TWI494508B - Screw compressor - Google Patents

Description

Screw compressor

The present invention relates to a screw compressor suitable for use in an apparatus for constituting a refrigeration cycle of an air conditioner, a cryogen unit, a refrigerator, and the like.

When a screw compressor is used in an air conditioner or a cryostat unit, the pressure in the helical rotor groove may be higher than the discharge pressure due to operating conditions due to the use of a wide range of suction pressure or discharge pressure. (hereinafter referred to as over-compression). Here, a screw compressor for reducing over-compression has been proposed (for example, see Patent Document 1).

The screw compressor disclosed in Patent Document 1 includes a male rotor (main rotor) and a female rotor (sub rotor) in which the rotating shafts rotate in a substantially parallel manner, and the teeth of the male and female rotors are accommodated. The inner hole, and a main casing (housing) having an end surface of the inner hole of the rotor axial discharge side opening; and a discharge casing (housing wall) connected to the rotor axial discharge side of the main casing. The spouting case has a discharge side end surface that abuts against an end surface of the main casing, covers an opening of the inner hole, a discharge port formed on the discharge end surface (discharge window), and a groove formed from the male rotor and the female rotor. At least one of the male rotor side and the female rotor side is opened at a position opposite to the rotor rotation direction in the vicinity of the discharge port on the discharge side end surface in the vicinity of the discharge port on the discharge side end surface. a valve hole (a hole); and a bypass flow path that communicates the valve hole and the discharge chamber, and a valve device (relief valve) that opens and closes the valve hole.

The valve device has a valve body disposed in the valve hole, and a spring (pushing spring) that pushes the valve body toward the main housing side. Further, for example, when the valve body is moved toward the main casing side and the valve hole is closed, the compressed gas is discharged from the compression chamber through the discharge to the discharge chamber. On the other hand, when the valve body is moved to the side opposite to the main casing side, when the valve hole is opened, not only the sputum is discharged, but also the compressed gas is discharged to the discharge chamber through the valve hole and the bypass flow path. Thereby, the over-compression is alleviated.

Further, as the brake of the valve body, a step portion is formed in the valve body and the valve hole. Thereby, for example, when the valve body is moved toward the main casing side, the front end surface of the valve body is flush with the end surface of the discharge casing, and the valve body is prevented from coming into contact with the end surface of the tooth portion of the rotor.

[Advanced technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 61-79886

However, it is known that the above prior art has the following problems that must be improved.

That is, in the above prior art, since the pressure from the compression operation chamber acts on the valve body, the compression operation chamber is in an over-compressed state (pressure of the compression operation chamber > pressure of the discharge chamber (discharge pressure)), overcoming the aforementioned spring When the pressure is pushed, the aforementioned valve body is opened. However, when the valve body is opened, the pressure on the compression chamber side of the valve body immediately becomes the same as the pressure on the discharge chamber side. On the other hand, since the back pressure of the valve body often becomes the pressure of the discharge chamber, the pressure acting on the valve body immediately balances. Therefore, the valve body is immediately closed by the action of the spring that pushes the valve body toward the main casing side. Therefore, when the compression actuating chamber is in the over-compressed state, the valve body is repeatedly opened and closed each time the compression actuating chamber passes through the valve body as the rotor rotates, and the valve body knocks the brake to cause a blow sound or vibration.

SUMMARY OF THE INVENTION An object of the present invention is to provide a screw compressor which can reduce the struck sound or vibration of an over-compressed valve body.

In order to achieve the above object, the present invention is directed to a male rotor and a female rotor in which a rotating shaft rotates while being substantially parallel to each other, a main casing having an inner hole for accommodating the male rotor and the female rotor, and a main casing The rotor of the body is connected to the axial discharge side, and abuts against the end surface of the main casing, covers the discharge casing of the discharge end surface of the opening of the inner hole, and includes a compression chamber formed by the male rotor and the female rotor. Discharging a compressed gas discharge chamber or a discharge flow path through a discharge port formed in at least one of the main casing or the discharge case; and at least in the vicinity of the discharge port and at least the male rotor or the female rotor a discharge side end surface of the discharge case on one side is formed in a valve hole at a position where the compression operation chamber is opened, a bypass flow path that communicates the valve hole with the discharge chamber or the discharge flow path, and a valve hole that is disposed in the valve hole The screw compressor of the valve body is characterized in that: a valve body driving device for opening and closing the valve body is provided; and detecting whether or not the compression operating chamber is present Compression occurs, and when it is detected that compression has occurred, the valve body driving device is controlled to open the control device for the valve body, and the control device is operated according to the suction pressure drawn into the compressor and the discharge pressure of the compressor. The pressure ratio in the middle, and comparing the pressure ratio with the set pressure ratio previously stored, and when the pressure ratio during operation is smaller than the set pressure ratio, it is judged that over-compression occurs, thereby controlling the foregoing The valve body driving device opens the valve body, and the valve body driving device includes a cylinder provided on a back side of the valve body, and the cylinder a reciprocating piston and a push rod connecting the piston and the valve body, when over-compression occurs, a pressure is applied to the piston, and the valve body is opened to be disposed in a cylinder on a valve body side of the piston The valve body side pushes the spring of the piston, and the compressed gas that guides the discharge side of the compressor is guided in the cylinder on the valve body side of the piston. When there is no over-compression, the valve body is closed and over-compressed. At the time of occurrence, the piston is moved toward the counter valve body side by the pressure on the compressor discharge side in the cylinder side of the valve body side of the piston, and the valve body is opened.

