WO2017175298A1

WO2017175298A1 - Screw compressor and refrigeration cycle device

Info

Publication number: WO2017175298A1
Application number: PCT/JP2016/061090
Authority: WO
Inventors: 克也前田; 雅章上川; 下地　美保子; 英彰永田
Original assignee: 三菱電機株式会社
Priority date: 2016-04-05
Filing date: 2016-04-05
Publication date: 2017-10-12

Abstract

A screw compressor according to the invention includes: a casing body having a cylindrical inner cylinder surface part; a screw rotor stored in the inner cylinder surface part and having a plurality of screw grooves on the outer circumferential surface thereof; a plurality of gate rotors provided on both sides of the screw rotor so as to be symmetric about the rotation axis of the screw rotor, and each having, on the outer circumference thereof, a plurality of teeth engaged with the screw grooves; a slide valve provided between the casing body and the screw rotor, and movable in the direction of the rotation axis; and a high-low pressure partition that separates a high pressure space to have a discharge pressure atmosphere from a low pressure space to have a suction pressure atmosphere in the casing body, wherein the high-low pressure partition and the back surface of a fixed outlet that forms a part of a discharge outlet for compressed fluid have a seal surface for suppressing fluid leakage together with the back surface of the slide valve.

Description

Screw compressor and refrigeration cycle equipment

The present invention relates to a screw compressor or the like. In particular, it relates to securing a discharge path for fluid discharged from a compression chamber of a screw compressor.

As the screw compressor, there is generally a single screw compressor having one screw rotor and two gate rotors.

In the single screw compressor, the screw rotor and the gate rotor are accommodated in the casing body. A plurality of spiral screw grooves are formed in the screw rotor. A pair of gate rotors arranged in the radial direction of the screw rotor mesh with and engage with the screw grooves. A compression chamber in which the refrigerant is compressed is formed between the screw groove, the gate rotor, and the casing body. Here, each gate rotor is fixed to a gate rotor support. Both ends of the shaft of the gate rotor support are supported by the bearing support via bearings. In the screw compressor, a low pressure chamber serving as a low pressure space and a discharge chamber serving as a high pressure space are formed. The low-pressure chamber becomes a suction pressure atmosphere, and the discharge chamber becomes a high-pressure space that becomes a discharge pressure atmosphere.

The screw rotor is fixed to the screw shaft. One end side of the screw shaft is supported by a bearing support via a bearing disposed on the discharge side of the screw rotor, and the suction side which is the other end side is connected to the motor rotor. When the screw rotor is rotationally driven by the motor, the fluid in the low-pressure chamber is sucked into the compression chamber and compressed, and the fluid compressed in the compression chamber is discharged into the discharge chamber.

In the conventional screw compressor as described above, at the time of operation, the discharge flow path side where the screw groove of the screw rotor is opened is the discharge pressure atmosphere. Moreover, the bearing side arranged facing the discharge side of the screw shaft becomes a suction pressure atmosphere. Here, in the screw compressor, since the discharge chamber and the low-pressure chamber are located in the vicinity, if a differential pressure occurs between the discharge chamber and the low-pressure chamber, the high pressure from the clearance between the screw rotor and the bearing support to the bearing side. Fluid leakage occurs. In addition, a clearance is required between the outer peripheral surface of the screw rotor and the casing so that the screw rotor can be rotationally driven. Leakage of high-pressure fluid also occurs from this clearance.

Also, in a screw compressor in which inverter control is performed, the motor may have a relatively low rotational speed when the operation load is small. When the rotational speed is low, the ratio of the leakage amount of the high-pressure fluid to the discharge amount of the screw compressor increases. For this reason, the greater the leakage of high-pressure fluid, the lower the operating efficiency of the compressor.

Therefore, in order to improve the operation efficiency of the screw compressor when the motor is in an operation state with a relatively low number of revolutions, a switching valve that can switch the compression chamber to a compression state or a non-compression state is provided. There are screw compressors that can perform the following operations (see, for example, Patent Document 1 and Patent Document 2).

In the operation in the one-side operation mode (one-side operation), for example, the switching valve is switched so that one of the two compression chambers is in an uncompressed state. By reducing the number of compression chambers capable of compressing fluid, the discharge amount of the compressed fluid is reduced, but the motor is operated with an increased number of revolutions. By increasing the number of rotations of the electric motor, the amount of high-pressure fluid leakage with respect to the discharge amount is reduced. In the normal operation, for example, the operation is a double-sided operation mode (both-side operation) in which fluid is compressed in all the compression chambers.

