KR20210138900A - Turbo compressor - Google Patents

Abstract

The present invention relates to a turbo-compressor having a rotational shaft which comprises: a cylindrical sleeve surrounding the outside of a rotor; a first shaft having a first insertion unit inserted into one side of the sleeve; and a second shaft having a second insertion unit inserted into the other side of the sleeve. The turbo-compressor prevents deformation since a weak portion strongly receives force by inertia moment by a shape and deformation by centrifugal force.

Description

Turbo Compressor {TURBO COMPRESSOR}

It relates to a turbocompressor having a rotating shaft that can be stably driven even at high speed rotation.

In general, a compressor is applied to a vapor compression type refrigeration cycle (hereinafter, abbreviated as a refrigeration cycle) such as a refrigerator or an air conditioner. The compressor may be classified into a reciprocating type, a rotary type, a scroll type, etc. according to a method of compressing the refrigerant.

A reciprocating compressor is a compressor in which a piston in a cylinder compresses gas by reciprocating motion. Among them, in the scroll compressor, the orbiting scroll engages with a fixed scroll fixed in the inner space of the sealed container and makes a pivoting motion, so that the fixed wrap of the fixed scroll and the orbiting scroll It is a compressor in which a compression chamber is formed between the orbital wraps of

A turbocompressor is a type of centrifugal compressor, which rotates an impeller of a curved blade in a casing and compresses gas using the centrifugal force. The turbo compressor has advantages such as large capacity, low noise, and low maintenance compared to the reciprocating type and screw type. In addition, it is possible to produce clean compressed gas that does not contain oil.

A centrifugal turbocompressor consists of an impeller to compress gas and a diffuser that decelerates the accelerated gas flow and converts it into pressure. When the motor rotates the impeller at high speed, external gas is sucked in along the axial direction of the impeller, and the sucked gas is discharged in the centrifugal direction of the impeller. The fluid discharged in the centrifugal direction of the impeller is compressed while moving along a flow path formed inside the turbocompressor.

The turbocompressor includes a fixed part that does not rotate and a rotating part that rotates about a rotation shaft, and when rotating at a high speed, heat is generated and bending occurs. Primary bending occurs at the resonance point of the rotation shaft, and the rotation shaft may be damaged. Therefore, the maximum speed of the rotating shaft needs to be designed with a margin of about 15 to 25% from the number of revolutions at which the first bending occurs. When the speed at which the primary bending occurs must be increased, it is possible to prevent the rotation shaft from being damaged due to the primary bending when the turbocompressor is driven. If the rotation shaft is made thick and short, the axial rigidity can be increased and the number of rotations of the primary bending can be increased.

On the other hand, in systems to which oilless bearings are applied, the weight of the shaft is related to bearing reliability. In other words, since the minimum speed of the rotating shaft is an oilless bearing, it is not affected by the weight of the shaft and thus does not float, and the bearing sliding becomes longer and reliability is lowered. In other words, it is necessary to design the shaft as small as possible for a high-efficiency system, but also consider the safety of the shaft. It is necessary to design a rotating shaft to satisfy both different characteristics.

US Patent Publication No. 2004-0005228 (published on January 8, 2004) uses a tie rod fastened to an impeller as a rotation shaft by fastening the rotation shaft using a tie bolt, but the thickness is thin and bending occurs easily, so maximum operation is possible. There is a problem in that the speed is lowered and the driving range is reduced.

US Patent Publication No. 2004-0005228 (published on January 8, 2004)

An object of the present invention is to provide a turbocompressor having a wide operating range by improving a rotating shaft.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the examples of the present invention. Moreover, it will be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

motor housing; a stator positioned inside the motor housing and including a shaft hole extending from one side to the other; a rotating shaft passing through the shaft hole of the stator; a rotor positioned inside the shaft hole and coupled to the rotation shaft; a first impeller coupled to one end of the rotation shaft; a second impeller coupled to the other end of the rotation shaft; and a disk-shaped thrust runner positioned between the first impeller and the rotor and having a predetermined diameter about the rotation shaft, wherein the rotation shaft includes: a cylindrical sleeve surrounding the outside of the rotor; a first shaft including a first insertion part inserted into one side of the sleeve; and a second shaft including a second insertion part inserted into the other side of the sleeve.

