An airtight motor

Abstract

The invention discloses an airtight motor, comprising a rotor (1), a stator (2), a front end cover (9), a rear end cover (7), and an inner end surface (32b) of the end cover. A recessed portion (32) is provided on the inner side of the inner end surface (32b) of the end cover. The recessed portion (32) comprises a radial inner circumferential surface (32a) of the end cover and an axial bottom surface (32c) of the end cover. The two ends of the outer shell (5) of the stator (2) respectively have a radial outer shell circumferential surface (52) and an axial outer shell sealing surface (53). When the two ends of the outer shell (5) are respectively inserted into the recessed portion (32), they can be respectively contacted and sealed with the recessed portion (32), wherein the outer shell circumferential surface (52) and the inner circumferential surface (32a) of the end cover cooperate in the radial direction to form a radial positioning structure, and the outer shell sealing surface (53) and the bottom surface (32c) of the end cover cooperate in the axial direction to form an axial sealing structure. The airtight motor structure of the invention is simple to process, easy to install, and has good airtightness.

Description

Technical Field

[0001] The invention belongs to the technical field of low-temperature refrigerators, in particular to an airtight motor used for a GM refrigerator, a pulse tube refrigerator and a Solvang refrigerator. Background Art

[0002] Ultra-low temperature refrigerators represented by Gifford-McMahon (GM) refrigerators have an expander and compressor for the working gas (also called refrigerant gas). This type of refrigerator is provided with a high-pressure airflow discharged by the compressor, which enters the push piston placed in the cylinder and reciprocating up and down through the valve mechanism, exchanges heat with the cold storage material, and then expands in the expansion chamber to do work, and then flows out of the valve mechanism through the push piston and returns to the low-pressure chamber of the compressor. Through the above continuous cycle process, a refrigeration effect is formed. The selected motor is connected to the equipment, and it is required to form an integral airtight system, that is, a sealing structure is required between the end covers at both ends of the motor and the stator.

[0003] [Patent Document 1] JP 2001-28501. Conventional airtight motor ( Figure 1 As shown in the figure, it consists of a rotor 1 (a main shaft 11 and a basic part 12 installed on the outer periphery, and a permanent magnet 13), a stator 2 (an iron core yoke 19 is fixed in a housing 5 and radially arranged on the outside of the rotor 1), a front cover 9 and a rear cover 7.

[0004] The front cover 9 and the rear cover 7 are integrally formed with an outer boss 33 and an outer boss outer peripheral surface 33a on the radial outer side thereof and an annular groove with an opening for placing a sealing ring 37. The boss structure 33 is inserted into the housing 5 of the stator 2 and is in contact with the housing inner peripheral surface 55 ( Figure 2 As shown) are airtightly connected and matched, and are fixed to the end cover inner end faces 32a of the front end cover 9 and the rear end cover 7 through the outer end faces 54 of the outer shell at both ends of the outer shell 5 along the axis O direction.

[0005] In order to reduce the vibration generated during the rotation of the main shaft 11, there are certain requirements for the processing of the front cover 9, the rear cover 7 and the outer shell 5. In the traditional process, taking the rear cover 7 as an example, the rear bearing 14 is installed on the inner circumference 31a of the inner boss 31; the front bearing 15 is installed on the front cover 9 in the same way, and the outer circumference 33a of the outer boss 33 is processed with the cover surface as the reference surface to control the coaxiality of the two places. In addition, the outer periphery 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 the reference; at the same time, the core yoke 19 on the stator 2 is internally honed to process the inner circumference 19a of the yoke, and the inner circumference 55 of the outer shell 5 at both ends along the axis O direction is processed with this surface. Through the above approach, it is ensured that the coaxial lines of the rear bearing 14 and the front bearing 15, that is, the axis of the main shaft 11, the outer peripheral surface of the permanent magnet 13, and the inner peripheral surface 19a of the yoke are coaxial, so as to keep the motor running well.

