JP2019201521A - Rotary machine - Google Patents

Abstract

To provide a rotary machine that enables efficient cooling of a stator while suppressing pressure loss due to a cooling medium passing through a cooling passage.SOLUTION: A rotary machine 1 includes an electric motor 2 including a rotor 22 and a stator 23, a cooling jacket 3 disposed around the stator 23, and a cooling passage 11 that is formed in the cooling jacket 3 and through which a cooling medium passes. The cooling passage 11 includes a first passage portion 11a provided in a region facing the stator core 24 of the stator 23, and a second passage portion 11b that is provided in a region facing the coil end 25a of the stator 23 and has an equivalent diameter d2 smaller than that of the first passage portion 11a.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to rotating machinery.

  Patent Document 1 discloses a rotary machine including a cooling jacket in which a spiral cooling passage is formed. The cooling passage is provided to face the outer peripheral surface of the stator core. Further, this rotating machine is provided with a structure for injecting a cooling liquid not only to the cooling passage but also to the end portions of the stator and the rotor.

JP-A-9-154257

  When trying to cool the entire stator by the cooling medium passing through the cooling passage, the cooling condition of the coil end is the strictest, and this condition setting can be a bottleneck in device design. As a countermeasure, for example, it is conceivable to enlarge the cooling flow path and increase the flow rate of the cooling medium, but as a result, the apparatus becomes larger. Further, when the heat transfer coefficient between the cooling medium and the stator is increased, the pressure loss of the cooling medium passing through the cooling passage is increased, which may make it difficult to efficiently cool the stator.

  The present disclosure describes a rotating machine that efficiently cools a stator while suppressing a flow rate of a cooling medium passing through a cooling passage and further suppressing a pressure loss of the cooling medium.

  A rotating machine according to an aspect of the present disclosure includes a motor including a rotor and a stator, a cooling jacket disposed around the stator, and a cooling passage formed in the cooling jacket and through which a cooling medium passes. The passage is provided in a region facing the stator core of the stator and a second passage portion provided in a region facing the coil end of the stator and having an equivalent diameter smaller than that of the first passage portion. And.

  Although the heat transfer coefficient is improved by reducing the equivalent diameter of the cooling passage, the pressure loss generated when the cooling medium passes increases. In the present disclosure, the cooling passage is divided into a first passage portion and a second passage portion, and the equivalent diameter of the second passage portion on the side facing the coil end is made smaller than that of the first passage portion. As a result, it is possible to efficiently cool the coil end of the stator while suppressing an increase in the overall pressure loss while suppressing the flow rate of the cooling medium passing through the cooling passage.

  In some embodiments, the cooling jacket is a casting. Compared with the case where the cooling passage is formed by machining, the wall surface constituting the cooling passage becomes rough due to the casting surface. As a result, the equivalent diameter is reduced, which is advantageous for improving the heat removal efficiency.

  In some embodiments, the cooling passage is provided in a spiral shape around the periphery of the stator, and the pitch of the second passage portion is smaller than the pitch of the first passage portion. By making the pitch of the second passage portion smaller than that of the first passage portion, it is advantageous for improving the heat removal efficiency at the coil end.

  In some embodiments, the cooling jacket includes a stator facing surface that abuts the stator, and a distance from the second passage portion to the stator facing surface is smaller than a distance from the first passage portion to the stator facing surface. As a result, the heat transfer distance from the second passage portion to the coil end is shortened, which is advantageous for improving the heat removal efficiency at the coil end.

  According to some aspects of the present disclosure, efficient cooling of the stator is possible while suppressing pressure loss of the cooling medium passing through the cooling passage.

It is sectional drawing which shows the rotary machine which concerns on one Embodiment of this indication. It is the elements on larger scale of FIG. It is an enlarged view which shows the outer periphery of an inner part. It is an expanded sectional view of the 1st passage part and the 2nd passage part. It is a figure for demonstrating the cross-sectional shape of the 1st channel | path part which concerns on a modification, and a 2nd channel | path part.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

  A rotating machine 1 shown in FIG. 1 is a rotating machine including a motor, for example. Specifically, the rotary machine 1 is a centrifugal compressor including a compressor 8, for example. The rotating machine 1 includes a rotating shaft 21, an electric motor 2, a cooling jacket 3, a motor casing 5, a magnetic bearing 6, a pair of auxiliary bearings 7, and a compressor 8. The compressor 8 is provided at each of both ends of the rotating shaft 21. The rotary machine 1 is a two-stage compressor, for example.

