Cryogenic pump

Abstract

The present invention discloses a cryogenic pump, comprising: a middle bearing having a receiving cavity formed with a first opening on the middle bearing, an impeller being received in the receiving cavity, the middle bearing having a liquid inlet end and a liquid outlet end; a pump cover disposed at the first opening; an isolation sleeve disposed on the middle bearing; a rotating shaft disposed on the middle bearing through a pair of cryogenic bearings, the middle bearing being provided with a main passage communicating the receiving cavity with the isolation sleeve, the pair of cryogenic bearings being located in the main passage, the front end of the rotating shaft being connected to the impeller; a fan disposed on the rotating shaft, the fan being located between the pair of cryogenic bearings; an inner magnetic assembly received in the isolation sleeve, the rear end of the rotating shaft being connected to the inner magnetic assembly; an outer magnetic assembly disposed on the outer periphery of the isolation sleeve and connected to a motor; wherein the fan is configured to suck the fluid in the isolation sleeve into the main passage during rotation, and the middle bearing is provided with a first liquid passing passage and a second liquid passing passage, the first liquid passing passage communicating the receiving cavity with the isolation sleeve, and the second liquid passing passage communicating the main passage with the isolation sleeve.

Description

Technical Field

[0001] The present invention relates to the technical field of pumps, and particularly to a cryogenic pump. Background Art

[0002] The cryogenic pump is used for pumping cryogenic liquids (liquid nitrogen). When the cryogenic pump is working, when the temperature inside the pump is higher than -196 °C, the liquid nitrogen will vaporize, resulting in the generation of gas inside the pump. The accumulation of gas in the pump will cause cavitation and damage the internal components of the pump, which is not desired.

[0003] In the prior art, the exhaust of the cryogenic pump usually requires manual operation by workers to regularly open the exhaust valve. The disadvantages of the above method are: real-time exhaust cannot be achieved, there are also safety hazards, and the hands of workers are easily splashed or frostbitten by liquid nitrogen. Therefore, it is necessary to improve the prior art to overcome the defects in the prior art. Summary of the Invention

[0004] The present invention provides a cryogenic pump with good exhaust effect.

[0005] To achieve the above object, a cryogenic pump proposed by the present invention includes: a middle support, which forms a receiving cavity. The receiving cavity forms a first opening at the front end of the middle support. An impeller is received in the receiving cavity. The middle support has a liquid inlet end and a liquid outlet end communicating with the receiving cavity; a pump cover, which is hermetically covered at the first opening; an isolation sleeve, which is arranged at the rear end of the middle support away from the pump cover; a rotating shaft, which is arranged on the middle support through a pair of cryogenic bearings. The middle support is provided with a main channel communicating the receiving cavity with the isolation sleeve. The pair of cryogenic bearings are located in the main channel. The front end of the rotating shaft is connected to the impeller; a fan, which is arranged on the rotating shaft and rotates together with the rotating shaft. The fan is located between the pair of cryogenic bearings; an inner magnetic component, which is received in the isolation sleeve. The rear end of the rotating shaft is connected to the inner magnetic component; an outer magnetic component, which is arranged on the outer periphery of the isolation sleeve and is connected to a motor; wherein, the fan is configured to suck the fluid in the isolation sleeve into the main channel during rotation. The middle support is provided with a first liquid passing channel and a second liquid passing channel. The first liquid passing channel communicates the receiving cavity with the isolation sleeve, and the second liquid passing channel communicates the main channel with the isolation sleeve.

[0006] Preferably, the inner magnetic component is axially recessed to form an inner magnetic cavity near the front end of the middle support. The rear end of the middle support extends into the inner magnetic cavity. The liquid inlet port of the main channel is located in the inner magnetic cavity;

[0007] Wherein, a thread groove spirally distributed along the axial direction is provided on the outer peripheral wall of the part of the middle bearing extending into the inner magnetic cavity. When the inner magnetic component rotates driven by the outer magnetic component, the fluid located between the thread groove and the cavity wall of the inner magnetic cavity is forced to accelerate and flow into the inner magnetic cavity.

[0008] Preferably, a positioning bushing located in the inner magnetic cavity is also sleeved on the rotating shaft. The front end of the positioning bushing abuts against the rear cryogenic bearing on the side far from the impeller among the pair of cryogenic bearings, and the rear end of the positioning bushing abuts against the bottom of the inner magnetic cavity.

[0009] Wherein, a first step groove for cooperating with the rear cryogenic bearing is formed on the pore wall of the main channel.