According to the present invention, a screw compressor capable of reducing the struck sound or vibration of an over-compressed valve body can be obtained.

[Formation for carrying out the invention]

Hereinafter, embodiments of the present invention will be described in accordance with the drawings.

[Example 1]

Embodiment 1 of the screw compressor of the present invention will be described with reference to Figs. 1 to 8 .

1 is a longitudinal cross-sectional view of a first embodiment of a screw compressor according to the present invention, FIG. 2 is a right side view of FIG. 1, and FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 1 (a view showing a discharge side end surface of the discharge case, and FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 1 (a view showing an end surface of the main casing, and showing the discharge shell with a two-dot chain line). FIG. 5 is a view for explaining the positional relationship between the compression operation chamber, the discharge port, the valve hole, and the bypass flow path in the first embodiment of the present invention.

In FIG. 1, a screw compressor includes a compressor main body 1, a motor (electric motor) 2 that drives the compressor main body 1, and a motor housing 13 that houses the motor 2. The motor casing 13 forms a suction chamber (low pressure chamber) 5 on the counter compressor main body side of the motor 2, and forms a gas flowing from the suction port 6 through the screen 7 into the suction chamber 5. The motor 2 is composed of a rotor 11 attached to the rotating shaft 10 and a stator 12 disposed on the outer peripheral side of the rotor 11, and the stator is fixed to the inner surface of the motor casing 13.

The compressor main body 1 is provided with a main casing 15 that is connected to the motor casing 13 and has a spiral rotor 14 built therein, and a discharge casing 16 that is connected to the discharge side of the main casing 15.

A cylindrical inner hole 20 for accommodating the tooth portion of the spiral rotor 14 is formed in the main casing 15, and the rotor axial discharge side of the inner hole 20 is an opening. A discharge port 23 in the radial direction is formed on the end surface 21 side of the main casing 15 that forms the opening, and a discharge flow path 90 connected to the discharge port 23 is also formed.

As shown in Fig. 4, the spiral rotor 14 is composed of a male rotor 14A and a female rotor 14B that rotate while rotating the shafts in parallel. Further, the inner hole 20 is composed of an inner hole 20A for accommodating the male rotor and an inner hole 20B for accommodating the female rotor, and the discharge port 23 is also provided by the discharge port 23A on the male rotor side and the discharge port 23B on the female rotor side. Composition.

The rotor axial suction side (the left side in FIG. 1) of the main casing 15 is connected to the motor casing 13, and a gap or the like between the rotor 11 and the stator 12 inside the motor casing 13 is formed to allow the aforementioned suction. The chamber 5 is formed by a suction passage that communicates with the compressor body 1.

In the tooth grooves of the male rotor 14A and the female rotor 14B, as shown in FIG. 4, compression operating chambers 36A, 36B are formed, which are sequentially changed and formed in the main casing together with the rotation of the spiral rotor. a compression operation chamber for an intake stroke in which the suction port 22 of the suction side (the motor casing 13 side) communicates with the compressor; a compression operation chamber that compresses a compression stroke of the inhaled gas; and a communication chamber that communicates with the discharge ports 23 and 25, and discharges The compression chamber of the discharge stroke of the compressed gas. The compression chambers of the discharge ports 23A and 23B with respect to the discharge stroke are formed on the outer side in the radial direction of the male rotor or the female rotor (upper side in FIG. 1).

As shown in FIGS. 1 and 3, an axial discharge spout 25 and a discharge chamber 26 are formed on the discharge-side end surface 24 of the discharge casing 16. In other words, the discharge case 16 has a discharge-side end surface 24 that abuts against the end surface 21 of the main casing 15, covers the opening of the inner holes 20A and 20B, and a discharge port 25A that is formed on the male-rotor side of the discharge-side end surface 24. And a discharge port 25B on the female rotor side; and a discharge chamber 26 into which the compressed gas discharged from the compression operation chamber through the discharge ports 23A, 23B, 25A, and 25B flows.