The thrust runner may include a disk portion having an opening into which the first shaft is inserted.

The disk portion may be in contact with one end of the sleeve.

The first shaft may further include a stepped portion in contact with one surface of the disk portion.

The thrust runner may further include a cylindrical portion extending from the opening of the disk portion to surround the outer circumferential surface of the first shaft, and the cylindrical portion may be located inside the sleeve.

In the first shaft, the diameter of the insertion part inserted into the cylindrical part may be larger than the diameter of the outer part located outside the cylindrical part.

The length of the cylindrical portion may have a length corresponding to the length of the first insertion portion.

The length of the first insertion part may be formed to be 20% or more of the length of the rotor.

The inner diameter of the sleeve may be smaller than the diameter of the first insertion portion and may be coupled by press-fitting.

A difference between the diameter of the first insertion part and the inner diameter of the sleeve relative to the diameter of the rotation shaft may have a value of 0.3% or more.

The second shaft may further include a stepped portion in contact with the other end of the sleeve.

The sleeve may include at least one of Inconel, titanium, stainless steel, and carbon fiber.

The turbocompressor according to the present invention can be prevented from being deformed by receiving a large force on a weak part due to the deformation by centrifugal force and the moment of inertia due to the shape.

Even at low speed rotation, the operation of the oilless bearing is maintained and the bearing does not slide, so reliability can be maintained.

A high-efficiency system can be realized through the design of a compact rotating shaft.

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

1 is a cross-sectional view illustrating an embodiment of a turbocompressor.
FIG. 2 is an exploded perspective view of the turbocompressor of FIG. 1 .
3 is a diagram illustrating a circulation system.
4 is a view showing an embodiment of a rotation shaft of a turbocompressor.
5 and 6 are views illustrating bending deformation of a rotating shaft of a turbocompressor.
7 is a graph showing the amount of deformation according to the length and press-fit amount of the insertion part and the load bearing capacity according to the insertion length and the press-fit amount.
8 is a graph and a table showing the elastic modulus, circular force, and fatigue strength according to the material of the sleeve.

Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but the same or similar components are assigned the same reference numerals regardless of reference numerals, and overlapping descriptions thereof will be omitted. The suffixes "module" and "part" for the components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have a meaning or role distinct from each other by themselves. In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in the present specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed herein is not limited by the accompanying drawings, and all changes included in the spirit and scope of the present invention , should be understood to include equivalents or substitutes.

Terms including an ordinal number, such as first, second, etc., may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

When a component is referred to as being “connected” or “connected” to another component, it is understood that the other component may be directly connected or connected to the other component, but other components may exist in between. it should be On the other hand, when it is mentioned that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present application, terms such as "comprises" or "have" are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

In general, the turbocompressor 100 is a type of the centrifugal compressor 100 and rotates the impellers 136 and 137 to compress the fluid by its centrifugal force. The turbocompressor 100 sucked in gas in the axial direction using the rotational force of the impellers 136 and 137 . Compression while discharging in the centrifugal direction is classified according to the number of impellers (136, 137). The two-stage turbocompressor 100 having two impellers 136 and 137 may further maximize efficiency by performing compression twice. The two-stage compressor 100 is a back-to-back type disposed to face the rear surfaces of the impellers 136 and 137 and a face to face type in which the suction ends of the impellers 136 and 137 are disposed to face each other. face) type.

1 is a view showing an embodiment of the turbocompressor 100 of the present invention, and FIG. 2 is an exploded perspective view of the turbocompressor 100 of FIG. 1 . The turbocompressor 100 according to the present embodiment includes a stator 131 , a rotation shaft 133 , a rotor 132 , a first impeller 136 , and a thrust runner 135 , and a frame for accommodating them.

