JPWO2017094057A1 - Single screw compressor and refrigeration cycle equipment - Google Patents

Abstract

Reduces power consumption during low-speed operation when the required refrigeration capacity is reduced. A single screw compressor that is driven by an inverter so that the rotational speed can be changed. When the compressor is operated at the minimum operable rotational speed and the required refrigeration capacity is reduced, the first is selected according to the reduced required refrigeration capacity. The opening position of the slide valve is adjusted to increase the area between the compression chamber and the low pressure space.

Description

  The present invention relates to a technology of a single screw compressor and a refrigeration cycle apparatus when a necessary refrigeration capacity is reduced.

  It is generally known that a single screw compressor has a large discharge pressure loss due to its high compression speed. One method for reducing the discharge pressure loss is to reduce the discharge flow path resistance.

  One part that forms part of the discharge flow path of a single screw compressor is a slide valve. The slide valve is integrated by providing a rod-shaped connecting portion between a member having a function of adjusting the suction capacity and a member forming a part of the discharge port. A slide valve having such a shape is frequently used. In the slide valve having such a shape, the rod-shaped connecting portion is disposed in the discharge flow path, which is one of the factors for increasing the discharge flow path resistance.

By separately providing a member having a function of adjusting the suction volume and a member forming a part of the discharge port, a rod-like connecting portion for integrating them is unnecessary, and the discharge flow There is a technique for reducing road resistance (see, for example, Patent Document 1).
In the technique of Patent Document 1, a member having a function of adjusting the suction capacity is adjusted to a position parallel to the screw shaft direction by a dedicated drive device. On the other hand, the member that forms a part of the discharge port is not connected to the driving device, but is formed into a casing. With such a configuration, the volume of the compression chamber where the discharge of the compressed gas is started is constant, and the discharge timing is unchanged. For this reason, discharge pressure loss is reduced and energy efficiency is improved compared to a single screw compressor using a conventional slide valve that has the function of adjusting the suction capacity and the function of forming part of the discharge port. It is planned.

  With the technique of Patent Document 1, it is possible to reduce the discharge flow path resistance that has a significant effect during high-speed operation, and it is possible to reduce the power consumption as compared with a single screw compressor using a conventional slide valve. However, Patent Document 1 does not disclose a method for controlling a slide valve dedicated to adjusting the suction capacity for improving energy efficiency during low-speed operation or a method for controlling the rotational speed using an inverter.

In an inverter-driven two-stage single screw compressor, there is a technique that includes a variable Vi valve that can change the internal volume ratio at a low stage or a high stage (see, for example, Patent Document 2).
In the technique of Patent Document 2, a variable Vi valve provided at a low stage or a high stage has a hole for taking out the internal pressure of the screw tooth groove before and after the start of discharge. Then, with reference to the internal pressure of the screw tooth groove taken out from the hole, the low-stage or high-stage internal volume ratio variable mechanism is driven to control the position of the low-stage or high-stage variable Vi valve.
Patent Document 2 discloses the operation of the variable Vi valve during undercompression operation or overcompression operation. However, a control method for the variable Vi valve during low-speed operation is not disclosed.

JP 2012-117477 A JP 2013-92091 A

  With the above-described conventional technology, it is possible to reduce the discharge pressure loss during high-speed operation. However, in a single screw compressor having a configuration including a slide valve dedicated to adjusting the suction capacity and an inverter, there is no disclosure of an operation method for reducing power consumption during low speed operation with a reduced required refrigeration capacity.

  The present invention is for solving the above-described problems, and an object of the present invention is to provide a single screw compressor and a refrigeration cycle apparatus that reduce power consumption during low-speed operation with a reduced required refrigeration capacity.

  A single screw compressor according to the present invention includes a screw having a helical tooth gap, a gate rotor that fits into the screw, the screw and the gate rotor, and a compression chamber together with the screw and the gate rotor. An amount of the working fluid sucked into the compression chamber by disposing the casing to be formed and a position away from the discharge port of the working fluid compressed in the compression chamber, and communicating the compression chamber and the low pressure space in the casing. A single screw compressor having a first slide valve to be adjusted and a second slide valve capable of changing the discharge timing of the compressed working fluid and driven by an inverter so that the rotation speed can be changed, and can be operated When the required refrigeration capacity is reduced by operating at a minimum rotational speed, the reduced required refrigeration Those that are configured to increase the area between said compression chamber to adjust the open position of the first slide valve wherein the low-pressure space in response to a force.

  The refrigeration cycle apparatus according to the present invention includes the single screw compressor described above.

