JP7344969B2 - Compressor and refrigeration cycle equipment - Google Patents

Description

The present invention relates to a compressor and a refrigeration cycle device.

Compressors are known that include a compression section and an open-wound motor that drives the compression section.

The open winding type motor has three-phase windings having a U phase, a V phase, and a W phase that are electrically isolated from each other. In open-wound motors, the windings of each phase are independent and not connected to each other. The open-wound motor includes a first inverter circuit connected to one end of the winding of each phase, and a second inverter circuit connected to the other end of the winding of each phase. Driven by a drive circuit.

JP2019-062626A

Open-winding motors can output high torque with less current than motors that are supplied with power from only one end of the windings, such as delta-connection type motors or Y-connection type motors. In other words, in an open winding type motor, compared to a motor in which power is supplied from only one end of the winding, the current flowing through the winding is suppressed, and thus the temperature rise of the winding is suppressed. Therefore, compressors driven by open-wound motors have higher torque output and lower temperature rises in the windings than compressors driven by motors that receive power from only one end of the windings. , to achieve both.

By the way, when using a compressor to compress R32 refrigerant or a mixed refrigerant containing R32 refrigerant, which has a vapor pressure of 2 megapascals (MPa) or more at a saturated vapor temperature of 50 degrees Celsius (°C), Torque output may be required.

In addition, refrigerants that are R32 refrigerants or mixed refrigerants containing R32 refrigerants and have a vapor pressure of 2 megapascals or more at a saturated vapor temperature of 50 degrees Celsius are refrigerants that have a high temperature of discharged refrigerant gas after being compressed. belongs to This hot discharged refrigerant gas heats the motor windings.

In other words, when compressing R32 refrigerant or a mixed refrigerant containing R32 refrigerant with a vapor pressure of 2 megapascals or more at a saturated vapor temperature of 50 degrees Celsius using a compressor driven by an open-wound motor, High torque output is required and the windings are superheated by the hot discharged refrigerant gas. Therefore, even if the compressor is driven by an open-wound motor, the refrigerant is applied to R32 refrigerant or a mixed refrigerant containing R32 refrigerant whose vapor pressure is 2 megapascals or more at a saturated steam temperature of 50 degrees Celsius. In such cases, there is a risk that the windings may overheat. Overheating of the windings reduces the efficiency of the motor and can cause deterioration and burnout of the winding insulation.

Therefore, the present invention is applicable to the compression of a refrigerant that is an R32 refrigerant or a mixed refrigerant containing an R32 refrigerant and has a vapor pressure of 2 megapascals (MPa) or more at a saturated vapor temperature of 50 degrees Celsius (°C). It is an object of the present invention to provide a compressor and a refrigeration cycle device that can prevent overheating of the windings of an open-winding type motor.

In order to solve the above problems, a compressor according to an embodiment of the present invention includes a hermetic container, an R32 refrigerant housed in the hermetic container, and a mixed refrigerant containing the R32 refrigerant introduced into the hermetic container. , a compression mechanism unit for compressing at least one of the refrigerants having a steam pressure of 2 megapascals or more at a saturated steam temperature of 50 degrees Celsius (° C.), and a cylindrical stator fixed to the inner surface of the closed container. and a rotor disposed inside the stator to rotationally drive the compression mechanism, the stator having an outermost diameter dimension of D meters (m). , when the thickness of the iron core of the stator is T meters (m), the volume of the compression chamber at the start of compression in the compression mechanism section is V cubic meters (m ³ ), and the circumference is π, then 14 The relationship is ≦(π×D ² ÷4)×T÷V≦21.

It is preferable that the stator of the compressor according to the embodiment of the present invention includes teeth provided inside the iron core and windings wound around the teeth in a concentrated manner.

The airtight container of the compressor according to the embodiment of the present invention has a vertical cylindrical shape and has a discharge port for the compressed refrigerant at the top thereof, and the motor is disposed above the compression mechanism section. The height from the upper end surface of the iron core to the top of the inner surface of the closed container is preferably greater than the thickness of the iron core.

In the compressor according to the embodiment of the present invention, the maximum load torque generated while the crank angle of the compression mechanism section progresses 360 degrees during steady operation is Tmax newton meters (N m), and the minimum load torque is Tmin newton meters (N m). meters (N·m) and the average load torque is Tmean newton meters (N·m), it is preferable that (Tmax−Tmin)÷Tmean≦0.5.

It is preferable that the compression mechanism section of the compressor according to the embodiment of the present invention is a rotary type having three or more cylinders.