  The rotating shaft 21 has a cylindrical shape and can rotate around its axis La. The electric motor 2 has a rotor 22 and a stator 23. The rotor 22 is attached to the rotating shaft 21. The rotor 22 is fixed to the approximate center of the axial direction (hereinafter simply referred to as “axial direction”) Da of the rotary shaft 21.

  The stator 23 surrounds the rotor 22 along the circumferential direction of the rotating shaft 21. The stator 23 includes a cylindrical stator core 24 disposed so as to surround the rotor 22, and a stator coil 25 wound around the stator core 24. The stator coil 25 includes a coil end 25 a that protrudes outward in the axial direction Da with respect to the stator coil 25. When an alternating current is passed through the stator coil 25 of the stator 23, the rotating shaft 21 rotates due to the interaction between the rotor 22 and the stator 23.

  The cooling jacket 3 is arranged so as to surround the stator 23, that is, along the circumferential direction. A cooling passage 11 through which the cooling medium passes is formed in the cooling jacket 3. The cooling medium is, for example, water. The cooling passage 11 is continuously formed so as to turn around the axis La of the rotating shaft 21. The cooling passage 11 includes a spiral region formed in a spiral shape along the periphery of the stator 23. One end of the cooling passage 11 is communicated with a flow path 5 b formed in the motor casing 5 and the outer portion 10. The other end of the cooling passage 11 is in communication with a flow path 5 c formed in the motor casing 5 and the outer portion 10. The cooling medium flows into the cooling passage 11 via the flow path 5c and flows out of the cooling passage 11 via the flow path 5b.

  The motor casing 5 accommodates the electric motor 2 and the cooling jacket 3. The motor casing 5 has a cylindrical shape, for example. The stator 23 and the cooling jacket 3 are integrated and fixed to the inner peripheral surface of the motor casing 5, and surround the rotating shaft 21 and the rotor 22. The material of the motor casing 5 is, for example, cast iron (FCD). A pair of bearing casings 63 are provided on both inner ends of the motor casing 5 in the axial direction Da.

  Next, the cooling jacket 3 will be described in detail. As shown in FIGS. 2, 3, and 4, the cooling jacket 3 includes a cylindrical inner portion 9 that surrounds the stator 23, and a cylindrical outer portion 10 that is sheathed by the inner portion 9. . The inner part 9 has a cylindrical shape, for example. The inner portion 9 is connected to the stator 23 in a replaceable manner by a cooling medium that passes through the cooling passage 11. The inner part 9 is a casting, for example, and examples of the material include aluminum (Al) and cast iron.

  The outer portion 10 surrounds the inner portion 9 and has, for example, a cylindrical shape. The heat transfer coefficient of the outer part 10 is smaller than the heat transfer coefficient of the inner part 9. The heat transfer coefficient of the outer portion 10 is smaller than the heat transfer coefficient of the motor casing 5. The outer part 10 is a casting, for example, cast iron.

  The inner portion 9 includes an inner peripheral surface 9 a that faces the stator 23. Of the inner peripheral surface 9 a, the portion closer to the center in the axial direction Da is in contact with the outer peripheral surface 24 b of the stator core 24. Further, of the inner peripheral surface 9a of the inner portion 9, a portion outside the above-mentioned center portion, that is, a portion near the end in the axial direction Da is opposed to the coil end 25a with a gap. .

  The inner portion 9 can be grasped by dividing it into a first region 9A that virtually includes the portion near the center and a second region 9B that includes the portion near the end. The boundary surface Bf between the first region 9A and the second passage portion is basically defined by a virtual cross section orthogonal to the rotation axis 21. When the both end shapes of the contact area between the inner peripheral surface 9a and the stator core 24 are complicated in the axial direction Da, etc., the virtual boundary surface Bf between the first area 9A and the second area 9B is uniquely defined. Sometimes it is difficult to define. In such a case, the imaginary cross section that is most outward, that is, near the end of the rotation shaft 21, becomes the boundary surface Bf between the first region 9A and the second passage portion.