[0006] However, this traditional structure has certain problems:

[0007] 1) Since the core yoke 19 has been installed in the housing 5 and the inner circumference 19a of the yoke has been honed, and since there are windings 21 protruding at both ends along the axis O, when processing the inner circumference 55 of the housing 5 at both ends, the cutter head (or grinding head) is likely to rub against the windings 21, causing damage to the coils of the stator 2.

[0008] 2) To avoid the above problems, the conventional structure extends the outer shell 5 of the stator 2 outwards along the axis O by a distance of l ( Figure 1 The distance between the two sides of L shown in the figure) can indeed avoid the winding 21 during processing. However, this is not conducive to the compact design of the motor. Moreover, since the inner circumference 55 of the shell is on the inner circumference of the two ends of the shell 5, it is necessary to "turn around" during processing, and the coaxiality of the inner circumference 55 of the shell at both ends is difficult to control.

[0009] 3) In order to ensure good coaxiality among the axis of the main shaft 11, the outer circumference of the permanent magnet 13, and the inner circumference 19a of the yoke, the clearance between the outer circumference 33a of the outer boss 33 of the rear cover 7 and the inner circumference 55 of the outer shell at both ends of the outer shell 5 is very small, so as to prevent the stator 2 and the rear cover 7 from moving in the radial direction. It is worth noting that the inner circumference 55 of the outer shell is both a sealing surface and a positioning surface. The sealing ring 37 is placed between the inner circumference 55 of the outer shell and the outer circumference 33a of the outer boss, and is laterally extruded by the outer end faces 54 of the outer shell at both ends of the outer shell 5 along the axis O direction, sealed in the annular groove of the inner circumference 55 of the outer shell and the outer circumference 33a of the outer boss in the radial outside, and the outer end face 54 of the outer shell is fixed to the inner end face 32b of the end cover of the rear cover 7. The airtight structure formed in this way is easy to squeeze and damage the sealing ring 37, reducing the assembly efficiency.

[0010] [Patent Document 2] CN 102904354 B. Document 2 proposes a structure for improving the rigidity of a motor. In the second implementation scheme provided in Document 2, the radial positioning structure is implemented on the core yoke. This structure avoids the processing problems in the traditional positioning structure and is more conducive to improving the coaxiality of the main shaft. However, since the core yoke is composed of overlapping magnetic steel sheets and does not have an airtight effect, the motor with this structure cannot be directly used in a low-temperature refrigerator system.

[0011] [Patent Document 3] CN 101521422 B. Document 3 proposes a low-vibration airtight motor. In the airtight structure of Document 3, the first sealing ring is still sealed radially outside the outer rib of the bracket, and there is still a possibility of shear damage by the motor housing. Summary of the invention

[0012] The purpose of the present invention is to provide an airtight motor for a GM refrigerator, a pulse tube refrigerator, and a Solvang refrigerator in view of the problems existing in the prior art, wherein the airtight motor is easier to manufacture and assemble.

[0013] The purpose of the present invention is to be solved by the following technical solutions:

[0014] An airtight motor comprises a rotor, a stator, a front end cover, a rear end cover, a rear bearing and a front bearing; the rotor comprises a main shaft, a base part fixedly mounted on the outer periphery of the main shaft, and a permanent magnet; the stator comprises an iron core yoke arranged radially outside the main shaft, windings 21 arranged on the iron core yoke at both ends along the axis O direction, and a cylindrical shell made of metal; the rear bearing and the front bearing are used to support the main shaft so that it rotates around the central axis O; a pair of front end covers and rear end covers, the front end covers and the rear end covers have an inner boss 31 and a bearing chamber formed by the inner circumferential surface 31a of the inner boss for radially fixing the front bearing and the rear bearing; The inner end faces of the end covers are arranged on the relative parts of the covers, and the inner side of the inner end faces of the end covers is provided with a recessed portion, and the recessed portion comprises a radial inner circumferential surface of the end cover and an axial bottom face of the end cover, and the two ends of the stator outer shell respectively have a radial outer shell circumferential surface and an axial outer shell sealing surface; when the two ends of the outer shell are respectively inserted into the recessed portions on the front end cover and the rear end cover along the axis O direction, they can be respectively contacted and sealed with the recessed portions, wherein the outer shell circumferential surface and the inner circumferential surface of the end cover cooperate in the radial direction to form a radial positioning structure, and the outer shell sealing surface and the end cover bottom surface cooperate in the axial direction to form an axial sealing structure; and the axial sealing structure also comprises a sealing ring located on the outer shell sealing surface and / or the end cover bottom surface.

