bypass passages on the male side and the female side, respectively, and to make the opening area of the male side bypass passage larger than the opening area of the female side bypass passage.
  • FIGS. 3A to 3C show still another modification of the embodiment shown in FIGS. 3A to 3C, and are enlarged views of the vicinity of the discharge port 10 in FIGS. 3A to 3C.
  • the bypass passages 50 and 51 provided in the discharge casing are elongated holes. By configuring in this way, a sufficiently large bypass passage area of the bypass passage can be secured. The flow path resistance of the compressed gas that is bypassed to the discharge chamber can be reduced.
  • a plurality of male side bypass passages 50 and 50a and a plurality of female side bypass passages 51 and 51a are provided at arbitrary different set volume ratio positions.
  • the bypass passages are provided at the positions of two different arbitrary set volume ratios on the male rotor side and the female rotor side
  • the bypass passages are provided at three or more different arbitrary set volume ratio positions. May be provided.
  • path in the position of arbitrary same setting volume ratios was shown, you may form with three or more holes.
  • FIG. 10 is a cross-sectional view of the valve section shown in FIG.
  • a leaf spring type valve 70 and a valve presser 71 to the main casing 1 together with a bolt 73 on the discharge chamber side of the bypass passage communicating the compression chamber and the discharge chamber.
  • the number of manufacturing steps of the valve mechanism can be reduced, the valve structure can be simplified, and the cost of the valve can be reduced.
  • configuring the valve that opens and closes the bypass passage with a leaf spring type valve, it is possible to provide a plurality of valves in a limited narrow space.
  • valve for opening and closing the bypass passage by a leaf spring type valve.
  • FIGS. 11 and 12 show another embodiment of the example shown in FIGS. 4 and 5.
  • the valve 110 is provided in the vertical direction (perpendicular to the axis).
  • the valve 110 is provided in the lateral direction (axial direction).
  • FIG. 12 is a cross-sectional view of the vicinity of the valve portion as viewed from the direction of arrows CC in FIG. 11 and 12, the same reference numerals as those in FIGS. 4 and 5 indicate the same or corresponding parts.
  • the valve 110 horizontally, the length of the bypass passage 50 that communicates the compression chamber and the discharge chamber can be made shorter than the example shown in FIGS.
  • reference numeral 117 denotes a spacer, which corresponds to the flange 113 in FIG.
  • FIG. 13 shows another example of the example shown in FIGS. 11 and 12, and is a cross-sectional view of a portion corresponding to FIG.
  • high-pressure oil is guided from the oil tank 25 to the valve cylinder 143 via the pipe 141, and the valve 140 that opens and closes the bypass passage 50 is hydraulically operated.
  • the valve 140 is pressed to a position where the bypass passage 50 and the discharge passage 100 are closed by high pressure oil pressure.
  • FIGS. 11 and 12 show still another example of the example shown in FIGS. 11 and 12, FIG. 14 is a sectional view corresponding to FIG. 12, and FIG. 15 is a view taken along the line EE in FIG. It is sectional drawing of the valve part vicinity seen from the direction.
  • a valve 135 having a hole in the center of a cylinder is provided in the middle of a bypass passage 50 that communicates the compression chamber and the discharge chamber 12, and the valve 135 is connected to the shaft 135 by a step motor 131 in FIG. 15.
  • the bypass passage 50 is opened and closed by turning 90 degrees.
  • the step motor 131 is controlled by inputting a signal from the pressure sensor 133 provided in the bypass passage 50 communicating with the compression chamber and the discharge chamber and the pressure sensor 133 installed in the discharge chamber 12 to the control device 132.
  • the valve 135 When the pressure of 50 becomes higher than the pressure of the discharge chamber 12, the valve 135 is opened, and when the pressure of the bypass passage 50 becomes lower than the pressure of the discharge chamber 12, the valve 135 is closed. It is something to control. According to this example, it is possible to provide a valve mechanism having a high followability with respect to a pressure change in the compression chamber.
  • FIG. 16 shows still another example of the example shown in FIGS. 11 and 12, and shows a cross-sectional view of a portion corresponding to FIG. 12 or FIG.
  • an electromagnetic valve 136 is provided in the middle of the bypass passage 50 that communicates the compression chamber and the discharge chamber 12, and the controller 132 controls the pressure in the bypass passage 50 and the discharge chamber 12 in the same manner as in the example shown in FIG.
  • the electromagnetic valve 136 is controlled by looking at the pressure and the pressure.
  • By opening the electromagnetic valve 136 the compressed gas in the compression chamber can be bypassed to the discharge chamber 12 via the bypass passage 50 and the discharge passage 100.
  • a complicated valve opening / closing mechanism can be used, and a valve mechanism having high followability to the pressure change in the compression chamber can be obtained as in the example shown in FIG.
  • a bypass passage that connects the compression chamber and the discharge chamber is provided in the vicinity of the discharge port, and a valve that opens and closes the bypass passage is provided. Can be maintained or opened to the discharge chamber.
  • the compression chamber pressure becomes higher than the discharge chamber pressure, it is possible to suppress overcompression in the compression chamber by opening the bypass passage.
  • the bypass passage valve opens and compression The compressed gas in the room can be discharged to the discharge chamber side via the bypass passage.
  • bypass passage is configured to be installed within a set volume ratio of 1.5 to 3.0, preferably 1.5 to 2.7, and an opening / closing valve for opening and closing the bypass passage is provided. This makes it possible to perform optimal operation during unload operation. Furthermore, by providing bypass passages that connect the compression chamber and the discharge chamber on both the male rotor side and the female rotor side, the compressed gas in the compression chamber can be efficiently discharged to the discharge chamber.
  • bypass passages that connect the compression chamber and the discharge chamber are respectively provided at positions that communicate with the compression chambers having different set volume ratios, over-compression during unload operation can be prevented in a wider operating range. effective.
  • the flow resistance of the bypass passage can be reduced, and the volume of the entire bypass passage can be kept small, thereby reducing the uncompressed volume generated by the bypass passage.
  • a decrease in volume efficiency can be suppressed.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)

Abstract

A screw compressor has a compression chamber formed by a pair of screw rotors which is provided with a male rotor (2) and a female rotor (2A) and by a casing which contains the pair of screw rotors.  The casing has a discharge port (10) out of which a compressed gas flows, and also has a discharge chamber (12) into which the compressed gas discharged from the discharge port flows.  Bypass paths for interconnecting the compression chamber and the discharge chamber are respectively provided to both a male rotor side portion and a female rotor side portion which are located near the discharge port formed in the casing.  The compressor also has a valve (110) for opening and closing the bypass paths.

Description

スクリュー圧縮機Screw compressor
　本発明は、冷凍空調用などに使用されるスクリュー圧縮機に関し、特に容量制御されるスクリュー圧縮機に好適なものである。 The present invention relates to a screw compressor used for refrigeration and air conditioning, and is particularly suitable for a screw compressor whose capacity is controlled.
　従来のスクリュー圧縮機としては特許文献１に記載のものがある。このスクリュー圧縮機は、吐出圧力が異常に上昇した場合、スライド弁に設けられたリリーフ弁が作動し圧縮ガスを吐出側にバイパスすることでスクリューロータ及びこれを支える軸受部材への異常負荷を軽減するようにしている。 A conventional screw compressor is described in Patent Document 1. This screw compressor reduces the abnormal load on the screw rotor and the bearing member that supports it by bypassing the compressed gas to the discharge side by operating the relief valve provided on the slide valve when the discharge pressure rises abnormally Like to do.
特開平４－４３８８３号公報JP-A-4-43883
　上記、特許文献１のものでは、スライド弁にリリーフ弁を設けることにより、異常負荷を軽減するようにしているので、リリーフ弁が一対のスクリューロータのボア部の一部を形成する必要があり、このため高い加工精度が要求される。また、リリーフ弁がケーシングにより形成される圧縮室ボア部の一部を形成するため、圧縮機が大型化する欠点がある。 In the above-mentioned Patent Document 1, since the abnormal load is reduced by providing the relief valve on the slide valve, the relief valve needs to form part of the bore portion of the pair of screw rotors, For this reason, high processing accuracy is required. Further, since the relief valve forms a part of the compression chamber bore portion formed by the casing, there is a disadvantage that the compressor becomes large.
　更に、最近は、期間成績係数（ＩＰＬＶ）の向上が求められており、スクリュー圧縮機の低負荷域での性能向上も求められている。 Furthermore, recently, the improvement of the period coefficient of performance (IPLV) is required, and the performance improvement in the low load region of the screw compressor is also required.