Japanese Patent No. 5445118 Japanese Patent No. 3214100

In Patent Document 1, etc., it is possible to achieve suppression of refrigerant leakage loss by preventing the motor speed from being lowered by properly using both-side operation and one-side operation. However, as the rotational speed increases, there is a concern that the effect of pressure loss in the discharge path will increase. Here, in patent document 2, in order to reduce the pressure loss in discharge, the area of the discharge port is expanded. However, the following problem arises when switching between one-side operation and both-side operation using the slide valve of Patent Document 2.

For example, in one-side operation, in order to move the slide valve to the discharge side most, it is necessary to increase the thickness of the high and low pressure partition walls separating the suction pressure and the discharge pressure toward the discharge side. Therefore, the high / low pressure partition wall becomes a factor of narrowing the discharge area when performing both-side operation. As a result, there is a possibility that performance will be degraded.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a screw compressor having a one-side operation function capable of ensuring a flow passage area in a discharge path. .

A screw compressor according to the present invention includes a casing body having a cylindrical inner cylinder surface, a screw rotor housed in the inner cylinder surface and having a plurality of screw grooves on an outer peripheral surface, and symmetrical with respect to the rotation axis of the screw rotor. In addition, a plurality of gate rotors that are arranged on both sides of the screw rotor and have a plurality of teeth meshing with the screw grooves on the outer periphery, and a slide that is movable between the casing body and the screw rotor and that can move in the direction of the rotation axis A fixed high-pressure partition wall and a high-low pressure partition wall that separates a high-pressure space serving as a discharge pressure atmosphere and a low-pressure space serving as a suction pressure atmosphere in the casing body, and is a part of a discharge port for compressed fluid The back surface of the mouth has a seal surface that suppresses fluid leakage with the back surface of the slide valve.

Further, the refrigeration cycle apparatus according to the present invention constitutes a refrigerant circuit in which the screw compressor, the condenser, the decompression device, and the evaporator described above are connected in order by refrigerant piping to circulate the refrigerant that is a fluid.

According to the present invention, the high and low pressure partition wall has a sealing surface that can seal the back surface of the slide valve on the back surface side of the fixed port. For example, even if the compression chamber is in an uncompressed state, the fixed port Thus, the backflow of fluid from the discharge chamber side can be eliminated. For this reason, it is possible to provide a screw compressor capable of performing one-side operation while securing a flow passage area in the discharge path.

It is a figure which shows the structure of the refrigerating-cycle apparatus 100 provided with the screw compressor 102 which concerns on Embodiment 1 of this invention. It is the schematic explaining the internal structure in the screw compressor 102 which concerns on Embodiment 1 of this invention. It is a figure which shows the compression principle of the screw compressor 102 which concerns on Embodiment 1 of this invention. It is a figure explaining the both-sides operation of screw compressor 102 concerning Embodiment 1 of the present invention. It is a figure which shows the flow of the refrigerant | coolant in the 1st compression chamber 11a in the both-sides driving | operation of the screw compressor 102 which concerns on Embodiment 1 of this invention. It is a figure showing the relationship between the screw rotor 9 and the 1st slide valve 14a in the both-sides operation of the screw compressor 102 which concerns on Embodiment 1 of this invention. It is a figure explaining the one-side driving | operation of the screw compressor 102 which concerns on Embodiment 1 of this invention. It is a figure which shows the flow of the refrigerant | coolant in the 1st compression chamber 11a in the one-side driving | operation of the screw compressor 102 which concerns on Embodiment 1 of this invention. It is a figure showing the relationship between the screw rotor 9 and the 1st slide valve 14a in the one-side driving | operation of the screw compressor 102 which concerns on Embodiment 1 of this invention. It is a figure explaining the relationship between the 1st fixed port 19a which concerns on Embodiment 1 of this invention, and the back side of the 1st slide valve 14a. It is a figure explaining the opening area of the 1st fixing port 19a which concerns on Embodiment 1 of this invention. It is FIG. (1) which shows the positional relationship of the slide valve 14 in each driving | operation which concerns on Embodiment 2 of this invention. It is FIG. (2) which shows the positional relationship of the slide valve 14 in each driving | operation which concerns on Embodiment 2 of this invention. It is FIG. (The 3) which shows the positional relationship of the slide valve 14 in each driving | operation which concerns on Embodiment 2 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, in the following drawings, what attached | subjected the same code | symbol is the same or it corresponds, and shall be common in the whole sentence of embodiment described below. Moreover, the form of the component shown by the whole specification is an illustration to the last, and is not limited to these description. In particular, the combination of the constituent elements is not limited to the combination in each embodiment, and the constituent elements described in the other embodiments can be applied to other embodiments as appropriate. The pressure level is not particularly determined in relation to the absolute value, but is relatively determined in terms of the state and operation of the system and apparatus. In addition, when there is no need to distinguish or identify a plurality of similar devices that are distinguished by subscripts, the subscripts may be omitted.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a refrigeration cycle apparatus 100 including a screw compressor 102 according to Embodiment 1 of the present invention. In the following description, the screw compressor 102 is described as being a device constituting a refrigerant circuit. For this reason, description will be made assuming that the fluid sucked, compressed and discharged by the screw compressor 102 of the first embodiment is a refrigerant.