Further, the refrigeration cycle device according to the embodiment of the present invention connects the compressor, the radiator, the expansion device, and the heat absorber; refrigerant piping for circulating refrigerant.

According to the present invention, it is applicable to the compression of R32 refrigerant or a mixed refrigerant containing R32 refrigerant, which has a vapor pressure of 2 megapascals (MPa) or more at a saturated vapor temperature of 50 degrees Celsius (°C). Accordingly, it is possible to provide a compressor and a refrigeration cycle device that can prevent overheating of the windings of an open-winding motor.

1 is a schematic diagram of a refrigeration cycle device and a compressor according to an embodiment of the present invention. FIG. 1 is a plan view of a cylinder of a compressor according to an embodiment of the present invention. FIG. 2 is a diagram showing the stator of the motor of the compressor according to the embodiment of the present invention from the direction of the center line of the rotating shaft. FIG. 3 is a diagram showing the relationship between the apparent volume of the electric motor and the total volume of the compression chamber in the compressor according to the embodiment of the present invention. FIG. 3 is a diagram showing the relationship between the crank angle and load torque of the compressor according to the embodiment of the present invention. FIG. 3 is a diagram showing the relationship between the torque fluctuation rate of the compressor and the amplitude of vibration in the rotational direction of the rotating shaft according to the embodiment of the present invention.

Embodiments of a compressor and a refrigeration cycle device according to the present invention will be described with reference to FIGS. 1 to 6. In addition, the same code|symbol is attached|subjected to the same or equivalent structure in several drawings.

FIG. 1 is a schematic diagram of a refrigeration cycle device and a compressor according to an embodiment of the present invention.

As shown in FIG. 1, a refrigeration cycle device 1 according to the present embodiment is, for example, an air conditioner. The refrigerant used in the refrigeration cycle device 1 is a single refrigerant of difluoromethane (HFC-32, R32, hereinafter referred to as "R32 refrigerant") or a mixed refrigerant containing R32, and the refrigerant has a saturated vapor temperature. It is a refrigerant with a vapor pressure of 2 megapascals (MPa) or more at 50 degrees Celsius (°C). The mixed refrigerant is, for example, R410A, R446A, R448A, R449A, R454B, R459A, R463A, and R466A. These R32 single refrigerants and mixed refrigerants containing R32 are simply referred to as "refrigerants."

The refrigeration cycle device 1 includes a hermetic compressor 2, a radiator 3, an expansion device 5, a heat absorber 6, an accumulator 7, and a refrigerant pipe 8. The refrigerant pipe 8 sequentially connects the compressor 2, the radiator 3, the expansion device 5, the heat absorber 6, and the accumulator 7, and allows the refrigerant to flow therethrough. The radiator 3 is also called a condenser. The heat absorber 6 is also called an evaporator.

The compressor 2 sucks in the refrigerant that has passed through the heat absorber 6 through the refrigerant pipe 8 , compresses it, and discharges the high-temperature and high-pressure refrigerant to the radiator 3 through the refrigerant pipe 8 .

The compressor 2 includes a cylindrical sealed container 11 placed vertically, an open-wound motor 12 (hereinafter simply referred to as "motor 12") disposed in the upper half of the sealed container 11, and a sealed container. A compression mechanism section 13 disposed in the lower half of the motor 11, a rotation shaft 15 that transmits the rotational driving force of the electric motor 12 to the compression mechanism section 13, a main bearing 16 that rotatably supports the rotation shaft 15, and a main bearing 16 that rotatably supports the rotation shaft 15. A sub-bearing 17 that rotatably supports the rotating shaft 15 in cooperation with the bearing 16 is provided.

The airtight container 11 includes a cylindrical body 11a extending in the vertical direction, a head plate 11b that closes the upper end of the body, and a head plate 11c that closes the lower end of the body.

A discharge pipe 8a for discharging refrigerant is connected to the upper end plate 11b of the closed container 11. The discharge pipe 8a is connected to the refrigerant pipe 8. Moreover, two sealed terminal portions 18 for power supply are provided on the end plate 11b on the upper side of the closed container 11.

The electric motor 12 generates a driving force that rotates the compression mechanism section 13. The electric motor 12 is arranged above the compression mechanism section 13. The electric motor 12 includes a cylindrical stator 21 fixed to the inner surface of the sealed container 11, a rotor 22 arranged inside the stator 21 to rotationally drive the compression mechanism section 13, and a rotor 22 pulled out from the stator 21 and sealed. A plurality of lead wires 23 are connected to the terminal portion 18.

