CN112134386A

CN112134386A - Airtight motor

Info

Publication number: CN112134386A
Application number: CN202011090174.3A
Authority: CN
Inventors: 李奥; 刁俊杰; 周志坡; 朱良友; 董文庆
Original assignee: Csic Pride Nanjing Cryogenic Technology Co ltd
Current assignee: Csic Pride Nanjing Cryogenic Technology Co ltd
Priority date: 2020-10-13
Filing date: 2020-10-13
Publication date: 2020-12-25

Abstract

The invention discloses an airtight motor which comprises a rotor (1), a stator (2), a front end cover (9), a rear end cover (7) and an inner end surface (32 b) of the end cover, wherein a concave part (32) is arranged on the inner side of the inner end surface (32 b) of the end cover, the concave part (32) comprises a radial inner circumferential surface (32 a) of the end cover and an axial bottom surface (32 c) of the end cover, and two ends of a shell (5) of the stator (2) are respectively provided with a radial outer circumferential surface (52) of the shell and an axial shell sealing surface (53); when the two ends of the shell (5) are respectively inserted into the concave parts (32), the shell can be respectively contacted with the concave parts (32) for sealing and fixing, wherein the outer peripheral surface (52) of the shell and the inner peripheral surface (32 a) of the end cover are matched in the radial direction to form a radial positioning structure, and the sealing surface (53) of the shell and the bottom surface (32 c) of the end cover are matched in the axial direction to form an axial sealing structure. The airtight motor has the advantages of simple structure processing, convenient installation and good air tightness.

Description

Airtight motor

Technical Field

The invention belongs to the technical field of low-temperature refrigerators, and particularly relates to an airtight motor for a GM refrigerator, a pulse tube refrigerator and a Solvin refrigerator.

Background

A cryogenic refrigerator, typified by a Gifford-McMahon (GM) refrigerator, has an expander and a compressor of a working gas (also referred to as a refrigerant gas). The refrigerator provides high pressure air flow from the compressor, and the high pressure air flow enters the pushing piston arranged in the cylinder via the air distributing mechanism and reciprocates up and down to exchange heat with the cold accumulating material, then the high pressure air flow enters the expansion cavity to do work expansion, and then the high pressure air flow flows out of the air distributing mechanism via the pushing piston and returns to the low pressure cavity of the compressor. Through the continuous circulation process, the refrigeration effect is formed. The selected motor is connected to the equipment, and an airtight system is required to be formed integrally, namely, a sealing structure is required to be arranged between end covers at two ends of the motor and the stator.

[ patent document 1 ] JP 2001-. A conventional hermetic motor (shown in fig. 1) is composed of a rotor 1 (a main shaft 11 and a base portion 12 and permanent magnets 13 mounted on the outer periphery), a stator 2 (a core yoke 19 fixed in a housing 5 and arranged radially outside the rotor 1), a front cover 9, and a rear cover 7.

An outer boss 33 and an outer boss outer peripheral surface 33a on a radially outer side thereof and an annular groove for placing an opening of a seal ring 37 are integrally formed on the front cover 9 and the rear cover 7. The boss structure 33 is inserted into the housing 5 of the stator 2, is airtightly connected and fitted to housing inner peripheral faces 55 (shown in fig. 2) at both ends of the housing 5 in the axis O direction, and is fixed to the end cover inner end faces 32a of the front end cover 9 and the rear end cover 7 by housing outer end faces 54 at both ends of the housing 5 in the axis O direction.

In order to reduce the vibration generated in the rotation process of the main shaft 11, certain requirements are required for processing the front end cover 9, the rear end cover 7 and the shell 5. In the conventional process, taking the rear end cover 7 as an example, the inner boss inner peripheral surface 31a of the inner boss 31 is provided with the rear bearing 14; the front bearing 15 is similarly attached to the front head cover 9, and the outer boss outer peripheral surface 33a of the outer boss 33 is machined using the cover surface as a reference surface, thereby controlling the coaxiality of the two positions. Then, the outer circumference of the basic part 12 or the permanent magnet 13 and the main shaft 11 are honed with the rear bearing 14 and the front bearing 15 as references; at the same time, the core yoke 19 on the stator 2 is internally honed to form a yoke inner peripheral surface 19a, and the housing inner peripheral surfaces 55 at both ends of the housing 5 in the direction of the axis O are machined with this surface. Through the above way, good coaxiality of the coaxial lines of the rear bearing 14 and the front bearing 15, namely the axis of the main shaft 11, the outer peripheral surface of the permanent magnet 13 and the inner peripheral surface 19a of the magnetic yoke is ensured, so that the motor can be kept to operate well.