The motor includes a stator 131 (stator) and a rotor 132 (rotor), and the stator 131 is fixed inside the first frame 111 having an inner space in which one side and the other side are open. The stator 131 may include a plurality of electromagnets made of a coil, and when a current flows through the coil, a magnetic field is formed. By adjusting the strength and direction of the current flowing through the coil, the strength and direction of the magnetic field formed by the stator 131 may be adjusted. The stator 131 is disposed around the rotor 132 including a magnetic material, and the rotor 132 may rotate under the influence of a magnetic field formed by the stator 131 .

The stator 131 has a donut shape including a shaft hole extending from one side to the other side, and the rotor 132 is coupled to the rotation shaft 133 extending along the shaft hole to rotate together with the rotation shaft 133 . The rotating shaft 133 may transmit the rotation of the rotor 132 to rotate the impellers 136 and 137 positioned at the ends of the rotating shaft 133 .

A bearing may be used to reduce frictional force generated when the rotating shaft 133 rotates. In particular, in the turbocompressor 100 of the present invention, since the rotation shaft 133 is disposed in the horizontal direction and force is applied in the direction of gravity, the journal bearing 127 supporting the force applied in the vertical direction to the axial direction may be used. The journal bearing 127 may be disposed between the rotation shaft 133 and the frame.

The rotation shaft 133 preferably has a short length and a large diameter so that rigidity of the shaft can be secured in order to be suitable for high-speed operation. However, as the diameter of the shaft increases, the area in contact with the frame increases and frictional force increases. In addition, there is a problem in that the size of the journal bearing 127 increases in order to offset the frictional force between the rotating shaft 133 and the frame. As the size of the compressor 100 increases and the weight increases as the rotation shaft 133 increases, there is also a limit to increasing the diameter of the rotation shaft 133 .

Instead of increasing the diameter of the rotating shaft 133 , the rotor 132 coupled to the rotating shaft 133 may be configured to protrude more than other parts of the rotating shaft 133 . The rotor 132 includes a permanent magnet, and as the size of the permanent magnet increases, it is easier to implement high-speed rotation. Since the diameter of the rotation shaft 133 of the portion where the motor housing 110 and the rotation shaft 133 are coupled is thinner than the portion where the rotor 132 is located, the size of the journal bearing 127 does not need to be increased.

The thrust runner 135 is a disk-shaped member coupled to the rotation shaft 133 and rotates according to the rotation of the rotation shaft 133 , and guides the axial movement of the rotation shaft 133 . When the impellers 136 and 137 are located at both ends of the rotation shaft 133, pressure is applied in the axial direction while the fluid is compressed through the impellers 136 and 137 during rotation. The force applied in the axial direction of the rotating shaft 133 may be asymmetrical and thus may move in the axial direction, so that a thrust runner 135 may be provided to fix it.

The thrust runner 135 is disposed between the second frame 112 and the third frame 113 to prevent the thrust runner 135 from moving in the axial direction, and the second frame 112 and the third frame 113 are It may be fixed to the first frame 111 , and one of the second frame 112 and the third frame 113 may be integrally formed with the first frame 111 . The second frame 112 may be positioned between the first impeller 136 and the thrust runner 135 , and the third frame 113 may be positioned between the thrust runner 135 and the motor.

The thrust runner 135 limits the axial movement of the rotation shaft 133 but should not affect the rotation of the rotation shaft 133 . In order to minimize friction between the thrust runner 135 and the frame, a thrust bearing 126 may be provided on a surface facing the thrust runner 135 on the frame. The thrust bearing 126 is a bearing in which a load is applied in the axial direction, and may reduce frictional force when rotating together with the rotating shaft 133 while preventing the thrust runner 135 from moving in the axial direction.