The rotor 22 includes a rotor core 25 having a magnet housing hole (not shown) and a permanent magnet accommodated in the magnet housing hole. The rotor 22 is fixed to the rotating shaft 15. The rotation center line C of the rotor 22 and the rotating shaft 15 substantially coincides with the center line of the stator 21 .

The plurality of lead wires 23 are wires that supply power to the stator 21 through the sealed terminal portion 18, and are so-called lead wires. A plurality of lead wires 23 are wired depending on the type of electric motor 12. In this embodiment, six lead wires 23 are wired.

The rotating shaft 15 connects the electric motor 12 and the compression mechanism section 13. The rotating shaft 15 transmits the rotational driving force generated by the electric motor 12 to the compression mechanism section 13.

An intermediate portion 15a of the rotating shaft 15 connects the electric motor 12 and the compression mechanism section 13, and is rotatably supported by a main bearing 16. A lower end portion 15b of the rotating shaft 15 is rotatably supported by a sub bearing 17. The main bearing 16 and the sub-bearing 17 are also part of the compression mechanism section 13. In other words, the rotating shaft 15 passes through the compression mechanism section 13.

Further, the rotating shaft 15 includes a plurality of eccentric portions 26 between an intermediate portion 15a supported by the main bearing 16 and a lower end portion 15b supported by the sub-bearing 17. Each eccentric portion 26 is a disk or a cylinder having a center parallel to and not coincident with the rotation center line of the rotation shaft 15.

The compression mechanism section 13 compresses a refrigerant, that is, a single refrigerant or a mixed refrigerant. When the electric motor 12 rotationally drives the rotating shaft 15 , the compression mechanism section 13 sucks in gaseous refrigerant from the refrigerant pipe 8 , compresses it, and discharges it into the closed container 11 .

The compression mechanism section 13 according to the present embodiment is a rotary type having a plurality of cylinders, for example, three cylinders. The compression mechanism section 13 includes a plurality of cylinders 32 each having a circular cylinder chamber 31, and a plurality of annular rollers 33 arranged in each cylinder chamber 31.

The cylinder 32 closest to the electric motor 12 is referred to as a first cylinder 32A, the cylinder 32 furthest from the electric motor 12 is referred to as a third cylinder 32C, and the cylinder 32 disposed between the first cylinder 32A and the third cylinder 32C is referred to as a second cylinder. It shall be 32B.

The upper surface of the first cylinder 32A is closed by the main bearing 16. The lower surface of the first cylinder 32A is closed by a first partition plate 35A. The upper surface of the second cylinder 32B is closed by a first partition plate 35A. The lower surface of the second cylinder 32B is closed by a second partition plate 35B. The upper surface of the third cylinder 32C is closed by a second partition plate 35B. The lower surface of the third cylinder 32C is closed by a secondary bearing 17.

The main bearing 16 is fixed to the first cylinder 32A by a fastening member (not shown) such as a bolt. The main bearing 16 is provided with a discharge valve mechanism 16a that discharges the refrigerant compressed within the cylinder chamber 31 of the first cylinder 32A, and a first discharge muffler 38A that covers the discharge valve mechanism 16a. The first partition plate 35A is provided with a discharge valve mechanism 35C that discharges the refrigerant compressed within the cylinder chamber 31 of the second cylinder 32B, and a discharge chamber 35D. The main bearing 16, the first cylinder 32A, and the first partition plate 35A have a hole (not shown) that connects the discharge chamber 35D to the first discharge muffler 38A. The discharge valve mechanism 16a closes the discharge port ( (not shown) is opened to discharge the compressed refrigerant into the first discharge muffler 38A. The discharge valve mechanism 35C opens the discharge port when the pressure difference between the pressure in the cylinder chamber 31 of the second cylinder 32B and the pressure in the discharge chamber 35D reaches a predetermined value due to the compression action of the compression mechanism section 13. Then, the compressed refrigerant is discharged into the discharge chamber 35D. The first discharge muffler 38A has a discharge hole (not shown) that connects the inside and outside of the first discharge muffler 38A. The compressed refrigerant discharged into the first discharge muffler 38A is discharged into the closed container 11 through the discharge hole.

The first cylinder 32A is fixed with bolts 37 to a frame that is fixed to the closed container 11 at a plurality of locations by welding, for example, spot welding.

The secondary bearing 17 is fixed to the third cylinder 32C by a fastening member (not shown) such as a bolt. The secondary bearing 17 is provided with a discharge valve mechanism 17a that discharges the refrigerant compressed within the cylinder chamber 31 of the third cylinder 32C, and a second discharge muffler 38B that covers the discharge valve mechanism. The discharge valve mechanism 17a closes the discharge port ( (not shown) is opened to discharge the compressed refrigerant into the second discharge muffler 38B. The space within the second discharge muffler 38B is connected to the space within the first discharge muffler 38A via a passage (not shown). The refrigerant compressed within the cylinder chamber 31 of the third cylinder 32C and discharged into the second discharge muffler 38B is discharged into the closed container 11 through the space within the first discharge muffler 38A.