　本発明の目的は、簡単な構造で過圧縮を防止することのできるスクリュー圧縮機を得ることにある。 An object of the present invention is to obtain a screw compressor capable of preventing over-compression with a simple structure.
　本発明の他の目的は、低負荷域の運転範囲での効率を向上させることで、期間成績係数の向上を図ることができるスクリュー圧縮機を得ることにある。 Another object of the present invention is to obtain a screw compressor capable of improving the period performance coefficient by improving the efficiency in the operating range of the low load region.
　上記目的を達成するために、本発明は、雄ロータ及び雌ロータを備える一対のスクリューロータと、これら一対のスクリューロータを収納するケーシングとで圧縮室を形成し、且つ前記ケーシングには被圧縮ガスを流出させる吐出ポートと、この吐出ポートから吐出される圧縮ガスが流入する吐出室とが形成されたスクリュー圧縮機において、前記吐出ポート近傍の前記雄ロータ側及び雌ロータ側の両方の前記ケーシングに、それぞれ前記圧縮室と前記吐出室とを連通するバイパス通路を設けると共に、該バイパス通路を開閉する弁を設けたことを特徴とする。 In order to achieve the above object, the present invention forms a compression chamber by a pair of screw rotors including a male rotor and a female rotor, and a casing that houses the pair of screw rotors, and the casing includes a compressed gas. In the screw compressor in which the discharge port for discharging the gas and the discharge chamber into which the compressed gas discharged from the discharge port flows are formed, the casing on both the male rotor side and the female rotor side in the vicinity of the discharge port. In addition, a bypass passage that connects the compression chamber and the discharge chamber is provided, and a valve that opens and closes the bypass passage is provided.
　ここで、前記バイパス通路を開閉する弁は、前記バイパス通路に連通する前記圧縮室の圧力が、前記吐出室の圧力よりも高くなった場合に開くように構成すると良い。 Here, the valve for opening and closing the bypass passage may be configured to open when the pressure in the compression chamber communicating with the bypass passage is higher than the pressure in the discharge chamber.
　また、前記バイパス通路は、設定容積比が１．５～３．０、好ましくは１．５～２．７の範囲内の前記圧縮室に連通される位置に形成すると良い。 Further, the bypass passage may be formed at a position communicating with the compression chamber within a set volume ratio of 1.5 to 3.0, preferably 1.5 to 2.7.
　前記雄ロータ側又は雌ロータ側に設けられたバイパス通路は、異なる設定容積比となる圧縮室に連通される位置に複数個設けるようにするとより効果的である。 It is more effective if a plurality of bypass passages provided on the male rotor side or the female rotor side are provided at positions communicating with the compression chambers having different set volume ratios.
　なお、インバータによる回転数制御可能な電動機により前記スクリューロータを駆動する構成としたものに適用して本発明は特に効果的である。 Note that the present invention is particularly effective when applied to a configuration in which the screw rotor is driven by an electric motor capable of controlling the number of revolutions by an inverter.
　本発明の他の特徴は、雄ロータ及び雌ロータを備える一対のスクリューロータと、これら一対のスクリューロータを収納するケーシングとで圧縮室を形成し、且つ前記ケーシングには被圧縮ガスを流出させる吐出ポートと、この吐出ポートから吐出される圧縮ガスが流入する吐出室とが形成されたスクリュー圧縮機において、前記吐出ポートを挟んでその両側の前記ケーシングに、それぞれ前記圧縮室と前記吐出室とを連通するバイパス通路を設け、更に該バイパス通路を開閉する弁を設けたことにある。 Another feature of the present invention is that a pair of screw rotors including a male rotor and a female rotor, and a casing that houses the pair of screw rotors form a compression chamber, and discharge that discharges compressed gas to the casing. In a screw compressor in which a port and a discharge chamber into which compressed gas discharged from the discharge port flows are formed, the compression chamber and the discharge chamber are respectively connected to the casings on both sides of the discharge port. A bypass passage is provided, and a valve for opening and closing the bypass passage is provided.
　本発明の更に他の特徴は、雄ロータ及び雌ロータを備える一対のスクリューロータと、これら一対のスクリューロータを収納するメインケーシングと、このメインケーシングの吐出側に設けた吐出ケーシングと、前記スクリューロータを駆動するための電動機を収容したモータケーシングと、前記メインケーシングと吐出ケーシングの少なくとも何れかに設けた吐出ポートと、前記一対のスクリューロータと前記メインケーシングにより形成される圧縮室と、前記吐出ケーシングに形成され前記吐出ポートから吐出される圧縮ガスが流入する吐出室とを備えたスクリュー圧縮機において、前記吐出ポートの近傍の前記吐出ケーシングに設けられ、前記圧縮室と前記吐出室とを連通するバイパス通路と、前記バイパス通路に連通する前記圧縮室の圧力が、前記吐出室の圧力よりも低い時には閉じ、高くなった時に開くように構成されて前記バイパス通路を開閉する弁とを備えることにある。 Still another feature of the present invention is that a pair of screw rotors including a male rotor and a female rotor, a main casing that houses the pair of screw rotors, a discharge casing provided on a discharge side of the main casing, and the screw rotor A motor casing containing an electric motor for driving the motor, a discharge port provided in at least one of the main casing and the discharge casing, a compression chamber formed by the pair of screw rotors and the main casing, and the discharge casing And a discharge chamber into which compressed gas discharged from the discharge port flows is provided in the discharge casing in the vicinity of the discharge port, and communicates the compression chamber and the discharge chamber. A bypass passage and the compression communicating with the bypass passage Pressure is closed when less than the pressure of the discharge chamber is to provided a valve for opening and closing the bypass passage is configured to open when high.
　ここで、前記バイパス通路は、ケーシングに形成された前記吐出ポートの雄ロータ側及び雌ロータ側の両方に設けるようにすると良い。 Here, the bypass passage may be provided on both the male rotor side and the female rotor side of the discharge port formed in the casing.
　本発明のスクリュー圧縮機によれば、吐出ポート近傍の雄ロータ側及び雌ロータ側の両方のケーシングに、それぞれ圧縮室と吐出室とを連通するバイパス通路を設けると共に、該バイパス通路を開閉する弁を設ける構成とすることにより、簡単な構造で過圧縮を防止することのできるスクリュー圧縮機を得ることができる。この結果、スクリューロータや該ロータを支持する軸受部材への異常負荷を軽減して、ロータの変形や軸受損傷を防止できる信頼性の高いスクリュー圧縮機も得ることができる。 According to the screw compressor of the present invention, both the male rotor side and female rotor side casings in the vicinity of the discharge port are provided with bypass passages that connect the compression chamber and the discharge chamber, respectively, and valves that open and close the bypass passage By providing the configuration, it is possible to obtain a screw compressor that can prevent over-compression with a simple structure. As a result, it is possible to obtain a highly reliable screw compressor that can reduce abnormal loads on the screw rotor and the bearing member that supports the rotor and prevent deformation of the rotor and damage to the bearing.
　また、前記バイパス通路を開閉する弁は、バイパス通路に連通する圧縮室の圧力が、吐出室の圧力よりも高くなった場合に開くように構成することで、過圧縮を防止でき、特に低負荷域の運転範囲での効率を向上できるから、期間成績係数の向上を図ることができる。 In addition, the valve that opens and closes the bypass passage is configured to open when the pressure in the compression chamber communicating with the bypass passage is higher than the pressure in the discharge chamber, so that overcompression can be prevented. Since the efficiency in the driving range of the area can be improved, the period coefficient of performance can be improved.
　更に、バイパス通路を異なる設定容積比の圧縮室に連通するように複数個設けることにより、幅広い運転領域で継続して過圧縮を防止することができる。
　本発明の他の目的、特徴及び利点は添付図面に関する以下の本発明の実施例の記載から明らかになるであろう。 Furthermore, by providing a plurality of bypass passages so as to communicate with compression chambers having different set volume ratios, overcompression can be continuously prevented in a wide operation region.
Other objects, features and advantages of the present invention will become apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.