The rotational force of the rotor 132 induced by the stator 131 is transmitted to the impellers 136 and 137 along the rotation shaft 133, and the impellers 136 and 137 rotate and the fluid supplied to the impellers 136 and 137. is passed through the diffusers 1162 and 1172 formed in the impeller casings 116 and 117 to increase the pressure of the fluid. The diffusers 1162 and 1172 formed in the impeller casings 116 and 117 are diffusion tubes in which the size of the flow path increases. When the size of the flow path increases, the pressure of the fluid passing through the diffusers 1162 and 1172 increases by using the property of converting kinetic energy into pressure energy as the flow velocity of the fluid becomes slow.

A pair of a first impeller 136 and a second impeller 137 may be provided at both ends of the rotation shaft 133 to increase the compression effect, and the motor housing 110 divides the first impeller 136 and the motor. The second frame 112 and the second impeller 137 may include a fourth frame 114 partitioning the motor. The space between the first impeller casing 116 and the second frame 112 that covers the first impeller 136 becomes the first diffuser 1162 and the second impeller casing 117 that covers the second impeller 137 ) and the space between the fourth frame 114 may be the second diffuser 1172 .

The first impeller casing 116 includes a first inlet 1161 for supplying fluid in the axial direction of the first impeller 136 and a first outlet 1163 for discharging fluid in the circumferential direction of the first impeller 136 . Including, the second impeller casing 117 is a second inlet 1171 for supplying a fluid in the axial direction of the second impeller 137 and a second outlet for discharging the fluid in the circumferential direction of the second impeller 137 ( 1173).

A larger compressed fluid can be obtained by recompressing (two-stage compression) the fluid compressed (one-stage compression) in the first impeller 136 using the second impeller 137 . The first outlet 1163 is connected to the second inlet 1171 and passes through the second diffuser 1172 of the second impeller casing 117 and is re-compressed.

3 is a view showing a circulation system using a fluid. Figure 3 (a) shows a circulation system, the circulation system includes a compressor (100, compressure), a condenser (200, condenser), an expansion valve (300, expansion valve) and an evaporator (400, evaporator), each It connects the components and includes a circulation path through which the fluid moves.

3 (b) is a graph showing the relationship between energy and pressure of a fluid circulating in the circulation system 10. The horizontal axis indicates energy accumulated in the fluid, that is, enthalpy, and the vertical axis indicates the pressure of the fluid. As described above, in the compressor 100, as the pressure increases while the fluid is compressed, entropy also increases.

The fluid passing through the compressor 100 is converted into a high-temperature and high-pressure fluid as the pressure and temperature increase, and maintains a gaseous state. The condenser 200 may discharge heat from the gaseous high-temperature and high-pressure gaseous fluid supplied from the compressor 100 to convert it into a low-temperature and high-pressure fluid. At this time, the gaseous fluid is converted to a liquid phase. At this time, the state of the fluid moves to the left on the graph of FIG. 3B.

The medium-temperature and high-pressure liquid fluid passes through the expansion valve 300 before moving to the evaporator 400. When the high-temperature and high-pressure fluid passes through a narrow flow path, the speed of the fluid increases according to Bernoulli's law. As the velocity increases, the pressure of the fluid decreases. The liquid fluid is expanded into a fluid state in which the liquid phase and the gas phase are mixed, and the low temperature and low pressure fluid in which the liquid phase and the gas phase are mixed moves to the evaporator 400 .

In the evaporator 400 , the fluid absorbs heat, lowers the ambient temperature, and liquefies water vapor in the air to lower the humidity of the surrounding air. The fluid is evaporated and vaporized while absorbing heat, and a high-temperature fluid in a gaseous state is supplied to the compressor 100 .

Such a circulation system 10 may be applied to an air conditioner or a dryer. The dryer needs parts for supplying high-temperature air to the inside of the dryer and parts for removing moisture from the high-temperature and humid air. One circulation using the condenser 200 and the evaporator 400 of the present circulation system 10 It can serve both roles in the system 10 at the same time.