However, the conventional structure has certain problems:

1) since the core yoke 19 has been already mounted in the housing 5 and the yoke inner peripheral surface 19a has been honed, since the windings 21 are protruded on both ends in the direction of the axis O, when the housing inner peripheral surfaces 55 of both ends of the above-mentioned housing 5 are processed, the cutter head (or the grinding head) easily rubs against the windings 21, causing damage to the coil of the stator 2.

2) In order to avoid the above problem, the conventional structure extends the outer shell 5 of the stator 2 to both sides of the axis O by a distance L (distance between both sides of L in fig. 1), and the winding 21 can be avoided during machining. But this does not facilitate a compact design of the motor. Further, since the housing inner peripheral surface 55 is formed on the inner peripheries of both ends of the housing 5, the "turning" processing is required in the processing, and the coaxiality of the housing inner peripheral surfaces 55 at both ends is not controlled well.

3) In order to ensure good coaxiality among the axis of the main shaft 11, the outer peripheral surface of the permanent magnet 13, and the yoke inner peripheral surface 19a, the fit clearance between the outer boss outer peripheral surface 33a of the outer boss 33 of the rear cover 7 and the housing inner peripheral surfaces 55 at both ends of the housing 5 is small, so that the stator 2 and the rear cover 7 are prevented from moving in the radial direction. It is noted that the housing inner peripheral surface 55 is both a sealing surface and a positioning surface. The seal ring 37 is placed between the case inner peripheral surface 55 and the outer boss outer peripheral surface 33a, is laterally pressed by the case outer end surfaces 54 at both ends of the case 5 in the axis O direction, is sealed in the annular groove radially outside the case inner peripheral surface 55 and the outer boss outer peripheral surface 33a, and is fixed to the case outer end surface 54 and the end cover inner end surface 32b of the rear cover 7. The airtight structure thus formed makes it easy to press and break the seal ring 37, and reduces the assembly efficiency.

[ patent document 2 ] CN 102904354B. Document 2 proposes a structure for improving the rigidity of the motor. Document 2 provides an embodiment of the embodiment of fig. 2, in which the radial positioning structure is implemented on the core yoke, which, indeed, avoids the problems of processing in the conventional positioning structure and is more advantageous for improving the coaxiality of the main shaft. However, since the core yoke is formed by overlapping magnetic steel sheets and does not have an airtight function, the motor having this structure cannot be directly applied to a cryogenic refrigerator system.

[ patent document 3 ] CN 101521422B. Document 3 proposes a low-vibration airtight motor. The first sealing ring in the air-tight structure in the document 3 still seals at the radial outside of the outer side rib of the bracket, and there is still a possibility of damage by shearing of the motor case.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides an airtight motor for a GM refrigerator, a pulse tube refrigerator and a Solvin refrigerator, which is easier to realize in processing and assembling.

The invention aims to solve the problems by the following technical scheme:

an airtight motor comprises a rotor, a stator, a front end cover, a rear bearing and a front bearing; a rotor including a main shaft, a base part fixedly attached to an outer periphery of the main shaft, and a permanent magnet; a stator including a core yoke disposed radially outward of the main shaft, a winding 21 provided on the core yoke at both ends in the direction of the axis O, and a cylindrical case made of metal; the rear bearing and the front bearing are used for supporting the main shaft to rotate around a central axis O; a pair of front and rear end caps having an inner boss 31 and a bearing chamber formed by an inner boss inner peripheral surface 31a for radially fixing the front and rear bearings; the stator comprises a front end cover, a rear end cover, a stator shell and a stator core, wherein the front end cover and the rear end cover are opposite to each other and are provided with end cover inner end surfaces; the two ends of the shell are respectively inserted into the concave parts on the front end cover and the rear end cover along the axis O direction and can be respectively contacted with the concave parts for sealing and fixing, wherein the outer peripheral surface of the shell and the inner peripheral surface of the end cover are matched in the radial direction to form a radial positioning structure, and the sealing surface of the shell and the bottom surface of the end cover are matched in the axial direction to form an axial sealing structure; and the axial sealing structure also comprises a sealing ring positioned on the sealing surface of the shell and/or the bottom surface of the end cover.