[0015] The outer diameter of the outer circumferential surface of the shell is the same as the inner diameter of the inner circumferential surface of the end cover.

[0016] An annular sealing groove with an axial opening is provided on the bottom surface of the end cover, and the annular sealing groove is used for accommodating the sealing ring.

[0017] An annular sealing groove with an axial opening is arranged on the sealing surface of the shell, and the annular sealing groove is used for accommodating the sealing ring.

[0018] A sector ring is cut out from the outer edges of both 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 the outer diameter of the shell, and the outer diameter of the shell is larger than the inner diameter of the inner circumference of the end cover.

[0019] The end surface of the outer shell located radially outside the outer shell sealing surface constitutes an outer shell stop surface, and the outer shell stop surface can cooperate with the inner end surface of the end cover in the axial direction to form an axial positioning structure.

[0020] The shell stop surface and the shell sealing surface form a stepped end surface.

[0021] The recessed portion is located radially outside the inner bosses on the front end cover and the rear end cover.

[0022] The recessed portion on the front end cover is integrally formed with the front end cover, and the recessed portion on the rear end cover is integrally formed with the rear end cover.

[0023] The airtight motor can be used in a refrigerator.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The shell of the airtight motor of the present invention is easy to process. The outer circumferential surfaces of the shell that need to match the inner circumferential surfaces of the end covers of the recessed parts of the end covers at both ends of the shell are on the outer edge surfaces of the shell. The processing does not require "turnaround" and can be formed in one step. The coaxiality is easy to control. The airtight motor is easy to install. Since the seal is a positive seal along the axis O, the axial sealing surface is separated from the radial positioning surface, the sealing ring will not be damaged during the installation process, and it is easy to seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Attached Figure 1 This is a schematic diagram of the structure of a traditional airtight motor;

[0027] Attached Figure 2 This is an enlarged schematic diagram of the traditional motor sealing structure;

[0028] Attached Figure 3 It is a schematic diagram of the structure of the airtight motor provided by the present invention;

[0029] Attached Figure 4 is an enlarged schematic diagram of the airtight structure of the first embodiment of the present invention;

[0030] Attached Figure 5 is an enlarged schematic diagram of the airtight structure of the second embodiment of the present invention;

[0031] Attached Figure 6 It is an enlarged schematic diagram of the airtight structure of the third embodiment of the present invention.

[0032] Among them: 1—rotor; 11—main shaft; 12—base; 13—permanent magnet; 14—rear bearing; 15—front bearing; 2—stator; 5—housing; 19—core yoke; 19a—inner circumference of yoke; 21—winding; 27—insulating cover; 31—inner boss; 31a—inner circumference of inner boss; 32—recess; 32a—inner circumference of end cover; 32b—inner end face of end cover; 32c—bottom face of end cover; 33—outer boss; 33a—outer circumference of outer boss; 37—sealing ring; 51—housing stop face; 52—outer circumference of housing; 53—housing sealing face; 54—outer end face of housing; 55—inner circumference of housing; 7—rear end cover; 7a—rear end cover through hole; 9—front end cover; 9a—front end cover through hole. DETAILED DESCRIPTION

[0033] In conjunction with the technical background, the traditional motor will not be described in detail. The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0034] like Figure 3 As shown, the airtight structure implementation of the front cover 9 and the rear cover 7 is the same, so the rear cover 7 is taken as an example for explanation.

[0035] The airtight motor of the present invention comprises 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 is composed of a main shaft 11, a base 12 formed by laminating magnetic steel sheets and fixedly mounted on the outer peripheral surface of the main shaft 11, and a permanent magnet 13 made of a neodymium iron boron material. The base 12 and the permanent magnet 13 rotate synchronously with the main shaft 11 along the rotation axis O. Ball bearings are mounted at both ends of the main shaft 11 as the rear bearing 14 and the front bearing 15, and are mounted in a bearing chamber formed by the inner peripheral surface 31a of the inner boss 31 in the front cover 9 and the rear cover 7, and have no radial margin.