Referring again to FIG. 2 , when the turbo compressor 100 rotates at a high speed, heat is generated. If the heat generated when the turbocompressor 100 is driven is not properly cooled, the frictional area and the driving motor may be damaged. In addition, when the temperatures of the motor and the thrust runner 135 increase, the temperature of the fluid compressed through the compressor 100 may also increase, thereby reducing the compression efficiency of the fluid. Due to the high temperature, surrounding parts may be damaged, and there is a risk of burns if the user touches them, so it is necessary to cool them.

A refrigerant may be used to reduce the internal temperature of the motor housing 110 , and the refrigerant may be introduced into the motor housing 110 through the refrigerant inlet 153 connected to the motor housing 110 . It may be discharged after absorbing heat through the surface of the high-temperature motor and thrust runner 135 .

As the refrigerant supplied through the refrigerant inlet 153 , a separate fluid may be used, but a fluid used in the above-described circulation system 10 may be used. The fluid compressed in the compressor 100 is converted to a high temperature, but since the fluid whose temperature is increased in the compressor 100 is also lower than the temperature inside the motor housing 110 , the fluid of the compressor 100 may be used. For example, by connecting the refrigerant inlet 153 by a bypass to the first outlet through which the first-stage compressed fluid is discharged, some fluid flows into the refrigerant inlet 153 to cool the temperature of the motor.

However, for a better cooling effect, a refrigerant having a low temperature in the circulation system 10 may be supplied through the refrigerant inlet 153 to further lower the temperature of the housing. For example, the refrigerant passing through the condenser 200 maintains a low temperature compared to the refrigerant of the compressor 100 and has a low enthalpy, so that the absorption efficiency of surrounding heat is high. Accordingly, the refrigerant passing through the condenser 200 may be bypassed and supplied to the refrigerant inlet 153 . At this time, the refrigerant is in a liquid state when supplied to the motor housing 110 , but absorbs heat from the motor and the thrust runner 135 in the motor housing 110 and may be discharged in a gaseous state through the refrigerant outlet 154 .

4 is a diagram illustrating an embodiment of the rotation shaft 133 of the turbocompressor 100 . The rotating shaft 133 is a member to which the rotor 132, the impellers 136, 137, and the thrust runner 135 are coupled, and is disposed through the motor housings 11, 112, and 113. For assembling, the rotating shaft 133 may be configured in multiple stages, and a cylindrical sleeve 1335 may be used to fix the multistage structure. The sleeve 1335 is a cylindrical member having rigidity and may include a high rigidity metal material such as Inconel, titanium, stainless steel, or carbon fiber.

The rotor 132 is inserted into the sleeve 1335 and may include a first shaft 1331 inserted into one side of the rotor 132 and a second shaft 1332 inserted into the other side with respect to the rotor 132 .

The first impeller 136 is coupled to the first shaft 1331 and may include a first insertion portion 1321a inserted into the sleeve 1335 . The second shaft 1332 is disposed symmetrically with the first shaft 1331 and includes a second insertion portion 1322a to which the second impeller 137 is coupled and is inserted into the other side of the sleeve 1335 .

The first shaft 1331 and the second shaft 1332 may be erroneously fastened to the sleeve 1335 by a press-fitting method. When using a fastener such as a screw, there is an advantage of high fastening force, but the rotation shaft 133 may be tilted in one direction and the size of the turbocompressor 100 may be small so that there may be insufficient space for fastening using the fastener.

By forming the outer diameter of the first shaft 1331 and the second shaft 1332 slightly larger than the inner diameter of the sleeve 1335, the first shaft 1331 and the second shaft 1332 can be press-fitted in a press-fitting manner. .

In the press-fitting, the fastening force between the sleeve 1335 and the first shaft 1331 and the second shaft 1332 is increased, and the difference in diameter between the two members is referred to as the press-fitting amount in the press-fitting method. If the amount of press fit is large, the fastening force is high, which is advantageous for the rigidity of the rotating shaft.