The outer diameter of the outer peripheral surface of the shell is the same as the inner diameter of the inner peripheral surface of the end cover.

The bottom surface of the end cover is provided with an annular sealing groove with an axial opening, and the annular sealing groove is used for placing the sealing ring.

The sealing surface of the shell is provided with an annular sealing groove with an axial opening, and the annular sealing groove is used for placing the sealing ring.

And fan-shaped rings are respectively cut off from the outer edges of the two ends of the shell to form the outer peripheral surface of the shell, the outer diameter of the outer peripheral surface of the shell is smaller than that of the shell, and the outer diameter of the shell is larger than the inner diameter of the inner peripheral surface of the end cover.

The end face of the housing located radially outside the housing sealing face forms a housing spigot face which can cooperate axially with the end cap inner end face to form an axial locating structure.

The shell spigot surface and the shell sealing surface form a step-shaped end surface.

The concave part is positioned at the radial outer side of the inner bosses on the front end cover and the rear end cover.

The concave part on the front end cover and the front end cover are integrally formed, and the concave part on the rear end cover and the rear end cover are integrally formed.

The airtight motor can be used for a refrigerator.

Compared with the prior art, the invention has the following advantages:

the housing of the airtight motor is easy to process, the outer peripheral surface of the housing, which is required to be matched with the inner peripheral surface of the end cover of the concave part of the end cover, at the two ends of the housing is arranged on the outer peripheral surface of the housing, the processing does not need to be turned around, the one-step processing molding is realized, and the coaxiality is convenient to control; the airtight motor is convenient to install, and because the seal belongs to positive seal along the axis O, an axial seal surface is separated from a radial positioning surface, a seal ring cannot be damaged in the installation process, and the airtight motor is easy to seal.

Drawings

Fig. 1 is a schematic structural view of a conventional airtight motor;

FIG. 2 is an enlarged schematic view of a conventional motor sealing structure;

fig. 3 is a schematic structural diagram of the airtight motor provided by the present invention;

FIG. 4 is an enlarged schematic view of a hermetic structure according to a first embodiment of the present invention;

FIG. 5 is an enlarged schematic view of the airtight structure according to the second embodiment of the present invention;

fig. 6 is an enlarged schematic view of the airtight structure according to the third embodiment of the present invention.

Wherein: 1-a rotor; 11-a main shaft; 12-a base portion; 13-a permanent magnet; 14-rear bearing; 15-front bearing; 2, a stator; 5, a shell; 19-a core yoke; 19 a-yoke inner peripheral surface; 21-winding; 27-an insulating cover; 31-inner boss; 31a — inner boss inner peripheral surface; 32-a recess; 32 a-inner circumferential surface of the end cap; 32 b-inner end face of end cap; 32c — bottom surface of end cap; 33-outer boss; 33 a-outer peripheral surface of the outer boss; 37-a sealing ring; 4, an annular sealing groove; 51-shell spigot surface; 52-outer peripheral surface of the housing; 53-housing sealing surface; 54-outer end surface of the shell; 55-inner peripheral surface of the housing; 7-rear end cap; 7 a-a rear end cover through hole; 9-front end cover; 9 a-front end cover through hole.

Detailed Description

In connection with the background, a detailed description of a conventional motor will not be repeated. The invention is further described with reference to the following figures and examples.

As shown in fig. 3, the front end cap 9 and the rear end cap 7 have the same airtight structure as the embodiment, and therefore, the description will be given by taking the rear end cap 7 as an example.

The airtight motor of the present invention has a rotor 1, a stator 2, a front cover 9, a rear cover 7, a rear bearing 14, and a front bearing 15. The rotor 1 includes a main shaft 11, a base portion 12 formed by laminating magnetic steel sheets and fixedly attached to an outer peripheral surface of the main shaft 11, and a permanent magnet 13 made of neodymium iron boron, and the base portion 12 and the permanent magnet 13 rotate synchronously with the main shaft 11 along a rotation axis O. Ball bearings are mounted on both ends of the main shaft 11 as the rear bearing 14 and the front bearing 15, and the inner bosses 31 mounted in the front cover 9 and the rear cover 7 are fitted in bearing chambers formed by inner boss inner peripheral surfaces 31a, with no allowance for play in the radial direction.