As shown in Fig. 1, the suction-side shaft portion of the male rotor 14A is supported by a rolling bearing 17 disposed in the main casing 15 and a ball bearing 91 disposed in the motor casing 13, and the male rotor 14A is discharged. The side shaft portion is supported by the rolling bearing 18 and the ball bearing 19 disposed in the discharge casing 16. Further, the suction-side shaft portion of the female rotor 14B is supported by a rolling bearing (not shown) disposed in the main casing 15, and the discharge-side shaft portion of the female rotor 14B is disposed to be discharged. The rolling bearing of the casing 16 and the ball bearing (not shown) are supported. The suction-side shaft portion of the male rotor 14A is directly coupled to the rotating shaft 10 of the motor 2, and the male rotor 14A is rotated by the driving of the motor 2. With this rotation, the female rotor 14B rotates while being engaged with the male rotor 14A.

The gas compressed by the spiral rotor 14 flows out from the discharge ports 23 and 25 into the discharge chamber 26 or the discharge flow path 90, and flows from the discharge passage 90 to the discharge port 9 provided in the main casing 15, via The discharge pipe 94 connected to the discharge port 9 is sent to the oil separator 92. In the oil separator 92, the gas compressed in the compressor main body 1 and the oil mixed in the gas are separated. The oil separated in the oil separator 92 is returned to the oil groove 95 provided in the lower portion of the compressor main body 1 via the oil return pipe 93, and is accumulated therein to lubricate the shaft portion of the spiral rotor 14 or the motor 2 The aforementioned bearings 17, 18, 19, 91 of the rotary shaft 10 are again supplied to the bearings. On the other hand, the high-pressure gas from which the oil is separated in the oil separator 92 is supplied to the outside via a pipe 96 (for example, a condenser constituting a refrigeration cycle).

The gas sucked into the suction chamber 5 from the suction port 6 passes through the inside of the motor casing 13, and cools the rotor 11 and the stator 12, and then flows into the spiral rotor 14 through the suction port 22 of the compressor main body 1. In the compression operation chamber, as the male rotor 14A and the female rotor 14B rotate, the compression actuating chambers 36A and 36B move toward the rotor in the axial direction to reduce the volume, and the gas is further compressed. The gas that is compressed in the compressor operation chamber flows into the discharge flow path 90 through the discharge ports 23A, 23B, 25A, and 25B and the discharge chamber 26, and is sent out from the discharge port 9 to the discharge pipe 94.

As shown in Fig. 3, the discharge case 16 is formed in the vicinity of the discharge port 25B on the side of the female rotor 14B on the discharge side end surface 24, on the opposite side to the rotation direction of the female rotor 14B (on the right side in Fig. 3). The valve hole (cylinder) 28 is opened at an approximate position, and the center of the valve hole 28 is an opening edge of the inner hole 20B on the side of the female rotor 14B of the end surface 21 of the main casing 15. Further, the discharge casing 16 is formed with a bypass groove 29 that communicates the valve hole 28 and the discharge chamber 26, which is located more in the rotor diameter than the opening edge of the inner hole 20B on the female rotor 14B side of the end surface 21 of the main casing 15. The bypass flow path is formed by the bypass groove 29 and the end surface 21 of the main casing 15 covering the groove. The valve body 31 is provided with a valve body 31 that opens and closes the valve hole 28.

Next, a valve body driving device for driving the valve body 31 will be described with reference to Figs. 6 to 8 .

6 and FIG. 7 are cross-sectional views taken along the line VI-VI of FIG. 2, and are views showing a structure of a valve body driving device that drives the valve body 31, and FIG. 6 is a view showing a closed state of the valve body 31, and FIG. A diagram of the open state of the valve body 31. Fig. 8 is a cross-sectional view taken along the line VIII-VIII of Fig. 6;

In FIG. 6 and FIG. 7 , the valve body driving device 30 is provided with a push rod 53 that is connected to one end side on the back side (the right side in FIG. 6 ) of the valve body 31 that is slidably provided in the valve hole 28 , A piston 51 connected to the other end side of the push rod 53 via a bolt 52 slidably houses the cylinder 35 of the piston 51. The cylinder 35 is formed in the discharge casing 16, and the discharge casing 16 is also provided with a rod hole 101 that slidably supports the push rod 53. A seal ring 50 is provided in the rod hole 101 to seal between the cylinder chamber of the cylinder 35 and the counter pressure chamber 28a of the valve body 31. Further, the pressure in the counter-pressure chamber 28a is introduced into the compressor discharge side via the communication hole 102 formed in the discharge casing 16. That is, as shown in FIGS. 6 and 8, one end side of the communication hole 102 is opened in the back pressure chamber 28a, and the other end side of the communication hole 102 communicates with the discharge chamber 26 (see FIG. 3).

A seal ring 54 for preventing leakage between the cylinder chambers 35A and 35B formed on both sides of the piston 51 is attached to the outer circumference of the piston 51. Further, in the cylinder chamber 35A (in the cylinder 35 on the valve body side), one end side of the communication hole 32 is opened at a portion outside the range of movement of the piston 51 (the right end side of the cylinder chamber 35A), and the other of the communication holes 32 On the other end side, it is opened in the aforementioned discharge chamber 26 as shown in FIG. That is, the cylinder chamber 35A communicates with the discharge chamber 26 (see FIG. 3) via the communication hole 32, and the pressure constituting the compressor discharge side is often introduced into the cylinder chamber 35A.