According to the single screw compressor and the refrigeration cycle apparatus according to the present invention, when the required refrigeration capacity is reduced when the refrigeration cycle is operated at the lowest operable rotational speed, the first slide valve is adjusted according to the reduced required refrigeration capacity. The area between the compression chamber and the low pressure space is increased by adjusting the valve opening position.
According to this, the compression work can be reduced at the time of low speed operation in which the required refrigeration capacity is reduced, and then the second slide valve can be set to an appropriate discharge timing. Therefore, energy efficiency can be improved and power consumption can be reduced during low-speed operation where the required refrigeration capacity is reduced.

It is explanatory drawing which shows the whole structure of the single screw compressor which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the low stage longitudinal cross-section of the single screw compressor which concerns on Embodiment 1 of this invention. It is a perspective view which shows the state at the time of the suction capacity 100% in the low stage of the single screw compressor which concerns on Embodiment 1 of this invention. It is a perspective view which shows the state at the time of the suction capacity adjustment in the low stage of the single screw compressor which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the drive system of the slide valve in the low stage of the single screw compressor which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the longitudinal cross-section of the high stage of the single screw compressor which concerns on Embodiment 1 of this invention. It is a perspective view which shows the Vi valve in the high stage of the single screw compressor which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the drive system of Vi valve in the high stage of the single screw compressor which concerns on Embodiment 1 of this invention. It is a figure which shows operation | movement of the slide valve in the low stage of the single screw compressor which concerns on Embodiment 1 of this invention. It is a figure which shows operation | movement of the Vi valve in the high stage of the single screw compressor which concerns on Embodiment 1 of this invention. It is a figure which shows the time chart at the time of the low speed driving | operation which the required refrigerating capacity of the single screw compressor which concerns on Embodiment 1 of this invention became small. It is a refrigerant circuit figure which shows the refrigerating-cycle apparatus to which the single screw compressor which concerns on Embodiment 3 of this invention is applied.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In addition, in each figure, what attached | subjected the same code | symbol is the same or it corresponds, and this is common in the whole text of a specification.
Furthermore, the forms of the constituent elements shown in the entire specification are merely examples and are not limited to these descriptions.

Embodiment 1 FIG.
FIG. 1 is an explanatory diagram showing the overall structure of a single screw compressor 100 according to Embodiment 1 of the present invention.
The single screw compressor 100 according to Embodiment 1 is a two-stage single screw compressor. The single screw compressor includes a low stage 10 and a high stage 20.

The low stage 10 is a twin gate rotor system having two gate rotors 11 and 12. The high stage 20 is a monogate rotor system having a single gate rotor 21.
The low stage 10 includes a low stage screw 13 having a helical tooth space. The high stage 20 includes a high stage screw 22 having a helical tooth space. The low-stage screw 13 and the high-stage screw 22 are arranged in series with the rotary shaft 30 that is pivotally supported. The low stage gate rotors 11 and 12 are fitted to the low stage screw 13. The high stage gate rotor 21 fits into the high stage screw 22.

A motor rotor 41 of the electric motor 40 is provided at one end of the rotating shaft 30. A stator 42 is provided on the outer peripheral side of the motor rotor 41 with a gap. When the electric motor 40 is driven, the rotary shaft 30 rotates.
The electric motor 40 is operated by using an inverter (not shown) and accelerating / decelerating the rotational speed of the rotary shaft 30. That is, the rotary shaft 30 on which the low-stage screw 13 and the high-stage screw 22 are arranged is driven by the inverter so that the rotation speed can be changed.

  The casing 1 includes a rotating shaft 30 on which the low-stage screw 13 and the high-stage screw 22 are arranged, two low-stage gate rotors 11 and 12, one high-stage gate rotor 21, and an electric motor 40. Housed inside.

FIG. 2 is an explanatory diagram showing a longitudinal section of the low stage 10 of the single screw compressor 100 according to Embodiment 1 of the present invention.
In the low stage 10, two low stage gate rotors 11 and 12 are accommodated in the casing 1. As shown in FIG. 2, a compression chamber 14 is formed on the upper side of the rotary shaft 30 in the lower casing 1. The compression chamber 15 is formed on the lower side of the rotary shaft 30 in the figure. The two compression chambers 14 and 15 are in a positional relationship opposite to the axis of the rotary shaft 30 by 180 °. The two compression chambers 14 and 15 are formed by the casing 1 of the low stage 10 together with the low stage gate rotors 11 and 12 and the low stage screw 13.
The compression chamber 14 includes a slide valve 16 dedicated to adjusting the suction capacity. The compression chamber 15 is provided with a slide valve 17 dedicated to adjusting the suction capacity.