本発明の実施例１を示すスクリュー圧縮機の縦断面図。The longitudinal cross-sectional view of the screw compressor which shows Example 1 of this invention. 図１に示すスクリューロータ部の任意の圧縮室における容積Ｖと圧力Ｐとの関係を示す線図。The diagram which shows the relationship between the volume V and the pressure P in the arbitrary compression chambers of the screw rotor part shown in FIG. 図１に示すスクリュー圧縮機のＡ－Ａ線矢視断面図で、吐出ケーシングに設けたバイパス通路の開放時或いは開放直後のスクリューロータ回転位置を示す図。FIG. 2 is a cross-sectional view taken along line AA of the screw compressor shown in FIG. 1 and showing a screw rotor rotation position when a bypass passage provided in a discharge casing is opened or just after being opened. 図１に示すスクリュー圧縮機のＡ－Ａ線矢視断面図で、バイパス通路が全開になった時或いはその直後のスクリューロータ回転位置を示す図。FIG. 2 is a cross-sectional view taken along line AA of the screw compressor shown in FIG. 1 and shows a screw rotor rotation position when a bypass passage is fully opened or immediately after that. 図１に示すスクリュー圧縮機のＡ－Ａ線矢視断面図で、圧縮室の被圧縮ガスが吐出ケーシングに設けられた雄側吐出ポート及び雌側吐出ポートから吐出室へ吐出開始される時のスクリューロータ回転位置を示す図。FIG. 2 is a cross-sectional view taken along line AA of the screw compressor shown in FIG. 1 when the gas to be compressed in the compression chamber is started to be discharged from the male discharge port and the female discharge port provided in the discharge casing into the discharge chamber. The figure which shows a screw rotor rotational position. 図１に示すスクリュー圧縮機における雄側のバイパス通路に設けた弁の部分における断面図。Sectional drawing in the part of the valve provided in the bypass passage of the male side in the screw compressor shown in FIG. 図４のＢ－Ｂ線矢視断面図。FIG. 5 is a cross-sectional view taken along line BB in FIG. 4. 図３Ａ～３Ｃに示した実施例の変形例を示すもので、図３Ａ～３Ｃに相当する図。FIG. 4 is a view showing a modification of the embodiment shown in FIGS. 3A to 3C and corresponding to FIGS. 3A to 3C. 図３Ａ～３Ｃに示した実施例の他の変形例を示すもので、図３Ａ～３Ｃに相当する図。FIG. 4 shows another modification of the embodiment shown in FIGS. 3A to 3C and corresponds to FIGS. 3A to 3C. 図３Ａ～３Ｃに示した実施例の更に他の変形例を示すもので、図３Ａ～３Ｃにおける吐出ポート付近を拡大して示す図。FIG. 4 is a view showing still another modified example of the embodiment shown in FIGS. 3A to 3C, and showing the vicinity of the discharge port in FIGS. 3A to 3C in an enlarged manner. 図３Ａ～３Ｃに示した実施例の更に他の変形例を示すもので、図３Ａ～３Ｃにおける吐出ポート付近を拡大して示す図。FIG. 4 is a view showing still another modified example of the embodiment shown in FIGS. 3A to 3C, and showing the vicinity of the discharge port in FIGS. 3A to 3C in an enlarged manner. 図３Ａ～３Ｃに示した実施例の更に他の変形例を示すもので、図３Ａ～３Ｃにおける吐出ポート付近を拡大して示す図。FIG. 4 is a view showing still another modified example of the embodiment shown in FIGS. 3A to 3C, and showing the vicinity of the discharge port in FIGS. 3A to 3C in an enlarged manner. 図３Ａ～３Ｃに示した実施例の更に他の変形例を示すもので、図３Ａ～３Ｃにおける吐出ポート付近を拡大して示す図。FIG. 4 is a view showing still another modified example of the embodiment shown in FIGS. 3A to 3C, and showing the vicinity of the discharge port in FIGS. 3A to 3C in an enlarged manner. 図８Ｂに示す吐出ポート部付近に設けたバイパス通路にそれぞれ板ばね式の弁と弁押えを設けた図で、図１のＦ－Ｆ線矢視断面に相当する図。8B is a view in which a leaf spring type valve and a valve presser are respectively provided in the bypass passage provided in the vicinity of the discharge port portion shown in FIG. 図９に示す弁部のＤ－Ｄ線矢視断面図。FIG. 10 is a cross-sectional view taken along line DD of the valve portion shown in FIG. 9. 図４に示した例の他の実施形態を示す図で、図４に相当する図。FIG. 5 is a diagram showing another embodiment of the example shown in FIG. 4 and corresponding to FIG. 4. 図１１のＣ－Ｃ線矢視方向から見た弁部付近の断面図。FIG. 12 is a cross-sectional view of the vicinity of the valve portion as viewed from the direction of arrows CC in FIG. 11. 図１１，図１２に示した例の別の例を示すもので、図１２に相当する部分の断面図。FIG. 13 shows another example of the example shown in FIGS. 11 and 12, and is a cross-sectional view of a portion corresponding to FIG. 図１１，図１２に示した例の更に別の例を示すもので、図１２に相当する部分の断面図。FIG. 13 is a cross-sectional view of a portion corresponding to FIG. 12, showing still another example of the example shown in FIGS. 11 and 12. 図１４のＥ－Ｅ線矢視方向から見た弁部付近の断面図。FIG. 15 is a cross-sectional view of the vicinity of the valve portion viewed from the direction of arrows EE in FIG. 14. 図１１，図１２に示した例の更に別の例を示すもので、図１２或いは図１４に相当する部分の断面図。FIG. 15 is a sectional view of a portion corresponding to FIG. 12 or FIG. 14, showing still another example of the example shown in FIG. 11 and FIG. 12.
　以下、本発明のスクリュー圧縮機の具体的実施例を図面を用いて説明する。各図において同一符号を付した部分は同一又は相当する部分を示す。 Hereinafter, specific examples of the screw compressor of the present invention will be described with reference to the drawings. In each figure, the part which attached | subjected the same code | symbol shows the part which is the same or corresponds.
　図１は本発明の実施例１を示すスクリュー圧縮機の縦断面図である。図１に示すスクリュー圧縮機は大きく分けて、圧縮機部１７とモータ部１８から構成されている。圧縮される気体（例えば、冷凍サイクルを流れる冷媒）は、モータ部１８側のモータケーシング１６に形成された吸込口２０から吸込まれ、モータ（駆動用電動機）２２を構成するステータ３とロータ４の部分を経て、吸入ポート９から一対のスクリューロータ（雄ロータ２，雌ロータ２Ａ）で構成された圧縮機部１７で圧縮される。その後、圧縮された気体は、吐出ポート１０及び吐出ラジアルポート４４から吐出室１２に吐出された後、油分離器８０に流入し、圧縮気体から油を分離して、吐出口１９から圧縮機外に吐出されるようになっている。 FIG. 1 is a longitudinal sectional view of a screw compressor showing Example 1 of the present invention. The screw compressor shown in FIG. 1 is roughly divided into a compressor unit 17 and a motor unit 18. The gas to be compressed (for example, the refrigerant flowing through the refrigeration cycle) is sucked from a suction port 20 formed in the motor casing 16 on the motor unit 18 side, and the stator 3 and the rotor 4 constituting the motor (drive motor) 22 After passing through the portion, the air is compressed from the suction port 9 by a compressor unit 17 including a pair of screw rotors (male rotor 2 and female rotor 2A). Thereafter, the compressed gas is discharged from the discharge port 10 and the discharge radial port 44 to the discharge chamber 12 and then flows into the oil separator 80 to separate the oil from the compressed gas, and from the discharge port 19 to the outside of the compressor. It is designed to be discharged.
　圧縮機部１７は、スクリューロータ２，２Ａを内包すると共にころ軸受６を収容するメインケーシング１と、吐出室１２を形成すると共にころ軸受７及び玉軸受８を収容する吐出ケーシング２１などから構成されている。前記メインケーシング１には、吸入ポート９，吐出ポート１０及び吐出ラジアルポート４４も形成されている。前記吸入口２０及び吸入ポート９はスクリューロータ２，２Ａへの吸込み流路を形成するものである。前記吐出ポート１０，吐出ラジアルポート４４及び吐出室１２は、スクリューロータ２，２Ａからの吐出通路を形成するものである。スクリューロータ２は、互いに噛合わされた一対の雄ロータ２及び雌ロータ２Ａ（図３Ａ～３Ｃ参照）から構成され、一対の円筒状ボア（図３Ａ～３Ｃに示す雄側ケーシングボア４０ａ及び雌側ケーシングボア４０ｂ）に収納され、前記円筒状ボアと、雄ロータ２及び雌ロータ２Ａとの噛合い部で圧縮室を形成している。雄ロータ２の両側に設けられた軸部は、メインケーシング１に設けられたころ軸受６と、吐出ケーシング２１に設けられたころ軸受７及び玉軸受８とにより支持されている。 The compressor unit 17 includes a main casing 1 that encloses the screw rotors 2 and 2A and accommodates the roller bearing 6, a discharge casing 21 that forms the discharge chamber 12 and accommodates the roller bearing 7 and the ball bearing 8. ing. The main casing 1 is also formed with a suction port 9, a discharge port 10 and a discharge radial port 44. The suction port 20 and the suction port 9 form a suction flow path to the screw rotors 2 and 2A. The discharge port 10, the discharge radial port 44, and the discharge chamber 12 form a discharge passage from the screw rotors 2 and 2A. The screw rotor 2 includes a pair of male rotor 2 and female rotor 2A (see FIGS. 3A to 3C) meshed with each other, and a pair of cylindrical bores (a male casing bore 40a and a female casing shown in FIGS. 3A to 3C). A compression chamber is formed by the meshed portion of the cylindrical bore and the male rotor 2 and female rotor 2A. The shaft portions provided on both sides of the male rotor 2 are supported by a roller bearing 6 provided in the main casing 1, and a roller bearing 7 and a ball bearing 8 provided in the discharge casing 21.
