CN111628612A

CN111628612A - Rotating electrical machine

Info

Publication number: CN111628612A
Application number: CN202010129917.7A
Authority: CN
Inventors: 藤久保诚
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2019-02-28
Filing date: 2020-02-28
Publication date: 2020-09-04
Also published as: TW202034610A; TWI745875B; JP2020141475A; JP7233966B2

Abstract

The invention provides a rotating electrical machine. The Cooling Liquid (CL) is simultaneously sprayed from the stator-side spraying holes (107) and the rotor-side spraying holes (108, 110) toward the inner space of the bottomed cylindrical portion (30) of the rotating shaft (14) externally fitted to the coil (34) of the stator (36) and the rotor (44), wherein the stator-side spraying holes (107) and the rotor-side spraying holes (108, 110) are formed in the liquid path (100) of the Cooling Liquid (CL) formed inside the bottom surface side of the motor cover (20). Liquid passages (121, 122, 123, 116) are formed inside the rotor (44), communicate with suction holes (111, 112, 113) formed on the inner surface of the bottomed cylindrical portion (30), and extend to discharge holes (131, 132) of end plates (48, 50). This enables efficient cooling of the stator and the rotor.

Description

Rotating electrical machine

Technical Field

The present invention relates to a rotary electric machine in which a rotor and a stator are cooled by a cooling liquid.

Background

For example, japanese patent laid-open publication No. 5158861 discloses a technique of cooling a rotor of a motor by flowing cooling oil through an oil passage provided in a shaft of a rotor-side rotating member that is rotated by the rotor; and a technique of cooling a stator of a motor by flowing cooling water through a cooling water path provided in a structure to which the stator is mounted (paragraphs [0037] and [0052] of japanese patent laid-open publication No. 5158861).

Disclosure of Invention

However, the cooling structure disclosed in japanese patent application laid-open No. 5158861 has a problem of low cooling efficiency because the structure indirectly cools the rotor (magnetic body and magnet) of the motor and the coil of the stator, which are heat generating components, respectively.

The present invention has been made in view of the above-described problems, and an object thereof is to provide a rotating electric machine capable of efficiently cooling a stator and a rotor.

A rotating

electrical machine

10, 10A to 10C according to an aspect of the present invention includes a motor main body 18 and a bottomed

cylindrical motor cover

20, 20A, 20B, wherein the motor main body 18 is composed of a stator 36 and a cylindrical rotor 44, the stator 36 is a stator in which coils 34 are arranged in a ring shape; the rotor 44 is coaxially disposed inside the stator 36, and is rotated by excitation of the stator 36; the rotating electrical machine is characterized by having a liquid path 100 for a cooling liquid CL, a stator-side injection hole 107, and rotor-

side injection holes

108, 110, 136, wherein the liquid path 100 for the cooling liquid CL is formed inside the bottom surface sides of the motor covers 20, 20A, 20B; the stator-side injection hole 107 is formed in the liquid passage 100 and injects the cooling liquid CL toward the stator 36; the rotor-

side injection holes

108, 110, 136 are formed in the liquid path 100, and inject the cooling liquid CL to the rotor 44.

According to the present invention, the cooling liquid is simultaneously injected from the stator-side injection hole and the rotor-side injection hole which are formed in the liquid path of the cooling liquid formed inside the bottom surface side of the motor cover. Accordingly, both the stator and the rotor can be cooled at the same time, and the cooling efficiency of the entire rotating electric machine can be improved.

The above objects, features and advantages will be readily understood from the following description of the embodiments with reference to the accompanying drawings.

Drawings

Fig. 1 is a partial cross-sectional view showing a vehicle mounted with a motor as a rotating electric machine according to an embodiment, focusing on a cooling system.

Fig. 2 is a partially enlarged view showing a flow of the cooling liquid of the motor shown in fig. 1.

Fig. 3 is a partially enlarged view focusing on a liquid path of the cooling liquid inside the motor cover of the motor shown in fig. 1.

Fig. 4 is a partial transverse cross-sectional view focusing on a liquid path of the cooling liquid in the rotor of the motor shown in fig. 1.

Fig. 5 is a partial cross-sectional view showing a vehicle mounted with a motor as a rotating electric machine according to modification 1, focusing on a cooling system.