In the cylinder chamber 35B (in the cylinder on the valve body side), as shown in FIGS. 6 and 7, one end of the communication hole 34 is opened at a portion outside the range of movement of the piston 51 (the left end side of the cylinder chamber 35B), and the communication hole is opened. The other end side of the 34 is connected to the oil groove 95 via the capillary 120 as shown in Fig. 2 to form a hydraulic supply path. Further, the communication hole 34 is configured to communicate with the low-pressure space (intake port 22 in FIG. 6) via the communication passage (hydraulic discharge passage) 80, and is provided to open and close the communication passage 80 in the middle of the communication passage 80. Solenoid valve 42. With such a configuration, the oil of the cylinder chamber 35B is discharged to the suction port 22 side via the communication passage 80 and the electromagnetic valve 42 while the high pressure oil of the oil groove 95 is introduced into the cylinder chamber 35B by the opening and closing of the electromagnetic valve 42. Further, the cylinder chamber 35B is provided with a spring 33 that pushes the piston 51 toward the end cover 60 side (on the reverse side of the valve body 31 side).

The valve body 31 is controlled to be in a closed state without being over-compressed in the compression operating chambers 36A and 36B. However, when the valve body 31 is closed, the solenoid valve 42 is opened to be opened. Thereby, the cylinder chamber 35B communicates with the suction port 22 side via the communication hole 34 and the communication path 80, and becomes a low pressure. On the other hand, in the cylinder chamber 35A, the gas pressure on the discharge side of the compressor acts constantly. Therefore, as shown in Fig. 6, the piston 51 is moved toward the main casing 15 side against the urging force of the spring 33, and the valve body 31 is pushed to the end surface 21 of the aforementioned main casing 15, and the valve hole 28 is thus closed.

Further, the communication hole 34 side of the capillary tube 120 is also in communication with the suction port 22, but since the flow of the oil through the capillary tube 120 is compressed, the amount of oil discharged from the oil groove 95 to the suction port 22 can be reduced to The minimum amount can reduce the overheating of the suction gas (for example, refrigerant gas) coming to the compressor due to the aforementioned oil, and does not inhibit the decrease in volumetric efficiency. Further, in the present embodiment, since the oil is discharged to the suction port 22, the time during which the refrigerant gas sucked into the compressor is overheated by the oil can be extremely reduced, and the oil heating can be reduced. In the case of a refrigerant gas, it is possible to suppress a decrease in volumetric efficiency.

Over-compression When the aforementioned compression-actuating chambers 36A, 36B occur, the valve body 31 is controlled to open. At this time, the state in which the electromagnetic valve 42 is closed is set, and the high-pressure oil of the oil groove 95 is introduced into the cylinder chamber 35B. That is, by closing the electromagnetic valve 42, the high-pressure oil of the oil groove 95 is introduced into the cylinder chamber 35B via the capillary 120, and the pressure of the cylinder chamber 35B is almost the discharge pressure. Therefore, since the pressure acting on the piston 51 is almost the same on the cylinder chamber 35A side and the cylinder chamber 35B side, only the amount of pressing force by the spring 33 provided in the cylinder chamber 35B is directed toward the valve body side. The force of pushing the aforementioned piston 51 on the side of the end cover 60 becomes large. Therefore, as shown in Fig. 7, the piston 51 moves toward the end cover 60 side, the valve body 31 is separated from the main casing 15, and the valve hole 28 is opened.

The valve body driving device 30 that opens and closes the valve body 31 has the above-described configuration. However, in the present embodiment, it is further provided that it is detected whether or not excessive compression occurs in the compression operating chambers 36A and 36B. When the over-compression occurs, the control device for opening the valve body 31 by the valve body driving device 30 is controlled, and the device will be described below with reference to Fig. 1 .

In FIG. 1, reference numeral 110 denotes a suction pressure sensor that detects the pressure of the gas sucked from the suction port 6, and 111 denotes a discharge pressure sensor that detects the pressure of the compressed gas discharged from the compressor main body 1, from which The signals of the pressure sensors 110, 111 are sent to the control device 112. At the control device 112, the pressure ratio (discharge pressure/suction pressure) during the operation at this time point is calculated based on the signals from the pressure sensors 110, 111. Further, the control device 112 stores a pressure ratio set in advance and compares it with the calculated pressure ratio during the operation.

As a result of the comparison, when the calculated pressure ratio during operation is the same or higher than the previously set pressure ratio, it is judged that the compression operation chambers 36A and 36B are not over-compressed, and the solenoid valve 42 is set to In the open state, the valve body 31 is pressed toward the main casing 15 side and is controlled to close the valve hole 28.