　モータ部１８は、モータケーシング１６，ステータ３，ロータ４などから構成されている。モータ部１８は、その駆動力を圧縮機部１７の雄ロータ２に伝達するように構成されている。ステータ３はモータケーシング１６に装着され、ロータ４は前記ステータ３の内周側で且つ雄ロータ２のモータ部側に設けた軸部に固着されている。この構成により、モータ２２の駆動力は雄ロータ２に伝達され、また、雌ロータ２Ａは雄ロータ２により駆動される。 The motor unit 18 includes a motor casing 16, a stator 3, a rotor 4, and the like. The motor unit 18 is configured to transmit the driving force to the male rotor 2 of the compressor unit 17. The stator 3 is mounted on a motor casing 16, and the rotor 4 is fixed to a shaft portion provided on the inner peripheral side of the stator 3 and on the motor portion side of the male rotor 2. With this configuration, the driving force of the motor 22 is transmitted to the male rotor 2, and the female rotor 2 </ b> A is driven by the male rotor 2.
　上記スクリュー圧縮機において、負荷に対する能力調整は、吸入圧力センサ（図示せず）からの信号と、吐出圧力センサ（図示せず）からの信号が制御装置（図示せず）に入力され、インバータ（図示せず）によりモータ２２の回転数が制御されることにより、吐出量を調整して行われる。負荷が小さくなり、吐出側圧力が低下すると、雄ロータ２及び雌ロータ２Ａで構成される圧縮室内の被圧縮ガス圧力が吐出側圧力より高くなり過圧縮となる。この過圧縮を防止するために、本実施例では、圧縮室を形成している吐出ケーシング２１に圧縮室と吐出室とを連通するバイパス通路（図３Ａ～３Ｃに示す雄側のバイパス通路５０及び雌側のバイパス通路５１を参照）と、このバイパス通路を開閉する弁１１０を設けており、これらバイパス通路５０，５１及び弁１１０により圧縮室内の圧力調整を行うようにしている。 In the screw compressor, the capacity adjustment with respect to the load is performed by inputting a signal from an intake pressure sensor (not shown) and a signal from a discharge pressure sensor (not shown) to a control device (not shown), and an inverter ( The number of revolutions of the motor 22 is controlled by an unillustrated) to adjust the discharge amount. When the load decreases and the discharge side pressure decreases, the compressed gas pressure in the compression chamber constituted by the male rotor 2 and the female rotor 2A becomes higher than the discharge side pressure, resulting in overcompression. In order to prevent this overcompression, in this embodiment, a bypass passage (the male bypass passage 50 shown in FIGS. 3A to 3C and the bypass passage communicating the discharge chamber 21 with the discharge casing 21 forming the compression chamber). And a valve 110 for opening and closing the bypass passage, and the pressure in the compression chamber is adjusted by the bypass passages 50 and 51 and the valve 110.
　図２は図１に示すスクリューロータ２，２Ａ部の任意の圧縮室における容積Ｖと圧力Ｐとの関係を示す線図である。図において、ＬＰは吸入圧力、ＨＰ２はフルロード運転時の吐出圧力、ＨＰ１はアンロード運転時の吐出圧力を示す。吸入圧力ＬＰ，吐出圧力ＨＰ２のフルロード運転時の場合、運転サイクルはａ１－ｂ１－ｃ１－ｄ１となる。また、吸入圧力ＬＰ，吐出圧力ＨＰ１のアンロード運転時の場合、圧縮室と吐出室とを連通するバイパス通路５０，５１及び弁１１０を有していない場合の運転サイクルは、ａ１－ｂ１－ｇ３－ｆ１－ｄ１となり、ｅ１－ｂ１－ｇ３が無駄に圧縮された過圧縮領域である。本実施例では、バイパス通路５０，５１及び弁１１０を設けたことにより、運転サイクルをａ１－ｅ１－ｆ１－ｄ１とすることができるから、無駄な過圧縮を防止できる。 FIG. 2 is a diagram showing the relationship between the volume V and the pressure P in an arbitrary compression chamber of the screw rotor 2, 2A shown in FIG. In the figure, LP represents the suction pressure, HP2 represents the discharge pressure during full load operation, and HP1 represents the discharge pressure during unload operation. In the case of the full load operation with the suction pressure LP and the discharge pressure HP2, the operation cycle is a1-b1-c1-d1. In the unloading operation of the suction pressure LP and the discharge pressure HP1, the operation cycle when the bypass passages 50 and 51 that connect the compression chamber and the discharge chamber and the valve 110 are not provided is a1-b1-g3. -F1-d1 and e1-b1-g3 is an overcompressed area where it was compressed unnecessarily. In the present embodiment, by providing the bypass passages 50 and 51 and the valve 110, the operation cycle can be set to a1-e1-f1-d1, and therefore, unnecessary overcompression can be prevented.
　バイパス通路５０，５１を設ける位置は、次のようにして決める。即ち、バイパス通路５０，５１は、アンロード運転時に、雄ロータと雌ロータとが噛合うことで形成される圧縮室の圧力Ｐが吐出圧力ＨＰ１になったとき、該圧縮室と吐出室１２とを連通させる位置に形成すればよい。このため、まず、吸入圧力ＬＰからアンロード運転時の任意の吐出圧力ＨＰ１になる時の設定容積比Ｖｉ
　　Ｖｉ＝（ＨＰ１／ＬＰ）１／ｎから、圧縮室容積ＶＤ１
　　ＶＤ１＝ＶＴ／Ｖｉ
を求め、該圧縮室容積ＶＤ１となるスクリューロータの回転角位置に前記バイパス通路５０，５１を設ければよい。 The position where the bypass passages 50 and 51 are provided is determined as follows. That is, when the pressure P in the compression chamber formed by the engagement of the male rotor and the female rotor becomes the discharge pressure HP1 during the unload operation, the bypass passages 50 and 51 are connected to the compression chamber and the discharge chamber 12, respectively. What is necessary is just to form in the position which connects. For this reason, first, the set volume ratio Vi when the suction pressure LP becomes the arbitrary discharge pressure HP1 during the unloading operation.
From Vi = (HP1 / LP) 1 / n , compression chamber volume VD1
VD1 = VT / Vi
And the bypass passages 50 and 51 may be provided at the rotation angle position of the screw rotor having the compression chamber volume VD1.
　上記式において、
　　ｎ　：冷媒毎に定まるポリトロープ指数
　　ＶＴ：吸入容積（ロータの最大空間容積）
である。 In the above formula,
n: Polytropic index determined for each refrigerant VT: Suction volume (maximum rotor volume)
It is.
　つまり、吸入圧力ＬＰ及び吐出室の吐出圧力ＨＰ１等の運転条件が決まれば設定容積比Ｖｉが決まるため、アンロード運転時の任意の吐出圧力ＨＰ１に対する圧縮室容積ＶＤ１が求まり、その圧縮室容積ＶＤ１に対応した雄ロータ２及び雌ロータ２Ａの回転角が決定されるから、その回転角における圧縮室に連通するように前記バイパス通路５０，５１を設ければよい。 That is, if the operating conditions such as the suction pressure LP and the discharge pressure HP1 of the discharge chamber are determined, the set volume ratio Vi is determined. Therefore, the compression chamber volume VD1 with respect to an arbitrary discharge pressure HP1 during the unload operation is obtained, and the compression chamber volume VD1. Since the rotation angles of the male rotor 2 and the female rotor 2A corresponding to the above are determined, the bypass passages 50 and 51 may be provided so as to communicate with the compression chamber at the rotation angle.