The refrigeration cycle apparatus 100 according to Embodiment 1 includes a screw compressor 102, a condenser 104, an expansion valve 105, and an evaporator 106 connected in order by refrigerant piping, and has a refrigerant circuit that circulates refrigerant. is doing.

The inverter device 101 controls the drive frequency of the screw compressor 102 by controlling the power supply to the screw compressor 102 based on the instructed frequency. The screw compressor 102 is driven by electric power supplied via an inverter device 101 from a power supply source (not shown). The configuration of the screw compressor 102 will be described later. The condenser 104 cools and condenses the gas refrigerant that is a gaseous refrigerant discharged from the screw compressor 102. The expansion valve 105 serving as a decompression device decompresses and expands the liquid refrigerant that is a liquid refrigerant that has flowed out of the condenser 104. The evaporator 106 evaporates the refrigerant that has passed through the expansion valve 105.

The refrigeration cycle apparatus 100 further includes a control device 110. The control device 110 controls the frequency of the inverter device 101, the opening degree of the expansion valve 105, and the like, and sends an instruction to each device. In particular, in the first embodiment, the control device 110 has a slide valve control device 111. As will be described later, the slide valve control device 111 performs position control of the two slide valves 14 included in the screw compressor 102 and the like.

(Screw compressor)
FIG. 2 is a schematic diagram illustrating the internal configuration of the screw compressor 102 according to Embodiment 1 of the present invention. Here, in FIG. 2, it is a figure which shows the structure of the part located in the upper side of the screw shaft 10 used as a rotating shaft. The structure of the lower part of the screw shaft 10 is the same as that of the upper part. In the screw compressor 102, when the part located on the upper side of the screw shaft 10 and the part located on the lower side are the same part, the part located on the upper side is given a subscript a, and the part located on the lower side is added. Is described with a subscript b.

As shown in FIG. 2, the screw compressor 102 according to the first embodiment includes a casing body 8, a screw rotor 9, a gate rotor 6, a motor 3 that rotationally drives the screw rotor 9, a slide valve 14, and the like.

The cylindrical casing body 8 accommodates the screw rotor 9, the gate rotor 6, the motor 3, the slide valve 14 and the like on the inner cylindrical surface that is the inner side of the cylinder. The motor 3 includes a stator 31 that is inscribed and fixed to the casing body 8 and a motor rotor 32 that is disposed inside the stator 31. The motor 3 serving as an electric motor rotates at a rotational speed based on the electric power supplied from the inverter device 101, rotates the screw shaft 10, and drives the screw compressor 102 at a driving frequency.

Further, a screw rotor 9 is disposed in the casing body 8. The screw rotor 9 and the motor rotor 32 are disposed on and fixed to the screw shaft 10 serving as a rotation shaft. The screw rotor 9 has a plurality of helical screw grooves 91 formed on the outer peripheral surface. The screw rotor 9 is rotated with the rotation of the motor rotor 32 fixed to the screw shaft 10.

The screw compressor 102 according to the first embodiment has two gate rotors 6. The two gate rotors 6 are disposed on both sides of the screw rotor 9 so as to be symmetric (point-symmetric) with respect to the screw shaft 10. Here, one is a first gate rotor 6a and the other is a second gate rotor 6b. Each gate rotor 6 has a disk shape. A plurality of teeth 61 are provided on the outer periphery of the gate rotor 6 along the circumferential direction. The teeth 61 of the gate rotor 6 are engaged with the screw grooves 91 of the screw rotor 9. A space surrounded by the teeth 61 of the gate rotor 6, the screw groove 91, and the inner cylindrical surface of the casing body 8 becomes the compression chamber 11. The compression chamber 11 surrounded by the teeth 61 of the first gate rotor 6a, the screw groove 91, and the inner cylindrical surface of the casing body 8 is defined as a first compression chamber 11a. The compression chamber 11 surrounded by the teeth 61 of the second gate rotor 6b, the screw groove 91, and the inner cylindrical surface of the casing body 8 is defined as a second compression chamber 11b.

