KR20230063609A - Blade built-in hollow shaft - Google Patents

Abstract

A hollow shaft with a built-in rotor according to an embodiment of the present invention is a hollow shaft with a built-in rotor installed in an impeller of an air compressor, and a hollow penetrating the shaft along an axial direction is formed inside the shaft. A rotary body having a plurality of blades is fastened to the shaft.

Description

Hollow shaft with built-in rotating body {BLADE BUILT-IN HOLLOW SHAFT}

The present invention relates to a hollow shaft with a built-in rotating body, and more particularly, to a hollow shaft with a built-in rotating body installed in an air compressor capable of amplifying the circulation of cooling air by mounting the rotating body in the hollow of the shaft.

Air compressors used in hydrogen-powered electric vehicles are high-speed rotating components that compress air by rotating the compressor wheel at 20,000 to 110,000 rpm using motor driving force. When the motor rotates at a high speed of 100,000 rpm or higher, high heat is generated inside the motor housing. If the internal temperature rises above 200℃, the permanent magnet is demagnetized, reducing the performance of the motor and increasing the risk of damage to the airfoil bearing due to thermal deformation. It rises.

In order to prevent this, it is important to cool the heating parts inside the air compressor, and a circulation method of cooling water and cooling air is employed. That is, the current cooling system circulates cooling water to cool the rotor, stator, motor housing, etc., and circulates cooling air that has passed through the rear surface of the compressor wheel into the shaft hollow to cool the rotating body.

1 is a cross-sectional view of an air compressor having a hollow shaft for circulation of cooling air according to the prior art. As shown, the air compressor 10 has a housing 100 forming an exterior, an impeller 400 coupled to the front of the housing 100 to suck air, and an impeller installed inside the housing 100 ( 400 is configured to include a blower motor 600 that drives rotation.

A cooling water jacket 110 is provided inside the housing 100 to cool heat generated during operation of the blower motor 600 . Since the cooling water jacket 110 is provided adjacent to the blower motor 600, it serves to cool the blower motor 600 through heat exchange with the cooling water.

However, this coolant circulation method is effective in cooling the outer portion of the coil due to the structural characteristics of the motor, but has limitations in cooling the rotating body in the center of the motor. Therefore, in addition to water cooling, an air cooling method of cooling the blower motor 600 using air is mixed.

In air-cooled cooling, air is circulated along the main flow path communicating with the air inlet 310, the impeller 400, and the air outlet 330. In addition, the thrust bearing 800 passes between the impeller 400 and the impeller support 200, passes between the front journal bearing 700 and the rotation shaft 650, and passes between the rear journal bearing 700' and the rotation shaft 650. ) and circulates along a flow path that communicates to the rear cover 500. The air introduced into the rear cover 500 is communicated again to the air inlet 310 along the hollow penetrating the center of the rotation shaft 650 between the rear cover 500 and the rotation shaft 650 . Some of the air compressed by the impeller 400 circulates along the aforementioned air cooling passage to cool the front journal bearing 700, cool the blower motor 600, and then cool the thrust bearing 800 through the hollow It is exhausted toward the air inlet 310.

However, such an air-cooled cooling method has a limitation in that the pressure decreases as the distance from the impeller decreases, resulting in lower cooling performance.

Accordingly, there is a need for a new type of cooling system capable of further improving the cooling efficiency of the central portion of the motor by circulation of cooling air.

The present invention was created to solve the above-described problems, and an object of the present invention is to embed a rotating body in the hollow of the shaft and forcefully introduce air from the rear of the shaft into the hollow as the rotating body rotates together with the shaft. An object of the present invention is to provide a hollow shaft that facilitates the circulation of air through the hollow of the shaft and finally increases the cooling efficiency of air-cooled cooling.

In order to achieve the above object, a hollow shaft embedded in a rotating body according to an embodiment of the present invention is installed in an impeller of an air compressor, and a hollow shaft penetrating the shaft along an axial direction is provided inside the shaft. is formed, and a rotating body having a plurality of blades is fastened to the shaft in the hollow.

