KR20170099551A

KR20170099551A - Turbo compressor

Info

Publication number: KR20170099551A
Application number: KR1020160021753A
Authority: KR
Inventors: 김철민; 정진희; 강정호; 황의식
Original assignee: 엘지전자 주식회사
Priority date: 2016-02-24
Filing date: 2016-02-24
Publication date: 2017-09-01
Also published as: KR101827622B1

Abstract

The present invention relates to a turbo compressor. The turbo compressor according to one aspect includes a driving unit including a main motor and a sub motor; A compression unit including an impeller rotating by a driving force of the driving unit; A planetary gear portion for shifting the rotational force of the driving portion and transmitting the rotational force to the compression portion; And an inverter for controlling power applied to the driving unit, wherein a first input shaft rotated by the main motor and a second input shaft rotated by the sub motor are connected to the planetary gear unit, And the rotational speed of the second input shaft is varied as controlled by the inverter.

Description

Turbo Compressor {TURBO COMPRESSOR}

The present invention relates to a turbo compressor.

2. Description of the Related Art Generally, a turbo compressor used in a refrigerator includes a casing having a refrigerant inlet port on one side thereof, an impeller for compressing a refrigerant introduced into the casing, and a compressor for compressing the kinetic energy of the refrigerant compressed by the impeller, And a volute for transferring the refrigerant passing through the diffuser to the discharge duct. The refrigerant flowing through the inlet of the turbo compressor is compressed by the impeller, passes through the diffuser, passes through the bolt, passes through the exhaust duct, and is transferred to the condenser.

The contents of such a turbo compressor are disclosed in Korean Patent Laid-Open Publication No. 10-2011-0082356.

The turbo compressor disclosed in the above prior art includes a gear box for increasing the rotation of the motor and a shaft connected to the gear box for rotating. The shaft is provided with an impeller, which rotates together with the rotation of the shaft.

On the other hand, in order to improve the partial load operation efficiency of the turbocompressor, the frequency supplied to the motor may be varied by using an inverter to control the number of revolutions of the motor.

However, as the capacity of the conventional turbo compressor increases, the capacity of the motor must increase. When the capacity of the motor increases, the capacity of the inverter for controlling the number of revolutions of the motor must also increase. For example, if the capacity of the turbocompressor is 1000RT or less, the power of the inverter is 380 to 440V. If the capacity of the turbo compressor is 1500RT or more, the power of the inverter must be 3300V or more. Inverter using a high power source is more expensive than an inverter using a low power source, so that an increase in the capacity of the turbocompressor increases the manufacturing cost excessively.

A problem to be solved by the present invention is to replace a high voltage inverter used in a large capacity turbo compressor with a low voltage inverter and obtain an efficiency equal to or higher than that in the case of using a high voltage inverter even if a low voltage inverter is used.

Another object of the present invention is to reduce power consumption in driving the turbo compressor.

In order to replace a high voltage inverter used in a turbocompressor with a low voltage inverter, a turbo compressor according to one aspect includes a driving unit including a main motor and a sub motor; A compression unit including an impeller rotating by a driving force of the driving unit; A planetary gear portion for shifting the rotational force of the driving portion and transmitting the rotational force to the compression portion; And an inverter for controlling power applied to the driving unit, wherein a first input shaft rotated by the main motor and a second input shaft rotated by the sub motor are connected to the planetary gear unit, And the rotational speed of the second input shaft is varied as controlled by the inverter.

The present invention can control the rotational speed of the impeller by using a planetary gear, a sub-motor, and a low-voltage inverter to improve efficiency during partial load operation of a large-capacity turbo compressor.

By using the compound planetary gear, the power consumption of the inverter controlling the sub motor can be reduced.

1 is a cross-sectional view of a conventional turbo compressor;
2 illustrates a planetary gear portion of a turbo compressor according to an embodiment of the present invention.
3 is a sectional view of the planetary gear portion of Fig.
FIG. 4 is a table showing required specifications for the operation load of the turbo compressor. FIG.
5 is a table showing the speed, torque and uniformity of the planetary gear portion to satisfy the requirements of Fig.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. It is to be understood, however, that the spirit of the invention is not limited to the embodiments shown and that those skilled in the art, upon reading and understanding the spirit of the invention, may easily suggest other embodiments within the scope of the same concept.

1 is a cross-sectional view of a conventional turbo compressor.

Referring to FIG. 1, a conventional turbo compressor 1 includes a motor 10 as a driving unit, a gear unit 20 for increasing rotation of the motor 10, and a compression unit 30).

The motor (10) provides power for driving the compressor (30) as a driving unit. The power of the drive shaft 12 provided in the motor 10 is transmitted to the output shaft 32 provided in the compression unit 30 through the gear unit 20.