[0036] The stator 2 is composed of a cylindrical housing 5 and a core yoke 19 fixedly installed therein, arranged on the radially outer side of the base 12 and the permanent magnet 13 of the rotor 1, and arranged coaxially with the axis O as the central axis. The core yoke 19 is wound with windings 21 on both end surfaces along the axis O direction, and an insulating cover 27 is installed on the outer side of the winding 21.

[0037] The housing 5 is cylindrical and made of steel and is disposed radially outermost of the stator 2. As described later, the housing 5 is airtightly connected to the front cover 9 and the rear cover 7 to ensure the pressure resistance and airtightness of the airtight motor for a low-temperature refrigerator.

[0038] Implementation Method 1

[0039] Take the rear end cover 7 as an example to further illustrate. Figure 3 , Figure 4 Implementation method 1 is introduced.

[0040] The annular inner boss 31 protruding along the axis O direction forms the inner boss inner peripheral surface 31a (bearing chamber) for accommodating the rear bearing 14. The recessed portion 32 and the end cover bottom surface 32c formed integrally with the rear end cover 7 on the inner end surface 32b of the end cover and located closer to the radial outside than the inner boss 31 are used to cooperate with the two ends of the housing 5 along the axis O direction to form a positioning and airtight effect.

[0041] Specifically, with the inner circumferential surface 31a of the inner boss of the bearing chamber as a reference, an end cover inner circumferential surface 32a and an end cover bottom surface 32c along the axis O are machined on the inner end surface 32b of the end cover to ensure the coaxiality of the end cover inner circumferential surface 32a and the inner circumferential surface 31a of the inner boss. And an annular sealing groove opening along the axis O direction is machined on the end cover bottom surface 32c. At the same time, the core yoke 19 and the outer shell 5 are fixed together, with the yoke inner circumferential surface 19a of the core yoke 19 as a reference, along the axis O direction, on the radially outer circumferential surface at both ends of the outer shell 5, two outer shell outer circumferential surfaces 52 with good coaxiality can be machined at one time without "turning around", and the radial dimension of the outer shell outer circumferential surface 52 is smaller than the outer diameter of the outer shell 5, thereby forming the outer shell stop surface 51 and the outer shell sealing surface 53 ( Figure 4 (as shown in the partial enlarged schematic diagram).

[0042] During installation, the housing 5 is inserted into the recessed portion 32 of the rear end cover 7. That is, the housing outer peripheral surface 52 of the housing 5 at both ends along the axis O direction and the radially outer side is matched with the end cover inner circumferential surface 32a of the recessed portion 32 of the rear end cover 7 in the radial direction without any movable margin, 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 rear end cover 7 form a good coaxiality.

[0043] The normal directions of the shell sealing surface 53 and the shell stop surface 51 are parallel to the axis O, forming parallel planes. When the rear end cover 7 and the stator 2 are extruded along the axis O direction by the outside, the shell sealing surface 53 will positively extrude the sealing ring 37 installed in the annular sealing groove on the bottom surface 32c of the end cover along the axis O direction, forming a positive shaft sealing structure.

[0044] External extrusion is achieved through the front cover through hole 9a and the rear cover through hole 7a of the front cover 9 and the rear cover 7 on the outside of the housing 5. The screws 30 for fastening are respectively inserted into the rear cover through hole 7a and connected with the front cover through hole 9a of the front cover 9 (in the actual design process, the front cover through hole 9a adopts a threaded hole structure). During the extrusion process, the housing stop surface 51 on the housing 5 is fixedly contacted with the inner end surface 32b of the end cover in the axial direction, so that the stator 2 is fixed with the front cover 9 and the rear cover 7.