The suction pipe 39 penetrates the closed container 11 and is connected to the cylinder chamber 31 of the cylinder 32. The cylinder 32 has a suction hole that is connected to a suction pipe 39 and reaches the cylinder chamber 31 . The first suction pipe 39A is connected to the cylinder chamber 31 of the first cylinder 32A. The second suction pipe 39B passes through the second partition plate 35B, branches at the second partition plate 35B, and is connected to the cylinder chamber 31 of the second cylinder 32B and the cylinder chamber 31 of the third cylinder 32C. The second partition plate 35B has a branched refrigerant passage (not shown).

The lower part of the closed container 11 is filled with lubricating oil 41. Most of the compression mechanism section 13 is immersed in the lubricating oil 41 inside the closed container 11.

The accumulator 7 prevents liquid refrigerant that has not been completely gasified by the heat absorber 6 from being sucked into the compressor 2.

Next, the cylinder 32 of the compression mechanism section 13 will be explained.

FIG. 2 is a plan view of a cylinder of a compressor according to an embodiment of the present invention.

Note that the first cylinder 32A, the second cylinder 32B, and the third cylinder 32C have similar structures, so one cylinder 32 will be explained.

As shown in FIG. 2, the compressor 2 according to this embodiment includes a blade 45 that reciprocates in contact with the outer peripheral surface of the roller 33. The blade 45 partitions the inside of the cylinder chamber 31 into a suction chamber 46 and a compression chamber 47. The suction chamber 46 is a portion connected to a suction hole 48 provided in the cylinder 32. The compression chamber 47 is connected to the first discharge muffler 38A or the second discharge muffler 38B.

The cylinder chamber 31 is a space inside the cylinder 32. The cylinder chamber 31 accommodates the eccentric portion 26 of the rotating shaft 15.

The roller 33 is fitted onto the circumferential surface of the eccentric portion 26. The outer peripheral surface of the roller 33 is in line contact with the inner peripheral surface of the cylinder chamber 31. As the rotating shaft 15 rotates, the roller 33 moves eccentrically while bringing its outer circumferential surface into line contact with the inner circumferential surface of the cylinder chamber 31 .

Note that the contact between the roller 33 and the cylinder 32 is not a direct contact, but an indirect one with an oil film (not shown) of the lubricating oil 41 interposed therebetween. This contact is simply referred to as "contact." Between the roller 33 and the eccentric portion 26, between the roller 33 and the main bearing 16, between the roller 33 and the sub-bearing 17, between the roller 33 and the first partition plate 35A, and between the roller 33 and the second partition plate The same applies to 35B.

Next, the stator 21 of the electric motor 12 will be explained.

FIG. 3 is a diagram showing the stator of the motor of the compressor according to the embodiment of the present invention from the direction of the center line of the rotating shaft.

As shown in FIG. 3 in addition to FIG. 1, the electric motor 12 according to this embodiment is, for example, a three-phase nine-slot type.

Stator 21 is a concentrated winding stator. The stator 21 includes a stator core 53 having a cylindrical yoke 51, a so-called yoke, and a plurality of teeth 52 that protrude inward from the yoke 51 and are arranged circumferentially at intervals. In addition, the stator 21 is wound between two insulating end plates 55 provided on each end surface of the stator core 53, a plurality of insulating thin plates (not shown), and the teeth 52 and the two insulating end plates 55. A winding 58 is provided.

The plurality of teeth 52 are arranged radially at substantially equal intervals in the circumferential direction. Each tooth 52 extends radially inward from the yoke 51.

The yoke 51 and two circumferentially adjacent teeth 52 define a slot 59. The number of slots 59 is the same as the number of teeth 52, that is, there are nine slots. The slot 59 has a slot opening between two adjacent teeth 52.

The winding 58 is wound around the teeth 52 of the stator core 53, the first insulating end plate 55A, and the second insulating end plate 55B by a concentrated winding method.