Fig. 6 is a partial cross-sectional view showing a vehicle mounted with a motor as a rotating electric machine according to modification 2, focusing on a cooling system.

Fig. 7 is a partial cross-sectional view showing a vehicle mounted with a motor as a rotating electric machine according to modification 3, focusing on a cooling system.

Detailed Description

A rotating electric machine according to the present invention will be described in detail below with reference to the accompanying drawings by way of examples.

In addition, in order to facilitate understanding of the present invention, the cross-section in the drawings is cut along a line other than the substantial center line.

In the drawings, the X1 and X2 directions are axial directions and indicate substantially horizontal directions, and the Z1 and Z2 directions are axial vertical directions and indicate substantially vertical directions. The Y1 and Y2 directions indicate directions orthogonal to the X1 and X2 directions in the horizontal plane.

[ embodiment ]

[ Structure ]

Fig. 1 is a partial cross-sectional view in the axial direction of a vehicle 12 in which a motor 10 as a rotating electric machine according to an embodiment is mounted, focusing on a cooling system 70. The vehicle 12 is, for example, an electric two-wheeled motor vehicle.

Fig. 2 is a partially enlarged view showing the flow of the cooling liquid inside the motor 10.

Fig. 3 is a partial cross-sectional view in the direction perpendicular to the axis of the liquid path of the cooling liquid in the motor cover 20 of the motor 10.

Fig. 4 is a partial transverse cross-sectional view in the axial vertical direction of the liquid path of the cooling liquid in the rotor 44 of the motor 10.

As shown in fig. 1, the motor 10 of the vehicle 12 is basically configured by a base portion 16, a motor main body 18, and a motor cover 20.

The base portion 16 and the motor cover 20 constitute a motor housing 22, and the motor main body 18 is disposed in an internal space (internal space of the motor housing 22) formed by the base portion 16 and the motor cover 20.

The rotary shaft 14 is provided along the axial direction of the motor 10 (base portion 16). A shaft 26 that is pivotally supported by a ball bearing 24 provided on the base 16 on the rotary shaft 14; and a bottomed cylindrical portion 30 fixed to a distal end portion of the shaft portion 26 extending toward the motor cover 20 by a nut 28.

The rotation shaft 14 is engaged with a not-shown speed reducer of the vehicle 12.

The motor main body 18 is configured by a stator 36 in which coils 34 wound around a yoke 32 are arranged in a ring shape (fig. 4) and a rotor 44 in which a magnet 40 is embedded in a yoke 38 in the axial direction.

The stator 36 is fixed to the base portion 16 by a bracket 46 with bolts 49.

The rotor 44 is fitted to the outer peripheral surface of the bottomed cylindrical portion 30 constituting the rotary shaft 14.

More specifically, both ends of the yoke 38 of the rotor 44 are sandwiched between the

end plates

48, 50, one end plate 48 is supported by the outer peripheral side surface of the bottomed cylindrical portion 30 and the flange portion 60, and the other end plate 50 is supported and fixed by the outer peripheral side surface of the bottomed cylindrical portion 30 and the nut 62.

A resolver rotor 56 is fixed to the outer periphery of the bottom surface portion side of the bottomed cylindrical portion 30 constituting the rotary shaft 14, and a resolver stator 58 is fixed to the base portion 16 of the motor case 22 so as to face the resolver rotor 56.

In a state where the rotary shaft 14 and the motor main body 18 are assembled to the base portion 16, the motor cover 20 is attached to the base portion 16 by the bolts 64, and thereby the motor main body 18 is disposed in the space inside the motor housing 22.

[ Structure of Cooling System 70 of vehicle 12 having Motor 10 mounted thereon ]

The cooling system 70 includes a liquid path 100 of the cooling liquid formed inside the bottom surface side (direction X2 in fig. 1) of the motor cover 20.

As shown in fig. 3, the fluid passage 100 in the motor cover 20 includes a supply port 102, and is constituted by a straight fluid passage 104 and a C-shaped fluid passage 106, wherein the supply port 102 is supplied with a cooling fluid from an electric pump not shown, and in the present embodiment, is supplied with oil that also serves as lubrication, for example; the linear liquid path 104 extends from the supply port 102 through the inlet liquid path 103 toward the axial center; the C-shaped liquid path 106 communicates with the linear liquid path 104 and extends in the circumferential direction from the intersection of the inlet liquid path 103 and the linear liquid path 104.