The gear portion (20) includes a speed increasing gear (22). The speed increasing gear 22 may be provided on the driving shaft 12. The speed increasing gear 22 may increase the rotational force generated by the motor 10. [

The compression unit 30 includes impellers 33 and 34 fixed to the output shaft 32 and rotating. The impeller (33, 34) can rotate together with the rotation of the output shaft (32). The refrigerant can be compressed by the rotation of the impellers (33, 34).

The compression unit 30 may be provided with a bolt 36. The refrigerant compressed by the impeller (33, 34) is directed to the discharge duct through the volute (36).

The compression unit 30 may further include a bearing 35 for supporting the output shaft 32. The bearing 35 may include a Kingsbury bearing.

The compression unit 30 may further include a casing 37 formed along the longitudinal direction of the output shaft 32. The casing (37) is provided with a suction port (38) for the inflow of the refrigerant.

The compression unit 30 may further include an inlet guide vane (IGV) The suction guide vane 39 is provided on the suction port 38 side and can adjust the suction flow rate of the refrigerant flowing through the suction port 38.

As described above, in the conventional turbo compressor 1, the driving force generated by the motor 10 is transmitted to the compression unit 30 by the gear unit 20.

On the other hand, the turbo compressor of the present invention is different from the conventional turbo compressor 1 in the configuration of the gear portion 20. [ Specifically, in the turbo compressor of the present invention, unlike the conventional turbo compressor 1, the gear portion 20 includes a planetary gear portion. Hereinafter, the turbo compressor of the present invention will be described in detail.

FIG. 2 is a plan view of a planetary gear unit of a turbo compressor according to an embodiment of the present invention, and FIG. 3 is a sectional view of the planetary gear unit of FIG.

2 and 3, the turbo compressor 1 according to the embodiment of the present invention includes a driving unit, a planetary gear unit 100, and a compression unit 130. The driving unit includes a main motor 110. The driving force generated by the main motor 110 is transmitted to the output shaft 132 of the compression unit by being shifted by the planetary gear unit 100. The output shaft 132 is provided with impellers 133 and 134 and the refrigerant can be compressed as the impellers 133 and 134 rotate. The plurality of impellers 133 and 134 may be provided.

The functions of the main motor 110 and the compression unit 130 may be substantially the same as those of the motor 10 and the compression unit 30 of FIG.

The planetary gear portion 100 may include a simple planetary gear or a complex planetary gear. Hereinafter, the case where the planetary gear unit 100 of the present invention is a complex planetary gear will be described in detail.

The planetary gear unit 100 includes a first gear unit 101 and a second gear unit 102. A first input shaft 112 may be connected to the first gear unit 101 and an output shaft 132 may be connected to the second gear unit 102.

The first input shaft 112 is rotated by the main motor 110 and the output shaft 132 is rotated by the planetary gear unit 100. That is, the rotational speed of the first input shaft 112 is shifted by the planetary gear unit 100 and is transmitted to the output shaft 132. The output shaft 132 is provided with the impellers 133 and 134 and the impeller 133 and 134 can be rotated together by the rotation of the output shaft 132.

The first input shaft 112 may be directly coupled to the main motor 110 or may be gear-engaged with a driving shaft of the main motor 110. When the first input shaft 112 and the drive shaft of the main motor 110 are gear-engaged, the first input shaft 112 may be formed with a gear.

The first gear portion 101 includes a first sun gear 111 to which the input shaft 12 is connected and a plurality of first planetary gears 113 which are engaged with the first sun gear 111 by being circumscribed .

The second gear portion 102 includes a second sun gear 121, a plurality of second planetary gears 123, and a ring gear 125.

The second sun gear 121 is connected to the output shaft 132. The diameter of the second sun gear 121 is larger than the diameter of the first sun gear 111. [

The plurality of second planetary gears 123 are engaged with the second sun gear 121 by being circumscribed. The second planetary gear 123 is formed integrally with the first planetary gear 113 and rotates at the same speed. The diameter of the second planetary gear 123 may be larger than the diameter of the first planetary gear 113. Accordingly, the rotational speed of the first sun gear 111 can be increased. The first planetary gear 113 and the second planetary gear 123 are generically referred to as planetary gears.

If the number of the planetary gears is large, there is an advantage in transmitting a large force. However, in the present invention, three planetary gears are provided.

The first and second planetary gears 113 and 123 can revolve around the first sun gear 111 and the second sun gear 121 while rotating.

The ring gear 125 is disposed so as to surround the second planetary gears 123. The ring gear 125 is in contact with and engaged with the plurality of second planetary gears 123, respectively. Therefore, the inner diameter of the ring gear 125 is a value obtained by adding the diameter of the first sun gear 111 to twice the diameter of the second planetary gear 123. An inner gear 126 meshing with the plurality of second planetary gears 123 is formed on an inner circumferential surface of the ring gear 125.