The casing body 8 has a high and low pressure partition wall 17 that divides the inside of the casing body 8 into a discharge pressure side and a suction pressure side. The high / low pressure partition wall 17 is formed in the casing body 8 so as to face the casing body 8 side of the slide valve 14 described later. A discharge chamber 12 in a high-pressure space serving as a discharge pressure atmosphere is formed on the discharge pressure side of the casing body 8. Further, the discharge port 13 is an opening portion that allows the compression chamber 11 and the discharge chamber 12 to communicate with each other. An opening portion of the slide valve 14 to be described later and a fixed port 19 are also part of the discharge port 13. As shown in FIG. 10 to be described later, the fixed port 19 is an opening portion to a compression chamber 11 in a space provided to prevent the refrigerant liquid and the like from being compressed.

Furthermore, a slide valve 14 is provided in the casing body 8. The slide valve 14 is connected to a drive device 16 via a rod 15 that is a connecting rod. The drive device 16 such as a piston moves and positions the slide valve 14 in the direction of the rotation axis around which the screw rotor 9 rotates based on an instruction from the slide valve control device 111. Here, the slide valve 14 is located inside the casing body 8 and faces the screw rotor 9. Therefore, the slide valve 14 becomes a part of the wall surface surrounding the compression chamber 11. The slide valve 14 is partially open, and the opening becomes a part of the discharge port 13 described above. In the following description, the surface facing the casing 8 main body side in the slide valve 14 is referred to as a “back surface”, and the surface facing the screw rotor 9 side is described as an “inner peripheral surface”. In the following description, the upper slide valve 14 shown in FIG. 2 will be described as a first slide valve 14a, and the lower slide valve 14 (not shown) will be described as a second slide valve 14b.

For example, when the slide valve 14 is positioned on the suction side in the direction of the rotation axis in which the screw rotor 9 rotates, the compression chamber 11 includes the casing body 8 including the screw groove 91, the teeth 61 of the gate rotor 6, and the slide valve 14. Sandwiched between. For this reason, the compression chamber 11 will be in the compression state which raises the pressure of the refrigerant | coolant in the compression chamber 11 by compression. On the other hand, when the slide valve 14 is located on the most discharge side, the compression chamber 11 communicates with a low pressure chamber that is a low pressure space of the suction pressure atmosphere. For this reason, a refrigerant | coolant is not compressed in the compression chamber 11, but it will be in the non-compression state by which the refrigerant | coolant of the compression chamber 11 is hold | maintained with the constant pressure close | similar to a suction pressure.

In the first embodiment, the slide valve control device 111 sends an instruction to the drive device 16 to move the first slide valve 14a to perform switching control for switching the first compression chamber 11a between the compressed state and the non-compressed state. be able to. An operation in which all the compression chambers 11 (the first compression chamber 11a and the second compression chamber 11b) among the plurality of compression chambers 11 that can be made into the screw compressor 102 are compressed is referred to as a double-side operation. In addition, an operation that is performed with some of the compression chambers 11 (first compression chambers 11a) in an uncompressed state is referred to as a one-side operation. When the screw compressor 102 performs one-side operation, the motor 3 is operated by increasing the number of revolutions of the motor 3. Here, the non-compressed state in which the fluid in the compression chamber 11 is held at a constant pressure is not only a state in which the fluid is not compressed at all, but even if the pressure in the compression chamber 11 fluctuates, the degree of variation is compared with the compressed state. In some cases, the compression is very small. Further, the driving device 16 such as a piston for driving the slide valve 14 is not limited in terms of driving means such as one driven by gas pressure, one driven by hydraulic pressure, one driven by a motor or the like separately from the piston. To do.

(Description of operation of screw compressor 102)
FIG. 3 is a diagram illustrating a compression principle of the screw compressor 102 according to the first embodiment of the present invention. Next, the operation of the screw compressor 102 according to Embodiment 1 will be described. For example, when the screw rotor 9 is rotated by the motor 3 shown in FIG. 2 via the screw shaft 10 shown in FIG. 2, the teeth 61 of the gate rotor 6 are compressed into the compression chamber 11 (screw groove) as shown in FIG. 91) Move relatively within. At this time, in the compression chamber 11, a suction stroke, a compression stroke, and a discharge stroke are sequentially performed. The cycle is repeated with the suction stroke, the compression stroke, and the discharge stroke as one cycle. Here, focusing on the compression chamber 11 indicated by dot-shaped hatching in FIG. 3, each stroke will be described.