[0010] Preferably, the bearing on the side close to the impeller among the pair of cryogenic bearings is a front cryogenic bearing, and a front bearing mounting structure for limiting the front cryogenic bearing is also provided in the main channel.

[0011] The front bearing mounting structure includes a bearing ring seat fixed in the main channel. The bearing ring seat is provided with a stepped hole axially penetrating through it. The stepped hole makes the bearing ring seat have a first hole part close to the impeller and a second hole part farther from the impeller than the first hole part. The front cryogenic bearing is arranged in the first hole part. A bearing gland is detachably provided at the front end of the bearing ring seat close to the impeller, and the bearing gland abuts against the front end of the front cryogenic bearing.

[0012] Wherein, the bearing gland has a gland central hole. The impeller includes a sleeve and a wheel part formed on the outer periphery of the sleeve. A plurality of blades are provided on the outer periphery of the wheel part. The thickness of the wheel part in the axial direction is less than the thickness of the sleeve in the axial direction. After the rear end of the sleeve passes through the gland central hole, it abuts against the front end of the front cryogenic bearing.

[0013] Preferably, the second liquid passing channel has a second liquid outlet, and the second liquid outlet is located on the pore wall of the main channel. Wherein, the second liquid outlet is located between the fan and the front cryogenic bearing on the side close to the impeller among the pair of cryogenic bearings.

[0014] Preferably, the first liquid passing channel is inclined relative to the rotating shaft. The first liquid passing channel has a first liquid inlet and a first liquid outlet. The first liquid inlet is formed on the cavity wall of the receiving cavity and is distributed close to the liquid outlet end. Wherein, the first liquid outlet is distributed lower than the first liquid inlet.

[0015] Preferably, the outer diameter of the part of the middle bearing located in the isolation sleeve shows a decreasing trend.

[0016] Preferably, an avoidance cavity for receiving the front end of the rotating shaft is provided on the pump cover, and the avoidance cavity and the receiving cavity enclose to form the pump cavity of the cryogenic pump;

[0017] Wherein, a third liquid passage communicating the avoidance cavity and the receiving cavity is further provided on the pump cover, a third liquid inlet of the third liquid passage is distributed near the liquid outlet end, and a third liquid outlet of the third liquid passage is distributed lower than the third liquid inlet.

[0018] Preferably, a lock washer and a lock nut are further provided at the front end of the rotating shaft, the lock washer abuts against the front end of the impeller, the lock nut abuts against the front end of the lock washer, and wherein, the former of the pair of cryogenic bearings abuts against the rear end of the impeller.

[0019] Preferably, a bracket is provided on the outer periphery of the outer magnetic assembly, and the bracket connects the housing of the motor and the middle bearing. After the bracket is connected to the middle bearing, the isolation sleeve is pressed against the middle bearing;

[0020] A sealing structure is provided between the middle bearing and the isolation sleeve. The sealing structure is an annular structure with a closed space inside. A pair of hard rubber rings are provided in the closed space, and an elastic member is provided between the pair of hard rubber rings. The elastic member is configured to provide an axial elastic force so that the pair of hard rubber rings respectively abut against both ends of the annular structure;

[0021] Wherein, the inner wall and the outer wall of the sealing structure are made of flexible materials, and the inner wall and the outer wall of the sealing structure can generate elastic deformation when subjected to external forces.

[0022] The technical solution provided by the present invention has the following advantages:

[0023] In this embodiment, after the fan rotates, the main channel can be in a negative pressure state, thereby sucking the liquid nitrogen in the isolation sleeve into the main channel, accelerating the flow of liquid nitrogen from the isolation sleeve to the receiving cavity, and thus accelerating the circulation speed of liquid nitrogen in the cryogenic pump, which is beneficial to the discharge of gas through the liquid inlet end and the liquid outlet end, and has the advantage of good exhaust effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the structures shown in these drawings without creative efforts.

[0025] Figure 1Schematic three-dimensional structure diagram of the cryopump provided by the present invention;

[0026] Figure 2 Schematic cross-sectional view of a partial structure of the cryopump provided by the present invention;

[0027] Figure 3 For Figure 2 Enlarged structure diagram of area A in

[0028] Figure 4 Schematic exploded view of the cryopump provided by the present invention;

[0029] Figure 5 Cross-sectional structure diagram between the middle bearing and the pump cover;

[0030] Figure 6 Schematic three-dimensional structure diagram of the middle bearing from the first perspective;

[0031] Figure 7 Schematic three-dimensional structure diagram of the inner magnetic component;

[0032] Figure 8 Schematic three-dimensional structure diagram of the middle bearing from the second perspective;

[0033] Figure 9 Schematic three-dimensional structure diagram of the isolation sleeve;

[0034] Figure 10 Cross-sectional structure diagram of the front bearing installation structure;

[0035] Figure 11 Cross-sectional structure diagram of the bearing ring seat;

[0036] Figure 12 Schematic three-dimensional structure diagram of the bearing gland;

[0037] Figure 13 Schematic three-dimensional structure diagram of the impeller;

[0038] Figure 14 Cross-sectional structure diagram of the sealing structure. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the protection scope of the present invention.