FIG. 3A is a perspective view showing a state when the suction capacity is 100% in the low stage 10 of the single screw compressor 100 according to Embodiment 1 of the present invention. FIG. 3B is a perspective view showing a state when the suction capacity is adjusted in low stage 10 of single screw compressor 100 according to Embodiment 1 of the present invention.
The slide valves 16 and 17 have a crescent-shaped rod shape in cross section, and are slidably accommodated in a space in which a part of the casing 1 is partially protruded in the radial direction. A rod 56 is fixed to the end face of the slide valve 16, and the slide valve 16 can move in parallel with the rotary shaft 30. A rod 57 is fixed to the end face of the slide valve 17, and the slide valve 17 can move in parallel with the rotary shaft 30.
The slide valves 16 and 17 are moved in parallel with the rotary shaft 30 so as to connect the compression chambers 14 and 15 and the low pressure space in the casing 1 to adjust the amount of working refrigerant sucked into the compression chambers 14 and 15. .
The slide valves 16 and 17 correspond to the first slide valve of the present invention.

  Here, the slide valve 16 shown in FIGS. 3A and 3B is disposed at a position away from the discharge port 18 provided in the casing 1 in the circumferential direction of the low-stage screw 13 so as to open to the discharge chamber on the low-stage 10 side. ing. The same applies to the slide valve 17. For this reason, the slide valves 16 and 17 and the drive systems of the slide valves 16 and 17 are arranged at positions where the discharge flow path resistance does not occur.

FIG. 4 is a schematic diagram showing a drive system of the slide valves 16 and 17 in the low stage 10 of the single screw compressor 100 according to Embodiment 1 of the present invention.
The drive device 50 for the slide valves 16 and 17 includes a cylinder 51, an arm 52, and springs 53a and 53b.
The cylinder 51 is provided on the high pressure side lid 2 which is the high stage 20 side.
The arm 52 is configured by connecting a rod 55 to a piston 54 of a movable part disposed in the cylinder 51. Rods 56 and 57 extending in parallel with the rotary shaft 30 are fixed to both ends of the arm 52. The rods 56 and 57 are connected to the slide valves 16 and 17.
The springs 53a and 53b are disposed at the high-pressure end portions of the rods 56 and 57, and are combined with the outer circumferences of the rods 56 and 57 to apply a force to the rods 56 and 57. The springs 53a and 53b always apply a force in a direction in which the slide valves 16 and 17 communicate the compression chambers 14 and 15 with the low-pressure space. Specifically, as shown in FIG. 4, the springs 53a and 53b apply a force in such a direction that the slide valves 16 and 17 move to the left side in the figure.

FIG. 5 is an explanatory view showing a longitudinal section of the high stage 20 of the single screw compressor 100 according to Embodiment 1 of the present invention.
The high stage 20 accommodates a high stage gate rotor 21 and a high stage screw 22 in the casing 1. One compression chamber 23 is formed inside the casing 1 of the high stage 20. One compression chamber 23 is formed by the casing 1 of the high stage 20 together with the high stage gate rotor 21 and the high stage screw 22.
The high stage 20 includes one Vi valve 24 whose discharge timing can be changed.
The Vi valve 24 corresponds to the second slide valve of the present invention.

FIG. 6 is a perspective view showing the Vi valve 24 in the high stage 20 of the single screw compressor 100 according to Embodiment 1 of the present invention.
The Vi valve 24 is integrated by providing a rod-like connecting portion 27 between a guide portion 25 having a function of adjusting the suction capacity on the high stage side and a valve main body 26 forming a part of the discharge port. Shape. The Vi valve 24 is different in function and shape from the slide valves 16 and 17 on the low stage 10 side.

FIG. 7 is a schematic diagram showing a drive system of the Vi valve 24 in the high stage 20 of the single screw compressor 100 according to Embodiment 1 of the present invention.
The drive device 60 for the Vi valve 24 includes a cylinder 61, a piston 62, a rod 63, and a spring 64.
The cylinder 61 is provided on the high pressure side lid 2 which is the high stage 20 side.
The piston 62 is disposed in the cylinder 61.
The rod 63 has one end connected to the piston 62 and the other end connected to the Vi valve 24. The rod 63 extends in parallel with the rotating shaft 30.
The spring 64 is disposed between the end face of the piston 62 and the fixed portion 65, and is combined with the outer periphery of the rod 63. As shown in FIG. 7, the spring 64 moves the piston 62 to the left side in the figure, and exerts a force in such a direction that the Vi valve 24 moves to the left side in the figure.