　図３Ａ～３Ｃは図１に示すスクリュー圧縮機のＡ－Ａ線矢視断面図（吐出ポート部）を示す。モータにより雄ロータ２を回転させると、雄ロータと噛合った雌ロータ２Ａも回転し、被圧縮ガスが圧縮室に閉じ込められる。雄側の圧縮室３０ａは、雄側ケーシングボア４０ａと雄ロータ２とで形成され、また雌側の圧縮室３０ｂは、雌側ケーシングボア４０ｂと雌ロータ２Ａとで形成される。また、雄側の圧縮室３０ａと雌側の圧縮室３０ｂも連通している。 3A to 3C are cross-sectional views (discharge port portion) taken along line AA of the screw compressor shown in FIG. When the male rotor 2 is rotated by the motor, the female rotor 2A meshing with the male rotor is also rotated, and the compressed gas is confined in the compression chamber. The male compression chamber 30a is formed by the male casing bore 40a and the male rotor 2, and the female compression chamber 30b is formed by the female casing bore 40b and the female rotor 2A. The male compression chamber 30a and the female compression chamber 30b are also communicated with each other.
　図３Ａは、吐出ケーシング２１に設けたバイパス通路５０の開放時或いは開放直後のスクリューロータ回転位置を示す。雄側のバイパス通路５０は、決定された回転角における雄ロータ２の後進面接線１２０に接するように設ければよい。また、雌側のバイパス通路５１は、決定された回転角における雌ロータの後進面接線１２３に接するように設ければよい。 FIG. 3A shows the screw rotor rotation position when the bypass passage 50 provided in the discharge casing 21 is opened or just after it is opened. The male bypass passage 50 may be provided so as to be in contact with the reverse surface tangent 120 of the male rotor 2 at the determined rotation angle. The female bypass passage 51 may be provided so as to be in contact with the reverse surface tangent 123 of the female rotor at the determined rotation angle.
　なお、前記バイパス通路５０，５１の孔の大きさは、隣接する圧縮室同士が連通しないように、雄ロータ及び雌ロータの最小歯厚以下になるようにする。 In addition, the size of the holes of the bypass passages 50 and 51 is set to be equal to or smaller than the minimum tooth thickness of the male rotor and the female rotor so that adjacent compression chambers do not communicate with each other.
　図３Ｂは、バイパス通路５０，５１が全開になった時或いはその直後のスクリューロータ回転位置を示す。被圧縮ガスは、雄側吐出ポート４２及び雌側吐出ポート４３からの吐出が開始されるまでの間、前記バイパス通路５０，５１から過圧縮されたガスが継続して吐出室１２にバイパスされる。 FIG. 3B shows the screw rotor rotation position when the bypass passages 50 and 51 are fully opened or just after that. The compressed gas continues to be bypassed to the discharge chamber 12 by the over-compressed gas from the bypass passages 50 and 51 until the discharge from the male discharge port 42 and the female discharge port 43 is started. .
　図３Ｃは、圧縮室３０ａ，３０ｂの被圧縮ガスが、吐出ケーシング２１に設けられた雄側吐出ポート４２及び雌側吐出ポート４３から吐出室１２へ吐出開始される時のスクリューロータ回転位置を示す。 FIG. 3C shows the screw rotor rotation position when the gas to be compressed in the compression chambers 30a and 30b starts to be discharged from the male side discharge port 42 and the female side discharge port 43 provided in the discharge casing 21 to the discharge chamber 12. .
　図４は図１に示すスクリュー圧縮機における雄側のバイパス通路５０に設けた弁１１０の部分における断面図を示す。図に示す弁通路１１５内には吐出室１２の圧力が吐出通路１００を介して作用するため、バイパス通路５０内の圧力が弁通路１１５内の圧力よりも高くなると、弁１１０が圧力差により押し上げられ、圧縮室３０ａ内の被圧縮ガスは弁通路１１５を通って吐出室１２に排出される。 FIG. 4 is a cross-sectional view of the valve 110 provided in the male bypass passage 50 of the screw compressor shown in FIG. Since the pressure of the discharge chamber 12 acts through the discharge passage 100 in the valve passage 115 shown in the figure, when the pressure in the bypass passage 50 becomes higher than the pressure in the valve passage 115, the valve 110 is pushed up by the pressure difference. The compressed gas in the compression chamber 30a is discharged to the discharge chamber 12 through the valve passage 115.
　なお、雌側バイパス通路５１においても同様に構成されている。 The female bypass passage 51 is configured in the same manner.
　図５は図４のＢ－Ｂ線矢視断面図である。弁１１０にはスプリング１１２により常に弁１１０を閉じる方向にバネ力が付加されている。弁１１０の弁部１１６に作用するバイパス通路５０側からのガス圧が、弁通路内１１５に作用する吐出室１２のガス圧と前記バネ力との合計値を上回ると、弁１１０は開放され、圧縮室３０ａの過圧縮されたガスが吐出室１２に流出する。 FIG. 5 is a cross-sectional view taken along line BB in FIG. A spring force is always applied to the valve 110 by a spring 112 in a direction to close the valve 110. When the gas pressure from the bypass passage 50 acting on the valve portion 116 of the valve 110 exceeds the total value of the gas pressure of the discharge chamber 12 acting on the valve passage 115 and the spring force, the valve 110 is opened, The over-compressed gas in the compression chamber 30 a flows out into the discharge chamber 12.
　尚、図５において、１１１は油孔、１１３は弁１１０を保持するフランジで、このフランジ１１３はネジ１１４を介して吐出ケーシング２１に取付けられている。 In FIG. 5, 111 is an oil hole, 113 is a flange that holds the valve 110, and this flange 113 is attached to the discharge casing 21 via a screw 114.
　図６Ａ～６Ｂは図３Ａ～３Ｂに示した実施例の変形例を示すもので、図３Ａ～３Ｃに相当する図である。この例は、雄側のバイパス通路５０が最初に開いて圧縮室３０ａの過圧縮ガスを吐出室にバイパスして吐出させ、遅れて雌側のバイパス孔５１が開いて同様に圧縮室３０ｂの過圧縮ガスを吐出室に吐出させるようにしたものである。 FIGS. 6A to 6B show a modification of the embodiment shown in FIGS. 3A to 3B and correspond to FIGS. 3A to 3C. In this example, the male-side bypass passage 50 is first opened to bypass and discharge the overcompressed gas in the compression chamber 30a to the discharge chamber, and the female-side bypass hole 51 is opened after a delay. The compressed gas is discharged into the discharge chamber.
　図６Ａにおいて、雄側のバイパス通路５０と雌側のバイパス通路５１を、一定区間オーバーラップして開口するような位置に設定することで、広範囲に亘って継続的に過圧縮を防止することができる。また、図６Ｂの例は、バイパス通路５０と５１の開口区間がオーバーラップしないようにずらして設置したもので、このようにバイパス通路を設定しても良い。 In FIG. 6A, by setting the male-side bypass passage 50 and the female-side bypass passage 51 at positions that overlap and open by a certain interval, it is possible to prevent over-compression continuously over a wide range. it can. In the example of FIG. 6B, the bypass passages 50 and 51 are installed so as to be shifted so that the opening sections do not overlap, and the bypass passage may be set in this way.
　図７Ａ～７Ｂは図３Ａ～３Ｃに示した実施例の更に他の変形例を示すもので、図３Ａ～３Ｃにおける吐出ポート１０付近を拡大して示す図である。図７Ａに示す例は、バイパス通路５０を雄側にのみ設置したもので、雌ロータの歯厚が薄く、雌側のバイパス通路を大きく設置できない場合には、雄側のみにバイパス通路を設けるようにすると良い。この例では雌側にバイパス通路及び弁が不要となり、コストダウンできる。なお、図７Ｂに示す例のように、雄側にはバイパス通路を設けず、雌側にのみバイパス通路５１を設けるようにしても良い。また、図示はしていないが、雄側と雌側にそれぞれバイパス通路を設け、且つ雄側バイパス通路の開口面積を雌側バイパス通路の開口面積より大きく構成することも有効である。 FIGS. 7A to 7B show still another modification of the embodiment shown in FIGS. 3A to 3C, and are enlarged views showing the vicinity of the discharge port 10 in FIGS. 3A to 3C. In the example shown in FIG. 7A, when the bypass passage 50 is installed only on the male side, and the tooth thickness of the female rotor is thin and the female bypass passage cannot be installed large, the bypass passage is provided only on the male side. It is good to make it. In this example, a bypass passage and a valve are not required on the female side, and the cost can be reduced. 7B, the bypass passage 51 may be provided only on the female side without providing the bypass passage on the male side. Although not shown, it is also effective to provide bypass passages on the male side and the female side, respectively, and to make the opening area of the male side bypass passage larger than the opening area of the female side bypass passage.