In addition, from the front end to the rear end of the shaft, the hollow has a first diameter portion having a constant diameter of a first diameter, a diameter expanding portion having a constantly increasing diameter, and a second diameter having a constant diameter larger than the first diameter. Divided into 2 diameter parts, the rotating body is fastened to the shaft at the rear end of the second diameter part, and the diameter of the rotating body may be larger than the first diameter.

In addition, the rotating body rotates in the same direction as the rotating direction of the hollow shaft, and the blade may be oriented so that air outside the rear end of the shaft is sucked into the hollow.

In addition, the hollow may have a constant diameter of a first diameter from the front end to the rear end of the shaft, and the rotating body may be fastened to the rear end of the shaft.

In addition, the hollow may have a constant diameter of a first diameter from the front end to the rear end of the shaft, and the rotating body may be fastened in the middle of the shaft.

In addition, the rotating body having the blade may be coupled to the hollow by press-fitting or bolt fastening.

According to one embodiment of the present invention, the present invention increases the cooling efficiency of the shaft, the air foil bearing, and the coil located in the center of the motor by introducing a large amount of air through the hollow of the shaft by installing a rotor having blades in the hollow. can be raised

Accordingly, it is possible to prevent performance deterioration of the motor due to temperature rise and solve the problem of damage of the air foil bearing due to thermal deformation.

On the other hand, as the air circulation becomes active through the hollow shaft, the pressure on the back of the compressor wheel and the diffuser decreases, reducing the thrust acting on the rotor (shaft, compressor wheel), and reinforcing the air layer in the thrust bearing and front journal bearing. By doing so, the lifting effect of the air foil bearing can be improved.

Accordingly, durability of the thrust bearing and the journal bearing can be improved.

1 is a cross-sectional view of an air compressor having a hollow shaft for circulation of cooling air according to the prior art.
2 is a perspective view of a hollow shaft with a built-in rotor according to an embodiment of the present invention.
Figure 3 is a cross-sectional view of Figure 2;
4 is a perspective view of a rotating body disposed in the hollow of FIG. 2;
5 is a conceptual diagram for explaining an air circulation mechanism of a hollow shaft with a built-in rotating body according to the present invention.
Figure 6a is a conceptual diagram for explaining the air circulation path of the hollow shaft built-in rotary body of the present invention.
Figure 6b is a conceptual diagram for explaining the cooling effect according to the air circulation of the hollow shaft built-in rotary body of the present invention.
7a is a modified example of a hollow shaft with a built-in rotary body according to the present invention.
Figure 7b is another modified example of the hollow shaft built-in rotary body of the present invention.
Figure 7c is another modified example of the hollow shaft built-in rotary body of the present invention.
8 is a conceptual diagram illustrating a modified example of a rotating body.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and the following examples may be modified in many different forms, and the scope of the present invention is as follows It is not limited to the examples. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the spirit of the invention to those skilled in the art.

In addition, in the following drawings, the thickness or size of each layer is exaggerated for convenience and clarity of explanation, and the same reference numerals refer to the same elements in the drawings. As used herein, the term "and/or" includes any one and all combinations of one or more of the listed items. In addition, the meaning of "connected" in the present specification means not only when member A and member B are directly connected, but also when member A and member B are indirectly connected by interposing member C between member A and member B. do. Terms used in this specification are used to describe specific embodiments and are not intended to limit the present invention. As used herein, the singular form may include the plural form unless the context clearly indicates otherwise. Also, when used herein, “comprise, include” and/or “comprising, including” refers to a referenced form, number, step, operation, member, element, and/or group thereof. presence, but does not preclude the presence or addition of one or more other shapes, numbers, operations, elements, elements and/or groups.

In this specification, terms such as first and second are used to describe various members, components, regions, layers and/or portions, but these members, components, regions, layers and/or portions are limited by these terms. It is self-evident that These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first member, component, region, layer or section described in detail below may refer to a second member, component, region, layer or section without departing from the teachings of the present invention.