The stator 2 is composed of a cylindrical housing 5 and a core yoke 19 fixedly mounted therein, and is disposed outside the base body 12 of the rotor 1 and outside the permanent magnet 13 in the radial direction, and is arranged coaxially with the axis O as a central axis. The core yoke 19 is wound with the winding 21 on both end surfaces along the axis O direction, and an insulating cover 27 is attached to the outside of the winding 21.

The housing 5 is formed in a cylindrical shape of steel and is disposed on the outermost side in the radial direction of the stator 2. As described later, the housing 5 is hermetically connected to the front cover 9 and the rear cover 7, and ensures pressure resistance and airtightness as a hermetic motor for a cryogenic refrigerator.

Implementation mode one

The rear end cap 7 is further described as an example, and a first embodiment is described with reference to fig. 3 and 4.

An annular inner boss 31 projecting in the axis O direction forms an inner boss inner peripheral surface 31a (bearing chamber) that accommodates the rear bearing 14. The recessed portion 32 formed integrally with the rear end cap 7 on the inner end surface 32b of the end cap and located radially outward of the inner boss 31 and the bottom surface 32c of the end cap are used to form positioning and airtight effects in cooperation with both ends of the housing 5 in the direction of the axis O.

Specifically, the end cover inner end surface 32b is formed with an end cover inner circumferential surface 32a and an end cover bottom surface 32c along the axis O with reference to the inner boss inner circumferential surface 31a of the bearing chamber, so as to ensure the coaxiality of the end cover inner circumferential surface 32a and the inner boss inner circumferential surface 31 a. And an annular seal groove 4 opening in the direction of the axis O is machined in the end cover bottom surface 32 c. Meanwhile, the core yoke 19 and the housing 5 are fixed together, and two housing outer peripheral surfaces 52 having good coaxiality can be machined at a time on the outer peripheral surfaces on the radial outer sides on both ends of the housing 5 in the axis O direction without "turning around" with reference to the yoke inner peripheral surface 19a of the core yoke 19, and the radial dimension of the housing outer peripheral surfaces 52 is smaller than the outer diameter of the housing 5, thereby forming a housing spigot surface 51 and a housing sealing surface 53 (shown in a partially enlarged schematic view in fig. 4).

When installed, the housing 5 is inserted into the recess 32 of the rear end cap 7. That is, the outer housing peripheral surface 52 of the outer housing 5 on the radially outer side of both ends in the axis O direction is fitted with the inner end cover peripheral surface 32a of the recess 32 of the rear end cover 7 in the radial direction with no margin for play, so that the yoke inner peripheral surface 19a of the core yoke 19 and the inner boss inner peripheral surface 31a of the inner boss 31 of the end cover 7 form a good coaxiality.

The normal directions of the housing sealing surface 53 and the housing spigot surface 51 are both parallel to the axis O to form parallel planes, and when the rear end cover 7 and the stator 2 are pressed in the direction of the axis O by the outside, the housing sealing surface 53 is mounted in the annular sealing groove 4 on the bottom surface 32c of the end cover by positive pressing in the direction of the axis O, so that a positive shaft sealing structure is formed.

The external pressing is performed by the front cover 9 and the rear cover 7 through the front cover through hole 9a and the rear cover through hole 7a on the outside of the housing 5. The fastening screws 30 are inserted into the rear end cover through holes 7a and connected to the front end cover through holes 9a of the front end cover 9, respectively (in the actual design process, the screw hole structure form adopted by the front end cover through holes 9 a). During the pressing, the housing spigot surface 51 on the housing 5 is fixed in axial contact with the end cover inner end surface 32b, so that the stator 2 is fixed with the front end cover 9 and the rear end cover 7.