On the other hand, when the calculated pressure ratio during operation is lower than the previously set pressure ratio, it is judged that over-compression is generated in the compression operation chambers 36A and 36B, and the electromagnetic valve 42 is set to the closed state. The valve body 31 is moved toward the opposite side (the right side of FIG. 6) from the main casing 15, thereby opening the control of the valve hole 28. As a result, since the compressed gas is discharged from the compression operation chambers 36A and 36B through the valve hole 28 and the bypass flow path (the bypass groove 29) toward the discharge chamber 26, the pressure in the compression operation chamber is almost lowered to the pressure in the discharge chamber 26. Therefore, over-compression can be alleviated, and unnecessary power consumption can be suppressed.

Further, in the present embodiment, the set volume ratio Vs/Vd which is a ratio of the volume Vs of the compression operation chamber at the time of suction closing to the volume Vd of the compression operation chamber when the valve hole 28 starts to be discharged is in the range of 1.5 to 3.0. Inside.

Further, in the present embodiment, the valve hole 28 of the discharge-side end surface 24 of the discharge casing 16 has a substantially centered position at the opening edge of the inner hole 20B of the end surface 21 of the main casing 15. That is, as shown in FIG. 3, the valve hole 28 is opened at the inner side of the inner side of the rotor in the radial direction of the inner side of the inner side of the rotor 20B, so that the opening area can be increased, and the valve hole 28 can be opened. On the other hand, the end surface 21 of the main casing 15 covers an outer region outside the opening edge of the inner hole 20B in the radial direction of the rotor. Thereby, the end surface 21 of the main casing 15 which can cover the outer region of the valve hole 28 functions as a brake of the valve body 31. (That is, the valve body 31 abuts against the end surface 21 to prevent tilting.) Therefore, as in the prior art, compared with the case where the valve body and the valve hole form a stepped portion as a brake for positioning the valve body, in this embodiment, For example, the brake for positioning the valve body can be simplified, and productivity can be improved because high-precision machining is not required as is conventional.

Further, for example, the valve body driving device 30 can be disposed on the outer side in the radial direction of the rotor as compared with the case where the center of the inner hole 20B is located on the inner side in the radial direction of the rotor hole 28, so that it can be prevented from being placed on the support side. The rolling bearing 18 and the ball bearing 19 of the discharge case 16 for the discharge-side shaft portion of the rotor 14B interfere with each other. Therefore, since it is not necessary to lengthen the discharge-side shaft portion of the spiral rotor 14, it is possible to suppress an increase in size of the compressor.

Further, in the present embodiment, the bypass flow path is constituted by the bypass groove 29 formed on the discharge side end surface 24 of the discharge case 16 and the end surface 21 of the main casing 15 covering the groove. The formation of the bypass groove 29 at the stage of casting can reduce the number of machining hours as compared with the case of forming a bypass passage as a bypass flow path.

Next, a modification of the above-described first embodiment will be described. In the first embodiment, as shown in FIG. 3, an example in which one valve hole 28 is provided on the female rotor 14B side of the discharge-side end surface 24 of the discharge casing 16 is described. However, the number of the valve holes or the number of the valve holes may be provided. The position is not limited thereto, and for example, the configurations of the modifications 1 to 3 shown in FIGS. 9 to 11 described below may be employed.

Fig. 9 shows a first modification. In this example, only one valve hole 37 is provided on the side of the male rotor 14A on the discharge side end surface 24 of the discharge casing 16. In other words, in the vicinity of the discharge port 25A on the side of the male rotor 14A on the discharge side end surface 24 of the discharge case 16, the valve hole 37 is provided at a position that is open on the side opposite to the rotation direction of the male rotor 14A. 38 is a bypass groove that connects the valve hole 37 and the discharge chamber 26. Similarly to those shown in FIGS. 6 to 8, the valve hole 37 is provided with a valve body driving device 30 for opening and closing the valve body 31 or the valve body 31. In addition, the set volume ratio Vs/Vd of the ratio of the volume Vs of the compression operation chamber at the time of suction closing to the volume Vd of the compression operation chamber at the start of discharge of the valve hole 37 is also 1.5 in the same manner as in the above-described first embodiment. Within the range of ~3.0. Further, the center of the valve hole 37 of the discharge-side end surface 24 of the discharge casing 16 is also configured to have an opening edge of the inner hole 20A almost at the end surface 21 of the main casing 15, similarly to the above-described first embodiment.

Therefore, even in the first modification shown in Fig. 9, almost the same effects as those of the first embodiment described above can be obtained.

FIG. 10 is a view showing a modification 2 in which one valve hole 28 or 37 is provided in each of the male rotor 14A side and the female rotor 14B side of the discharge side end surface 24 of the discharge casing 16 . In other words, on the side of the female rotor 14B of the discharge casing 16, a valve hole 28, a bypass groove 29, a valve body driving device 30, and the like are provided in the same manner as those shown in Fig. 3, and the male rotor 14A side of the discharge casing 16 is provided. Similarly to the case shown in Fig. 9, a valve hole 37, a bypass groove 38, a valve body driving device, and the like are provided. In this example, the ratio of the volume Vs of the compression operation chamber when the suction is closed to the volume Vd of the compression operation chamber at the start of discharge of each valve hole on the valve hole 28 side and the valve hole 37 side is set. The volume ratios Vs/Vd may also be identical to each other or different from each other.