The driving unit may further include a sub motor 140. The sub motor 140 may be connected to the planetary gear unit 100 to transmit power. The capacity of the sub motor 140 may be 40% or less of the capacity of the main motor 110.

The turbocompressor may further include an inverter 150 for controlling a voltage applied to the sub motor 140.

The gear portion 141 may be provided on the second input shaft 142 of the sub motor 140. The gear portion 141 can be engaged with the ring gear 125 by being circumscribed. And an outer gear 127 which is engaged with the gear portion 141 may be formed on the outer side of the ring gear 125.

The sub motor 140 may be controlled by the inverter 150. The inverter 150 can vary the frequency of the second input shaft 142 of the sub motor 140 by varying the frequency supplied to the sub motor 140, The number of revolutions can be changed. Accordingly, the partial load efficiency of the turbo compressor can be improved. Hereinafter, the operation of the planetary gear unit 100 will be described in detail.

When the first input shaft 112 is rotated by driving the main motor 110, the first sun gear 111 rotates. The first input shaft 112 and the first sun gear 111 may rotate clockwise. At this time, the first input shaft 112 rotates at a constant speed, so that the first sun gear 111 also rotates at a constant speed.

When the first sun gear 111 rotates, the plurality of first planetary gears 113 rotate. At this time, the plurality of first planetary gears 113 rotate counterclockwise. That is, the plurality of first planetary gears 113 rotate in a direction opposite to the first sun gear 111.

The plurality of second planetary gears 123 are formed integrally with the plurality of first planetary gears 113, respectively, so that they rotate together with the plurality of first planetary gears 113. Accordingly, the plurality of second planetary gears 123 rotate in the counterclockwise direction. At this time, the first and second planetary gears 113 and 123 can revolve about the first and second sun gears 111 and 121.

The second sun gear 121 is also rotated by the rotation of the plurality of second planetary gears 123. At this time, the second sun gear 121 rotates in a clockwise direction opposite to the direction of rotation of the plurality of second planetary gears 123. That is, the first sun gear 111 and the second sun gear 121 rotate in the same direction.

As the second sun gear 121 rotates, the output shaft 132 rotates. Accordingly, the driving force of the main motor 110 is transmitted to the compression unit 130.

The ring gear 125 meshes with the plurality of second planetary gears 123 and rotates counterclockwise.

Meanwhile, a driving force may be applied to the ring gear 125 using the sub motor 140 to vary the rotational speed of the output shaft 132 according to the system operation load.

Specifically, when the sub motor 140 is operated, the gear portion 141 provided on the second input shaft 142 may be rotated counterclockwise. Accordingly, the gear portion 141 can engage with the outer gear 127 of the ring gear 125 and apply a rotational force to the ring gear 125 in the opposite direction. Accordingly, a rotational force is applied in a direction opposite to the rotational direction of the ring gear 125, so that the rotational force of the second sun gear 121 can be reduced.

In contrast, when the sub motor 140 is operated, the gear portion 141 provided on the second input shaft 142 can be rotated clockwise. Accordingly, a rotational force can be added to the ring gear 125. Accordingly, the rotational force of the second sun gear 121 can be increased.

The number of revolutions of the second input shaft 142 may be controlled by the inverter 150. Specifically, by varying the frequency of the inverter 150, the rotational speed of the second input shaft 142 can be changed by adjusting the voltage applied to the sub motor 140. Accordingly, the number of rotations of the second sun gear 121 and the output shaft 132 can be changed. Accordingly, the number of revolutions of the impellers 133 and 134 can be varied.

Therefore, the compression head of the compression unit 130 can be appropriately adjusted according to the operation load by the above-described method of providing the voltage applied to the sub motor 140 to the output shaft 132.

The gear included in the planetary gear unit 100 may be a spur gear or a helical gear. That is, the gear of the planetary gear unit 100 may have a shape in which the twisted teeth are cut. Since the helical gear has a better fitting ratio than the spur gear, the helical gear is smoothly rotated and the amount of noise generated by friction during operation can be reduced.

Hereinafter, speed, torque, and uniformity of each configuration of the planetary gear unit 100 will be described for each operation load.

FIG. 4 is a table showing required specifications for each operation load of the turbo compressor, and FIG. 5 is a table showing the speed, torque, and uniformity of the planetary gear unit to satisfy the requirements of FIG.

Referring to FIG. 4, it is assumed that the cooling capacity of the conventional turbo compressor, that is, the load ratio is 100% when the operation load is 1500 RT. The vertical axis in FIG. 4 indicates the case where the operation load of the conventional turbo compressor is 100%, 75%, 50%, and 25%, respectively.