When the thrust runner 135 is also integrally formed, it is difficult to manufacture the rotation shaft 133 , so the disk-shaped thrust runner 135 including an opening inserted into the first shaft 1331 may be fastened. In order to fasten the disk-shaped thrust runner 135 to the first shaft 1331 by a press-fit method, the opening of the thrust runner 135 may be slightly smaller than the diameter of the first shaft 1331 .

The other surface of the thrust runner 135 may be disposed in contact with one end of the sleeve 1335 to fix the position of the thrust runner 135 . A stepped portion (not shown) in contact with one surface of the thrust runner 135 may be formed on the first shaft 1331 to fix the position of the thrust runner 135 in one lateral direction.

Before inserting the first shaft 1331 into the sleeve 1335 , the thrust runner 135 is inserted from the other side of the first shaft 1331 and press-fitted to the stepped portion, until the thrust runner 135 comes into contact with the first shaft 1331 may be inserted into the sleeve 1335 to be fastened.

As shown in (a) of FIG. 4 , the thrust runner 135 has an advantage in that it is simple to assemble when only the disc part is included. The fastening force between the shaft 1331 and the sleeve 1335 is also affected.

In order to increase the fastening force, as shown in (b) of FIG. 4 , it may further include a circular plate part 1351 and a cylindrical part 1352 extending from the opening of the circular plate part 1351 . The cylindrical portion 1352 extends from the disk portion 1351 to the other side of the rotation shaft 133, that is, in the direction in which the rotor 132 is located, and as shown in FIG. 4(b), the first shaft 1331 It can be extended to the same position as the other end of the. In this case, the diameter of the first shaft 1331 may be formed smaller in the first insertion portion 1331a,

Since a part of the thrust runner 135 is also inserted into the sleeve 1335, the fastening force of the thrust runner 135 is improved, and the coupling force between the first shaft 1331 and the sleeve 1335 is also stably possible, but the press-in process (a) There is a disadvantage in that processing is increased because it is more difficult than the embodiment.

5 and 6 are views illustrating bending deformation of the rotation shaft 133 of the turbocompressor 100 . The rotation shaft 133 may exhibit bending deformation when rotating at a high speed. In particular, if the rotation shaft 133 is long and rigid, bending deformation may be large at the same force. When the bending deformation occurs large, both ends of the rotary shaft 133 are precessed, so that the driving cannot be made stably. In other words, the rigidity must be increased so that bending is below a certain level.

Since there is a thrust runner 135 in the direction of the first shaft 1331 and the first impeller 136 is larger than the second impeller 137, one direction of the rotation shaft 133 is fixed and the end of the other direction is relatively fixed. can be bent. Compared to the integrally formed rotary shaft 133, the multi-stage rotary shaft 133 as shown in FIG. 4 has an advantage in assembling, but has a weak problem in bending deformation. In order to reduce the bending deformation, it is advantageous to lengthen the insertion length (a) of the first shaft 1331 .

5 (a) is an embodiment in which the length (a) of the first insertion part 1321a of the first shaft 1331 is 5 mm, and FIG. 5 (b) is the first insertion of the first shaft 1331 It is an embodiment in which the length (a) of the portion 1321a is 10 mm. The amount of press-fitting of the first shaft 1331 is 20 μm, and the length b of the rotor 132 is 50 mm, showing the bending deformation of the rotary shaft 133 under a load of 300N with respect to the rotary shaft 133 . The deformation of the other end is shown in a state in which one end is fixed, and the bending deformation of the rotating shaft 133 of FIG. When the insertion length (a) is shorter, it can be seen that the bending deformation occurs larger.

6 is a view showing the stress applied to the first insertion part 1321a and the sleeve 1335 of FIG. 5, (a) of FIG. 6 corresponds to the embodiment of FIG. 5 (a) and (b) corresponds to the embodiment of FIG. 5 (b).

The stress in the dark part acts greatly, and the stress at one end of the sleeve 1335 is greater in the short insertion length (a) than in the long insertion length (b).