Also in the second modification, the same effects as those of the above-described embodiment can be obtained, and since the valve holes 28 or 37 are provided on both the side of the male rotor 14A and the side of the female rotor 14B, the compression operation chamber can be obtained from the compression. Exhausting the compressed gas toward the discharge side at a faster rate prevents over-compression and suppresses excessive power consumption.

Fig. 11 is a view showing a modification 3. In each of the above-described examples, one valve hole 28 or 38 is provided on the female rotor 14B side or the male rotor 14A side, or one valve hole 28 or 38 is provided on each of the female rotor 14B side and the male rotor 14A side. . On the other hand, in the third modification, a plurality of valve holes are provided on either the female rotor 14B side or the male rotor 14A side, or a plurality of valve holes are provided in each of the two. For example, as shown in Fig. 11, in the discharge casing 16, two valve holes 28A, 28B are provided on the female rotor 14B side, and a bypass groove 29A that communicates the valve holes 28A, 28B and the discharge chamber 26 is formed. Similarly to the above-described embodiment, a valve body is provided in each of the valve holes 28A and 28B, and a valve body driving device that opens and closes the valve bodies is also provided.

Further, in this example, the set volume ratio Vs/Vd which is a ratio of the volume Vs of the compression operation chamber at the time of suction closing to the volume Vd of the compression operation chamber at the start of discharge of each of the valve holes 28A and 28B is set as a valve. Both sides of the holes 28A and 28B are in the range of 1.5 to 3.0. However, since the valve hole 28A side and the 28B side are arranged to be offset from each other in the rotation direction of the female rotor, each of the set volume ratios Vs/Vd is different from each other. Moreover, in this example, the respective centers of the valve holes 28A and 28B of the discharge-side end surface 24 of the discharge case 16 are also the opening edges of the inner holes 20B which are almost at the end faces 21 of the main casing 15, respectively.

Also in the third modification, the same effects as those of the above-described embodiment can be obtained, and since the valve holes are arranged to be offset from each other in the rotation direction of the rotor, the total passage area of the plurality of valve holes can be prevented from interfering with the rotor. It can be increased efficiently.

Fig. 12 is a view showing the configuration of a refrigeration cycle in which the screw compressor shown in the first embodiment of the present invention is incorporated in the cold cooler unit.

In Fig. 12, 130 is the screw compressor shown in the first embodiment, and the refrigerant gas discharged from the compressor 130 enters the oil separator 92 via the discharge pipe 94. Here, the oil is separated, and the refrigerant gas passes through the pipe (refrigerant pipe). 96 is sent to the condenser 140. In the condenser, the refrigerant gas is cooled and condensed as a liquid refrigerant, and is sent to the electronic expansion valve 142 to be expanded. An evaporator 141 is provided downstream of the electronic expansion valve 142, and the expanded refrigerant is taken up by the coolant 141 from external cooling water or the like to be evaporated, and then sucked into the compressor 130. The cooling water cooled by the evaporator 141 is used as a cold room or the like.

A suction pressure sensor 110 is provided on the suction side of the compressor 130, and a discharge pressure sensor 111 is provided on the discharge side of the compressor 130 to detect the suction pressure and the discharge pressure of the refrigerant gas. 42 is a solenoid valve similar to the solenoid valve 42 shown in FIGS. 6 and 7, and the solenoid valve 42 is opened and closed in accordance with a command from the control device 112. The control device 112 determines the pressure ratio during operation based on the suction pressure of the compressor 130 and the discharge pressure of the compressor 130, and compares the pressure ratio with the set pressure ratio stored in advance, during operation. When the pressure ratio is smaller than the pressure ratio set as described above, it is judged that over-compression occurs, and as shown in FIG. 7, the valve body driving device 30 controls the solenoid valve 42 to open the valve body 31.

In the cold cooler unit, since the temperature of the cooling water is usually controlled to a target value, there is little variation in the suction pressure affected by the temperature of the cooling water, but the cooling condensing pressure in the condenser is when the external air becomes low. Since the pressure is lowered, the pressure on the discharge side of the compressor detected by the discharge pressure sensor 111 fluctuates. Therefore, in the compressor 130, although over-compression is likely to occur, the use of the screw compressor shown in this embodiment can reduce the occurrence of over-compression and obtain a cold-cooler unit with less power loss.