Space-related terms such as “beneath,” “below,” “lower,” “above,” and “upper” are associated with an element or feature shown in a drawing. It can be used for easy understanding of other elements or features. Terminology related to this space is for easy understanding of the present invention according to various process conditions or use conditions of the present invention, and is not intended to limit the present invention. For example, if an element or feature in a figure is turned over, an element or feature described as "lower" or "below" becomes "above" or "above." Accordingly, "below" is a concept encompassing "upper" or "below".

2 is a perspective view of a hollow shaft with a built-in rotating body according to an embodiment of the present invention, FIG. 3 is a cross-sectional view of FIG. 2, FIG. 4 is a perspective view of a rotating body disposed in the hollow of FIG. 2, and FIG. 5 is a rotating body of the present invention. It is a conceptual diagram to explain the air circulation mechanism of the built-in hollow shaft. Hereinafter, a hollow shaft with a built-in rotating body according to an embodiment of the present invention will be described.

The hollow shaft 100 with a built-in rotor according to the present invention is a shaft coupled to an impeller of an air compressor, and a hollow 110 penetrating the shaft 100 along the axial direction is formed inside the shaft 100. As shown in the drawing, the impeller is fitted into the shaft 100 and is fixedly coupled to the front of the shaft. Since the shaft 100 in which the hollow 110 is formed has substantially the same structure as the hollow shaft 100 according to the prior art described above with reference to FIG. 1, a separate additional description thereof will be omitted.

Meanwhile, a rotating body 120 having a plurality of blades 121 is coupled to the shaft 100 in the hollow 110 of the shaft 100 . Referring to FIG. 4, the rotating body 120 has a structure in which at least three or more blades 121 are spaced apart at equal intervals in a radial direction, and a hollow cylindrical casing is provided at the outermost part of the rotating body 120. (121) are surrounded inside. The rotating body 120 may be coupled to the shaft 100 by press-fitting the casing to the hollow 110 or by bolting the casing to the hollow 110 . In addition, the rotation body 120 does not rotate by itself but is coupled to the shaft 100 and rotates together with the shaft 100, and the rotation body 120 has the same number of rotations as the shaft 100. On the other hand, the rotating body 120 is rotated in the same direction as the rotational direction of the hollow shaft 100, and at this time, the blade 121 allows the air outside the rear end of the shaft 100 to be sucked into the hollow 110. Its orientation is designed so that For example, in FIG. 4 , all five blades 121 are oriented obliquely with respect to the central axis of rotation toward the same direction, and the orientation is designed in a form capable of realizing air intake according to the rotation direction of the shaft 100 .

On the other hand, the type of the rotation body 120 described above can be variously modified. 8 is a conceptual diagram illustrating a modified example of a rotating body. As shown in the figure, the rotation body of the present invention, in particular, the shape of the blade can be variously modified.

On the other hand, according to one embodiment of the present invention, as shown in Figure 3, the hollow 110 from the front end to the rear end of the shaft 100, the first diameter portion 111, the diameter of which is constant as the first diameter, It may be divided into an enlarged diameter part 113 whose diameter constantly increases and a second diameter part 112 whose diameter is constant as a second diameter greater than the first diameter. Then, the rotation body 120 is coupled to the shaft 100 at the rear end of the second diameter portion 112, the diameter of the rotation body 120 is larger than the first diameter. The first diameter portion 111 is a small diameter portion and may correspond to the diameter of the hollow 110 of the shaft 100 according to the prior art. The feature of the present invention is that even if the hollow 110 at the front of the shaft 100 maintains a small diameter, it leads to an enlarged diameter portion 113 whose diameter gradually increases toward the rear of the shaft 100, and the rear portion of the enlarged diameter portion 113 That is, the second diameter portion 112 is provided as a large diameter portion having a larger diameter than the first diameter portion.

