CN217908610U

CN217908610U - Moving magnet external drive type left ventricular blood pump for pumping blood by fluctuation

Info

Publication number: CN217908610U
Application number: CN202220296538.1U
Authority: CN
Inventors: 胡盛寿; 柳光茂; 吕燊
Original assignee: Fuwai Hospital of CAMS and PUMC
Current assignee: Fuwai Hospital of CAMS and PUMC
Priority date: 2022-02-14
Filing date: 2022-02-14
Publication date: 2022-11-29
Anticipated expiration: 2032-02-14

Abstract

The utility model discloses a undulant pump sending blood left ventricle blood pump of moving magnetism external drive formula, which comprises an upper and lower pump body lock forms, it is equipped with the blood inlet pipe to go up pump body top, pump body bottom is equipped with the blood outlet pipe down, blood inlet pipe and blood outlet pipe are relative and blood inlet pipe diameter is greater than blood outlet pipe diameter from top to bottom, unsettled flexible membrane subassembly that is equipped with between a pump body inner chamber internal fixation water conservancy diversion dish and the blood outlet pipe, the blood inlet pipe overcoat of going up the pump body is equipped with the moving magnetism driver, the flexible membrane subassembly is connected with the moving magnetism driver through the linkage post that passes the pump body. Under the action of the alternating magnetic field of the moving magnetic driver, the flexible membrane of the flexible membrane component is driven by the linkage column to oscillate up and down, and meanwhile, the flexible membrane generates wave motion along the radial direction of the flexible membrane so as to pump blood from the blood inlet pipe to the blood outlet pipe. The utility model discloses an effect of undulant pump sending blood can reduce complications such as hemolysis, thrombus and take place the risk, improves blood compatibility etc..

Description

Dynamic magnetic external drive type left ventricle blood pump capable of pumping blood by fluctuation

Technical Field

The utility model relates to a move undulant pump sending blood left ventricle blood pump of magnetism external drive formula belongs to ventricle blood pump technical field.

Background

In recent years, ventricular assist devices have played an increasingly important role in the treatment of end-stage heart failure, mainly left ventricular assist devices. The core component of the left ventricle auxiliary device is a left ventricle blood pump, and the existing mature left ventricle blood pump mainly comprises two types, namely an axial flow type and a magnetic suspension centrifugal type. The two left ventricular blood pumps adopt a mechanical rotation principle, and rely on a rotor rotating at a high speed to do work on blood to convert rotation mechanical energy into pressure potential energy on the blood, so that a blood pumping effect is generated. In practical use, it can be found that long-term use of the left ventricular blood pump can cause various complications, such as organ inflammation, gastrointestinal bleeding, aortic valve regurgitation and other complications caused by blood flow loss pulsatility in patients, and even increase the death rate of patients in severe cases. In addition, long-term use causes hemocompatibility problems such as hemolysis and thrombosis. Therefore, the design of the ventricular blood pump capable of well solving the problems is a problem which is urgently needed to be solved at present.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a undulant pump sending blood left ventricle blood pump of moving magnet external drive formula, it has realized the effect of undulant pump sending to blood, has the characteristics such as can reduce complications such as hemolysis, thrombus and take place the risk, improve blood compatibility.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a dynamic magnetic external drive type left ventricular blood pump for pumping blood by fluctuation is characterized in that: it includes the pump body that the lock formed about the last pump body and the lower pump body, the top of going up the pump body is equipped with the blood inlet pipe, the bottom of the lower pump body is equipped with the blood outlet pipe, the blood inlet pipe is relative about with the blood outlet pipe and the pipe diameter of blood inlet pipe is greater than the pipe diameter of blood outlet pipe, an inner chamber fixed mounting flow guide disc of the pump body and unsettled flexible membrane subassembly that is equipped with between flow guide disc and blood outlet pipe, the outside cover of the blood inlet pipe of going up the pump body is equipped with the moving magnet driver, the flexible membrane subassembly is connected with the moving magnet driver through the interlock post that passes the setting of the last pump body, wherein: under the action of an alternating magnetic field generated by the moving magnetic driver, the flexible membrane of the flexible membrane component is driven by the linkage column to do up-and-down oscillating motion, and simultaneously, the flexible membrane generates wave motion along the radial direction of the flexible membrane so as to pump the blood flowing in from the blood inlet pipe to the blood outlet pipe to flow out.

The utility model has the advantages that:

the utility model discloses can turn into the pressure potential energy to blood with the deformation of flexible membrane, the effect of undulant pumping has been realized to blood, on the one hand make the mobile production of blood have the pulsatility of physiological characteristics, promote the perfusion effect of blood to whole body organ, on the other hand, the flexible membrane motion that rigidity is little is soft, compare with existing left ventricle blood pump, shear stress to blood production is little a lot, and the flexible membrane does not exist rotatoryly, therefore high rotational speed has effectively been avoided at the in-process of pumping blood, the production of non-physiological flow characteristics such as high shear force, the hemolysis has been reduced, the emergence risk of complications such as thrombus. Additionally, the utility model discloses a structural design has improved blood compatibility, and moves the magnetic drive ware and can guarantee reliable powerful driving performance, provides the guarantee for the stable fluctuation of flexible membrane.