Next, the operation of the single screw compressor 100 according to Embodiment 1 will be described.
The two-stage single screw compressor 100 driven by an inverter is used in a refrigerant circuit that includes a condenser and an evaporator and an expansion valve between them, and is connected in a closed loop by piping.
The electric motor 40 that drives the single screw compressor 100 is activated in response to a signal from the inverter. The opening positions of the slide valves 16 and 17 are adjusted to a position where the opening area where the compression chambers 14 and 15 communicate with the low-pressure space is maximized before activation.

When the electric motor 40 is started, the working refrigerant is sucked into the pair of compression chambers 14 and 15, and the suction is completed at the same timing in each of the compression chambers 14 and 15. Inhaled.
After the completion of the suction, the volume of the compression chambers 14 and 15 is reduced, and the internal pressure of the compression chambers 14 and 15 is increased.
The timing at which the working refrigerant in the compression chambers 14 and 15 is discharged is set to be the same for the pair of compression chambers 14 and 15, and after the volume is reduced to the set compression chamber volume, the compression chambers 14 and 15 become discharge ports. The discharge gas is discharged into the discharge chamber through communication.

Here, in the first embodiment, the slide valves 16 and 17 are adjusted to a plurality of positions by the dedicated drive device 50.
In addition, the drive apparatus which can adjust a position continuously without a floor may be sufficient, and it is not limited to several steps.

FIG. 8 is a diagram illustrating operations of the slide valves 16 and 17 in the low stage 10 of the single screw compressor 100 according to Embodiment 1 of the present invention.
As shown in FIG. 8, the slide valves 16 and 17 are movable in three stages of operation A, operation B, and operation C.
During the operation A, 20% of the maximum suction capacity can be sucked into the compression chambers 14 and 15.
In the operation B, 60% of the maximum suction capacity can be sucked into the compression chambers 14 and 15.
During the operation C, 100% of the maximum suction capacity can be sucked into the compression chambers 14 and 15.
Here, the ejection timing is set to be the same in the operations A, B and C.

In the operation A, the suction volume is smaller than that in the operation B, and the ejection timing is set to be the same in the operation A and the operation B. For this reason, the internal volume ratio can be set higher during operation B than during operation A.
Similarly, in the operation B, the suction volume is smaller than that in the operation C, and the ejection timing is set to be the same in the operation B and the operation C. For this reason, the internal volume ratio can be set higher during operation C than during operation B.

The operation of the slide valves 16 and 17 will be described.
In the driving device 50 shown in FIG. 4, by introducing pressure into the back space of the piston 54, the slide valves 16 and 17 move to the right side in the figure and act so that the compression chambers 14 and 15 do not communicate with the low pressure space. .
On the other hand, in the driving device 50, the slide valve 16, 17 opens the bypass port in the opposite direction due to the balance between the pressure and the acting force of the springs 53 a, 53 b by reducing the pressure in the back space of the piston 54. It moves so that the compression chambers 14 and 15 and the low pressure space communicate with each other.
Thus, the slide valves 16 and 17 move by adjusting the balance between the pressure acting on the slide valves 16 and 17 and the acting force of the springs 53a and 53b from the pressure in the space before and after the piston 54. By the movement of the slide valves 16 and 17, the degree of opening of the bypass port, that is, the opening area of the compression chambers 14 and 15 and the low pressure space is adjusted, and the amount of working refrigerant sucked into the compression chambers 14 and 15 can be adjusted. . Thereby, the slide valves 16 and 17 can be adjusted to the operation A, the operation B, and the operation C.

Similarly to the operation method of the slide valves 16 and 17, the Vi valve 24 of the high stage 20 is moved by the pressure of the back space of the piston 62 in the cylinder 61 to move the Vi valve 24 to the open position. Adjust.
The opening degree of the Vi valve 24 of the high stage 20 can be adjusted continuously or in a plurality of stages.
FIG. 9 is a diagram illustrating the operation of the Vi valve 24 in the high stage 20 of the single screw compressor 100 according to Embodiment 1 of the present invention.
As shown in FIG. 9, the Vi valve 24 is movable in two stages of operation D and operation E.
During the operation D, 20% of the maximum suction capacity of the high stage 20 can be sucked into the compression chamber 23.
During the operation E, 100% of the maximum suction capacity of the high stage 20 can be sucked into the compression chamber 23.

  In operation D, the timing of completion of inhalation is later than in operation E. For this reason, the internal volume ratio can be set smaller during operation D than during operation E.