In this structure, as the rotating body 120 rotates together with the rotation of the shaft 100, the air outside the rear end of the shaft 100 is forcibly sucked in and introduced into the hollow 110 of the shaft 100. Accordingly, since the air staying outside the shaft 100 is momentarily introduced into the hollow 110 at the rear end of the shaft 100, it is necessary to accommodate this large amount of air. In this respect, the diameter of the hollow 110 at the rear end of the shaft 100 was expanded to a second diameter. In addition, if the inner diameter is rapidly reduced from the second diameter part 112, which is a large diameter part, to the first diameter part 111, which is a small diameter part, in the process of moving the air introduced into the second diameter part 112 forward, the hollow 110 ) can generate resistance in Accordingly, an enlarged diameter portion 113 is formed between the second diameter portion 112 and the first diameter portion 111 to minimize air resistance.

On the other hand, Figure 5 is a conceptual diagram for explaining the air circulation mechanism of the hollow shaft built-in rotary body of the present invention. Referring to this, the principle of air circulation in the present invention is described. First, as the shaft 100 rotates, the rotating body 120 fixed to the rear end of the shaft 100 also rotates with the shaft, The blade forms an air flow in a direction in which air flows into the hollow, so that the air remaining outside the rear end of the shaft 100 is forcibly sucked and introduced into the hollow 110 . At this time, the air that has just entered the hollow 110 from the outside of the rear end of the shaft 100 has a very high pressure (+). Moreover, since the compressor wheel sucks air in front of the impeller at the front end of the shaft 100 while the shaft rotates, negative pressure (-) is generated outside the front end of the shaft 100. Accordingly, a pressure difference is generated between the front and rear ends of the shaft 100, thereby generating a forced flow of cooling air. That is, a flow of cooling air is generated from the hollow 110 at the rear end of the shaft 100 having a high pressure toward the hollow 110 at the front end of the shaft 100 having a low pressure. In this way, the air moves in front of the shaft through the hollow and cools the components around the shaft. On the other hand, the air that has cooled the surrounding components becomes hot by itself. As the air is mixed with new air at the front end of the shaft 100, the temperature is lowered again, and the air whose temperature has dropped is introduced to the rear of the compressor wheel again. Thereafter, the part is cooled while moving along a path described with reference to FIGS. 6A and 6B.

Next, a component cooling mechanism according to air circulation will be described.

Figure 6a is a conceptual diagram for explaining the air circulation path of the hollow shaft built-in rotary body of the present invention, Figure 6b is a conceptual diagram for explaining the cooling effect according to the air circulation of the hollow shaft built-in rotary body of the present invention. Referring to these drawings, some of the compressed air passing through the impeller ① passes through the back of the compressor wheel and ② passes through the diffuser. At this time, the cooling air passing through the diffuser cools the thrust bearing in the vicinity. Next, the cooling air moves backward through ③ the space between the front bearing housing and the shaft, and at this time cools the front journal bearing. After that, it goes through the space between ④ the outer circumferential surface of the shaft and the rotator of the motor, and at this time, the motor coil is cooled. Thereafter, ⑤ flows through the space between the rear bearing housing and the shaft to the chamber behind the shaft, and at this time cools the rear journal bearing. The cooling air flowing to the rear of the shaft cools the rear cover while coming into contact with ⑥ the rear cover, and is introduced into the hollow 110 by the suction force of the rotating body 120. The cooling air moves toward the front of the hollow shaft 100 through the hollow 110, and at this time, ⑦ cools the permanent magnet of the motor. Then, it returns to the inlet of ⑧ the compressor housing.

On the other hand, Figure 7a shows another modification of the hollow shaft built-in rotary body of the present invention. In the modified example of FIG. 7A, the hollow 110 is divided into a first diameter part 111, an enlarged diameter part 113, and a second diameter part 112, and the rotating body 120 is in the second diameter part 112. It is disposed at a position adjacent to the enlarged diameter part 113, not the rear end. Also, the space of the enlarged diameter portion 113 is short.