A center injection hole (rotor side injection hole) 108 directed toward the center of the rotary shaft 14 and a center injection hole (rotor side injection hole) 110 provided at a position offset from the center injection hole 108 are provided at the tip end portion of the linear liquid path 104. Either the center spouting hole 108 or the center spouting hole 110 may be provided, but it is necessary to provide a position for spouting the cooling liquid CL into the internal space of the bottomed cylindrical portion 30.

On the other hand, the C-shaped liquid passage 106 is provided with injection holes (stator side injection holes) 107 which inject the cooling liquid CL toward the inner surface side of the space in parallel with the axial direction at substantially equal intervals along the circumference. The ejection holes 107 need to be provided at positions where the cooling liquid CL is ejected toward the coil 34.

[ Effect of Cooling System 70 of vehicle 12 having Motor 10 mounted thereon ]

(1) Cooling of rotor 44

As shown in fig. 2 and 3, the cooling liquid CL supplied (flowed) from the electric pump (not shown) to the supply port 102 of the liquid passage 100 passes through the inlet liquid passage 103 and is injected from the center injection hole 108 and the center injection hole 110 to the internal space of the motor 10 through the linear liquid passage 104 (fig. 2).

In this case, the cooling liquid CL ejected from the central ejection hole 108 is directed toward the center of the inner bottom surface of the bottomed cylindrical portion 30 (the axial center of the rotary shaft 14). The cooling liquid CL ejected from the central ejection hole 110 is ejected to an inner bottom surface position offset from the center of the inner bottom surface of the bottomed cylindrical portion 30.

The cooling liquid CL ejected to the inner bottom surface of the bottomed cylindrical portion 30 flows toward the inner circumferential side surface of the bottomed cylindrical portion 30 by centrifugal force.

As shown in fig. 1 and 2,

suction holes

111, 112, and 113 are provided radially at three positions along the axis on the inner peripheral side surface of the bottomed cylindrical portion 30 (fig. 4).

As shown in fig. 2 and 4, the

suction holes

111, 112, and 113 communicate with one end sides of radial

liquid passages

121, 122, and 123 provided in the yoke 38 of the rotor 44, and the other end sides of the

liquid passages

121, 122, and 123 communicate with a liquid passage 116 provided in the yoke 38 of the rotor 44 in the axial direction in parallel with the magnet 40. Both ends of the liquid passage 116 in the axial direction communicate with

discharge holes

131 and 132 provided in the

end plates

48 and 50.

The

discharge holes

131 and 132 communicate with the inner space facing both bottom surfaces of the rotor 44.

Accordingly, the cooling liquid CL supplied (flowed) from the electric pump (not shown) to the supply port 102 of the liquid passage 100 and ejected from the central ejection hole 108 and the central ejection hole 110 into the internal space of the bottomed cylindrical portion 30 flows toward the inner circumferential surface of the bottomed cylindrical portion 30 by centrifugal force, is further transmitted to the

suction holes

111, 112, and 113 and the

liquid passages

121, 122, and 123 by centrifugal force to join in the liquid passage 116, and is discharged from the liquid passage 116 into the internal space of the motor 10 through the

discharge holes

131 and 132.

By the flow of the cooling liquid CL, the rotor 44 (the yoke 38 and the magnet 40 embedded in the yoke 38) is cooled.

The cooling liquid CL discharged into the internal space of the motor 10 from the

discharge holes

131 and 132 provided in the

end plates

48 and 50 on both bottom sides of the cylindrical rotor 44 directly falls or comes into contact with the rotary shaft 14 or the stator 36 and falls, and is stored in the oil pan 120.

The cooling liquid CL stored in the oil pan 120 is pumped up by the electric pump, and is heat-exchanged by a radiator, not shown, and is supplied to the supply port 102 again.

In this way, the rotor 44 is mainly directly cooled.

(2) Cooling of stator 36

On the other hand, the cooling liquid CL supplied from the electric pump (not shown) to the supply port 102 of the liquid passage 100 and ejected in the axial direction from the ejection holes 107 (see also fig. 3) directly contacts and cools the coils 34 (the remaining nine coils 34 in fig. 4 excluding the lower three coils 34) of the coils 34 of the stator 36 excluding the coils 34 cooled by the cooling liquid CL of the oil pan 120 (the lower three coils 34 in the Z2 direction in fig. 4) as shown in fig. 2.