  A groove 9c for circulating the cooling medium is formed on the outer peripheral surface 9b of the inner portion 9. The groove 9c has a rectangular cross section, and is continuously formed so as to turn around the axis line La of the rotating shaft 21. The inner peripheral surface 10 a of the outer portion 10 is in close contact with the outer peripheral surface 9 b of the inner portion 9. A cooling passage 11 through which a cooling medium flows is formed by the inner peripheral surface 10 a of the outer portion 10 and the groove 9 c of the inner portion 9.

  A groove 9 d for the packing 31 is formed on the outer peripheral surface 9 b of the inner portion 9. The groove 9 d is formed on the outer side in the axial direction Da, that is, closer to both ends of the rotating shaft 21 than the groove 9 c serving as the cooling passage 11. A packing 31 such as an O-ring is disposed in the groove 9d. The packing 31 prevents leakage of the cooling medium flowing through the cooling passage 11. Moreover, the inner part 9 and the outer part 10 are being fixed with the volt | bolt via the flange part 9f provided in the inner part 9. FIG.

  The cooling passage 11 will be further described in detail. The spiral region of the cooling passage 11 is provided over the first region 9A and the second region 9B of the inner portion 9. The cooling passage 11 according to the present embodiment is substantially rectangular in cross-sectional view when cut along a virtual plane including the axis La of the rotation shaft 21. The cross-sectional shape of the cooling passage 11 (hereinafter referred to as “first passage portion”) 11a formed in the first region 9A facing the stator core 24 and the second region 9B facing the coil end 25a are formed. This is different from the cross-sectional shape of the cooling passage (hereinafter referred to as “second passage portion”) 11b.

  In addition, the 1st channel | path part 11a and the 2nd channel | path part 11b are formed of the groove | channel 9c which continues spirally. Although the shape of the area | region which forms the 1st channel | path part 11a differs from the shape of the area | region which forms the 2nd channel | path part 11b among the groove | channels 9c, both connection locations are connected smoothly.

  The cross-sectional shape of the 1st channel | path part 11a is a rectangular shape long in the axial direction Da, The cross-sectional shape of the 2nd channel | path part 11b is a rectangular shape long in the direction (radial direction) orthogonal to the axial direction Da. The equivalent diameter of the cross-sectional shape of the first passage portion 11a is larger than the equivalent diameter of the cross-sectional shape of the second passage portion 11b. In the cooling passage 11, a smaller cross-sectional equivalent diameter is advantageous in improving heat extraction efficiency. Hereinafter, the equivalent diameter of the cross-sectional shape of the cooling passage 11 will be described.

  The equivalent diameter means a representative length indicating how much the diameter of a flow path having a certain cross-sectional shape is equivalent to a circular pipe. For example, when the equivalent diameter is d, the channel cross-sectional area is A, and the edge length is L, the equivalent diameter d can be obtained by the following equation (1). Here, the edge length means the length of the wall surface on the cross section. For example, when the wall surface is a rough surface, the unevenness is larger than the mirror surface, and the edge length L is also larger.

  In the present embodiment, since the cross-sectional shape of the first passage portion 11a is rectangular, when the long side is x1 and the short side is y1, the edge length L1 = 2 (x1 + x1). The cross-sectional area A1 of the first passage portion 11a is x1 × y1. Accordingly, the equivalent diameter d1 of the first passage portion 11a is expressed by the following formula (2).

  Further, since the cross-sectional shape of the second passage portion 11b is rectangular, when the long side is x2 and the short side is y2, the equivalent diameter d2 is expressed by the following formula (3).

Here, since x1 is larger than x2 and y1 is larger than y2, the equivalent diameter d1 of the first passage portion 11a is larger than the equivalent diameter d2 of the second passage portion 11b. The smaller the equivalent diameter, the greater the Reynolds number (Re number). Specifically, when the flow rate is Q (m ³ / s), the kinematic viscosity coefficient is ν (m ² / s), and the equivalent diameter is d (m), the Re number can be expressed by the following equation (4). it can.

  And by increasing the Re number, the heat transfer rate is improved, and as a result, the heat removal efficiency is improved. That is, since the equivalent diameter of the second passage portion 11b is smaller than the equivalent diameter of the first passage portion 11a, the heat extraction efficiency of the second passage portion 11b is higher than that of the first passage portion 11a. high.