[0040] It should be noted that if there are directional indications involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship, movement conditions, etc. between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0041] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and / or" appearing throughout the text includes three parallel scenarios. Taking "A and / or B" as an example, it includes scenario A, or scenario B, or the scenario where both A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] The present invention provides a cryogenic pump for pumping cryogenic liquids. The cryogenic pump can be a liquid nitrogen pump, or a liquid helium pump, a cryogenic circulation pump, a cryogenic adsorption pump, etc. When the cryogenic pump is a liquid nitrogen pump, the cryogenic liquid is liquid nitrogen; when the cryogenic pump is a liquid helium pump, the cryogenic liquid is liquid helium. The following will take the cryogenic pump being a liquid nitrogen pump as an example for elaboration. However, based on the above description, it can be seen that the protection scope of the present invention is not limited thereby.

[0043] As Figures 1 to 4 shown, the cryogenic pump includes a middle bearing 100, a pump cover 200, an impeller 120, a spacer sleeve 400, a rotating shaft 300, a fan 320, an inner magnetic assembly 500, an outer magnetic assembly 600, and a motor 700. The pump cover 200 and the motor 700 are respectively located at the front and rear ends of the cryogenic pump. For the convenience of describing the positional relationship between various components, hereinafter, the direction where the pump cover 200 is located is defined as the front end of the cryogenic pump, the direction where the motor 700 is located is defined as the rear end of the cryogenic pump, and the axial direction of the rotating shaft 300 is defined as the axial direction of the cryogenic pump. The "axial direction" mentioned hereinafter refers to the axial direction of the cryogenic pump.

[0044] As Figure 5 and Figure 6As shown in the figure, a receiving cavity 110 and a main channel 130 are formed on the middle bearing 100. The receiving cavity 110 and the main channel 130 are axially connected and axially penetrate the middle bearing 100. Among them, the receiving cavity 110 forms a first opening at the front end of the middle bearing 100. The middle bearing 100 has a liquid inlet end 111 and a liquid outlet end 112 communicating with the receiving cavity 110. The liquid inlet end 111 is used to pump liquid nitrogen into the receiving cavity 110, and the liquid outlet end 112 is used to pump liquid nitrogen out of the receiving cavity 110. An impeller 120 is received in the receiving cavity 110. The pump cover 200 is hermetically covered at the first opening to enclose the impeller 120 in the receiving cavity 110.

[0045] As Figure 2 shown in the figure, the rotating shaft 300 is arranged on the middle bearing 100 through a pair of cryogenic bearings 310. The pair of cryogenic bearings 310 are located in the main channel 130. The front end of the rotating shaft 300 is located in the receiving cavity 110 and is connected to the impeller 120. A fan 320 is arranged on the rotating shaft 300 and is located between the pair of cryogenic bearings 310. The fan 320 rotates together with the rotating shaft 300. Among them, the pair of cryogenic bearings 310 include a front cryogenic bearing 312 on the side close to the impeller 120 and a rear cryogenic bearing 311 on the side far from the impeller 120. The fan 320 is located between the front cryogenic bearing 312 and the rear cryogenic bearing 311. Compression rings 360 are arranged on the outer peripheries of the rear cryogenic bearing 311 and the front cryogenic bearing 312, and the compression rings 360 are used to hold the rear cryogenic bearing 311 and the front cryogenic bearing 312 tightly.

[0046] An isolation sleeve 400 is arranged on the middle bearing 100 and is located at the rear end of the middle bearing 100 away from the pump cover 200. The main channel 130 on the middle bearing 100 communicates the receiving cavity 110 with the isolation sleeve 400. An inner magnetic component 500 is received in the isolation sleeve 400. The rear end of the rotating shaft 300 is located in the isolation sleeve 400 and is connected to the inner magnetic component 500.