According to the present embodiment described above, since it is a pressure ratio (discharge pressure/suction pressure) set in advance, when the pressure ratio calculated from the measured suction pressure and the discharge pressure is high, the suction toward the compressor is performed. The valve body is closed by the oil pressure in the cylinder on the valve body side of the side discharge piston, and the valve body is closed when the pressure ratio calculated from the measured suction pressure and the discharge pressure is low with respect to the previously set pressure ratio. Since the oil pressure in the cylinder opens the valve body, the valve body can be surely opened and closed, and over-compression can be alleviated. As a result, the consumption of excess power can be suppressed and performance can be improved. As compared with the case where the valve is opened and closed by the balance between the pressure acting on the compression chamber of the valve body and the pressure on the discharge side and the spring force, the valve body can be surely opened and closed, and the pressure fluctuation of the compression chamber can be controlled. The valve body is prevented from rattling, and therefore, a screw compressor that reduces the struck sound or vibration of the valve body can be obtained.

In particular, since the spring that presses the piston toward the valve body side is provided in the cylinder on the valve body side of the piston, even if the pressure in the compression chamber is fluctuated, there is no possibility that the spring is struck against the valve body by the brake. Therefore, the struck sound of the valve body knocking brake and the vibration of the valve body can be eliminated, and since the spring provided in the cylinder does not have a repetitively elastic expansion and contraction, the reliability can be improved.

Further, in the conventional article described in Patent Document 1, when the valve is opened and closed, when the gas passes through the valve portion, the flow rate is compressed, so that the fluid friction is increased, and the over-compression cannot be sufficiently alleviated. On the other hand, according to the present embodiment, since the valve body is controlled to be fully open or fully closed by the control device, it is possible to prevent the compression from the valve body portion due to the change in the degree of opening of the valve body as in the related art. The outflowing gas causes the fluid to become frictionally large, so that the over-compression can be sufficiently alleviated.

1. . . Compressor body

2. . . motor

5. . . Inhalation chamber

6. . . suction point

9. . . Spit

10. . . Rotary axis

13. . . Motor housing

14. . . Spiral rotor (14A: male rotor, 14B: female rotor)

15. . . Main housing (21: end face)

16. . . Spit shell (24: discharge side end face)

17, 18. . . Rolling bearing

19, 91. . . Ball bearing

20. . . Inner hole (20A: male rotor side inner hole, 20B: female rotor side inner hole)

twenty two. . . Inhalation 埠 (low pressure space)

23, 23A, 23B. . . Spit in the radial direction埠

25, 25A, 25B. . . Axial spitting

26. . . Spit room

28, 28A, 28B, 37. . . Valve hole (28a: back pressure chamber)

29, 29A, 38. . . Bypass groove (bypass flow path)

30. . . Valve body drive

31. . . Valve body

32. . . Connecting hole (gas pressure supply path)

34, 120. . . Hydraulic supply path (34: communication hole, 120: capillary)

35. . . Cylinder (35A, 35B: cylinder chamber)

36A, 36B. . . Compression chamber

42. . . The electromagnetic valve

50, 54. . . Sealing ring

51. . . piston

52. . . Screw

53. . . Putt

60. . . End cap

80. . . Connecting road (oil pressure discharge road)

90. . . Spit out the flow

92. . . Oil separator

93. . . Oil return piping

94. . . Spit pipe

95. . . Oil tank

96. . . Piping (refrigerant piping)

102. . . Connecting hole

110. . . Suction pressure sensor

111. . . Spit pressure sensor

112. . . Control device

130. . . Screw compressor

140. . . Condenser

141. . . Evaporator

142. . . Electronic expansion valve

Fig. 1 is a longitudinal sectional view showing a first embodiment of a screw compressor according to the present invention.

FIG. 2 is a right side view of FIG. 1. FIG.

Fig. 3 is a cross-sectional view taken along line III-III of Fig. 1;

Fig. 4 is a cross-sectional view taken along line IV-IV of Fig. 1;

Fig. 5 is a view for explaining a positional relationship between a compression operation chamber, a discharge port, a valve hole, and a bypass flow path in the first embodiment of the present invention.

Fig. 6 is a cross-sectional view taken along the line VI-VI of Fig. 2, showing a closed state of the valve body.

Fig. 7 is a cross-sectional view taken along the line VI-VI of Fig. 2, showing a state in which the valve device is opened.

Fig. 8 is a cross-sectional view taken along the line VIII-VIII of Fig. 6;

Fig. 9 is a view for explaining a first modification of the first embodiment, showing a discharge-side end surface of the discharge casing.

FIG. 10 is a view corresponding to FIG. 9 for explaining a modification of the second embodiment.

Fig. 11 is a view corresponding to a third modification of the first embodiment, showing a view corresponding to Fig. 9 .

Fig. 12 is a view showing a configuration of a refrigeration cycle in which an example of a cold cooler unit showing the screw compressor of the first embodiment is mounted.