The winding 58 includes a U-phase winding 58U, a V-phase winding 58V, and a W-phase winding 58W. The winding 58 of each phase is an independent winding that is continuously wound around the three teeth 52 independently for each phase, and to which a voltage is individually applied. Two ends of each of the windings 58U, 58V, and 58W are connected to the drive circuit 61 via the lead wire 23 and the sealed terminal portion 18. That is, one U-phase lead wire 23 is connected to the U-phase of the first inverter circuit 62 of the drive circuit 61 of the electric motor 12 via one of the two sealed terminal portions 18 . The other U-phase lead wire 23 is connected to the U-phase of the second inverter circuit 63 of the drive circuit of the motor 12 via the other of the two sealed terminal portions 18 . The lead wire 23 of the winding 58V is also connected to the V phase of the first inverter circuit 62 and the V phase of the second inverter circuit 63, similarly to the U-phase lead wire 23. One V-phase lead wire 23 is connected to the V-phase of the first inverter circuit 62 of the drive circuit 61 of the motor 12 via one of the two sealed terminal portions 18 . The other V-phase lead wire 23 is connected to the V-phase of the second inverter circuit 63 of the drive circuit of the motor 12 via the other of the two sealed terminal portions 18 . The lead wire 23 of the winding 58W is also connected to the W phase of the first inverter circuit 62 and the W phase of the second inverter circuit 63, similarly to the lead wire 23 of the U phase. One W-phase lead wire 23 is connected to the W-phase of the first inverter circuit 62 of the drive circuit 61 of the motor 12 via one of the two sealed terminal portions 18 . The other W-phase lead wire 23 is connected to the W-phase of the second inverter circuit 63 of the drive circuit of the motor 12 via the other of the two sealed terminal portions 18 .

Note that the number of poles of the electric motor 12 is preferably six or more. By increasing the number of poles, the circumferential length of the winding 58 is shortened, and the winding resistance is suppressed. This suppression of the winding resistance contributes to preventing the winding 58 from overheating.

Here, as shown in FIG. 1, the outermost diameter of the stator 21 is D meters (m), and the thickness of the stator core 53 of the stator 21 is T meters (m). Also, let pi be π.

Then, the apparent volume Vm cubic meters (m ³ ) of the electric motor 12 is expressed by the following formula.

[Number 1]
(Volume Vm) = (Pi) x (Outermost diameter dimension of stator D) ² ÷ 4 x T

Furthermore, the total volume of the compression chamber 47 at the time of starting compression in the compression mechanism section 13 shown in FIG. 2 is assumed to be Vct cubic meters (m ³ ). This total volume Vct is the sum of the volumes Vc cubic meters (m ³ ) of the compression chambers 47 in each cylinder chamber 31 at the start of compression. That is, in the three-cylinder compression mechanism section 13 according to the present embodiment, the following relationship exists.

[Number 2]
(Total volume Vct) = (Number of cylinders N) x (Volume of compression chamber Vc)

Note that the volume Vc of each cylinder does not necessarily have to be the same volume. Further, the compression mechanism section 13 only needs to include at least one cylinder 32. The number of cylinders N according to this embodiment is three. The total volume Vct is also called the excluded volume of the compression mechanism section 13.

Let the volume ratio R be a dimensionless number obtained by dividing the apparent volume Vm of the electric motor 12 by the displacement volume Vct of the compression mechanism section 13 as shown in the following equation.

[Number 3]
(Volume ratio R) = (Volume Vm) ÷ (Total volume Vct)

FIG. 4 is a diagram showing the relationship between the apparent volume of the electric motor and the total volume of the compression chamber of the compressor according to the embodiment of the present invention.

The horizontal axis of FIG. 4 shows the volume ratio R, and the vertical axis of FIG. 4 shows the temperature of the windings of the open-wound motor 12.

Further, the double line AT in FIG. 4 indicates the allowable temperature AT of the windings of the open winding type motor 12. The windings of the open winding motor 12 function properly if the temperature is below the allowable temperature AT. The allowable temperature AT is set in consideration of the heat resistance of the windings and the efficiency of the electric motor 12. The allowable temperature AT is set to, for example, 125 degrees Celsius (° C.).

The solid line α in FIG. 4 represents the volume ratio R of the open-wound motor 12 and the temperature of the winding of the open-wound motor 12 of the compressor 2 during operation, which is exposed to the high-temperature refrigerant gas compressed by the compressor 2. It shows the relationship between. The solid line α is the temperature of the winding during steady operation when the compressor 2 is operated with an AC power source with an AC voltage of 200 volts (V).

As shown by the solid line α, in the compressor 2 including the open-wound motor 12, the temperature of the windings decreases as the volume ratio R increases. This result is due to the fact that the volume Vm of the electric motor 12 per compression load increases as the volume ratio R increases. An increase in the volume Vm of the electric motor 12 per compression load improves the efficiency of the electric motor 12 and increases the heat dissipation area of the electric motor 12. This will reduce the temperature of the winding.