In the implementation of the above structure, the two ends of the housing 5 only need to be slightly longer than the axial length of the winding 21, and the length of the inner peripheral surface 55 of the housing is not increased to avoid the processing of the housing sealing surface 53 of the winding 21, because a certain length "l" is needed in the conventional structure for processing the outer boss outer peripheral surface 33a for positioning and the radial annular groove. The sealing structure is externally arranged, so that the processing problem is avoided.

The annular seal groove 4 in the above embodiment is formed in the end cover bottom surface 32c of the recess 32 of the front end cover 9 and the rear end cover 7, and may be formed in the case seal surfaces 53 at both ends of the case 5. This also achieves axial sealing of the housing sealing surface 53 of the housing 5 and the end cap bottom surface 32c of the recess 32.

Second embodiment

The rear end cap 7 is taken as an example for further explanation, and a second embodiment is described in fig. 5.

Further, at both ends of the housing 5 in the direction of the axis O, the outer peripheral surface 52 of the housing has a size not smaller than the outer diameter of the housing 5. In specific implementation, the following scheme can be adopted: that is, the housing 5 is made of a metal cylinder, and the core yoke 19 is press-fitted into the housing 5 with interference, thereby forming a fixed structure. The outer diameter of the finished housing 5 and the end surfaces at both ends in the direction of the axis O form a housing outer peripheral surface 52 and a housing sealing surface 53, respectively, also with reference to the inner peripheral surface 19a of the core yoke 19. Meanwhile, the size of the end cover inner circumferential surface 32a of the recess 32 of the rear end cover 7 is made to be equivalent to the outer diameter size of the housing 5.

The difference from the first embodiment is that the housing 5 is not formed with the housing spigot surface 51 and the housing sealing surface 53 having a step shape at both ends in the direction of the axis O, but is formed with the same plane as the spigot sealing surface to function as both the spigot and the sealing. When the housing 5 is inserted into the recess 32 of the rear end cap 7, a portion of the spigot seal surface positively presses the sealing ring 37 to form an axial seal; the other area positively presses against the end cap bottom surface 32c (indicated by the arrow in the figure) to achieve the seam allowance function as in the first embodiment.

Third embodiment

The rear end cap 7 is taken as an example for further explanation, and a third embodiment is described in fig. 6.

When the housing 5 is machined, a seal groove is machined in the end faces at both ends in the axis O direction, that is, the housing seal surface 53, and it is not necessary to machine a seal groove in the end cover bottom surface 32c of the recess 32 of the rear end cover 7. The remaining embodiments are the same as the second embodiment, and will not be described again.

The effects of the present invention will be described in detail below. Table 1 compares the amount of O-ring damage during installation of 10 conventional and 10 structural motors of the present invention.

Table 1 comparison of efficiency of process of installing 10 motors

	Traditional motor	The invention
			Number of damaged O-ring	11	0
Average individual installation time	17min	6min

The implementation process is carried out by assembling the motor with the traditional structure, and 20 sealing rings are needed. In the conventional motor, since the radial positioning surface and the sealing surface are the same surface, i.e., the inner peripheral surface 55 of the housing and the outer peripheral surface 33a of the outer boss in fig. 2, the sealing rings 37 are pressed by both ends of the housing 5 in the lateral direction during the installation process. Although the edge between the outer end surface 54 of the housing and the inner circumferential surface 55 of the housing is designed to be chamfered in the actual design process so as to compress the sealing ring 37 (not shown in fig. 2), the 11O-rings are damaged by lateral shearing force and are crushed, so that the sealing ring cannot be used, and therefore, the sleeve motor with the traditional structure 20 has to be disassembled and reassembled, and the actual usage amount of the sleeve motor is 31 sealing rings. The average assembly time per unit is about 17 min. In comparison, the motor in the invention adopts a forward sealing mode, positioning and sealing are separated, and no O ring is damaged in the assembling process, so that the overall assembling efficiency is greatly improved.