The efficiency of the motor 10 is equal to 0.95 regardless of the load ratio of the turbo compressor and the rotation speed of the input shaft 12 is equal to 3564 rpm because the input shaft 12 rotates at a constant speed, Is equal to 0.98. The power consumption of the turbo compressor decreases as the load factor decreases.

Since the rotational speed of the input shaft 12 is constant, the shaft power and torque of the input shaft 12 decrease.

As the load factor of the turbo compressor decreases, the required shaft power, rotational speed, and torque of the output shaft 32 decrease.

When the capacity of the turbocompressor is 1000RT or less, the inverter power is generally 380-440V. However, when the capacity of the turbo compressor is 1500RT or more, the high voltage (3300V or more) is used. .

5, the rotational speed Speed and the torque of the first sun gear 111, the second sun gear 121, and the ring gear 125 of the planetary gear unit 100, ) And power (power) are shown by operating load according to the simulation results.

It is assumed that the number of gear teeth of the first sun gear 111, the second sun gear 121 and the ring gear 125 is 51, 39, and 120, respectively. Since the ring gear 125 rotates in a direction opposite to that of the first sun gear 111 and the second sun gear 121, the rotational speed and the torque are denoted by negative signs.

The torque and the uniformity of the first sun gear 111 decrease as the load ratio of the turbo compressor decreases. However, even if the load factor of the turbo compressor is reduced, the rotation speed of the first sun gear 111 is constant.

The torque and the uniformity of the second sun gear 121 decrease as the load factor of the turbo compressor decreases. The rotational speed of the second sun gear 121 decreases as the load factor decreases, but is the same when the load factor is 50% and 25%.

The torque and the uniformity of the ring gear 125 decrease as the load factor of the turbo compressor decreases. The rotational speed of the ring gear 125 is reduced as the load ratio is decreased, but is the same when the load ratio is 50% and 25%.

The turbocompressor of the present invention shifts the power of the main motor 110 to the output shaft 132 by using the planetary gear unit 100 and transmits the power of the sub motor 140 to the planetary gear unit 100 So that the output shaft 132 can be controlled. The main motor 110 operates at a constant speed and the sub motor 140 is controlled using an inverter 150 to control the rotation of the output shaft 132 according to the operation load of the turbo compressor. If the capacity of the sub motor 140 is smaller than that of the main motor 110, the inverter 150 can control the power at a low voltage, thereby increasing the efficiency of the turbo compressor. In addition, since a low-voltage inverter can be used in place of the high-voltage inverter, manufacturing cost of the turbo compressor can be reduced.

100: planetary gear unit 110: first gear unit
111: first sun gear 112: first input shaft
120: second gear portion 121: second sun gear
130 compression section 132 output shaft

Claims

A driving unit including a main motor and a sub motor;
A compression unit including an impeller rotating by a driving force of the driving unit;
A planetary gear portion for shifting the rotational force of the driving portion and transmitting the rotational force to the compression portion; And
And an inverter for controlling power applied to the driving unit,
A first input shaft rotated by the main motor and a second input shaft rotated by the sub motor are connected to the planetary gear unit,
And the rotational speed of the second input shaft is variable as the sub motor is controlled by the inverter.

The method according to claim 1,
And the main motor rotates the first input shaft at a constant speed.

The method according to claim 1,
The planetary gear unit
A first sun gear connected to the first input shaft;
A plurality of planetary gears rotated by engagement with an outer peripheral surface of the first sun gear;
The second sun gear engaged with the plurality of planetary gears and rotated; And
And a ring gear engaged with the outer circumferential surface of the plurality of planetary gears and rotating,
And the second sun gear is connected to the compressor to rotate the impeller.

The method of claim 3,
And the ring gear is connected to the second input shaft to provide the driving force of the sub motor.

5. The method of claim 4,
And the rotational speed of the ring gear is reduced when the second input shaft rotates in the same direction as the ring gear.

5. The method of claim 4,
And the gear portion provided on the second input shaft is engaged with the outer peripheral surface of the ring gear.

The method of claim 3,
And the diameter of the second sun gear is larger than the diameter of the first sun gear.

The method of claim 3,
The above-
A first planetary gear engaged with the first sun gear,
And a second planetary gear engaged with the ring gear.

9. The method of claim 8,
Wherein the first planetary gear and the second planetary gear are integrally formed.

9. The method of claim 8,
And the diameter of the second planetary gear is larger than the diameter of the first planetary gear.

The method according to claim 1,
Wherein the sub motor has a smaller capacity than the main motor.

The method according to claim 1,
Wherein the plurality of impellers are provided.