When the volume ratio R is 14 or more, the temperature of the winding falls below the allowable temperature AT, while when the volume ratio R is smaller than 14, the temperature of the winding exceeds the allowable temperature AT.

In addition, the broken line β in FIG. It shows the relationship between the temperature of the compressor motor windings and The broken line β is the temperature of the winding during steady operation when operating a compressor equipped with a motor that is supplied with power only from one end of the winding using an AC power source with an AC voltage of 200 volts (V). .

As shown by the broken line β, even in a compressor equipped with a motor to which power is supplied only from one end of the winding, the temperature of the winding decreases as the volume ratio R increases. Further, the vertical axis intercept of the broken line β is higher than the vertical axis intercept of the solid line α. In other words, the broken line β is biased upward in FIG. 4 from the solid line α. Furthermore, the broken line β does not intersect the solid line α. When the volume ratio R is 21 or more, the temperature of the winding falls below the allowable temperature AT, while when the volume ratio R is smaller than 21, the temperature of the winding exceeds the allowable temperature AT.

The electric motor 12 is driven by a plurality of inverter circuits (a first inverter circuit 62 and a second inverter circuit 63). Therefore, power loss in the drive circuit 61 increases compared to a motor in which power is supplied from only one end of the winding. In other words, in the range of (volume ratio R) > 21, the temperature of the winding of both the motor to which power is supplied from only one end of the winding and the electric motor 12 can be kept within the range below the allowable temperature AT. A motor in which power is supplied from only one end of the winding is superior to the electric motor 12 in terms of efficiency.

Therefore, based on the relationships shown in FIG. 4, the compressor 2 has the following relationship.

[Number 4]
14≦(volume ratio R)=(π×D ² ÷4)×T÷Vct≦21

Further, the height H from the upper end surface of the stator core 53 of the electric motor 12 to the top of the inner surface of the closed container 11 is greater than the thickness T of the stator core 53.

[Number 5]
(Height H)>(Thickness T)

FIG. 5 is a diagram showing the relationship between the crank angle and load torque of the compressor according to the embodiment of the present invention.

The horizontal axis of FIG. 5 indicates the crank angle θ (0 degrees≦crank angle θ≦360 degrees) of the compression mechanism section 13, and the vertical axis indicates the torque fluctuation Tf expressed by the following equation.

[Number 6]
(Torque fluctuation Tf) = (Load torque T) ÷ (Average load torque Tmean)

Further, the torque fluctuation rate Tr is determined by the following equation.

[Number 7]
(Torque fluctuation rate Tr) = ((Maximum load torque Tmax) - (Minimum load torque Tmin)) ÷ (Average load torque Tmean)

Note that the load torque acting on the electric motor 12 is T newton meters (N m), the maximum load torque acting on the electric motor 12 is Tmax newton meters (N m), and the minimum load torque acting on the electric motor 12 is Tmin newton meters. meters (N·m), and the average load torque acting on the electric motor 12 is Tmean newton meters (N·m).

Further, the solid line α, the broken line β, and the double line are compared under the condition that the total volume Vct (that is, the excluded volume) of the cylinder chamber 31 is made the same.

A solid line α in FIG. 5 indicates the relationship between the crank angle θ and the torque fluctuation Tf in the three-cylinder rotary compressor 2. The torque fluctuation rate Tr on the solid line α is 0.25 (dimensionless number). The three-cylinder rotary compressor 2 has three maximum values in the compression strokes of the three cylinders 32 during one revolution of the rotating shaft 15, in the range of 0 degrees≦crank angle θ≦360 degrees.

A broken line β in FIG. 5 indicates the relationship between the crank angle θ and the torque fluctuation rate Tr in the two-cylinder rotary compressor 2. The torque fluctuation rate Tr at the broken line β is 0.79 (dimensionless number). In the two-cylinder rotary compressor 2, the compression strokes of the two cylinders 32 have two maximum values during one rotation of the rotating shaft 15. The two-cylinder rotary compressor 2 is inferior to the three-cylinder rotary compressor 2 in the torque fluctuation rate Tr, the magnitude of the local maximum value, and the magnitude of the local minimum value.

The double line γ in FIG. 5 indicates the relationship between the crank angle θ and the torque fluctuation rate Tr in the one-cylinder scroll compressor 2. The torque fluctuation rate Tr at the double line γ is 0.25 (dimensionless number). In the one-cylinder scroll type compressor 2, the compression stroke of the scroll type cylinder 32 has one maximum value during one rotation of the rotating shaft 15. The one-cylinder scroll type compressor 2 has the same characteristics as the three-cylinder rotary compressor 2 in terms of the torque fluctuation rate Tr, the magnitude of the local maximum value, and the size of the local minimum value.