The operation of the Vi valve 24 will be described.
In the driving device 60 shown in FIG. 7, when there is no pressure difference in the space before and after the piston 62, the spring 64 applies a force that moves the piston 62 to the left side in the drawing. When a high pressure is applied to the back space of the piston 62, the Vi valve 24 moves to the right in the figure due to the relationship between the operating pressure and the operating area.
When a low pressure is applied to the back space of the piston 62, the Vi valve 24 moves to the left side in the figure due to the relationship between the operating pressure and the operating area.

When the electric motor 40 is started, in order to reduce the starting torque, the slide valve 16 is moved to a position where the compression chambers 14 and 15 communicate with the suction space in the casing 1 and the opening area is maximized by the operation A. 17 is moved and activated.
When a predetermined rotational speed or a predetermined operation time is reached after activation, control is performed in which the slide valves 16 and 17 of the low stage 10 sequentially move to positions where the compression chambers 14 and 15 do not communicate with the suction space. That is, operation B and operation C are performed.

An example is a system in which brine is cooled by the refrigerant circuit described above, and another cooling target is cooled using the cooled brine.
In this system, the excess or deficiency of the refrigerating capacity is determined using the brine outlet temperature of the evaporator that exchanges heat between the refrigerant circulating in the refrigerant circuit and the brine circulating in another closed loop circuit.

  The brine, which has been deprived of heat in the evaporator and cooled, exchanges heat with the object to be cooled, and then returns to the evaporator. At that time, the brine inlet temperature of the evaporator is Tb. In the evaporator, the brine is cooled from the brine inlet temperature Tb to the target brine outlet temperature Ta (Tb> Ta).

When the required refrigeration capacity for cooling the object to be cooled from this state becomes smaller, the difference between the brine inlet temperature Tb and the target brine outlet temperature Ta becomes smaller. That is, when the temperature difference between the brine at the brine outlet temperature and the object to be cooled becomes small, the heat exchange amount decreases and the brine inlet temperature Tb does not decrease, so the difference from the brine outlet temperature becomes small. Thereby, the necessary refrigeration capacity for cooling the brine by the evaporator is reduced, and control for reducing the refrigeration capacity is performed.
From the above, during operation, it is possible to determine whether the refrigeration capacity is excessive or insufficient by detecting the brine outlet temperature.

  In the first embodiment, when it is determined that the refrigerating capacity is insufficient in the refrigerant circuit, the slide valves 16 and 17 for adjusting the suction capacity are arranged in the compression chamber 14, as in the operation A to the operation B and then the operation C. 15 and adjust to a position where the suction space does not communicate. Then, in order to increase the refrigeration capacity to reach the target brine outlet temperature Ta, the rotational speed of the rotary shaft 30 is increased by the inverter.

Next, the operation when the determination that the necessary refrigeration capacity is obtained is performed will be described.
When the rotational speed of the rotating shaft 30 during operation is lower than the maximum operable rotational speed, the valve opening position of the Vi valve 24 of the high stage 20 is adjusted so that the operating pressure ratio and the internal volume ratio are close. That is, when the required refrigeration capacity is obtained, the valve opening position of the Vi valve 24 of the high stage 20 is adjusted in accordance with the operating pressure ratio, and control is performed to change the internal volume ratio.

  In the Vi valve 24 provided in the high stage 20, the numerical value obtained by dividing the high pressure by the low pressure is expressed as the operating pressure ratio using the measured numerical values of the high pressure and the low pressure in the refrigerant circuit. Further, a numerical value obtained by dividing the volume immediately after the start of compression by the compression volume when the compression chamber 23 communicates with the discharge port is expressed as an internal volume ratio. The valve opening position of the Vi valve 24 is adjusted so that the internal volume ratio is close to the operating pressure ratio. That is, when the operating pressure ratio is greater than or equal to the reference value, operation E is performed. When the operating pressure ratio is less than the reference value, operation D is performed. The reference value is a threshold value that becomes a delimiter for bringing the operating pressure ratio set in advance by experiment, verification, or the like close to the internal volume ratio.

Next, the operation when the required refrigeration capacity is reduced and the target refrigeration capacity is corrected to be small will be described.
First, before controlling the slide valves 16 and 17 for adjusting the suction capacity, the rotational speed of the rotary shaft 30 is reduced by an inverter. That is, the slide valves 16 and 17 reduce the rotational speed of the rotary shaft 30 while being maintained at a position where the compression chambers 14 and 15 and the low pressure space are not in communication. The rotation speed is reduced by the inverter until the target brine outlet temperature Ta is reached.