[0047] The middle bearing 100 is also provided with a first liquid passing channel 140 and a second liquid passing channel 150. The first liquid passing channel 140 communicates the receiving cavity 110 with the isolation sleeve 400, and the second liquid passing channel 150 communicates the main channel 130 with the isolation sleeve 400. The liquid nitrogen in the receiving cavity 110 enters the isolation sleeve 400 through the first liquid passing channel 140, and the liquid nitrogen in the isolation sleeve 400 enters the receiving cavity 110 through the main channel 130. There are the following two ways for the liquid nitrogen in the isolation sleeve 400 to enter the main channel 130: The first way is to enter the main channel 130 through the above-mentioned second liquid passing channel 150; the second way is to enter the main channel 130 through the gap on the rear cryogenic bearing 311.

[0048] Specifically, as Figure 5As shown, the first liquid passing channel 140 has a first liquid inlet 141 and a first liquid outlet 142. The first liquid passing channel 140 is arranged obliquely relative to the rotating shaft 300, and the first liquid outlet 142 is distributed lower than the first liquid inlet 141. Among them, the first liquid inlet 141 is formed on the cavity wall of the accommodating cavity 110 and is distributed close to the liquid outlet end 112. Considering that the pressure at the liquid outlet end 112 is relatively high, after the first liquid inlet 141 is distributed close to the liquid outlet end 112, the efficiency of liquid nitrogen entering the isolation sleeve 400 can be effectively improved. The inclined arrangement of the first liquid passing channel 140 can further accelerate the entry of liquid nitrogen into the isolation sleeve 400, and the liquid inlet efficiency of the isolation sleeve 400 is high.

[0049] An external magnetic component 600 is provided on the outer periphery of the isolation sleeve 400, and the external magnetic component 600 is magnetically coupled with the internal magnetic component 500 inside the isolation sleeve 400. The external magnetic component 600 is connected to the motor 700. Specifically, the motor 700 has an output shaft, and the external magnetic component 600 is connected to the output shaft of the motor 700. When the output shaft of the motor 700 rotates, it drives the external magnetic component 600 to rotate. After the external magnetic component 600 rotates, it drives the internal magnetic component 500 to rotate synchronously. Since the internal magnetic component 500 is fixedly connected to the rotating shaft 300, the rotating shaft 300 rotates under the drive of the internal magnetic component 500. After the rotating shaft 300 rotates, it drives the fan 320 and the impeller 120 thereon to rotate. It should be noted that a large amount of heat is generated during the process of the external magnetic component 600 driving the internal magnetic component 500 to rotate. The above heat is mainly concentrated at the isolation sleeve 400, resulting in an increase in the temperature of the liquid nitrogen in the isolation sleeve 400, thereby causing a vaporization phenomenon.

[0050] The fan 320 can suck the fluid (a mixture of liquid nitrogen and nitrogen) in the isolation sleeve 400 into the main channel 130 during rotation. This is because, after the fan 320 rotates, it can make the main channel 130 in a negative pressure state, thereby sucking the fluid in the isolation sleeve 400 into the main channel 130, accelerating the flow of the fluid from the isolation sleeve 400 to the accommodating cavity 110, and increasing the circulation speed of the fluid in the isolation sleeve 400 in the cryogenic pump, which is beneficial to the gas formed by vaporization to be discharged through the liquid outlet end 112.

[0051] In one embodiment, as Figure 7As shown, an inner magnetic cavity 510 is formed by axially recessing the front end of the inner magnetic component 500 close to the middle bearing 100. The rear end of the middle bearing 100 extends into the inner magnetic cavity 510, and the liquid inlet port 131 of the main channel 130 is located in the inner magnetic cavity 510. Among them, a thread groove 160 spirally distributed along the axis is provided on the outer peripheral wall of the part of the middle bearing 100 extending into the inner magnetic cavity 510. When the inner magnetic component 500 rotates driven by the outer magnetic component 600, the fluid located between the thread groove 160 and the cavity wall of the inner magnetic cavity 510 is forced to accelerate and flow into the inner magnetic cavity 510. That is to say, the cooperation of the above-mentioned inner magnetic cavity 510 and the thread groove 160 can accelerate the flow rate of the fluid, which is beneficial to gas discharge.

[0052] Specifically, the middle bearing 100 has a first part located outside the isolation sleeve 400 and a second part extending into the isolation sleeve 400. Among them, the receiving cavity 110 is provided on the first part. A part of the main channel 130 is located on the first part, and the other part is located on the second part. The thread groove 160 is provided on the outer peripheral wall of the rear end of the second part. As Figure 8 and Figure 9 shown, a first step portion 170 and a second step portion 180 are further provided on the outer peripheral wall of the second part. The first step portion 170 cooperates with the convex ring portion 420 at the open end 410 of the isolation sleeve 400 for the installation limit of the isolation sleeve 400, and the second step portion 180 is located inside the isolation sleeve 400.