The cooling liquid CL that directly abuts against the coil 34 to cool the coil 34 is transferred to the coil 34 to further cool the coil 34, and falls from the coil 34 to be stored in the oil pan 120.

Thus, according to the above embodiment, the cooling liquid CL is simultaneously injected into the internal space of the bottomed cylindrical portion 30 of the rotary shaft 14 fitted around the coils 34 of the stator 36 and the rotor 44 from the stator-side injection holes 107 and the rotor-side injection holes 108 and 110, respectively, which are formed in the liquid path 100 of the cooling liquid CL formed inside the bottom surface side of the motor cover 20.

In this case, since the

liquid passages

121, 122, 123, and 116 communicating with the suction holes 111, 112, and 113 formed in the inner surface of the bottomed cylindrical portion 30 and extending to the discharge holes 131 and 132 of the

end plates

48 and 50 are formed in the rotor 44, the rotor 44 can be efficiently cooled from inside by the cooling liquid CL flowing through the

liquid passages

121, 122, 123, and 116.

Accordingly, according to the above embodiment, since the coil 34 of the stator 36, the yoke 38 of the rotor 44, and the embedded magnet 40 (fig. 4) which are main heat generation sources can be directly cooled at the same time, the cooling efficiency of the cooling system 70 of the motor 10 can be improved.

[ modified examples ]

The above embodiment may be modified as follows.

Note that the same components as those in the embodiments are denoted by the same reference numerals, and only different portions will be described.

< modification 1 >

Fig. 5 is a partial cross-sectional view of a vehicle 12A in which a motor 10A as a rotating electric machine according to modification 1 is mounted, focusing on a cooling system 70A.

In the cooling system 70A of the motor 10A of the vehicle 12A according to modification 1, an annular protrusion 130 extending in the center direction is integrally provided on the inner peripheral side of the flange portion 60 of the bottomed cylindrical portion 30 fixed to the rotary shaft 14.

By providing the annular projection 130, the inner surface cross section of the bottomed cylindrical portion 30 fitted to the outside of the rotor 44 in the axial direction is formed as a recess 133. The recessed portion 133 facilitates accumulation of the cooling liquid CL collected on the inner surface of the bottomed cylindrical portion 30 by centrifugal force, and most of the cooling liquid CL collected on the inner surface of the bottomed cylindrical portion 30 is discharged from the discharge holes 131 and 132 through the suction holes 111, 112, 113, and 116, thereby improving the cooling effect.

< modification 2 >

Fig. 6 is a partial cross-sectional view of a vehicle 12B in which a motor 10B as a rotating electric machine according to modification 2 is mounted, focusing on a cooling system 70B.

In a cooling system 70B of a motor 10B of a vehicle 12B according to modification 2, in contrast to the cooling system 70A according to modification 1, a hollow rod-shaped portion 134 protruding to the internal space of the bottomed cylindrical portion 30 is newly formed in a liquid passage 100 of a cooling liquid CL formed inside the bottom surface side of a motor cover 20A, and an ejection hole 136 is provided on the tip end side of the hollow rod-shaped portion 134.

One injection hole 136 provided in the hollow rod-like portion 134 is provided in the axial direction, and four injection holes are provided in the axial direction (cross-shaped in cross section in the axial direction) so as to communicate with the injection hole in the axial direction.

The cooling liquid CL can be more reliably ejected into the internal space of the rotary shaft 14 where the suction holes 111, 112, and 113 of the bottomed cylindrical portion 30 are located by the ejection hole 136 of the hollow rod-shaped portion 134 provided so as to enter the internal space of the bottomed cylindrical portion 30.

The cooling liquid CL can be reliably ejected to the inner bottom surface and the inner side surface of the bottomed cylindrical portion 30 of the rotary shaft 14 by the ejection hole 136 provided on the distal end portion side of the hollow rod-shaped portion 134.

Further, even if the injection holes 136 are only injection holes facing the inner surface side of the bottomed cylindrical portion 30 of the rotary shaft 14, a certain cooling effect can be achieved. The same applies to modification 3 described below.