　図８Ａ～８Ｂは図３Ａ～３Ｃに示した実施例の更に他の変形例を示すもので、図３Ａ～３Ｃにおける吐出ポート１０付近を拡大して示す図である。図８Ａに示す例は、吐出ケーシングに設けるバイパス通路５０，５１を長穴としたもので、このように構成することにより、バイパス通路のバイパス流路面積を十分大きく確保することができ、バイパス通路から吐出室にバイパスされる圧縮ガスの流路抵抗を低減できる。 8A to 8B show still another modification of the embodiment shown in FIGS. 3A to 3C, and are enlarged views of the vicinity of the discharge port 10 in FIGS. 3A to 3C. In the example shown in FIG. 8A, the bypass passages 50 and 51 provided in the discharge casing are elongated holes. By configuring in this way, a sufficiently large bypass passage area of the bypass passage can be secured. The flow path resistance of the compressed gas that is bypassed to the discharge chamber can be reduced.
　図８Ｂに示す例は、任意の異なる設定容積比の位置に雄側バイパス通路５０，５０ａ、雌側バイパス通路５１，５１ａをそれぞれ複数設けるようにしたものである。この例では、雄ロータ側及び雌ロータ側に、それぞれ２つの異なる任意の設定容積比の位置にバイパス通路を設けた例を説明したが、３以上の異なる任意の設定容積比の位置にバイパス通路を設けるようにしても良い。また、この例では、任意の同じ設定容積比の位置にバイパス通路を形成する孔をそれぞれ２個形成した例を示したが、３個以上の孔で形成しても良い。この例のように、バイパス通路を複数個の孔で形成することで、図８Ａに示す例と比較し、加工し易く、加工時間短縮が可能となる。 In the example shown in FIG. 8B, a plurality of male side bypass passages 50 and 50a and a plurality of female side bypass passages 51 and 51a are provided at arbitrary different set volume ratio positions. In this example, the example in which the bypass passages are provided at the positions of two different arbitrary set volume ratios on the male rotor side and the female rotor side has been described, but the bypass passages are provided at three or more different arbitrary set volume ratio positions. May be provided. Moreover, in this example, although the example which formed two holes each forming a bypass channel | path in the position of arbitrary same setting volume ratios was shown, you may form with three or more holes. By forming the bypass passage with a plurality of holes as in this example, it is easier to process and the processing time can be shortened compared to the example shown in FIG. 8A.
　図９及び図１０は、図８Ｂに示す吐出ポート部付近に設けたバイパス通路５０，５０ａ，５１，５１ａにそれぞれ板ばね式の弁７０と弁押え７１を設けたもので、図１の吐出ポート部付近のＦ－Ｆ線矢視断面に相当する図である。なお、図１０は図９に示す弁部のＤ－Ｄ線矢視断面図である。この例に示すように、圧縮室と吐出室とを連通するバイパス通路の吐出室側に、板バネ式の弁７０と弁押え７１をボルト７３でメインケーシング１に共締めして取付けることで、弁機構の製造工数を低減し、弁構造を簡略化することができ、弁のコスト低減を図ることができる。また、バイパス通路を開閉する弁を板ばね式の弁で構成することにより、限られた狭い空間に複数の弁を設けることが可能となる。 9 and FIG. 10 show a case where a leaf spring type valve 70 and a valve presser 71 are provided in the bypass passages 50, 50a, 51, 51a provided in the vicinity of the discharge port portion shown in FIG. 8B, respectively. It is a figure equivalent to the FF line | wire arrow cross section of a part vicinity. FIG. 10 is a cross-sectional view of the valve section shown in FIG. As shown in this example, by attaching a leaf spring type valve 70 and a valve presser 71 to the main casing 1 together with a bolt 73 on the discharge chamber side of the bypass passage communicating the compression chamber and the discharge chamber, The number of manufacturing steps of the valve mechanism can be reduced, the valve structure can be simplified, and the cost of the valve can be reduced. Further, by configuring the valve that opens and closes the bypass passage with a leaf spring type valve, it is possible to provide a plurality of valves in a limited narrow space.
　なお、図１～図７に示す例においてもバイパス通路を開閉する弁を板ばね式の弁で構成することは同様に可能である。 In the examples shown in FIGS. 1 to 7, it is also possible to configure the valve for opening and closing the bypass passage by a leaf spring type valve.
　図１１，図１２は、図４，図５に示した例の他の実施形態を示すもので、図４では弁１１０を縦方向（軸直角方向）に設けたが、図１１，図１２の例では弁１１０を横方向（軸方向）に設けた例を示している。なお、図１２は図１１のＣ－Ｃ線矢視方向から見た弁部付近の断面図である。また、図１１，図１２において図４，図５と同一符号を付した部分は同一又は相当する部分を示している。この例に示すように、弁１１０を横に設置することで、圧縮室と吐出室とを連通するバイパス通路５０の長さを図４，図５に示した例よりも短く構成することが可能となり、バイパス通路の容積を小さくできることにより、非圧縮容積を減少でき、体積効率の低下を抑えることができる。なお、図１２において、１１７はスペーサで、図５のフランジ１１３に相当するものである。 FIGS. 11 and 12 show another embodiment of the example shown in FIGS. 4 and 5. In FIG. 4, the valve 110 is provided in the vertical direction (perpendicular to the axis). In the example, the valve 110 is provided in the lateral direction (axial direction). FIG. 12 is a cross-sectional view of the vicinity of the valve portion as viewed from the direction of arrows CC in FIG. 11 and 12, the same reference numerals as those in FIGS. 4 and 5 indicate the same or corresponding parts. As shown in this example, by installing the valve 110 horizontally, the length of the bypass passage 50 that communicates the compression chamber and the discharge chamber can be made shorter than the example shown in FIGS. Thus, by reducing the volume of the bypass passage, the uncompressed volume can be reduced, and the decrease in volume efficiency can be suppressed. In FIG. 12, reference numeral 117 denotes a spacer, which corresponds to the flange 113 in FIG.
　図１３は図１１，図１２に示した例の別の例を示すもので、図１２に相当する部分の断面図である。この例は、オイルタンク２５から高圧の油を配管１４１を介して弁シリンダ１４３に導き、バイパス通路５０を開閉する弁１４０を油圧により作動させるようにしたものである。弁１４０は、高圧の油圧によりバイパス通路５０及び吐出通路１００を塞ぐ位置に押し付けられる。また、圧縮室と吐出室１２とを連通するバイパス通路５０の圧力が油圧より大きくなった場合、シリンダ１４３内の高圧油を配管１４１を介してオイルタンク２５に押し戻すことで、弁１４０が図の右方向に作動し、吐出室１２からバイパス通路５０及び吐出通路１００を介して被圧縮ガスが吐出室１２にバイパスされるようにしている。 FIG. 13 shows another example of the example shown in FIGS. 11 and 12, and is a cross-sectional view of a portion corresponding to FIG. In this example, high-pressure oil is guided from the oil tank 25 to the valve cylinder 143 via the pipe 141, and the valve 140 that opens and closes the bypass passage 50 is hydraulically operated. The valve 140 is pressed to a position where the bypass passage 50 and the discharge passage 100 are closed by high pressure oil pressure. Further, when the pressure in the bypass passage 50 communicating with the compression chamber and the discharge chamber 12 becomes higher than the hydraulic pressure, the high pressure oil in the cylinder 143 is pushed back to the oil tank 25 through the pipe 141, so that the valve 140 is The gas to be compressed is bypassed to the discharge chamber 12 from the discharge chamber 12 through the bypass passage 50 and the discharge passage 100.