[0053] The outer diameter of the first step portion 170 is larger than the outer diameter of the second step portion 180. The above-mentioned first step portion 170 and second step portion 180 make the outer diameter of the second part of the middle bearing 100 show a decreasing trend. Thus, the space for liquid nitrogen to flow is in an increasing trend. As Figure 2 、 Figure 7 and Figure 8 shown, the increasing space refers to the space between the first liquid outlet 142 and the front end 511 of the inner magnetic component 500. The increasing space can provide a space for storing liquid nitrogen, which is beneficial to the flow of liquid nitrogen throughout the isolation sleeve 400.

[0054] It should be noted that, as Figure 2 and Figure 5 shown, the second liquid passing channel 150 has a second liquid outlet 151 and a second liquid inlet 152. The second liquid outlet 151 is located on the hole wall of the main channel 130, and the second liquid inlet 152 is located on the outer peripheral wall of the middle bearing. Among them, the second liquid outlet 151 is located between the fan 320 and the front ultra-low temperature bearing 312. That is to say, the second liquid outlet 151 of the second liquid passing channel 150 is located downstream of the fan 320.

[0055] There are two paths for the fluid in the isolation sleeve 400 to enter the main channel 130. One path is that the fluid enters the main channel 130 through the liquid inlet port 131 and the rear ultra-low temperature bearing 311. In this case, the fluid needs to flow through the fan 320. The other path is that part of the fluid in the isolation sleeve 400 flows directly to the downstream of the fan 320 through the second liquid passage 150. In this case, part of the fluid can avoid the fan 320 and enter the main channel 130. Therefore, the pressure on the fan 320 can be effectively reduced, which is very beneficial to the normal operation of the fan 320.

[0056] Furthermore, the second liquid passage 150 is arranged perpendicular to the rotating shaft 300 and is distributed closer to the fan 320 relative to the front ultra-low temperature bearing 312 to shorten the length of the second liquid passage 150 as much as possible, thereby making it easier for the fluid to enter the main channel 130 from the isolation sleeve 400.

[0057] Regarding the axial limit of the rear cryogenic bearing 311, Figure 2 As shown, the rotating shaft 300 is also sleeved with a positioning sleeve 330 located in the inner magnetic cavity 510, the front end of the positioning sleeve 330 abuts against the rear ultra-low temperature bearing 311, and the rear end of the positioning sleeve 330 abuts against the cavity bottom of the inner magnetic cavity 510, and a first step groove 132 that cooperates with the rear ultra-low temperature bearing 311 is formed on the hole wall of the main channel 130. Under the joint action of the above-mentioned positioning sleeve 330 and the first step groove 132, the axial limitation of the rear ultra-low temperature bearing 311 can be achieved. Among them, the positioning sleeve 330 can ensure that there is a predetermined spacing between the rear end of the second part of the middle bearing 100 and the cavity bottom of the inner magnetic cavity 510 in the axial direction to form a buffer zone, which is conducive to the liquid nitrogen in the inner magnetic cavity 510 entering the main channel 130 through the liquid inlet port 131.

[0058] Furthermore, a front bearing mounting structure 800 for limiting the front cryogenic bearing 312 is also provided in the main channel 130. Figures 10 to 12As shown, the front bearing mounting structure 800 includes a bearing ring seat 810 fixedly provided in the main channel 130. The bearing ring seat 810 is provided with a stepped hole axially penetrating therethrough, which makes the bearing ring seat 810 have a first hole portion 811 close to the impeller 120 and a second hole portion 812 farther from the impeller 120 than the first hole portion 811. The front cryogenic bearing 312 is provided in the first hole portion 811. A bearing gland 820 is detachably provided at the front end of the bearing ring seat 810 close to the impeller 120, and the bearing gland 820 abuts against the front end of the front cryogenic bearing 312. Among them, the bearing gland 820 has a gland center hole 821, and a retaining ring 822 is provided at the rear end of the bearing gland 820. The inner diameter of the retaining ring 822 is equal to the aperture of the gland center hole 821 and they are coaxially distributed. The retaining ring 822 abuts against the front cryogenic bearing 312. Thus, the front cryogenic bearing 312 is axially positioned through the bearing ring seat 810 and the bearing gland 820.