FIG. 3A shows the state of the compression chamber 11 in the suction stroke. The screw rotor 9 is driven by the motor 3 and rotates in the direction of the solid arrow. When the screw rotor 9 rotates, the volume of the compression chamber 11 decreases as shown in FIG.

When the screw rotor 9 continues to rotate, the compression chamber 11 communicates with the discharge chamber 12 through the discharge port 13 as shown in FIG. Thereby, the high-pressure refrigerant gas compressed in the compression chamber 11 is discharged from the discharge port 13 to the discharge chamber 12. Then, the same compression is performed again on the back surface of the screw rotor 9.

FIG. 4 is a diagram for explaining the both-side operation of the screw compressor 102 according to the first embodiment of the present invention. For example, the slide valve control device 111 of the control device 110 sends an instruction to the drive device 16 to position, for example, the first slide valve 14a on the suction side as shown in FIG. Here, it is located on the most suction side.

FIG. 5 is a diagram showing a refrigerant flow in the first compression chamber 11a in the both-side operation of the screw compressor 102 according to Embodiment 1 of the present invention. Moreover, FIG. 6 is a figure showing the relationship between the screw rotor 9 and the 1st slide valve 14a in the both-sides operation of the screw compressor 102 which concerns on Embodiment 1 of this invention. Since the first slide valve 14a is positioned on the suction side, the first compression chamber 11a is spatially separated from the low pressure chamber that is the suction pressure atmosphere after the suction stroke. For this reason, the compression stroke is possible in the first compression chamber 11a. As shown in FIG. 6, the opening portion of the first slide valve 14a also functions as the first discharge port 13a. The first compression chamber 11a and the discharge chamber 12 communicate with each other and are compressed in the first compression chamber 11a. The refrigerant is discharged into the discharge chamber 12. The first fixed port 19a also becomes the first discharge port 13a.

On the other hand, the slide valve control device 111 sends an instruction to the drive device 16 to move the second slide valve 14b in the direction of the screw shaft 10 to move it to an arbitrary position where the refrigerant can be compressed. Also in the second compression chamber 11b, a compression stroke is possible.

As described above, in both-side operation, the refrigerant can be compressed in the first compression chamber 11a and the second compression chamber 11b. Then, the high-pressure refrigerant gas compressed in the compression chamber 11 is discharged from the discharge port 13 to the discharge chamber 12.

FIG. 7 is a diagram for explaining the one-side operation of the screw compressor 102 according to the first embodiment of the present invention. For example, the slide valve control device 111 of the control device 110 sends an instruction to the drive device 16 to position the first slide valve 14a closest to the discharge side as shown in FIG.

FIG. 8 is a diagram showing a refrigerant flow in the first compression chamber 11a in the one-side operation of the screw compressor 102 according to Embodiment 1 of the present invention. Moreover, FIG. 9 is a figure showing the relationship between the screw rotor 9 and the 1st slide valve 14a in the one-side driving | operation of the screw compressor 102 which concerns on Embodiment 1 of this invention. As described above, since the first slide valve 14a is located on the most discharge side, the first compression chamber 11a communicates with the low pressure chamber in the suction pressure atmosphere. For this reason, the first compression chamber 11a is not compressed and is in an uncompressed state. Further, as shown in FIGS. 8 and 9, the opening portion of the first slide valve 14a does not function as the first discharge port 13a, and the first slide valve 14a is connected to the first fixed port 19a of the first discharge port 13a. Block the parts other than the part. Therefore, the first compression chamber 11a and the discharge chamber 12 do not communicate with each other, and the refrigerant does not flow from the first compression chamber 11a side to the discharge chamber 12.

On the other hand, the slide valve control device 111 sends an instruction to the drive device 16 to move the second slide valve 14b in the direction of the screw shaft 10 and to an arbitrary position where the refrigerant can be compressed. In the second compression chamber 11b, the compression stroke can be performed as in the case of the double-side operation.

As described above, in the one-side operation, the high-pressure refrigerant gas compressed in the second compression chamber 11b is discharged from the discharge port 13 to the discharge chamber 12. The compressed refrigerant gas is not discharged from the first compression chamber 11a. Therefore, in the first embodiment, the component with the subscript “a” is compressed in the refrigerant during the both-side operation, but does not contribute to the compression of the refrigerant in the one-side operation. On the other hand, the component with the suffix “b” contributes to the compression of the refrigerant in the one-side operation and the both-side operation.