On the other hand, Figure 7b is another modification of the hollow shaft built-in rotation body of the present invention. In the modified example of FIG. 7B , the diameter of the hollow 110 is constant as the first diameter from the front end to the rear end of the shaft 100 , and the rotating body 120 is fastened to the rear end of the shaft 100 .

On the other hand, Figure 7c is another modified example of the hollow shaft built-in rotary body of the present invention. In the modified example of FIG. 7A, the diameter of the hollow 110 is constant as the first diameter from the front end to the rear end of the shaft 100, and the rotating body 120 is fastened in the middle of the shaft 100. That is, the position of the rotating body 120 can be changed in the longitudinal direction of the hollow inside the shaft.

The present invention increases the amount of air circulation passing through the hollow 110 by installing the rotating body 120 having the blade 121 in the hollow 110. The first purpose of increasing the amount of air circulation is to more directly and effectively cool parts that receive less cooling effect by the cooling water, that is, parts such as the center of the motor, coil, air foil bearing, permanent magnet of the shaft 100, etc. . As described above, the cooling water circulation method is effective for cooling the outer portion of the coil, but has limitations in cooling the rotating body 120 in the center of the motor. To solve this problem, cooling air is supplied through the hollow 110 of the shaft 100. The center of the motor close to the shaft 100 is cooled by circulation, and the cooling efficiency of the center of the motor increases as a large amount of air is introduced through the hollow 110 of the shaft 100.

Meanwhile, another object is to generate lift of the thrust bearing and the journal bearing. As shown in FIG. 6A, the cooling air reaching the rear of the shaft 100 is circulated to the front of the impeller through the hollow 110 of the shaft 100, and the circulated cooling air rides on the back of the compressor wheel to form a diffuser and thrust It moves to the rear of the shaft 100 again while passing through the bearing and the front journal bearing. Referring to this movement path, when a large amount of air flows into the hollow 110 of the shaft 100 and moves through the hollow 110 at high speed to the impeller side, the air layer is reinforced in the thrust bearing and the front journal bearing. As a result, lift is generated in the bearing. Accordingly, it performs the function of lubricating the air foil bearing (thrust or journal).

What has been described above is only one embodiment for implementing the hollow shaft with a built-in rotor according to the present invention, and the present invention is not limited to the above-described embodiments, and as claimed in the following claims, the present invention Anyone with ordinary knowledge in the field to which the present invention pertains without departing from the gist of the invention will say that the technical spirit of the present invention exists to the extent that various changes can be made.

100: hollow shaft 110: hollow
111: first diameter part 112: second diameter part
113: expansion part 120: rotating body
121: blade

Claims (6)

A hollow shaft with a built-in rotating body installed in the impeller of an air compressor,
A hollow penetrating the shaft along an axial direction is formed inside the shaft,
A hollow shaft with a built-in rotating body, characterized in that a rotating body having a plurality of blades is fastened to the shaft in the hollow. According to claim 1,
The hollow is, from the front end to the rear end of the shaft, a first diameter portion having a constant diameter as a first diameter, a diameter expanding portion having a constantly increasing diameter, and a second diameter having a constant second diameter greater than the first diameter. divided into parts,
The rotating body is fastened to the shaft at the rear end of the second diameter portion, and the diameter of the rotating body is larger than the first diameter. According to claim 1,
The rotary body rotates in the same direction as the rotation direction of the hollow shaft, and the blades are oriented so that air outside the rear end of the shaft is sucked into the hollow shaft. According to claim 1,
The hollow shaft has a constant diameter of a first diameter from the front end to the rear end of the shaft, and the rotating body is fastened to the rear end of the shaft. According to claim 1,
The hollow shaft has a constant diameter of a first diameter from the front end to the rear end of the shaft, and the rotary body is fastened in the middle of the shaft. According to claim 1,
The rotary body with the blade is coupled to the hollow by press-fitting or bolt fastening, the rotary body built-in hollow shaft.

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