[0059] Regarding the axial positioning of the impeller 120, as Figure 13 shown, the impeller 120 includes a sleeve 121 and a wheel portion 122 formed on the outer periphery of the sleeve 121. A plurality of blades 123 are provided on the outer periphery of the wheel portion 122. The thickness of the wheel portion 122 in the axial direction is less than the thickness of the sleeve 121 in the axial direction. After the rear end of the sleeve 121 passes through the gland center hole 821, it abuts against the front end of the front cryogenic bearing 312.

[0060] As Figure 2 shown, a lock washer 340 and a lock nut 350 are further provided at the front end of the rotating shaft 300. The lock washer 340 abuts against the front end of the impeller 120, and the lock nut 350 abuts against the front end of the lock washer 340. Among them, the front cryogenic bearing 312 abuts against the rear end of the impeller 120. Thus, the axial limit of the impeller 120 can be achieved. During use, when it is found that the impeller 120 axially moves, axial locking can be achieved by tightening the lock nut 350, and the adjustment is relatively convenient.

[0061] Furthermore, as Figure 5 shown, the pump cover 200 is provided with an avoidance cavity 210 for receiving the front end of the rotating shaft 300. The avoidance cavity 210 and the receiving cavity 110 enclose to form the pump cavity of the cryogenic pump. The pump cover 200 is further provided with a third liquid passage 220 communicating the avoidance cavity 210 and the receiving cavity 110. The third liquid inlet of the third liquid passage 220 is distributed close to the liquid outlet end 112, and the third liquid outlet of the third liquid passage 220 is distributed lower than the third liquid inlet. Thus, it is beneficial for the liquid nitrogen at the liquid outlet end 112 to quickly enter the avoidance cavity 210. Thus, the liquid nitrogen can flow continuously and quickly in the cryogenic pump to facilitate the discharge of gas to the outside.

[0062] To protect the outer magnetic assembly 600, a bracket 710 is provided on the outer periphery of the outer magnetic assembly 600, as Figure 2As shown, the bracket 710 connects the housing of the motor 700 and the middle bearing 100. The middle bearing 100, the pump cover 200 and the bracket 710 are connected by long bolts 720. After the middle bearing 100, the pump cover 200 and the bracket 710 are connected, the isolation sleeve 400 is pressed by the bracket 710 onto the middle bearing 100, thereby realizing the installation of the isolation sleeve 400.

[0063] As can be seen from the above, there is no need to connect the isolation sleeve 400 and the middle bearing 100 by bolts, which simplifies the structure of the isolation sleeve 400. More importantly, in order to adapt to low-temperature environments, the isolation sleeve 400 is made of ceramic material. Since ceramic material is brittle, its processing difficulty is relatively large. When machining some hole positions, it is easy for the isolation sleeve 400 to break.

[0064] To prevent the liquid nitrogen in the isolation sleeve 400 from leaking out, a sealing structure 900 is provided between the middle bearing 100 and the isolation sleeve 400, as Figure 14 shown. The sealing structure 900 is an annular structure with a sealed space inside. The sealing structure 900 is provided at the first step portion 170. The outer ring of the sealing structure 900 abuts against the inner wall of the bracket 710. A positioning shoulder 711 is also formed on the inner wall of the bracket 710. The positioning shoulder 711 abuts against the rear end of the convex ring portion 420. The convex ring portion 420 abuts against the rear end of the sealing structure 900. The sealing structure 900 abuts against the front end of the convex ring portion 420. The sealing structure 900 is located in the space surrounded by the middle bearing 100, the bracket 710 and the convex ring portion 420.

[0065] A pair of hard rubber rings 930 are provided in the above-mentioned sealed space of the sealing structure 900. An elastic member 940 is provided between the pair of hard rubber rings 930. The elastic member 940 is preferably a spring. The elastic member 940 is used to provide an axial elastic force so that the pair of hard rubber rings 930 respectively abut against the two end portions of the annular structure. Among them, the inner ring wall and the outer ring wall of the sealing structure 900 are made of flexible materials. The inner ring wall and the outer ring wall of the sealing structure 900 can produce elastic deformation when subjected to external forces. After the middle bearing 100 and the bracket 710 are connected, the inner ring wall and the outer ring wall of the sealing structure 900 are axially compressed, and the inner ring wall and the outer ring wall produce a certain deformation in the radial direction, so that the sealing structure 900 can better seal the gap between the middle bearing 100 and the isolation sleeve 400 to prevent liquid nitrogen from leaking out.