FIG. 10 is a diagram for explaining the relationship between the first fixed port 19a and the back side of the first slide valve 14a according to Embodiment 1 of the present invention. The first slide valve 14 a is a part of the wall surface surrounding the compression chamber 11. Therefore, even if the first slide valve 14a moves, it is necessary to seal between the first slide valve 14a and a member facing the first slide valve 14a so that the refrigerant does not leak from the discharge chamber 12a side to the low pressure chamber side.

At least a fixed port that separates the discharge chamber 12a side from the first fixed port 19a by a seal with the back surface of the first slide valve 14a on the back side of the first fixed port 19a on the first compression chamber 11a side that is in an uncompressed state. It has a back seal surface 20a. By having the fixed port back seal surface 20a, it is possible to prevent the refrigerant from flowing backward from the discharge chamber 12a side to the low pressure chamber side via the first fixed port 19a. The fixed port rear seal surface 20a fills the gap between the first slide valve 14a and the first fixed port 19a so as to partially bury the casing, thereby forming the fixed port rear seal surface 20a.

Also, the high and low pressure partition wall 17 has a thickness that separates the discharge chamber 12 from the low pressure chamber so that the refrigerant does not leak from the discharge chamber 12 side to the low pressure chamber side by sealing with the back surface of the slide valve 14. For example, as described above, the first slide valve 14a is located on the most discharge side in the case of one-side operation, so that the movement range during both-side operation and one-side operation is widened. On the other hand, the movement range of the second slide valve 14b is narrower than that of the first slide valve 14a. Therefore, the thickness of the second high / low pressure partition wall 17b is arbitrarily less than the thickness of the first high / low pressure partition wall 17a shown in FIG. 2 (thickness of the second high / low pressure partition wall 17b ≦ thickness of the first high / low pressure partition wall 17a). Can be configured. By reducing the thickness of the second high / low pressure partition wall 17b, for example, a reduction in discharge pressure loss from the second discharge port 13b to the second high / low pressure partition wall 17b can be expected.

FIG. 11 is a diagram for explaining the opening area of the first fixed port 19a according to Embodiment 1 of the present invention. The first fixing port 19a is configured such that the axial width is narrower than the second fixing port 19b and the opening area is smaller than that of the second fixing port 19b within a range that does not affect liquid compression prevention. May be. The position of the discharge-side end of the first fixed port 19a is set to the same position as the second fixed port 19b. On the other hand, the position of the end (suction side wall surface) on the suction side in the axial direction of the first fixed port 19a is set to a position closer to the discharge side than the vicinity of the position of the end of the slide valve 14 during one-side operation. In addition, it can be set at an arbitrary position from the viewpoint of expanding the discharge port and reducing the liquid compression section. By narrowing the width toward the discharge side in the axial direction, the first slide valve 14a can be moved more toward the discharge side. For this reason, the start of compression can be further delayed, and useless compression (work) can be suppressed. Moreover, as shown in FIG. 10, the dead volume can be reduced by reducing the distance in the depth direction of the first fixed port 19a. Therefore, the dead volume loss in the one-side operation can be reduced. The volume of the first fixed port 19a may be smaller than the volume of the second fixed port 19b, for example, by reducing the axial width of the first fixed port 19a. Here, the dead volume is a volume in which compressed high-pressure fluid is not discharged but re-expands in communication with a low-pressure compression chamber or the like to generate useless compression power.

As described above, according to the screw compressor 102 of the first embodiment, since the fixed port back surface seal surface 20a that can seal the back surface of the first slide valve 14a is provided, in the one-side operation, the first fixed port 19a. Thus, the refrigerant can be prevented from leaking from the discharge chamber 12 side to the low pressure chamber side. Therefore, it is possible to provide the screw compressor 102 that can perform the one-side operation while ensuring the flow passage area in the discharge path. By performing the one-side operation, the highly efficient screw compressor 102 can be obtained including both-side operation.

Further, according to the screw compressor 102 of the first embodiment, the axial width of the first fixed port 19a is narrower than that of the second fixed port 19b, and the opening is larger than that of the second fixed port 19b. Since the area is reduced, the volume of the first fixed port 19a is reduced, and the dead volume loss in the one-side operation can be reduced. Even if the volume of the first fixing port 19a is reduced by reducing the length in the depth direction, the same effect can be obtained. Furthermore, according to the screw compressor 102 of the first embodiment, the second high / low pressure partition wall 17b is thinner than the first high / low pressure partition wall 17a. A reduction in discharge pressure loss to the partition wall 17b can be expected. The thickness of the high and low pressure partition wall 17 such as the volume of the fixed port 19 can be set according to the load state in each compression chamber 11.