TABLE 2 comparative test of leakage rate of motor with structure of the invention (Pa.m)³/s)

	Implementation mode one	Second embodiment	Third embodiment	Conventional structure
					Initial leak rate	8.3×10^-7	1.1×10^-6	9.5×10^-7	8.9×10^-6
Leakage rate after 24hr operation	8.5×10^-7	/	/	1.1×10^-5
					Leakage rate after 3 months of operation	1.3×10^-6	5.3×10^-6	3.8×10^-6	2.6×10^-5

Table 2 gives the motor leakage rate comparison data. In the conventional structure, the inner peripheral surfaces 55 of the housing at the two ends of the housing 5 need to be turned around, so that the possibility of decentration exists, and the sealing ring 37 is greatly extruded by one side of the rear end cover 7 or the front end cover 9, and the other side of the sealing ring is slightly extruded. In the structure of the invention, because the verticality between the plane of the sealing surface 53 of the shell and the axis O can be processed better, the sealing ring 37 is extruded in the positive direction of the whole plane, and the sealing effect is better. From the overall results, the airtight motor of the invention is superior to the airtight motor of the traditional structure in sealing effect.

The airtight motor provided by the invention is suitable for any type of refrigerating machines, is not limited to a Gifford-Memmarflood refrigerating machine, a Solvin refrigerating machine, a pulse tube refrigerating machine and the like, and can be applied to a single-stage or double-stage refrigerating machine.

The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby, and any modification made on the basis of the technical scheme according to the technical idea proposed by the present invention falls within the protection scope of the present invention; the technology not related to the invention can be realized by the prior art.

Claims

1. The utility model provides an airtight type motor, includes rotor (1), stator (2), front end housing (9), rear end housing (7), rear bearing (14) and front bearing (15), all is equipped with end cover inner end face (32 b), its characterized in that on the relative part of front end housing (9) and rear end housing (7): the inner side of the inner end surface (32 b) of the end cover is provided with a concave part (32), the concave part (32) comprises a radial inner circumferential surface (32 a) of the end cover and an axial bottom surface (32 c) of the end cover, and two ends of a shell (5) of the stator (2) are respectively provided with a radial outer circumferential surface (52) of the shell and an axial shell sealing surface (53); when two ends of the shell (5) are respectively inserted into the concave parts (32) on the front end cover (9) and the rear end cover (7) along the axis O direction, the shell can be respectively contacted with the concave parts (32) for sealing and fixing, wherein the outer peripheral surface (52) of the shell and the inner peripheral surface (32 a) of the end cover are matched in the radial direction to form a radial positioning structure, and the sealing surface (53) of the shell and the bottom surface (32 c) of the end cover are matched in the axial direction to form an axial sealing structure; and the axial sealing structure also comprises a sealing ring (37) positioned on the sealing surface (53) of the shell and/or the bottom surface (32 c) of the end cover.

2. A hermetic motor according to claim 1, wherein: the outer diameter of the outer peripheral surface (52) of the shell is the same as the inner diameter of the inner peripheral surface (32 a) of the end cover.

3. A hermetic motor according to claim 1, wherein: the end cover bottom surface (32 c) on be equipped with axial open-ended annular seal groove (4), annular seal groove (4) be used for placing sealing washer (37).

4. A hermetic motor according to claim 1, wherein: the sealing surface (53) of the shell is provided with an annular sealing groove (4) with an axial opening, and the annular sealing groove (4) is used for placing the sealing ring (37).

5. A hermetic motor according to claim 1, wherein: the outer edges of two ends of the shell (5) are respectively cut off a fan-shaped ring to form a shell outer peripheral surface (52), the outer diameter of the shell outer peripheral surface (52) is smaller than that of the shell (5), and the outer diameter of the shell (5) is larger than the inner diameter of an end cover inner peripheral surface (32 a).

6. The hermetic motor according to claim 5, wherein: the end face of the housing (5) located radially outside the housing sealing surface (53) forms a housing stop face (51), and the housing stop face (51) can be axially fitted with the end cap inner end face (32 b) to form an axial positioning structure.

7. A hermetic motor according to claim 6, wherein: the shell spigot surface (51) and the shell sealing surface (53) form a step-shaped end surface.

8. A hermetic motor according to claim 1, wherein: the concave part (32) is positioned at the radial outer side of the inner boss (31) on the front end cover (9) and the rear end cover (7).

9. A hermetic motor according to claim 1, wherein: the concave part (32) on the front end cover (9) and the front end cover (9) are integrally formed, and the concave part (32) on the rear end cover (7) and the rear end cover (7) are integrally formed.

10. Use of a machine of the gastight type according to any of the claims 1-9, wherein: the airtight motor can be used for a refrigerator.