[0045] 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 there is no need to increase the length of the housing inner circumference 55 in order to avoid the winding 21 in processing the housing sealing surface 53, because in the traditional structure, a certain length "l" is required to process the outer circumference 33a of the outer boss for positioning and the radial annular groove. The present invention externalizes the sealing structure to avoid the above processing problems.

[0046] The annular sealing groove in the above-mentioned embodiment is processed on the end cover bottom surface 32c of the recessed portion 32 of the front end cover 9 and the rear end cover 7, and can also be processed on the shell sealing surfaces 53 at both ends of the shell 5. In this way, the axial sealing between the shell sealing surface 53 of the shell 5 and the end cover bottom surface 32c of the recessed portion 32 can also be achieved.

[0047] Implementation Method 2

[0048] Take the rear end cover 7 as an example to further illustrate. Figure 5 Introduce implementation method 2.

[0049] Furthermore, at both ends of the housing 5 along the axis O, the size of the housing outer circumference 52 is not less 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 pressed into the interior of the housing 5 by interference fit to form a fixed structure. Still taking the inner circumference 19a of the core yoke 19 as the reference, the outer diameter of the housing 5 and the end surfaces at both ends along the axis O are finely processed to form the housing outer circumference 52 and the housing sealing surface 53 respectively. At the same time, the size of the inner circumference 32a of the end cover of the recessed portion 32 of the rear end cover 7 is made to be equivalent to the outer diameter of the housing 5.

[0050] The difference from the first embodiment is that the two ends of the housing 5 along the axis O direction do not form a stepped housing stop surface 51 and a housing sealing surface 53, but form the same plane as the stop sealing surface to play the role of stop and seal at the same time. When the housing 5 is inserted into the recessed portion 32 of the rear end cover 7, a part of the stop sealing surface positively presses the sealing ring 37 to form an axial seal; the other part of the area positively presses the bottom surface 32c of the end cover (the position indicated by the arrow in the figure), achieving the stop function of the first embodiment.

[0051] Implementation Method 3

[0052] Take the rear end cover 7 as an example to further illustrate. Figure 6 Introduce implementation method three.

[0053] When processing the housing 5, sealing grooves are processed on the end faces at both ends in the direction of the axis O, that is, the housing sealing surfaces 53, and no sealing grooves are required to be processed on the end cover bottom surface 32c of the recessed portion 32 of the rear end cover 7. The remaining embodiments are consistent with the above-mentioned embodiment 2 and will not be repeated.

[0054] The following is a detailed description of the implementation effects of the present invention. Table 1 is a comparison of the number of O-rings damaged during the installation of 10 conventional motors and 10 motors of the present invention.

[0055] Table 1 Efficiency comparison of the process of installing 10 motors

[0056] Traditional motor The present invention Number of O-ring damages 11 0 Average installation time per unit 17min 6min

[0057] During the implementation process, a total of 20 sealing rings are required to assemble the motor with the traditional structure. The radial positioning surface and the sealing surface of the motor with the traditional structure are the same surface, that is, Figure 2 The inner peripheral surface 55 of the middle shell and the outer peripheral surface 33a of the outer boss, during the installation process, the two ends of the shell 5 squeeze the sealing ring 37 in the lateral direction. Although in the actual design process, the edge between the outer end surface 54 of the shell and the inner peripheral surface 55 of the shell is designed to be chamfered to facilitate squeezing the sealing ring 37 ( Figure 2 Not shown), but 11 O-rings were still damaged by lateral shear force and squeezed and broken, making them unusable. Therefore, they had to be disassembled and reassembled. The actual amount of 20 sets of motors with traditional structures was 31 seals. The average assembly time for each motor was about 17 minutes. In comparison, the motor in the present invention adopts a positive seal form, and the positioning and sealing are separated. There is no O-ring damage during the assembly process, so the overall assembly efficiency is also greatly improved.