Embodiment 2. FIG.
12 to 14 are views showing the positional relationship of the slide valve 14 in each operation according to Embodiment 2 of the present invention. In the first embodiment, the slide valve 14 of the screw compressor 102 is not particularly mentioned. In the second embodiment, it is assumed that one of the plurality of slide valves 14 included in the screw compressor 102 is a slide valve 14 that can change the internal volume ratio. The slide valve 14 capable of changing the internal volume ratio is assumed to be the second slide valve 14b. Other configurations are the same as those in the first embodiment. Here, the internal volume ratio is a ratio of the volume of the compression chamber 11 at the time of completion of suction (start of compression) and the volume of the compression chamber 11 just before the discharge. The internal volume ratio is changed by adjusting the timing at which the refrigerant is discharged from the discharge port 13. For example, when the operation load is small, as shown in FIG. 13, the second slide valve 14b is moved to the suction side, thereby shortening the discharge timing and achieving performance improvement by suppressing overcompression. Further, when the operation load is large, as shown in FIG. 14, by moving the second slide valve 14b to the discharge side, the discharge timing can be delayed and the performance improvement due to insufficient compression suppression can be expected.

In the screw compressor 102 according to the second embodiment, not only the two-side operation and the one-side operation are switched as in the first embodiment, but also the operation can be performed while controlling the internal volume ratio of the compression chamber 11 in the one-side operation. it can.

(Description of operation)
When the slide valve control device 111 of the control device 110 determines that the target refrigeration capacity is exceeded even if the screw compressor 102 is driven at the lower limit frequency during the both-side operation shown in FIG. 12, the screw compressor An instruction to switch 102 to operate on one side is sent to the drive device 16. Furthermore, about the 2nd slide valve 14b used as the side which compresses a refrigerant | coolant, it moves to the position which changes an internal volume ratio.

At this time, if the slide valve control device 111 determines that the compression is overcompressed, as shown in FIG. 13, the slide valve control device 111 moves the second slide valve 14b to a position where the internal volume ratio becomes small. If it is determined that the compression is insufficient, the second slide valve 14b is moved to a position where the internal volume ratio increases as shown in FIG. As described above, by making the internal volume ratio in the second compression chamber 11b changeable, power loss due to over-compression or under-compression can be suppressed. Therefore, the highly efficient screw compressor 102 can be provided.

Embodiment 3 FIG.
In Embodiment 2, the 2nd slide valve 14b shall be the slide valve 14 which can change an internal volume ratio. In the third embodiment, the first slide valve 14a is also a slide valve 14 capable of changing the internal volume ratio. Other configurations are the same as those in the first and second embodiments.

The screw compressor 102 according to the third embodiment can be operated while controlling the internal volume ratio of the compression chamber 11 during both-side operation and one-side operation.

(Description of operation)
The control device 110 moves the first slide valve 14a and the second slide valve 14b to positions where the internal volume ratio is optimal depending on the differential pressure condition or the like during both-side operation. Similarly to the second embodiment, when the controller 110 determines that the target refrigeration capacity has been exceeded even when the screw compressor 102 is driven at the lower limit frequency during both-side operation, the screw compressor 102 is switched to one-side operation. At this time, the second slide valve 14b on the side that compresses the refrigerant is moved to a position where the internal volume ratio is changed. As described above, the input loss due to overcompression or undercompression can be suppressed by making it possible to change the internal volume ratio in the compression chamber even in both-side operation. Therefore, the highly efficient screw compressor 102 can be provided.

Embodiment 4 FIG.
In Embodiments 1 to 3 described above, the number is not limited as long as the number of slide valves is two or more.

3 motor, 6 gate rotor, 6a 1st gate rotor, 6b 2nd gate rotor, 8 casing body, 9 screw rotor, 10 screw shaft, 11 compression chamber, 11a 1st compression chamber, 11b 2nd compression chamber, 12 discharge chamber , 13 discharge port, 13a 1st discharge port, 13b 2nd discharge port, 14 slide valve, 14a 1st slide valve, 14b 2nd slide valve, 15 rod, 16 drive unit, 17 high / low pressure partition, 17a first high / low pressure Bulkhead, 17b Second high / low pressure bulkhead, 19 fixed port, 19a first fixed port, 19b second fixed port, 20 fixed port back seal surface, 31 stator, 32 motor rotor, 61 teeth, 91 screw groove, 100 refrigeration cycle device, 101 inverter device, 102 screw compressor, 10 Condenser, 105 an expansion valve, 106 an evaporator, 110 controller, 111 slide valve control device.