FIG. 6 is a diagram showing the relationship between the torque fluctuation rate of the compressor and the amplitude of vibration in the rotational direction of the rotating shaft according to the embodiment of the present invention.

The horizontal axis of FIG. 6 shows the torque fluctuation rate shown in [Equation 7], and the vertical axis shows the amplitude of vibration in the rotational direction of the rotating shaft 15. The unit of amplitude is micrometer (μm). This vibration amplitude is generated by the operation of the compression mechanism section 13. Further, the vibration amplitude is evaluated at the connection portion 65 (FIG. 1) between the accumulator 7 and the refrigerant pipe 8 where the vibration response is noticeable.

A solid line α in FIG. 6 indicates the relationship between the torque fluctuation rate and the amplitude of vibration in the rotational direction of the rotating shaft 15. There is a positive correlation between the torque fluctuation rate and the amplitude of vibration in the rotational direction of the rotating shaft 15. The solid line α is the temperature of the winding during steady operation when the compressor 2 that satisfies the relationship [Equation 4] is operated with an AC power source with an AC voltage of 200 volts (V). The rotation speed of the electric motor 12 at this time is 30 revolutions per second (rps).

By the way, in the connection portion 65 between the accumulator 7 and the refrigerant pipe 8, it is desired to suppress the maximum amplitude to 50 micrometers (μm) or less in consideration of mechanical soundness such as fatigue failure at the portion. The double line AA in FIG. 6 indicates the permissible amplitude AA at the connection portion 65.

Therefore, the torque fluctuation rate Tr is preferably 0.5 or less as shown in the following equation.

[Number 8]
(Torque fluctuation rate Tr)≦0.5
∴((Maximum load torque Tmax)-(Minimum load torque Tmin))÷(Average load torque Tmean)≦0.5

Under the condition of volume ratio R≦21, the volume Vm of the electric motor 12 relative to the load torque is smaller than that of a general compressor. In other words, there is a tendency that the moment of inertia of the rotor 22 is small and the vibration of the compression mechanism section 13 in the rotational direction becomes large. Therefore, if the torque fluctuation rate Tr becomes larger than 0.5, the vibration amplitude at the connection portion 65, which is the evaluation point of the vibration amplitude, becomes larger than the allowable amplitude AA under the operating condition where the solid line α is drawn. In such a case, in controlling the operation of the electric motor 12, there is a method of implementing torque control to reduce the load torque and reduce the vibration amplitude. In torque control, the motor torque is changed according to the load torque by changing the voltage supplied to the electric motor 12 while the rotating shaft 15 is rotating. This reduces the difference between the motor torque and the load torque and reduces the excitation force.

However, when implementing torque control with the compressor 2 equipped with the open-wound motor 12, power loss for matching the motor torque to the load torque is caused by the power loss of multiple inverter circuits (first inverter circuit 62, second inverter circuit 63). ) occurs. In other words, when performing torque control with the compressor 2 equipped with the open-wound motor 12, power loss in the drive circuit 61 increases compared to a motor in which power is supplied from only one end of the winding. Put it away.

Therefore, the compressor 2 according to the present embodiment satisfies the condition [Equation 8], eliminates torque control, and suppresses the deterioration of performance.

As explained above, the compressor 2 and the refrigeration cycle device 1 according to the present embodiment have the relationship expressed by [Equation 4], that is, 14≦(volume ratio R)≦21. Therefore, the compressor 2 and the refrigeration cycle device 1 are designed to compress R32 refrigerant or a mixed refrigerant containing R32 refrigerant, which has a vapor pressure of 2 megapascals (MPa) or more at a saturated vapor temperature of 50°C. Even if the electric motor 12 is required to have a high torque output, an increase in the current flowing through the winding 58 can be suppressed and overheating of the winding 58 can be avoided.

Furthermore, the compressor 2 and the refrigeration cycle device 1 according to the present embodiment include a winding 58 that is wound using a concentrated winding method. Therefore, the compressor 2 and the refrigeration cycle device 1 can shorten the circumferential length of the winding 58 to suppress winding resistance. This suppression of the winding resistance contributes to preventing the winding 58 from overheating.