　図１４，図１５は図１１，図１２に示した例の更に別の例を示すもので、図１４は図１２に相当する部分の断面図、図１５は図１４のＥ－Ｅ線矢視方向から見た弁部付近の断面図である。この例は、圧縮室と吐出室１２とを連通するバイパス通路５０の途中に円柱の中心に穴を設けた弁１３５を設置し、該弁１３５をステップモータ１３１によりシャフト１３４を介して図１５に示すように例えば９０度回動させ、バイパス通路５０を開閉するようにしたものである。ステップモータ１３１の制御は、圧縮室と吐出室とを連通するバイパス通路５０に設けた圧力センサ１３３と、吐出室１２に設置された圧力センサ１３３からの信号を制御装置１３２に入力し、バイパス通路５０の圧力が吐出室１２の圧力より大きくなった場合、弁１３５を開の状態に、バイパス通路５０の圧力が吐出室１２の圧力より小さくなった場合、弁１３５を閉の状態になるように制御するものである。この例によれば、圧縮室の圧力変化に対して追従性の高い弁機構とすることが可能となる。 14 and 15 show still another example of the example shown in FIGS. 11 and 12, FIG. 14 is a sectional view corresponding to FIG. 12, and FIG. 15 is a view taken along the line EE in FIG. It is sectional drawing of the valve part vicinity seen from the direction. In this example, a valve 135 having a hole in the center of a cylinder is provided in the middle of a bypass passage 50 that communicates the compression chamber and the discharge chamber 12, and the valve 135 is connected to the shaft 135 by a step motor 131 in FIG. 15. As shown, for example, the bypass passage 50 is opened and closed by turning 90 degrees. The step motor 131 is controlled by inputting a signal from the pressure sensor 133 provided in the bypass passage 50 communicating with the compression chamber and the discharge chamber and the pressure sensor 133 installed in the discharge chamber 12 to the control device 132. When the pressure of 50 becomes higher than the pressure of the discharge chamber 12, the valve 135 is opened, and when the pressure of the bypass passage 50 becomes lower than the pressure of the discharge chamber 12, the valve 135 is closed. It is something to control. According to this example, it is possible to provide a valve mechanism having a high followability with respect to a pressure change in the compression chamber.
　図１６は図１１，図１２に示した例の更に別の例を示すもので、図１２或いは図１４に相当する部分の断面図を示す。この例は、圧縮室と吐出室１２とを連通するバイパス通路５０の途中に電磁弁１３６を設け、制御装置１３２により、図１４に示す例と同様に、バイパス通路５０の圧力と吐出室１２の圧力との圧力を見て電磁弁１３６を制御するようにしたものである。電磁弁１３６を開くことで、圧縮室の圧縮ガスを、バイパス通路５０及び吐出通路１００を介して吐出室１２にバイパスさせることができる。この例では複雑な弁開閉機構にすることなく、図１４に示した例と同様に、圧縮室の圧力変化に対して追従性の高い弁機構とすることが可能になる。 FIG. 16 shows still another example of the example shown in FIGS. 11 and 12, and shows a cross-sectional view of a portion corresponding to FIG. 12 or FIG. In this example, an electromagnetic valve 136 is provided in the middle of the bypass passage 50 that communicates the compression chamber and the discharge chamber 12, and the controller 132 controls the pressure in the bypass passage 50 and the discharge chamber 12 in the same manner as in the example shown in FIG. The electromagnetic valve 136 is controlled by looking at the pressure and the pressure. By opening the electromagnetic valve 136, the compressed gas in the compression chamber can be bypassed to the discharge chamber 12 via the bypass passage 50 and the discharge passage 100. In this example, a complicated valve opening / closing mechanism can be used, and a valve mechanism having high followability to the pressure change in the compression chamber can be obtained as in the example shown in FIG.
　以上説明した実施例によれば、吐出ポート近傍に、圧縮室と吐出室とを連通するバイパス通路を設け、更に該バイパス通路を開閉する弁を設ける構成としたことにより、圧縮室内の被圧縮ガスを維持若しくは吐出室に開放することが可能となる。圧縮室圧力が吐出室圧力よりも高くなった場合にバイパス通路を開とすることにより、圧縮室で過圧縮されるのを抑制できる。特に低圧縮比運転時の際には、圧縮室の圧力が吐出室側の運転圧力以上に過圧縮され易くなり、圧縮室の圧力が吐出室側圧力以上になるとバイパス通路の弁が開き、圧縮室内の圧縮ガスをバイパス通路を介して吐出室側に吐出させることができる。従って、過圧縮運転を防止して、圧縮機の軸動力を低減し、特に低圧縮比運転域での性能を向上させることができる。この結果、軸受部材やスクリューロータへの異常負荷を軽減でき、ロータの変形や軸受損傷を防止できる。 According to the embodiment described above, a bypass passage that connects the compression chamber and the discharge chamber is provided in the vicinity of the discharge port, and a valve that opens and closes the bypass passage is provided. Can be maintained or opened to the discharge chamber. When the compression chamber pressure becomes higher than the discharge chamber pressure, it is possible to suppress overcompression in the compression chamber by opening the bypass passage. In particular, during operation at a low compression ratio, the pressure in the compression chamber is likely to be overcompressed above the operating pressure on the discharge chamber side, and when the pressure in the compression chamber exceeds the pressure on the discharge chamber side, the bypass passage valve opens and compression The compressed gas in the room can be discharged to the discharge chamber side via the bypass passage. Therefore, it is possible to prevent the overcompression operation, reduce the shaft power of the compressor, and improve the performance particularly in the low compression ratio operation region. As a result, abnormal loads on the bearing member and the screw rotor can be reduced, and deformation of the rotor and bearing damage can be prevented.
　また、前記バイパス通路を、設定容積比１．５～３．０、好ましくは１．５～２．７の範囲内に設置するように構成し、このバイパス通路を開閉する開閉弁を設けることにより、アンロード運転時の最適な運転が可能となる。更に、圧縮室と吐出室とを連通するバイパス通路を、雄ロータ側及び雌ロータ側の両方に設けることにより、圧縮室の被圧縮ガスを効率的に吐出室に流出させることが可能となる。 Further, the bypass passage is configured to be installed within a set volume ratio of 1.5 to 3.0, preferably 1.5 to 2.7, and an opening / closing valve for opening and closing the bypass passage is provided. This makes it possible to perform optimal operation during unload operation. Furthermore, by providing bypass passages that connect the compression chamber and the discharge chamber on both the male rotor side and the female rotor side, the compressed gas in the compression chamber can be efficiently discharged to the discharge chamber.
　更に、圧縮室と吐出室とを連通する前記バイパス通路を、異なる設定容積比の圧縮室に連通する位置にそれぞれ設けるようにすれば、アンロード運転時の過圧縮をより広い運転範囲で防止できる効果がある。また、バイパス通路を複数個の孔で形成することにより、バイパス通路の流路抵抗を低減できると共に、バイパス通路全体の容積も小さく抑えることが可能となるから、バイパス通路により生じる非圧縮容積を低減して体積効率の低下を抑えることができる。
　上記記載は実施例についてなされたが、本発明はそれに限らず、本発明の精神と添付の請求の範囲の範囲内で種々の変更および修正をすることができることは当業者に明らかである。 Furthermore, if the bypass passages that connect the compression chamber and the discharge chamber are respectively provided at positions that communicate with the compression chambers having different set volume ratios, over-compression during unload operation can be prevented in a wider operating range. effective. In addition, by forming the bypass passage with a plurality of holes, the flow resistance of the bypass passage can be reduced, and the volume of the entire bypass passage can be kept small, thereby reducing the uncompressed volume generated by the bypass passage. Thus, a decrease in volume efficiency can be suppressed.
While the above description has been made with reference to exemplary embodiments, it will be apparent to those skilled in the art that the invention is not limited thereto and that various changes and modifications can be made within the spirit of the invention and the scope of the appended claims.