15. . . Main housing

twenty two. . . Inhalation 埠 (low pressure space)

80. . . Connected road

42. . . The electromagnetic valve

twenty one. . . End face

31. . . Valve body

29. . . Bypass

16. . . Spit shell

twenty four. . . Discharge side face

33. . . spring

120. . . Capillary

34. . . Connecting hole

35. . . cylinder

30. . . Valve body drive

54. . . Sealing ring

51. . . piston

32. . . Connecting hole (gas pressure supply path)

60. . . End cap

52. . . Screw

35A. . . Cylinder chamber

35B. . . Cylinder chamber

14B. . . Female rotor

36B. . . Compression chamber

twenty four. . . Discharge side face

28. . . Valve hole

28a. . . Back pressure chamber

50. . . Sealing ring

102. . . Connecting hole

101. . . Rod hole

35B. . . Cylinder chamber

53. . . Putt

Claims (11)

A screw compressor having a male rotor and a female rotor that rotate while rotating a shaft substantially parallel to each other; a main casing having an inner hole for accommodating the male rotor and the female rotor; and a rotor having the main casing The end surface of the main casing that is connected to the axial discharge side and covers the discharge casing of the discharge end surface of the inner hole opening, and includes a compression operation chamber formed by the male rotor and the female rotor. a discharge port formed in at least one of the main casing or the discharge case, and a discharge chamber or a discharge flow path for discharging compressed gas; and at least one of the male rotor and the female rotor in the vicinity of the discharge port a discharge side end surface of the discharge case on the side is formed in a valve hole at a position where the compression operation chamber is opened, a bypass flow path that communicates the valve hole with the discharge chamber or the discharge flow path, and is disposed in the valve hole The valve body screw compressor is characterized in that: a valve body driving device for opening and closing the valve body; and detecting whether or not there is excessive compression in the compression operating chamber When it is detected that compression has occurred, the valve body driving device is controlled to open the control device of the valve body, and the control device determines the operating pressure based on the suction pressure drawn into the compressor and the discharge pressure of the compressor. a pressure ratio, and comparing the pressure ratio with a preset pressure ratio that is previously memorized, and determining that over-compression occurs when the pressure ratio during operation is smaller than the set pressure ratio, thereby controlling the valve body a driving device that opens the valve body, and the valve body driving device is provided on a back side of the valve body a cylinder, a piston reciprocating in the cylinder, and a push rod connecting the piston and the valve body, when over-compression occurs, a pressure is applied to the piston to form a valve body that opens the valve body and the piston The spring in the side of the cylinder is provided with a spring that urges the piston toward the valve body side, and the compressed gas that guides the discharge side of the compressor is guided in the cylinder on the valve body side of the piston. When there is no over-compression, the above-mentioned state is closed. In the valve body, when the over-compression occurs, the pressure is applied to the cylinder on the valve body side of the piston, and the piston is moved toward the valve body side to open the valve body. The screw compressor according to claim 1, wherein the inside of the cylinder on the valve body side of the piston and the discharge side of the compressor are connected by a passage having a capillary tube, and a cylinder side of the passage and a low pressure of the compressor are provided. A communication passage that communicates with the space is provided with a solenoid valve that opens and closes the communication passage in the middle of the communication passage, and the communication passage is opened when no over-compression occurs, and when the over-compression occurs, the communication passage is closed to open the compressor discharge side. The pressure acts on the valve body side of the piston to open the valve body. The screw compressor according to the first aspect of the invention, wherein the valve hole of the discharge-side end surface of the discharge casing is slightly centered at an opening edge of the inner hole of the end surface of the main casing. The screw compressor according to claim 2, wherein the cylinder passage having the capillary passage is outside the movement range of the piston, and the communication passage communicating with the low pressure space is opened in the suction port of the compressor. The screw compressor according to the fourth aspect of the invention, wherein the passage having the capillary is a hydraulic pressure supply passage having an oil groove opening that communicates with the compressor discharge side on the upstream side. The screw compressor according to the first aspect of the invention, wherein the discharge case forms a gas pressure supply path on the cylinder inner end side of the counter valve body side to which the piston is connected and the discharge side of the compressor. The screw compressor according to the first aspect of the invention, wherein the bypass flow path is: a bypass groove formed on an ejection end surface of the discharge case; and an end surface of the main case covering the bypass groove Composition. The screw compressor according to the first aspect of the invention, wherein the valve hole is a ratio of a ratio of a volume Vs of the compression chamber when the suction is closed to a volume Vd of the compression chamber when the valve hole is discharged. The volume ratio Vs/Vd is formed in the range of 1.5 to 3.0. The screw compressor according to the first aspect of the invention, wherein the valve hole is formed in plural, and is a compression chamber that is a volume of a compression operation chamber when the suction is closed and a discharge chamber that is started by the discharge of each of the valve holes. The set volume ratio of the volume Vd is formed such that the ratio Vs/Vd is different from each other. The screw compressor according to the first aspect of the invention, comprising: a suction pressure sensor for detecting a suction pressure; and a discharge pressure sensor for detecting a discharge pressure. The screw compressor according to the first aspect of the invention, wherein the discharge port is formed by a discharge port formed in a radial direction of a discharge side end portion of the main casing, and a discharge port formed on the discharge side of the discharge case The axial discharge of the end face is formed.