  When the target brine outlet temperature Ta is reached, the valve opening position of the Vi valve 24 of the high stage 20 is adjusted to a position where the internal volume ratio is close to the operating pressure ratio in accordance with the operating pressure ratio. Even in this case, the measured values of high pressure and low pressure in the refrigerant circuit are used, and the numerical value obtained by dividing the high pressure by the low pressure is expressed as the operating pressure ratio. Further, a numerical value obtained by dividing the volume immediately after the start of compression by the compression volume when the compression chamber 23 communicates with the discharge port is expressed as an internal volume ratio. Then, the valve opening position of the Vi valve 24 is adjusted so that the internal volume ratio is close to the operating pressure ratio. That is, when the operating pressure ratio is greater than or equal to the reference value, operation E is performed. When the operating pressure ratio is less than the reference value, operation D is performed.

FIG. 10 is a diagram showing a time chart at the time of low speed operation in which the required refrigeration capacity of the single screw compressor 100 according to Embodiment 1 of the present invention is reduced.
As shown in FIG. 10, when the target refrigeration capacity is corrected to be small in the operation in which the rotation speed of the rotating shaft 30 reaches the minimum operable rotation speed, the slide valve is used regardless of the measured operation pressure ratio. The valve opening positions 16 and 17 are sequentially adjusted from operation C to operation B and then to operation A. Thereby, the compression chambers 14 and 15 and the low pressure space are communicated with each other.
That is, in the operation at the minimum rotational speed, in order to further reduce the refrigerating capacity, the slide valves 16 and 17 are sequentially opened to control the opening degree regardless of the measured operating pressure ratio.
After that, after a predetermined time after the adjustment to the operation A, the opening position of the Vi valve 24 of the high stage 20 is adjusted so that the operating pressure ratio and the internal volume ratio are close to each other. That is, when the operating pressure ratio is greater than or equal to the reference value, operation E is performed. When the operating pressure ratio is less than the reference value, operation D is performed. In order to further reduce the refrigeration capacity, the Vi valve 24 shifts from the operation E to the operation D.

As described above, the operation when the refrigeration capacity is determined to be insufficient and the target refrigeration capacity is corrected is as follows. First, the opening position of the slide valves 16 and 17 is changed between the compression chambers 14 and 15 and the low pressure space. Adjust so as not to communicate. That is, the slide valves 16 and 17 are adjusted to the valve closing position.
If it is determined that the refrigerating capacity is insufficient even when the slide valves 16 and 17 are closed, the rotational speed of the rotary shaft 30 is increased by the inverter so as to reach the target brine outlet temperature Ta. The control after reaching the necessary refrigerating capacity and obtaining the target brine outlet temperature Ta is as described above.

The effect of the first embodiment will be described.
Conventionally, during low-speed operation, since the low-stage slide valve is closed so that the compression chamber and the low-pressure space do not communicate with each other, the minimum refrigerating capacity is determined by the minimum rotation speed of the electric motor by the inverter.
On the other hand, in the first embodiment, the slide valves 16 and 17 of the low stage 10 are opened at the minimum rotation speed of the electric motor 40 by the inverter, and the compression chambers 14 and 15 are communicated with the low-pressure space to complete the suction. Slow timing. Therefore, the compression work can be reduced as compared with the prior art. After adjusting to the minimum compression work, the position of the Vi valve 24 of the high stage 20 is controlled in accordance with the operating pressure ratio, so the power consumption of the single screw compressor 100 can be reduced.

  Considering year-round operation of large chillers, low pressure operation is often performed at low loads. For this reason, when the load is low, the compression work is reduced to reduce the input, and then the Vi valve 24 of the high stage 20 is controlled. Therefore, the driving | operation which exhibits high energy efficiency can be performed.

Embodiment 2. FIG.
In the first embodiment, the example of the two-stage single screw compressor 100 has been described. However, the present invention can also be applied to a single-stage single screw compressor. In the second embodiment, an example of a single-stage single screw compressor will be described.
In the second embodiment, only differences from the first embodiment will be described.

In the second embodiment, only the low stage or the high stage in the first embodiment is used, and it is driven by an electric motor whose rotational speed is controlled by an inverter.
Here, the single-stage compression section is either a twin gate rotor system with two gate rotors or a monogate rotor system with one gate rotor.

A Vi valve capable of adjusting the discharge timing is disposed at the discharge port of the compressed working fluid provided in the casing. In the second embodiment, the Vi valve and the drive device for the Vi valve provided in the high stage in the first embodiment are provided in a single-stage compression unit.
The method for driving or controlling the slide valve and the Vi valve in the second embodiment is the same as that in the first embodiment.