Furthermore, the compressor 2 and the refrigeration cycle device 1 according to the present embodiment have a relationship expressed by [Equation 5]. That is, the height from the upper end surface of stator core 53 to the top of the inner surface of sealed container 11 is greater than the thickness dimension of stator core 53. Therefore, the compressor 2 and the refrigeration cycle device 1 have a space above the motor 12 that accommodates the six lead wires 23 connected to both ends of the windings 58 of the open-wound motor 12. Moreover, there is a space above the electric motor 12 in which the two sealed terminal parts 18 can be installed. Further, even if oil contained in the compressed refrigerant gas adheres to the lead wire 23 or the sealed terminal portion 18, the amount of oil flowing out from the space above the motor 12 to the discharge pipe 8a can be reduced.

Further, the compressor 2 and the refrigeration cycle device 1 according to the present embodiment have a relationship expressed by [Equation 8], that is, (torque fluctuation rate Tr)≦0.5. Therefore, the compressor 2 and the refrigeration cycle device 1 can omit torque control and suppress a decrease in performance.

Therefore, the refrigeration cycle device 1 and the compressor 2 according to the present embodiment are applicable to the compression of R32 refrigerant or a mixed refrigerant containing R32 refrigerant, and the overheating of the windings 58 of the open-wound motor 12 can be prevented.

Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

DESCRIPTION OF SYMBOLS 1... Refrigeration cycle device, 2... Compressor, 3... Heat radiator, 5... Expansion device, 6... Heat absorber, 7... Accumulator, 8... Refrigerant piping, 8a... Discharge pipe, 11... Airtight container, 11a... Body part , 11b... Upper end plate, 11c... Lower end plate, 12... Open winding type motor (electric motor), 13... Compression mechanism section, 15... Rotating shaft, 15a... Intermediate portion, 15b... Lower end portion, 16... Main bearing, 17... Secondary bearing, 18... Sealed terminal part, 21... Stator, 22... Rotor, 23... Lead wire, 25... Rotor core, 26... Eccentric part, 31... Cylinder chamber, 32... Cylinder, 32A... No. 1 cylinder, 32B...Second cylinder, 32C...Third cylinder, 33...Roller, 35A...First partition plate, 35B...Second partition plate, 37...Bolt, 38A...First discharge muffler, 38B...Second discharge muffler , 39... Suction pipe, 39A... First suction pipe, 39B... Second suction pipe, 41... Lubricating oil, 45... Blade, 46... Suction chamber, 47... Compression chamber, 48... Suction hole, 51... Yoke, 52... Teeth, 53... Stator core, 55... Insulated end plate, 55A... First insulated end plate, 55B... Second insulated end plate, 58... Winding wire, 58U... U phase winding, 58V... V phase winding , 58W... W-phase winding, 59... Slot, 61... Drive circuit, 62... First inverter circuit, 63... Second inverter circuit, 65... Connection portion.

Claims (6)

an airtight container;
An R32 refrigerant contained in the sealed container and introduced into the sealed container, and a mixed refrigerant containing the R32 refrigerant, which has a steam pressure of 2 megapascals (MPa) or more at a saturated steam temperature of 50 degrees Celsius (°C). a compression mechanism unit that compresses at least one of the refrigerants;
an open-wound motor having a cylindrical stator fixed to the inner surface of the closed container, and a rotor disposed inside the stator to rotationally drive the compression mechanism,
The outermost diameter of the stator is D meters (m), the thickness of the stator core is T meters (m), and the volume of the compression chamber at the start of compression in the compression mechanism section is V cubic meters (m ³ ) and pi is π, then
14≦(π× ^D2 ÷4)×T÷V≦21
A compressor with the following relationship. The compressor according to claim 1, wherein the stator includes teeth provided inside the iron core, and windings wound around the teeth in a concentrated manner. The airtight container is vertically cylindrical and has a discharge port for the compressed refrigerant at the top thereof,
The motor is arranged above the compression mechanism section,
The compressor according to claim 1 or 2, wherein the height from the upper end surface of the iron core to the top of the inner surface of the closed container is greater than the thickness of the iron core. The maximum load torque that occurs while the crank angle of the compression mechanism advances 360 degrees during steady operation is Tmax newton meters (N m), the minimum load torque is Tmin newton meters (N m), and the average load The compressor according to any one of claims 1 to 3, wherein (Tmax-Tmin)÷Tmean≦0.5, where Tmean is Newton meter (Nm). The compressor according to any one of claims 1 to 4, wherein the compression mechanism is a rotary type having three or more cylinders. The compressor, the heat radiator, the expansion device, and the heat absorber according to any one of claims 1 to 5, and the compressor, the heat radiator, the expansion device, and the heat absorber are connected. A refrigeration cycle device comprising: refrigerant piping through which the refrigerant flows.

Images