[0066] Specifically, the sealing structure 900 includes an outer-layer flexible ring 910, an inner-layer flexible ring 920 provided inside the outer-layer flexible ring 910, a pair of the above-mentioned hard rubber rings 930 provided between the outer-layer flexible ring 910 and the inner-layer flexible ring 920, the above-mentioned elastic member 940 provided between the pair of hard rubber rings 930, and sealing gaskets 950 provided at both ends of the outer-layer flexible ring 910 and the inner-layer flexible ring 920.

[0067] Among them, the outer flexible ring 910 is the outer ring wall of the above-mentioned sealing structure 900, and the inner flexible ring 920 is the inner ring wall of the above-mentioned sealing structure 900. The outer flexible ring 910 and the inner flexible ring 920 can generate elastic deformation when subjected to external forces. The two ends of the outer flexible ring 910 and the inner flexible ring 920 are evenly distributed. There are a pair of sealing gaskets 950, which are respectively arranged at the two ends of the outer flexible ring 910 and the inner flexible ring 920 by means of adhesion.

[0068] The outer flexible ring 910 and the inner flexible ring 920 are coaxially distributed. There is a space between the outer ring of the inner flexible ring 920 and the inner ring of the outer flexible ring 910. The sealing gasket 950, the outer flexible ring 910 and the inner flexible ring 920 together enclose the above-mentioned closed space. A pair of hard rubber rings 930 are sleeved on the outer periphery of the inner flexible ring 920 and are located in the closed space. The pair of hard rubber rings 930 are spaced apart axially. The elastic member 940 is abutted between the pair of hard rubber rings 930, and the hard rubber ring 930 abuts against the sealing gasket 950. The elastic member 940 enables the two ends of the sealing structure 900 to be respectively abutted against the middle bearing 100 and the spacer sleeve 400, thereby ensuring the sealing performance of the sealing structure 900.

[0069] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structures made by using the description and drawings of the present invention, directly or indirectly applied in other related technical fields, are equally included in the patent protection scope of the present invention.

Claims

1. A cryogenic pump, characterized in that: include: A middle support (100) is formed with a receiving cavity (110), wherein the receiving cavity (110) is formed with a first opening at the front end of the middle support (100), an impeller (120) is received in the receiving cavity (110), and the middle support (100) has a liquid inlet end (111) and a liquid outlet end (112) which are in communication with the receiving cavity (110); A pump cover (200), wherein the sealing cover is arranged at the first opening; An isolation sleeve (400) is arranged at a rear end of the middle support (100) away from the pump cover (200); A rotating shaft (300) is arranged on the middle bearing (100) via a pair of ultra-low temperature bearings (310); the middle bearing (100) is provided with a main channel (130) communicating with the receiving cavity (110) and the isolation sleeve (400); the pair of ultra-low temperature bearings (310) are located in the main channel (130); and the front end of the rotating shaft (300) is connected to the impeller (120); a fan (320) disposed on the rotating shaft (300) and rotating together with the rotating shaft (300), wherein the fan (320) is located between the pair of ultra-low temperature bearings (310); An internal magnetic component (500) is accommodated in the isolation sleeve (400), and the rear end of the rotating shaft (300) is connected to the internal magnetic component (500); An external magnetic component (600) is arranged on the outer periphery of the isolation sleeve (400) and is connected to the motor (700); The fan (320) is configured to suck the fluid in the isolation sleeve (400) into the main channel (130) during rotation, and the middle support (100) is provided with a first liquid passage (140) and a second liquid passage (150), wherein the first liquid passage (140) connects the receiving cavity (110) and the isolation sleeve (400), and the second liquid passage (150) connects the main channel (130) and the isolation sleeve (400).

2. The cryopump according to claim 1, wherein: The front end of the inner magnetic component (500) close to the middle support (100) is axially recessed to form an inner magnetic cavity (510); the rear end of the middle support (100) extends into the inner magnetic cavity (510); and the liquid inlet port (131) of the main channel (130) is located in the inner magnetic cavity (510); The outer peripheral wall of the portion of the middle bearing (100) extending into the inner magnetic cavity (510) is provided with a thread groove (160) distributed in an axial spiral, and when the inner magnetic component (500) rotates driven by the outer magnetic component (600), the fluid between the thread groove (160) and the cavity wall of the inner magnetic cavity (510) is forced to flow into the inner magnetic cavity (510) at an accelerated speed.

3. The cryopump according to claim 2, wherein: The rotating shaft (300) is also sleeved with a positioning sleeve (330) located in the inner magnetic concave cavity (510), the front end of the positioning sleeve (330) abuts against a rear ultra-low temperature bearing (311) of the pair of ultra-low temperature bearings (310) which is located away from the impeller (120), and the rear end of the positioning sleeve (330) abuts against the bottom of the inner magnetic concave cavity (510); Wherein, a first step groove (132) that cooperates with the rear ultra-low temperature bearing (311) is formed on the hole wall of the main channel (130).