Drawings

Fig. 1 is a schematic structural diagram of the left ventricular blood pump of the present invention.

FIG. 2 is a schematic perspective view of a flexible membrane assembly.

Fig. 3 is a perspective view of the metal ring.

Fig. 4 is a schematic perspective sectional view of the pump body with the diaphragm and the leaf spring mounted thereon.

Fig. 5 is a perspective view of the upper pump body with the diaphragm and the leaf spring installed.

Fig. 6 is a perspective view of the lower pump body.

Fig. 7 is a schematic perspective view of the upper pump body with the diaphragm, leaf springs and flexible membrane assembly installed.

FIG. 8 is a schematic diagram of a moving magnet drive configuration.

Fig. 9 is a schematic view of the structure of the housing.

Fig. 10 is a schematic view of the flexible membrane of the present invention in a wave state.

Detailed Description

As shown in fig. 1 to fig. 10, the utility model discloses the fluctuating pumping blood left ventricle blood pump of moving magnet external drive formula includes the pump body 30 that is formed by last pump body 31 and lower pump body 32 lock from top to bottom, the top of going up the pump body 31 is equipped with blood inlet pipe 310, the bottom of lower pump body 32 is equipped with blood outlet pipe 320, the blood inlet pipe 310 of going up the pump body 31 should be relative from top to bottom with the blood outlet pipe 320 of lower pump body 32, and the pipe diameter of blood inlet pipe 310 should be greater than the pipe diameter of blood outlet pipe 320, so that blood flows, a baffle 50 of fixed mounting in the inner chamber of pump body 30 and the unsettled flexible membrane module 10 that is equipped with in the narrow flow path 80 that forms between baffle 50 and blood outlet pipe 320, the overcoat of the blood inlet pipe 310 of going up the pump body 31 is equipped with the moving magnet driver 70, the flexible membrane module 10 is connected with the moving magnet driver 70 through the linkage post 40 that passes the setting of the pump body 31, wherein: under the action of the alternating magnetic field generated by the moving magnetic driver 70, the flexible membrane 11 of the flexible membrane module 10 is driven by the linkage column 40 to make up-and-down oscillatory motion in the narrow flow channel 80, and at the same time, the flexible membrane 11 generates wave motion along the radial direction of the flexible membrane 11, that is, the flexible membrane 11 generates an effect similar to flapping of a fin of a fishtail, and then under the wave-like pushing action of the flexible membrane 11, the blood flowing in the blood inlet pipe 310 is pumped to the blood outlet pipe 320 by wave pumping, so that the effect of pumping blood by wave pumping is achieved.

As shown in fig. 2 and 3, the flexible membrane module 10 includes a circular flexible membrane 11 having elasticity, the flexible membrane 11 is provided with a diversion port 110 at the center, the diameter of the diversion port 110 is equal to or close to the inner diameter of the blood outlet pipe 320 to facilitate the outflow of blood, a metal ring 12 is embedded in the circumferential edge of the flexible membrane 11, the metal connecting seat 121 for connecting with the actuating post 40 is provided on the metal ring 12, the metal connecting seat 121 extends out of the flexible membrane 11, and at the same time, the side wall of the metal connecting seat 121 is wrapped by the extending flexible membrane 11 (see the part indicated by reference numeral 113 in fig. 2), in other words, the metal connecting seat 121 only exposes the end surface thereof for connecting with the actuating post 40.

Generally, the metal connecting seats 121 are uniformly distributed on the metal ring 12 along the circumference, the number of the metal connecting seats 121 can be reasonably designed according to actual conditions, and fig. 3 shows a situation that 3 metal connecting seats 121 are designed.

In the present invention, the diversion opening 110 is used to better distribute the blood on the upper and lower surfaces of the flexible membrane 11 when the blood flows through the flexible membrane 11.

The utility model discloses in, the effect of becket 12 lies in can strengthening flexible membrane 11 self circumference edge part and carry out reciprocating motion's effect, is favorable to promoting the pressure to blood.

As shown in fig. 2, the peripheral edge portion (i.e., the inclined region 112 shown in fig. 2) of the embedded metal ring 12 of the flexible film 11 is thicker outside and thinner inside, and the remaining portion (i.e., the horizontal region 111 shown in fig. 2) of the embedded metal ring 12 of the flexible film 11 has a uniform thickness twice that of the metal ring 12, wherein: when the flexible membrane 11 is located in the narrow flow channel 80, a gap is left between the flexible membrane 11 and the lower end surface of the deflector 50, and between the flexible membrane 11 and the inner end surface of the lower pump body 32; the metal ring 12 with the metal connection socket 121 is injection molded integrally with the flexible membrane 11.

In a practical design, for example, the flexible membrane 11 may be designed such that the horizontal region 111 has a thickness of 0.5mm to 1mm, the inclined region 112 has a thickness increasing from the inside to the outside, and the final circumferential rim has a thickness of 1mm to 1.5mm.