That is, when the length of the first insertion portion 1321a of the first shaft 1331 is short, more bending deformation occurs. It is advantageous to lengthen the length (a) of the first insertion part 1321a so that bending deformation of the rotation shaft 133 does not appear at the maximum speed, but if it is too long, the entire length of the rotation shaft 133 becomes too long, and the rotor 132 ), the driving force is reduced when reducing the length, so it must be designed with an appropriate length.

7 is a graph showing the deformation amount and the stress of the sleeve 1335 according to the length and press-in amount of the first insertion part 1321a, and FIG. 8 is a graph showing the load bearing force according to the insertion length and the press-in amount.

7A is a graph showing the load and the amount of deformation for six examples in which the indentation amount and the indentation length are different. The amount of press-in means the difference in diameter between the sleeve 1335 and the first insertion portion 1321a of the first shaft 1331 and the unit is μm, and the press-fit length is the first insertion portion 1321a inserted into the sleeve 1335 . It means the length (a) of , and the unit is mm. Taking 40/5 as an example, the press-fit amount is 40 μm and the length of the first insertion part 1321a is 5 mm.

The load is a force applied to the rotation shaft 133 in a direction perpendicular to the shaft, and the load becomes larger during high-speed rotation. It can be seen that the amount of deformation increases as the rotation speed increases. The greater the press-fitting amount, the smaller the deformation amount, and the longer the insertion length, the smaller the deformation amount. In terms of load, the larger the indentation amount, the larger the load can be supported, and the longer the insertion length, the larger the load can be supported.

7 (b) is a graph showing the limit load according to the press-fit amount of the first shaft 1331 and the sleeve 1335 when the limit deformation amount that the rotary shaft 133 can normally drive is 200 μm. The larger the indentation amount, the greater the limiting load, and the larger the indentation length, the greater the limiting load. As the supporting load increases, the operating range of the turbocompressor 100 may be widened.

Since one end and both ends of the rotation shaft 133 are supported by the motor housing, the length of the first insertion part 1321a is increased according to the length b of the rotor 132 in order to minimize the bending deformation of the rotor 132 part. can be decided. If the length (b) of the rotor 132 is long, the length of the first insertion portion 1321a should also be increased, and the length of the first insertion portion 1321a of the first shaft 1331 compared to the length of the rotor 132 . must have a length of about 20% or more to minimize bending deformation and enable rotational motion.

The graph of FIG. 7 is experimental data based on the case where the length of the rotor 132 is about 50 mm. In this embodiment, the length of the first insertion part 1321a of the first shaft 1331 is 10 mm or more. can

The larger the press-fitting amount, the greater the support load. 8A is a graph showing the stress of the sleeve 1335 according to the press-fit amount and the insertion length. When the load is small, there is no significant difference between the insertion length and the stress of the sleeve 1335, but when the insertion length is small (5 mm), the stress applied to the sleeve 1335 is sharply increased as the load increases by operating at a high speed. When the insertion length is 10 mm, the change in the stress applied to the sleeve 1335 is not large, but there is a problem in that the greater the indentation amount, the greater the stress.

Therefore, it is better to set a large press-in amount for the support load, and a small press-in amount is advantageous in order to reduce the stress applied to the sleeve 1335 , so an appropriate press-in amount should be designed.

As a material of the sleeve 1335 , Inconel alloy, which is an alloy of nickel, chromium, iron, etc., and stainless steel, which is an alloy of iron and chromium, may be typically used. Since the turbocompressor 100 generates heat when rotating at a high speed, the change in the elastic modulus should not be large in a high-temperature environment. When the turbocompressor 100 is driven, it can rise to about 450°C, so an Inconel alloy (Inconel) or stainless steel (SUS) having a small change in the elastic modulus up to 450°C can be used.

Figure 8 (b) shows the centrifugal force ( It is a table showing the unit: MPa).

The magnitude of the centrifugal force means the stress applied to the sleeve 1335 during rotation, and both the Inconel alloy and the stainless steel show a similar centrifugal force.