< modification 3 >

Fig. 7 is a partial cross-sectional view of a vehicle 12C in which a motor 10C as a rotating electric machine according to modification 3 is mounted, focusing on a cooling system 70C.

In a cooling system 70C of a motor 10C of a vehicle 12C according to modification 3, a hollow rod-shaped portion 134A provided separately from a motor cover 20B is manufactured as compared with a cooling system 70B according to modification 2.

The hollow rod-shaped portion 134A is fixed to the bottom surface of the cylindrical protruding portion 138 of the motor cover 20B via a seal 140.

By separately producing the hollow rod 134A, the same effect as in modification 2 can be achieved, and mass production (mold release) of the motor cover 20B and the hollow rod 134A is facilitated.

[ invention that can be grasped according to the embodiment ]

Here, the following describes inventions that can be grasped from the above-described embodiments and modifications 1 to 3. Note that, for the sake of easy understanding, the reference numerals used in the above description (in the embodiment and modifications 1 to 3) are given in parentheses to the structural elements, but the structural elements are not limited to the structural elements given the reference numerals.

A rotating electrical machine (10, 10A-10C) according to the present invention includes a motor main body (18) and a bottomed cylindrical motor cover (20, 20A, 20B), wherein the motor main body (18) is configured by a stator (36) and a cylindrical rotor (44), the stator (36) is a stator in which coils (34) are arranged in a ring shape, the rotor (44) is coaxially arranged inside the stator (36), and rotates by excitation of the stator (36); a bottomed cylindrical motor cover (20, 20A, 20B) covering one main surface side of the motor main body (18), wherein the rotating electrical machine (10, 10A to 10C) has a liquid path (100) of a Cooling Liquid (CL), a stator side injection hole (107), and a rotor side injection hole (108, 110, 136), wherein the liquid path (100) of the Cooling Liquid (CL) is formed inside the bottom surface side of the motor cover (20, 20A, 20B); the stator-side injection hole (107) is formed in the liquid path (100) and injects the Cooling Liquid (CL) to the stator (36); the rotor-side injection holes (108, 110, 136) are formed in the liquid path (100) and inject the Cooling Liquid (CL) to the rotor (44).

According to the present invention, the Cooling Liquid (CL) is simultaneously injected from the stator-side injection holes (107) and the rotor-side injection holes (108, 110, 136) of the liquid path (100) for the Cooling Liquid (CL) formed inside the bottom surface sides of the motor covers (20, 20A, 20B). Thus, both the stator (36) and the rotor (44) can be cooled at the same time, and the cooling efficiency of the entire rotating electrical machine (10, 10A-10C) can be improved.

The rotor (44) is fixed to the outer peripheral side surface of a bottomed cylindrical portion (30) of a rotating shaft (14), and the rotor-side injection holes (108, 110, 136) are provided at positions at which the Cooling Liquid (CL) is injected toward the inner peripheral side of the bottomed cylindrical portion (30).

Accordingly, the Cooling Liquid (CL) accumulated on the inner peripheral side of the bottomed cylindrical portion (30) of the rotating shaft (14) is diffused over the entire cylindrical inner periphery and the entire bottom surface inner periphery by the rotation of the rotor (44), and therefore the entire rotor (44) is efficiently cooled by the rotating shaft (14).

An annular protrusion (130) facing the axial center direction is provided on the inner peripheral surface of the opening-side end of the bottomed cylindrical portion (30).

Thus, the inner side surface cross section of the bottom cylindrical part (30) externally fitted to the rotor (44) in the axial direction becomes the recessed part (133), and the Cooling Liquid (CL) is easily accumulated in the recessed part (133) by the centrifugal force, thereby enhancing the cooling effect.

Further, a liquid path (100) for the Cooling Liquid (CL) formed inside the bottom surface side of the motor covers (20A, 20B) is formed in hollow rod-shaped portions (134, 134A) that protrude into the internal space of the bottomed cylindrical portion (30), and the rotor-side ejection holes (136) are provided on the tip end sides of the hollow rod-shaped portions (134, 134A).

Thus, the Cooling Liquid (CL) can be more reliably ejected into the internal space of the bottomed cylindrical portion (30) of the rotary shaft (14) by the ejection hole (136) of the hollow rod-shaped portion (134, 134A) provided so as to protrude (enter) into the internal space of the bottomed cylindrical portion (30).