Claims

A casing body having a cylindrical inner cylindrical surface;
A screw rotor housed in the inner cylindrical surface and having a plurality of screw grooves on the outer peripheral surface;
A plurality of gate rotors arranged on both sides of the screw rotor symmetrically with respect to the rotation axis of the screw rotor, and having a plurality of teeth meshing with the screw grooves on the outer periphery;
A slide valve located between the casing body and the screw rotor and movable in the direction of the rotating shaft;
In the casing main body, a high-low pressure partition that separates a high-pressure space that becomes a discharge pressure atmosphere and a low-pressure space that becomes a suction pressure atmosphere,
A screw compressor having a back surface of the high and low pressure partition walls and a fixed port that is a part of a discharge port of the compressed fluid has a seal surface that suppresses fluid leakage with the back surface of the slide valve.
Surrounded by each gate rotor, the screw groove and the casing body, and having a plurality of compression chambers provided with the discharge port,
2. The screw compressor according to claim 1, wherein at least one of the fixed ports is located on a discharge side at a position of a suction side wall surface that forms the fixed port in the direction of the rotation axis with respect to the other fixed ports.
A screw compressor capable of one-side operation in which fluid is not compressed by moving at least one slide valve, wherein the fixed port on the side not compressed by one-side operation is on the side compressed by one-side operation. The screw compressor according to claim 2, wherein a position of a suction side wall surface that forms the fixed port in a direction of the rotation shaft with respect to the fixed port is on a discharge side.
Surrounded by each gate rotor, the screw groove and the casing body, and having a plurality of compression chambers provided with the discharge port,
The screw compressor according to any one of claims 1 to 3, wherein a length of at least one of the fixed ports in the depth direction is smaller than a length of the other fixed ports in the depth direction.
A screw compressor capable of one-side operation in which fluid is not compressed by moving at least one slide valve, and the length in the depth direction of the fixed port on the side not compressed by one-side operation is one side The screw compressor according to claim 4, wherein the screw compressor is smaller than a length in a depth direction of the fixed port on a side to be compressed by operation.
Surrounded by each gate rotor, the screw groove and the casing body, and having a plurality of compression chambers provided with the discharge port,
The screw compressor according to any one of claims 1 to 3, wherein a volume of at least one of the fixed ports is smaller than a volume of the other fixed ports.
A screw compressor capable of one-side operation in which fluid is not compressed by moving at least one slide valve, wherein the volume of the fixed port that is not compressed by one-side operation is compressed by one-side operation. The screw compressor according to claim 6, wherein the screw compressor is smaller in volume than the fixed port on the side.
The screw compressor according to claim 2, 4 or 6, wherein the size of at least one of the fixed ports and the other fixed port differs depending on the load state of the compression chamber.
A screw compressor capable of one-side operation in which fluid is not compressed by moving at least one slide valve, the fixed port on the side not compressed by one-side operation, and the side compressed by one-side operation The screw compressor according to claim 3, 5 or 7, wherein a size of the fixing port is different depending on a load state of the compression chamber.
A plurality of compression chambers surrounded by each gate rotor, the screw groove and the casing body;
The screw compressor according to any one of claims 1 to 9, wherein a thickness of at least one of the high and low pressure partition walls is thinner than that of the other high and low pressure partition walls.
A screw compressor capable of one-side operation in which fluid is not compressed by moving at least one slide valve, wherein the high-low pressure partition that is not compressed by one-side operation is compressed by one-side operation. The screw compressor according to claim 10, wherein the screw compressor is thinner than the thickness of the high and low pressure partition walls.
A screw compressor capable of one-side operation in which fluid is not compressed by moving at least one slide valve, the high-low pressure partition wall on the side not compressed by one-side operation and the side compressed by one-side operation The screw compressor according to claim 11, wherein a thickness of the high-low pressure partition differs depending on a load state of the compression chamber.
A plurality of compression chambers surrounded by each gate rotor, the screw groove and the casing body;
The screw compressor according to any one of claims 1 to 12, wherein an internal volume ratio of at least one of the compression chambers is changed according to a position of the slide valve corresponding to the compression chamber.
14. A refrigeration cycle device comprising a refrigerant circuit in which the screw compressor, the condenser, the decompression device, and the evaporator according to any one of claims 1 to 13 are connected in order through a refrigerant pipe to circulate a refrigerant that is a fluid. .
The refrigeration cycle apparatus according to claim 14, further comprising an inverter device for controlling a drive frequency of the screw compressor.