4. The cryopump according to claim 1, wherein: The bearing on the side of the pair of ultra-low temperature bearings (310) closer to the impeller (120) is a front ultra-low temperature bearing (312), and a front bearing mounting structure (800) for limiting the position of the front ultra-low temperature bearing (312) is also provided in the main channel (130); The front bearing mounting structure (800) comprises a bearing ring seat (810) fixedly arranged in the main channel (130), the bearing ring seat (810) being provided with a step hole penetrating the bearing ring seat (810) in the axial direction, the step hole enabling the bearing ring seat (810) to have a first hole portion close to the impeller (120) and a second hole portion farther from the impeller (120) than the first hole portion, the front ultra-low temperature bearing (312) being arranged in the first hole portion, the front end of the bearing ring seat (810) close to the impeller (120) being detachably provided with a bearing pressure cover (820), the bearing pressure cover (820) being in abutment with the front end of the front ultra-low temperature bearing (312); The bearing gland (820) has a gland center hole (821), the impeller (120) comprises a sleeve (121), and a wheel portion (122) formed on the outer periphery of the sleeve (121), a plurality of blades (123) are provided on the outer periphery of the wheel portion (122), the axial thickness of the wheel portion (122) is smaller than the axial thickness of the sleeve (121), and the rear end of the sleeve (121) abuts against the front end of the front ultra-low temperature bearing (312) after passing through the gland center hole (821).

5. The cryopump according to claim 1, wherein: The second liquid passage (150) has a second liquid outlet (151), and the second liquid outlet (151) is located on the hole wall of the main channel (130), wherein the second liquid outlet (151) is located between the fan (320) and a front ultra-low temperature bearing (312) of the pair of ultra-low temperature bearings (310) close to the impeller (120).

6. The cryopump according to claim 1, wherein: The first liquid passage (140) is arranged obliquely relative to the rotating shaft (300), and the first liquid passage (140) has a first liquid inlet (141) and a first liquid outlet (142), wherein the first liquid inlet (141) is formed on the cavity wall of the receiving cavity (110) and is distributed close to the liquid outlet end (112), wherein the first liquid outlet (142) is distributed lower than the first liquid inlet (141).

7. The cryopump according to claim 1, wherein: The outer diameter of the portion of the center bearing (100) located inside the isolation sleeve (400) is in a decreasing state.

8. The cryopump according to claim 1, wherein: The pump cover (200) is provided with an avoidance cavity (210) for accommodating the front end of the rotating shaft (300), and the avoidance cavity (210) and the accommodating cavity (110) are surrounded to form a pump cavity of the cryopump; The pump cover (200) is further provided with a third liquid passage (220) connecting the avoidance chamber (210) and the receiving chamber (110); a third liquid inlet of the third liquid passage (220) is arranged close to the liquid outlet end (112); and a third liquid outlet of the third liquid passage (220) is arranged lower than the third liquid inlet.

9. The cryopump according to claim 1, wherein: The front end of the rotating shaft (300) is also provided with an anti-loosening gasket (340) and an anti-loosening nut (350), wherein the anti-loosening gasket (340) abuts against the front end of the impeller (120), and the anti-loosening nut (350) abuts against the front end of the anti-loosening gasket (340), wherein the front ultra-low temperature bearing (312) of the pair of ultra-low temperature bearings (310) abuts against the rear end of the impeller (120).

10. The cryopump according to claim 1, wherein: A bracket (710) is provided on the outer periphery of the external magnetic assembly (600), and the bracket (710) is connected to the outer shell of the motor (700) and the middle bearing (100), wherein after the bracket (710) is connected to the middle bearing (100), the isolation sleeve (400) is pressed onto the middle bearing (100); A sealing structure (900) is provided between the center bearing (100) and the isolation sleeve (400); the sealing structure (900) is an annular structure having a sealed space inside; a pair of hard rubber rings (930) are provided in the sealed space; an elastic member (940) is provided between the pair of hard rubber rings (930); the elastic member (940) is configured to provide an elastic force in the axial direction so that the pair of hard rubber rings (930) are respectively in contact with two ends of the annular structure; The inner ring wall and the outer ring wall of the sealing structure (900) are made of a flexible material, and the inner ring wall and the outer ring wall of the sealing structure (900) are capable of elastic deformation when subjected to an external force.

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