[0058] Table 2 Comparative test of leakage rate of motor with structure of the present invention (Pa·m 3 / s)

[0059] Implementation Method 1 Implementation Method 2 Implementation Method 3 Traditional structure Initial leak rate <![CDATA[8.3×10 -7 ]]> <![CDATA[1.1×10 -6 ]]> <![CDATA[9.5×10 -7 ]]> <![CDATA[8.9×10 -6 ]]> Leakage rate after 24 hours of operation <![CDATA[8.5×10 -7 ]]> / / <![CDATA[1.1×10 -5 ]]> Leakage rate after 3 months of operation <![CDATA[1.3×10 -6 ]]> <![CDATA[5.3×10 -6 ]]> <![CDATA[3.8×10 -6 ]]> <![CDATA[2.6×10 -5 ]]>

[0060] Table 2 gives the comparison data of motor leakage rate. In the traditional structure, the inner peripheral surface 55 of the shell at both ends of the shell 5 needs to be "turned around" for processing, so there is a possibility of eccentricity, which causes the sealing ring 37 to be squeezed more on one side by the rear end cover 7 or the front end cover 9, and less on the other side. In the structure of the present invention, since the perpendicularity between the plane of the shell sealing surface 53 and the axis O can be well processed, the overall plane positively squeezes the sealing ring 37, which has a better sealing effect. From the overall result, the airtight motor of the present invention is superior to the airtightness of the motor of the traditional structure in terms of sealing effect.

[0061] The airtight motor provided by the present invention is applicable to any type of refrigerator, not limited to Gifford-McMahon refrigerator, Solvang refrigerator, pulse tube refrigerator, etc., and can be applied to single-stage or double-stage refrigerators.

[0062] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention; any technology not involved in the present invention can be realized by existing technologies.

Claims

1. An airtight motor, comprising a rotor (1), a stator (2), a front end cover (9), a rear end cover (7), a rear bearing (14) and a front bearing (15), wherein the front end cover (9) and the rear end cover (7) are provided with end cover inner end surfaces (32b) at the opposite positions thereof, and characterized in that: A recessed portion (32) is provided on the inner side of the inner end surface (32b) of the end cover, the recessed portion (32) comprising a radial inner circumferential surface (32a) of the end cover and an axial bottom surface (32c) of the end cover. The two ends of the outer shell (5) of the stator (2) respectively comprise a radial outer shell circumferential surface (52) and an axial outer shell sealing surface (53). When the two ends of the outer shell (5) are respectively inserted into the recessed portions (32) on the front end cover (9) and the rear end cover (7) along the axis O direction, they can respectively contact and seal with the recessed portions (32), wherein the outer shell circumferential surface (52) and the inner circumferential surface (32a) of the end cover cooperate in the radial direction to form a radial positioning structure, and the outer shell sealing surface (53) and the bottom surface (32c) of the end cover cooperate in the axial direction to form an axial positioning structure. A sealing structure; an annular sealing groove with an axial opening is provided on the bottom surface (32c) of the end cover, and the annular sealing groove is used to place a sealing ring (37); a sector ring is cut out from the outer edges of both ends of the outer shell (5) to form an outer shell peripheral surface (52), the outer diameter of the outer shell peripheral surface (52) is smaller than the outer diameter of the outer shell (5), and the outer diameter of the outer shell (5) is larger than the inner diameter of the inner circumferential surface (32a) of the end cover; the end surface of the outer shell (5) located radially outside the outer shell sealing surface (53) forms an outer shell stop surface (51), and the outer shell stop surface (51) can cooperate with the inner end surface (32b) of the end cover in the axial direction to form an axial positioning structure; the outer shell stop surface (51) and the outer shell sealing surface (53) form a stepped end surface.

2. The airtight motor according to claim 1, characterized in that: The outer diameter of the outer circumferential surface (52) of the housing is the same as the inner diameter of the inner circumferential surface (32a) of the end cover.

3. The airtight motor according to claim 1, characterized in that: The recessed portion (32) is located radially outside the inner boss (31) on the front end cover (9) and the rear end cover (7).

4. The airtight motor according to claim 1, characterized in that: The recessed portion (32) on the front end cover (9) is integrally formed with the front end cover (9), and the recessed portion (32) on the rear end cover (7) is integrally formed with the rear end cover (7).

5. The use of the airtight motor according to any one of claims 1 to 4, characterized in that: The airtight motor can be used in a refrigerator.

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