  In general, the pressure loss increases as the equivalent diameter decreases. However, in the case of the present embodiment, the equivalent diameter d1 of the first passage portion 11a facing the stator core 24 is set large in consideration of pressure loss. On the other hand, the equivalent diameter d2 of the second passage portion 11b facing the coil end 25a is set smaller than the equivalent diameter d1 of the first passage portion 11a. As a result, the coil end 25a can be efficiently cooled while suppressing an increase in pressure loss in the entire cooling passage 11.

  In the above embodiment, the equivalent diameter d1 of the first passage portion 11a and the equivalent diameter d2 of the second passage portion 11b are compared by taking a rectangular cross section as an example. However, even in other shapes, it is possible to grasp the magnitude relationship by comparing the equivalent diameter d1 of the first passage portion 11a and the equivalent diameter d2 of the second passage portion 11b. For example, a case will be described in which at least one of the cross-sectional shapes of the first passage portion 11a and the second passage portion 11b can approximate a triangle.

  When the lengths of the three sides of the triangle are a, b, and c, the channel cross-sectional area A is obtained by the following formula (5) using the Heron formula. S is half the circumference of the triangle (S = (a + b + c) / 2).

  As a result, the equivalent diameter d is obtained by the following equation (6). Note that L is a circumferential length (edge length) of the triangle.

  That is, when the cross-sectional shape of the first passage portion 11a and the second passage portion 11b can be approximated as a triangle, the equivalent diameter can be obtained by using the above equation (6), and the equivalent diameter Can be compared.

  Next, the pitches Pa and Pb of the cooling passage 11 formed in a spiral shape will be described. In the present embodiment, the pitch Pa of the first passage portion 11a is basically constant, and the pitch Pb of the second passage portion 11b is constant. And the pitch Pb of the 2nd channel | path part 11b is smaller than the pitch Pa of the 1st channel | path part 11a. Considering the predetermined range in the axial direction Da as a reference, the smaller the pitches Pa and Pb of the cooling passages 11 increase the number of times the cooling medium circulates within the predetermined range, which is advantageous for improving the heat removal efficiency. That is, in this embodiment, the heat removal efficiency of the second passage portion 11b is higher than that of the first passage portion 11a also from the viewpoint of the pitches Pa and Pb of the cooling passages 11.

  In addition, when the pitches Pa and Pb of at least one of the first passage portion 11a and the second passage portion 11b are uneven, the average values of the uneven pitches Pa and Pb are obtained, and the magnitude relationship is determined by the average value. Can be judged.

  Next, the distance from the cooling passage 11 to the stator 23 will be described. This distance is considered based on the inner peripheral surface 9a (stator facing surface) of the inner portion 9 that contacts the stator core 24. In the present embodiment, the distance Dy from the second passage portion 11b to the inner peripheral surface 9a is smaller than the distance Dx from the first passage portion 11a to the inner peripheral surface 9a. That is, the distance Dx that is closest between the first passage portion 11a and the inner peripheral surface 9a and the second passage portion 11b in a cross-sectional view when cut along an imaginary plane including the axis line La of the rotation shaft 21 When the distance Dy that is closest to the inner peripheral surface 9a is compared, the distance Dy is smaller than the distance Dx.

  Next, as a modification of the cooling passage 11, the first passage portion 11a has a circular cross section (see FIG. 5B), and the second passage portion 11b has a star shape (see FIG. 5). The case of (a) see FIG.) Will be described as an example. In this modification, the cross-sectional area of the first passage portion 11a and the cross-sectional area of the second passage portion 11b are the same. However, the edge length of the cross-sectional shape of the second passage portion 11b is longer than the edge length of the cross-sectional area of the first passage portion 11a. As a result, the second passage portion 11b has a smaller equivalent diameter, and the second passage portion 11b has higher heat removal efficiency.

  Next, the effect of the rotary machine 1 provided with the cooling jacket 3 according to the present embodiment will be described. Usually, since the coil end is not in direct contact with the cooling jacket, the cooling condition of the coil end is the strictest, and this condition setting can be a bottleneck in device design. As a countermeasure, for example, it is conceivable to enlarge the cooling flow path and increase the flow rate of the cooling medium.

  However, when the cooling flow path is enlarged and the flow rate of the cooling medium is increased, the apparatus becomes larger as a result. Further, when the heat transfer coefficient between the cooling medium and the stator is increased, the pressure loss of the cooling medium passing through the cooling passage is increased, which may make it difficult to efficiently cool the stator. Therefore, for example, a high performance pump (a large flow rate and a high head) is required to satisfy the cooling condition.