Embodiment 3 FIG.
FIG. 11 is a refrigerant circuit diagram showing a refrigeration cycle apparatus 200 to which the single screw compressor 100 according to Embodiment 3 of the present invention is applied.
As shown in FIG. 11, the refrigeration cycle apparatus 200 includes a single screw compressor 100, a condenser 80, an expansion valve 81, and an evaporator 82. The single screw compressor 100, the condenser 80, the expansion valve 81, and the evaporator 82 are connected by a refrigerant pipe to form a refrigeration cycle circuit. Then, the refrigerant flowing out of the evaporator 82 is sucked into the single screw compressor 100 and becomes high temperature and pressure. The high-temperature and high-pressure refrigerant is condensed in the condenser 80 to become a liquid. The refrigerant that has become liquid is decompressed and expanded by the expansion valve 81 to become a low-temperature and low-pressure gas-liquid two-phase, and the gas-liquid two-phase refrigerant is heat-exchanged in the evaporator 82.
The single screw compressor 100 according to the first and second embodiments can be applied to such a refrigeration cycle apparatus 200. An example of the refrigeration cycle apparatus 200 is a refrigeration air conditioner.

According to the above first to third embodiments, the single screw compressor 100 includes the screws 13 and 22 having spiral tooth spaces, the gate rotors 11, 12, and 21 that fit into the screws 13 and 22, and the screw 13. , 22 and the gate rotor 11, 12, 21, and the casing 1 forming the compression chambers 14, 15, 23 together with the screws 13, 22 and the gate rotors 11, 12, 21, and compressed by the compression chambers 14, 15. A slide valve 16 which is disposed at a position away from the discharge port 18 of the working fluid and adjusts the amount of the working fluid sucked into the compression chambers 14 and 15 by communicating the compression chambers 14 and 15 and the low pressure space in the casing 1; 17 and a Vi valve 24 that can change the discharge timing, and is driven by an inverter so that the rotation speed can be changed. Then, when the required refrigerating capacity is reduced by operating at the minimum operable rotation speed, the opening positions of the slide valves 16 and 17 are adjusted according to the reduced required refrigerating capacity, and the compression chambers 14 and 15 Increase the area between the low-pressure space.
According to this configuration, the slide valves 16 and 17 are opened, the compression chambers 14 and 15 are communicated with the low pressure space, and the timing of completion of suction is delayed. Therefore, the compression work can be reduced and adjusted to the minimum compression work as compared with the prior art. In addition, the Vi valve 24 can be set to an appropriate discharge timing. Therefore, energy efficiency can be improved and power consumption can be reduced during low-speed operation where the required refrigeration capacity is reduced.

After the opening position of the slide valves 16 and 17 is moved to a position where the area between the compression chambers 14 and 15 and the low pressure space is maximized in accordance with the required refrigeration capacity that has become smaller, the Vi valve 24 is opened. The position is adjusted according to the operating pressure ratio obtained by dividing the high pressure in the refrigerant circuit by the low pressure, and the operating pressure ratio and the volume immediately after the start of compression are the compression volume when the compression chamber 23 communicates with the discharge port. The internal volume ratio obtained by the division should be close.
According to this configuration, after adjusting to the minimum compression work, the Vi valve 24 can be set to an appropriate discharge timing. Therefore, energy efficiency can be improved and power consumption can be reduced during low-speed operation where the required refrigeration capacity is reduced.

The opening position of the Vi valve 24 that is adjusted according to the operating pressure ratio increases the amount of suction that can be sucked into the compression chamber 23 when the operating pressure ratio is greater than or equal to the reference value than when the operating pressure ratio is less than the reference value. Adjusted to position.
According to this configuration, after adjusting to the minimum compression work, the Vi valve 24 can be set to an appropriate discharge timing. Therefore, energy efficiency can be improved and power consumption can be reduced during low-speed operation where the required refrigeration capacity is reduced.

The lower stage 10 in which the slide valves 16 and 17 are disposed and the higher stage 20 in which the Vi valve 24 is disposed are provided.
According to this configuration, the energy efficiency can be improved and the single screw compressor 100 capable of reducing power consumption can be applied to a two-stage single screw compressor at the time of low speed operation where the required refrigeration capacity is reduced. it can.

A compression part in which a slide valve and a Vi valve are arranged is provided.
According to this configuration, a single screw compressor capable of improving energy efficiency and reducing power consumption during low speed operation with a reduced required refrigeration capacity can be applied to a single stage single screw compressor. .