　１　メインケーシング
　２　雄ロータ
　２Ａ　雌ロータ
　３　ステータ
　４　ロータ
　６，７　ころ軸受
　８　玉軸受
　９　吸入ポート
　１０　吐出ポート
　１２　吐出室
　１５　エンドカバー
　１６　モータケーシング
　１７　圧縮機部
　１８　モータ部
　１９　吐出口
　２０　吸入口
　２１　吐出ケーシング
　２２　モータ
　２５　オイルタンク
　２６，７３　ボルト
　３０ａ，３０ｂ　圧縮室
　４０ａ　雄側ケーシングボア
　４０ｂ　雌側ケーシングボア
　４２　雄側吐出ポート
　４３　雌側吐出ポート
　４４　吐出ラジアルポート
　５０，５０ａ，５１，５１ａ　バイパス通路
　７０　弁
　７１　弁押え
　８０　油分離器
　１００　吐出通路
　１１０，１３５，１４０　弁（開閉弁）
　１１１　油孔
　１１２　スプリング
　１１３，１４２　フランジ
　１１４　ネジ
　１１５　弁通路
　１１６　弁部
　１１７　スペーサ
　１２０　雄ロータ後進面接線
　１２３　雌ロータ後進面接線
　１３１　ステップモータ
　１３２　制御装置
　１３３　圧力センサ
　１３４　シャフト
　１３６　電磁弁
　１４１　油配管
　１４３　シリンダ DESCRIPTION OF SYMBOLS 1 Main casing 2 Male rotor 2A Female rotor 3 Stator 4 Rotor 6, 7 Roller bearing 8 Ball bearing 9 Suction port 10 Discharge port 12 Discharge chamber 15 End cover 16 Motor casing 17 Compressor part 18 Motor part 19 Discharge port 20 Suction port 21 Discharge casing 22 Motor 25 Oil tank 26, 73 Bolts 30a, 30b Compression chamber 40a Male casing bore 40b Female casing bore 42 Male discharge port 43 Female discharge port 44 Discharge radial port 50, 50a, 51, 51a Bypass passage 70 Valve 71 Valve presser 80 Oil separator 100 Discharge passage 110, 135, 140 Valve (open / close valve)
111 Oil hole 112 Spring 113, 142 Flange 114 Screw 115 Valve passage 116 Valve portion 117 Spacer 120 Male rotor reverse surface tangent 123 Female rotor reverse surface tangent 131 Step motor 132 Controller 133 Pressure sensor 134 Shaft 136 Electromagnetic valve 141 Oil piping 143 Cylinder

Claims (12)

  1. 　雄ロータ及び雌ロータを備える一対のスクリューロータと、これら一対のスクリューロータを収納するケーシングとで圧縮室を形成し、且つ前記ケーシングには被圧縮ガスを流出させる吐出ポートと、この吐出ポートから吐出される圧縮ガスが流入する吐出室とが形成されたスクリュー圧縮機において、
    　前記吐出ポート近傍の前記雄ロータ側及び雌ロータ側の両方の前記ケーシングに、それぞれ前記圧縮室と前記吐出室とを連通するバイパス通路を設けると共に、該バイパス通路を開閉する弁を設けたことを特徴とするスクリュー圧縮機。     A pair of screw rotors including a male rotor and a female rotor, and a casing that houses the pair of screw rotors form a compression chamber, and a discharge port that discharges compressed gas to the casing, and a discharge port from the discharge port In a screw compressor in which a discharge chamber into which compressed gas flows is formed,
    Provided in the casing on both the male rotor side and the female rotor side in the vicinity of the discharge port are a bypass passage for communicating the compression chamber and the discharge chamber, respectively, and a valve for opening and closing the bypass passage. A featured screw compressor.
  2. 　請求項１において、前記バイパス通路を開閉する弁は、前記バイパス通路に連通する前記圧縮室の圧力が、前記吐出室の圧力よりも高くなった場合に開くように構成されていることを特徴とするスクリュー圧縮機。 2. The valve according to claim 1, wherein the valve for opening and closing the bypass passage is configured to open when a pressure in the compression chamber communicating with the bypass passage is higher than a pressure in the discharge chamber. Screw compressor to do.
  3. 　請求項１において、前記バイパス通路は、設定容積比が１．５～３．０の範囲内の前記圧縮室に連通される位置に形成されていることを特徴とするスクリュー圧縮機。 2. The screw compressor according to claim 1, wherein the bypass passage is formed at a position communicating with the compression chamber within a set volume ratio of 1.5 to 3.0.
  4. 　請求項３において、前記バイパス通路は、設定容積比が１．５～２．７の範囲内の前記圧縮室に連通される位置に形成されていることを特徴とするスクリュー圧縮機。 4. The screw compressor according to claim 3, wherein the bypass passage is formed at a position communicating with the compression chamber within a set volume ratio of 1.5 to 2.7.
  5. 　請求項１において、前記雄ロータ側又は雌ロータ側に設けられたバイパス通路は、異なる設定容積比となる圧縮室に連通される位置に複数個設けられていることを特徴とするスクリュー圧縮機。 2. The screw compressor according to claim 1, wherein a plurality of bypass passages provided on the male rotor side or the female rotor side are provided at positions communicating with compression chambers having different set volume ratios.
  6. 　請求項１において、インバータによる回転数制御可能な電動機により前記スクリューロータを駆動する構成としたことを特徴とするスクリュー圧縮機。 2. The screw compressor according to claim 1, wherein the screw rotor is driven by an electric motor capable of controlling the rotation speed by an inverter.
  7. 　雄ロータ及び雌ロータを備える一対のスクリューロータと、これら一対のスクリューロータを収納するケーシングとで圧縮室を形成し、且つ前記ケーシングには被圧縮ガスを流出させる吐出ポートと、この吐出ポートから吐出される圧縮ガスが流入する吐出室とが形成されたスクリュー圧縮機において、
    　前記吐出ポートを挟んでその両側の前記ケーシングに、それぞれ前記圧縮室と前記吐出室とを連通するバイパス通路を設け、更に該バイパス通路を開閉する弁を設けたことを特徴とするスクリュー圧縮機。     A pair of screw rotors including a male rotor and a female rotor, and a casing that houses the pair of screw rotors form a compression chamber, and a discharge port that discharges compressed gas to the casing, and a discharge port from the discharge port In a screw compressor in which a discharge chamber into which compressed gas flows is formed,
    A screw compressor characterized in that a bypass passage for communicating the compression chamber and the discharge chamber is provided in each casing on both sides of the discharge port, and a valve for opening and closing the bypass passage is further provided.
  8. 　雄ロータ及び雌ロータを備える一対のスクリューロータと、これら一対のスクリューロータを収納するメインケーシングと、このメインケーシングの吐出側に設けた吐出ケーシングと、前記スクリューロータを駆動するための電動機を収容したモータケーシングと、前記メインケーシングと吐出ケーシングの少なくとも何れかに設けた吐出ポートと、前記一対のスクリューロータと前記メインケーシングにより形成される圧縮室と、前記吐出ケーシングに形成され前記吐出ポートから吐出される圧縮ガスが流入する吐出室とを備えたスクリュー圧縮機において、
    　前記吐出ポートの近傍の前記吐出ケーシングに設けられ、前記圧縮室と前記吐出室とを連通するバイパス通路と、
    　前記バイパス通路に連通する前記圧縮室の圧力が、前記吐出室の圧力よりも低い時には閉じ、高くなった時に開くように構成されて前記バイパス通路を開閉する弁と
    を備えることを特徴とするスクリュー圧縮機。     A pair of screw rotors including a male rotor and a female rotor, a main casing for storing the pair of screw rotors, a discharge casing provided on the discharge side of the main casing, and an electric motor for driving the screw rotor are stored. A motor casing; a discharge port provided in at least one of the main casing and the discharge casing; a compression chamber formed by the pair of screw rotors and the main casing; and a discharge chamber formed in the discharge casing and discharged from the discharge port. A screw compressor having a discharge chamber into which compressed gas flows.
    A bypass passage provided in the discharge casing near the discharge port and communicating the compression chamber and the discharge chamber;
    A screw configured to close when the pressure of the compression chamber communicating with the bypass passage is lower than the pressure of the discharge chamber and to open when the pressure becomes high, and to open and close the bypass passage. Compressor.
  9. 　請求項８において、前記バイパス通路は、ケーシングに形成された前記吐出ポートの雄ロータ側及び雌ロータ側の両方に設けられていることを特徴とするスクリュー圧縮機。 9. The screw compressor according to claim 8, wherein the bypass passage is provided on both the male rotor side and the female rotor side of the discharge port formed in the casing.
  10. 　請求項８において、前記バイパス通路は、設定容積比が１．５～２．７の範囲内の前記圧縮室に連通される位置に形成されていることを特徴とするスクリュー圧縮機。 9. The screw compressor according to claim 8, wherein the bypass passage is formed at a position communicating with the compression chamber within a set volume ratio of 1.5 to 2.7.
  11. 　請求項８において、前記雄ロータ側又は雌ロータ側に設けられたバイパス通路は、異なる設定容積比となる圧縮室に連通される位置に複数個設けられていることを特徴とするスクリュー圧縮機。 9. The screw compressor according to claim 8, wherein a plurality of bypass passages provided on the male rotor side or the female rotor side are provided at positions communicating with compression chambers having different set volume ratios.
  12. 　請求項８において、インバータによる回転数制御可能な電動機により前記スクリューロータを駆動する構成としたことを特徴とするスクリュー圧縮機。 9. The screw compressor according to claim 8, wherein the screw rotor is driven by an electric motor capable of controlling the rotation speed by an inverter.
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JP2010077897A (en) 2010-04-08

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