  In contrast, in this embodiment, the cooling passage 11 is divided into a first passage portion 11a and a second passage portion 11b, and the equivalent diameter of the second passage portion 11b on the side facing the coil end 25a is set to the first diameter. It is made smaller than the passage part 11a. As a result, the coil end 25a can be efficiently cooled while the flow rate of the cooling medium passing through the cooling passage 11 is suppressed and the overall pressure loss is suppressed, and the pump head can be kept low. Become. That is, according to the present embodiment, the coil end 25a of the stator 23 can be efficiently cooled.

  The cooling jacket 3 according to the above embodiment is a casting. As a result, compared with the case where the cooling passage 11 is formed by machining, the wall surface constituting the cooling passage 11 is rough due to the casting surface. As a result, the equivalent diameter d is reduced, which is advantageous for improving the heat removal efficiency.

  Further, in the cooling passage 11 of the cooling jacket 3 according to the above embodiment, the pitch Pb of the second passage portion 11b is smaller than the pitch Pa of the first passage portion 11a, and the coil end 25a is pulled out. This is advantageous for improving thermal efficiency.

  In the cooling passage 11 of the cooling jacket 3 according to the above embodiment, the distance from the second passage portion 11b to the inner peripheral surface 9a of the inner portion 9 is the inner periphery of the inner portion 9 from the first passage portion 11a. It is smaller than the distance to the surface 9a. As a result, the heat transfer distance from the second passage portion 11b to the coil end 25a is shortened, which is advantageous for improving the heat removal efficiency at the coil end 25a.

  Further, in the above-described embodiment, the cooling jacket 3 has been described as an example of a casting formed using a forming die. However, the cooling jacket 3 can also be manufactured using 3D printer technology. By manufacturing using 3D printer technology, a more complicated shape can be adopted as the cross-sectional shape of the cooling passage 11 of the cooling jacket 3. For example, even if it is a form that is difficult to die by casting or a form that requires a complicated shape core, it can be easily molded by 3D printer technology, and the shape adjusted appropriately by the uneven shape of the wall surface It is also possible to make it. As a result, for example, the first passage portion 11a and the second passage portion 11b have the same concavo-convex shape (for example, a star shape) but the cross-sectional shapes have different edge lengths, thereby providing the second The equivalent diameter of the passage portion 11b can be made smaller than the equivalent diameter of the first passage portion 11a.

  The present disclosure is not limited to the above embodiments. For example, in the above embodiment, the rotary machine has been described by taking a two-stage compressor as an example, but a single-stage compressor may be used. The rotating machine may be used for a blower or a chiller, for example. At this time, the rotating machine does not include the compressor 8.

  In the above-described embodiment, a spiral passage has been described as an example of the cooling passage. However, as long as the equivalent diameter of the cross-sectional shape of the second passage portion can be made smaller than the equivalent diameter of the cross-sectional shape of the first passage portion, the present invention is not limited to the spiral shape, and may take other forms.

DESCRIPTION OF SYMBOLS 1 Rotating machine 2 Electric motor 3 Cooling jacket 9a Inner peripheral surface 11 Cooling passage 11a First passage portion 11b Second passage portion 22 Rotor 23 Stator 25a Coil end Pa Pitch of first passage portion Pb Pitch of second passage portion pitch

Claims (4)

A motor including a rotor and a stator;
A cooling jacket disposed around the stator;
A cooling passage formed in the cooling jacket and through which a cooling medium passes,
The cooling passage is provided in a region facing the stator core of the stator and a region facing the coil end of the stator, and has an equivalent diameter smaller than that of the first passage portion. A rotating machine comprising a second passage portion.   The rotating machine according to claim 1, wherein the cooling jacket is a casting. The cooling passage is provided spirally along the periphery of the stator,
The rotating machine according to claim 1 or 2, wherein a pitch of the second passage portion is smaller than a pitch of the first passage portion. The cooling jacket includes a stator facing surface that contacts the stator,
The rotary machine according to any one of claims 1 to 3, wherein a distance from the second passage portion to the stator facing surface is smaller than a distance from the first passage portion to the stator facing surface.

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