The refrigeration cycle apparatus 200 includes a single screw compressor 100.
According to this configuration, the refrigeration cycle apparatus 200 reduces the compression work when the load is low to reduce the input, and then controls the Vi valve 24 of the high stage 20. Therefore, the driving | operation which exhibits high energy efficiency can be performed. And power consumption can be reduced.

  1 casing, 2 lid, 10 low stage, 11 low stage gate rotor, 12 low stage gate rotor, 13 low stage screw, 14 compression chamber, 15 compression chamber, 16 slide valve, 17 slide valve, 18 discharge port, 20 high Stage, 21 High stage gate rotor, 22 High stage screw, 23 Compression chamber, 24 Vi valve, 25 Guide part, 26 Valve body, 27 Connecting part, 30 Rotating shaft, 40 Electric motor, 41 Motor rotor, 42 Stator, 50 Drive device , 51 cylinder, 52 arm, 53a spring, 53b spring, 54 piston, 55 rod, 56 rod, 57 rod, 60 drive device, 61 cylinder, 62 piston, 63 rod, 64 spring, 65 fixing part, 80 condenser, 81 Expansion valve, 82 evaporator, 100 single screw pressure Aircraft, 200 refrigeration cycle apparatus.

A single screw compressor according to the present invention includes a screw having a helical tooth gap, a gate rotor that fits into the screw, the screw and the gate rotor, and a compression chamber together with the screw and the gate rotor. An amount of the working fluid sucked into the compression chamber by disposing the casing to be formed and a position away from the discharge port of the working fluid compressed in the compression chamber, and communicating the compression chamber and the low pressure space in the casing. A single screw compressor comprising a first slide valve to be adjusted and a second slide valve capable of changing a discharge timing of the compressed working fluid, and driven by an inverter so that the rotation speed can be changed . A lower stage in which one slide valve is disposed, and a higher stage in which the second slide valve is disposed; Provided, is driven at a driving lowest possible rotational speed, when the required refrigerating capacity is reduced, and the compression chamber by adjusting the opening position of the first slide valve according to the required refrigerating capacity becomes smaller the The opening position of the first slide valve is set to a position where the area between the compression chamber and the low-pressure space is maximized in accordance with the required refrigeration capacity that is increased and reduced in area between the low-pressure space. The opening position of the second slide valve is adjusted according to the operating pressure ratio obtained by dividing the high pressure in the refrigerant circuit by the low pressure, and the operating pressure ratio and the volume immediately after the start of compression are The internal volume ratio obtained by dividing by the compression volume when the compression chamber communicates with the discharge port is configured to be close .

Claims (6)

A screw having a helical tooth space;
A gate rotor that fits into the screw;
A casing for accommodating the screw and the gate rotor, and forming a compression chamber together with the screw and the gate rotor;
A first slide which is disposed at a position away from the discharge port of the working fluid compressed in the compression chamber and adjusts the amount of the working fluid sucked into the compression chamber by communicating the compression chamber and the low pressure space in the casing. A valve,
A second slide valve capable of changing the discharge timing of the compressed working fluid;
A single screw compressor driven by an inverter so that the rotation speed can be changed,
When the required refrigerating capacity is reduced by operating at the minimum operable rotation speed, the opening position of the first slide valve is adjusted according to the reduced required refrigerating capacity, and the compression chamber and the low pressure space are adjusted. Single screw compressor configured to increase the area between.   After the opening position of the first slide valve is moved to a position where the area between the compression chamber and the low-pressure space is maximized according to the reduced refrigeration capacity, the second slide valve The valve opening position is adjusted according to the operating pressure ratio obtained by dividing the high pressure in the refrigerant circuit by the low pressure, and the operating pressure ratio and the volume immediately after the start of compression are communicated with the discharge port of the compression chamber. The single screw compressor according to claim 1, wherein the single screw compressor is configured to be close to an internal volume ratio obtained by dividing by a compression volume.   The opening position of the second slide valve that is adjusted according to the operating pressure ratio can be sucked into the compression chamber when the operating pressure ratio is greater than or equal to a reference value than when the operating pressure ratio is less than the reference value. The single screw compressor according to claim 2, wherein the single screw compressor is configured to be adjusted to a position where the suction amount is increased. A lower stage in which the first slide valve is disposed;
A high stage in which the second slide valve is disposed;
The single screw compressor according to any one of claims 1 to 3.   The single screw compressor of any one of Claims 1-3 provided with the compression part by which the said 1st slide valve and the said 2nd slide valve are arrange | positioned.   A refrigeration cycle apparatus comprising the single screw compressor according to any one of claims 1 to 5.

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