The tensile strength and fatigue strength of Inconel alloy and stainless steel refer to the strength at which the product can be damaged when a force greater than the tensile strength or fatigue strength is applied. Since the fatigue strength is smaller than the tensile strength, it must be operated within the indentation amount where centrifugal force less than the fatigue strength is generated. Therefore, the sleeve 1335 and the first insertion portion 1321a must be designed to have a press-fitting amount of 60 μm or less so that the sleeve 1335 is not damaged.

The rotation shaft 133 may be designed with a maximum press-fitting amount of 60 μm between the sleeve 1335 and the first insertion portion 1321a in a range not to be damaged.

As described above, the turbocompressor of the present invention can be prevented from being deformed by receiving a large force on a weak part due to the deformation due to centrifugal force and the moment of inertia due to the shape.

Even at low speed rotation, the operation of the oilless bearing is maintained and the bearing does not slide, so reliability can be maintained.

A high-efficiency system can be realized through the design of a compact rotating shaft.

For those of ordinary skill in the art to which the present invention pertains, various substitutions, modifications and changes are possible within the scope of the present invention without departing from the technical spirit of the present invention. is not limited by

111: first frame 112: second frame
113: third frame 114: fourth frame
116, 117: impeller frame 1161, 1171: inlet
1162, 1172: diffuser 1163, 1173: outlet
126: thrust bearing 127: journal bearing
128: impeller bearing 131: stator (stator)
132: rotor (rotor) 133: axis of rotation
1331: first shaft 1331a: first insertion portion
1332: second shaft 1332a: second insert
1332b: step 1335: sleeve
135: thrust runner 136: first impeller
137: second impeller 151, 152: circulation passage
1551: first refrigerant passage 1552: second refrigerant passage
1553: third refrigerant passage

Claims (12)

motor housing;
a stator positioned inside the motor housing and including a shaft hole extending from one side to the other;
a rotating shaft passing through the shaft hole of the stator;
a rotor positioned inside the shaft hole and coupled to the rotation shaft;
a first impeller coupled to one end of the rotation shaft;
a second impeller coupled to the other end of the rotation shaft;
and a disk-shaped thrust runner positioned between the first impeller and the rotor and having a predetermined diameter about the rotation axis,
The rotating shaft is
a cylindrical sleeve surrounding the outside of the rotor;
a first shaft including a first insertion part inserted into one side of the sleeve; and
and a second shaft including a second insertion part inserted into the other side of the sleeve. According to claim 1,
wherein the thrust runner includes a disk portion having an opening into which the first shaft is inserted. 3. The method of claim 2,
The turbocompressor, characterized in that the disk portion abuts against one end of the sleeve. 3. The method of claim 2,
The first shaft turbocompressor, characterized in that it further comprises a stepped portion in contact with one surface of the disk portion. 3. The method of claim 2,
The thrust runner is
Further comprising a cylindrical portion extending around the outer circumferential surface of the first shaft in the opening of the disk portion,
The turbocompressor, characterized in that the cylindrical portion is located inside the sleeve. 6. The method of claim 5,
In the first shaft, a diameter of the insertion portion inserted into the cylindrical portion is greater than a diameter of the outer portion positioned outside the cylindrical portion. 6. The method of claim 5,
The length of the cylindrical part corresponds to the length of the first insertion part. According to claim 1,
The length of the first insertion portion is 20% or more of the length of the rotor. According to claim 1,
The inner diameter of the sleeve is smaller than the diameter of the first insertion part, and the turbocompressor is coupled by press-fitting. 10. The method of claim 9,
The turbocompressor, characterized in that the difference between the diameter of the first insertion part and the inner diameter of the sleeve relative to the diameter of the rotation shaft has a value of 0.3% or more. According to claim 1,
the second shaft
Turbocompressor, characterized in that it further comprises a stepped portion in contact with the other end of the sleeve. According to claim 1,
The sleeve is a mobile terminal, characterized in that it comprises at least one of Inconel, titanium, stainless steel, and carbon fiber.

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