The hollow rod-shaped portion (134A) may be formed separately from a liquid path (100) for the Cooling Liquid (CL) formed inside the bottom surface side of the motor cover (20B).

Accordingly, the hollow rod-shaped part (134A) does not need to be integrally provided with the motor cover (20B), and therefore the motor cover (20B) is easy to manufacture.

Further, it is preferable that the injection hole (136) provided on the distal end side of the hollow rod-shaped portion (134, 134A) is provided at a position where the Cooling Liquid (CL) faces the inner circumferential side surface of the bottomed cylindrical portion (30).

Thus, the Cooling Liquid (CL) can be directly sprayed and brought into contact with a portion having a cross-sectional shape of the recessed portion (133) formed by the inner peripheral surface of the bottomed cylindrical portion (30) in which the rotor (44) is fitted to the outer peripheral surface, and therefore the cooling effect can be further improved.

In addition, the following may be also possible: the injection hole (136) provided on the tip end side of the hollow rod-shaped portion (134, 134A) is provided at a position where the Cooling Liquid (CL) faces the inner circumferential side surface of the bottomed cylindrical portion (30) and at a position where the Cooling Liquid (CL) faces the inner bottom surface of the bottomed cylindrical portion (30).

Accordingly, the Cooling Liquid (CL) can be directly sprayed to the concave portion (133) and the inner bottom surface of the inner cross section in the axial direction of the bottomed cylindrical portion (30) externally fitted to the rotor (44), and therefore the cooling effect can be further improved.

The present invention is not limited to the above-described embodiments, and it is needless to say that various configurations can be adopted according to the contents described in the present specification.

Claims

1. A rotating electrical machine (10, 10A-10C) having a motor main body (18) and a bottomed cylindrical motor cover (20, 20A, 20B),

the motor main body (18) is configured from a stator (36) and a cylindrical rotor (44), the stator (36) is a stator in which coils (34) are arranged in a ring shape, the rotor (44) is coaxially arranged inside the stator (36), and is rotated by excitation of the stator (36);

a bottomed cylindrical motor cover (20, 20A, 20B) covering one principal surface side of the motor main body (18),

the rotating electrical machine has a liquid path (100) for a Cooling Liquid (CL), a stator-side injection hole (107), and a rotor-side injection hole (108, 110, 136), wherein,

a liquid path (100) for the Cooling Liquid (CL) is formed inside the bottom surface side of the motor covers (20, 20A, 20B);

the stator-side injection hole (107) is formed in the liquid path (100) and injects the Cooling Liquid (CL) to the stator (36);

the rotor-side injection holes (108, 110, 136) are formed in the liquid path (100) and inject the Cooling Liquid (CL) to the rotor (44).

2. The rotating electric machine according to claim 1,

the rotor (44) is fixed to the outer peripheral side surface of the bottomed cylindrical portion (30) of the rotating shaft (14),

the rotor-side injection holes (108, 110, 136) are provided at positions at which the Cooling Liquid (CL) is injected toward the inner circumferential side of the bottomed cylindrical portion (30).

3. The rotating electric machine according to claim 2,

4. The rotating electric machine according to claim 2,

a liquid path (100) for the Cooling Liquid (CL) formed inside the bottom surface side of the motor covers (20A, 20B) is formed in hollow rod-shaped portions (134, 134A) that protrude into the internal space of the bottomed cylindrical portion (30), and the rotor-side spray holes (136) are provided on the tip end sides of the hollow rod-shaped portions (134, 134A).

5. The rotating electric machine according to claim 4,

the hollow rod-shaped part (134A) is formed separately from a liquid path (100) for a Cooling Liquid (CL) formed inside the bottom surface side of the motor cover (20B).

6. The rotating electric machine according to claim 4 or 5,

an injection hole (136) provided on the distal end side of the hollow rod-shaped portion (134, 134A) is provided at a position where the Cooling Liquid (CL) faces the inner circumferential side surface of the bottomed cylindrical portion (30).

7. The rotating electric machine according to claim 6,

the injection hole (136) provided on the tip end side of the hollow rod-shaped portion (134, 134A) is provided at a position where the Cooling Liquid (CL) faces the inner circumferential side surface of the bottomed cylindrical portion (30) and at a position where the Cooling Liquid (CL) faces the inner bottom surface of the bottomed cylindrical portion (30).