In practical design, the clearance between the flexible membrane 11 and the diaphragm 50 and the lower pump body 32 is designed to be about 1mm. In addition, a gap 81 should be left between the flexible membrane 11 and the inner side wall of the upper pump body 31, and the gap 81 should be smaller than 1mm, so as to greatly reduce the phenomenon that blood flows back, flows back or swirls.

The utility model discloses in, flexible membrane 11 is made for organosilicon or polyurethane combined material, has the characteristics that rigidity is little, density is low, and this kind of elasticity characteristics of flexible membrane 11 can be stored deformation energy and release again when taking place the large deformation, turn into the pressure potential energy to blood. In practice, the material of the flexible film 11 is not limited as long as it can generate a large deformation wave effect along its radial direction under the combined action of the oscillating force, the fluid force, and the like.

The utility model discloses in, becket 12 and metal connecting seat 121 thereon make for the titanium alloy material, because becket 12's rigidity, hardness all are greater than flexible membrane 11, consequently, the centre of a circle department of flexible membrane 11 can produce the effect of similar piston acting to blood, has reinforceed the mobility of blood near flexible membrane 11, has played the effect that blood transmitted smoothly to and effectively erode the runner, reduce the effect that the thrombus produced.

As shown in fig. 1, a guiding cone 51 similar to a cone is disposed on an end surface of the guiding disc 50 facing the flexible film 11, and the guiding cone 51 is disposed opposite to the guiding opening 110 and the blood outlet tube 320 on the flexible film 11. As shown in fig. 4, the baffle 50 has a structure that is convex in the middle and gradually decreases in thickness radially outward, so that the design can promote the blood flow and further reduce the possibility of the blood generating a vortex.

As shown in fig. 1, a platform 321 is convexly disposed on an inner end surface of the lower pump body 32, a cross-sectional area of the platform 321 is equal to or approximately equal to a cross-sectional area of the diversion disc 50, a flow channel 80 with a thin middle part and a thick periphery is formed between the platform 321 and the diversion disc 50, that is, the flow channel 80 has a structure in which a central space is the smallest and a space is gradually expanded outward along a radial direction thereof, which is beneficial for the flexible membrane 11 to be closer to the surfaces of the platform 321 and the diversion disc 50 when performing an oscillating motion and a wave motion in a radial direction thereof, so that a "blood bag" beneficial for outward blood transportation can be formed, and a backflow phenomenon is reduced, further, an annular groove 322 with a certain depth is formed between the platform 321 and an inner side wall of the lower pump body 32, the annular groove 322 is disposed opposite to the metal ring 12 of the flexible membrane assembly 10, so that when the flexible membrane 11 performs an up-and-down oscillating motion, the horizontal region 111 of the flexible membrane 11 can generate a certain compression effect on blood in the annular groove 322, which is similar to a process of a piston doing work, thereby greatly increasing blood pressure and being capable of helping blood flow smoothly.

As shown in fig. 1 and 8, the moving magnet driver 70 includes a cylindrical inner yoke 74 sleeved outside the blood inlet tube 310 of the upper pump body 31, the inner yoke 74 is used for enhancing magnetic field strength, an iron cylindrical mounting bracket 75 used for connecting with the linkage column 40 is movably sleeved on an outer circumferential side wall of the inner yoke 74, the mounting bracket 75 is used for enhancing driving force and induction strength, a plurality of annular permanent magnets 76 (fig. 8 shows a situation that 3 permanent magnets 76 are embedded vertically) are embedded on a side wall of the mounting bracket 75, magnetic poles of the vertically adjacent permanent magnets 76 are opposite, for example, magnetic poles of the vertically adjacent permanent magnets 76 of the permanent magnets 76 with N magnetic poles are S, a cylindrical stator core 71 is arranged around the permanent magnets 76, the stator core 71 is used for enhancing induction strength, two wire slots 710 are formed on the inner side of the stator core 71 facing the permanent magnets 76, of course, the number of the wire slots 710 is not limited, a magnet 72 is wound in each wire slot 710, and a gap is formed between the stator core 71 wound with a magnet coil 72 and the mounting bracket 75 embedded with a magnet 76, and the magnet coil 76, and the gap should be less than 1mm.

Further, the stator core 71 is formed by vertically splicing an upper annular cover-shaped core 711, an annular middle core 712 and a lower annular cover-shaped core 713, and a slot 710 is formed between the middle core 712 and the upper and

lower cores

711 and 713, respectively, wherein: after the electromagnetic coil 72 is wound in the wire groove 710, the electromagnetic coil 72 is covered by the coil cover 73 made of non-magnetic conducting materials (such as titanium alloy materials and other well-known materials), and the coil cover 73 not only can play a role in restraining and fixing the electromagnetic coil 72 to move, but also can reduce the possibility that the electromagnetic coil 72 made of copper wires is contacted with blood, thereby avoiding causing the problem of blood compatibility.

In practical manufacturing, the electromagnetic coil 72, the permanent magnet 76 and the inner yoke 74 should be designed coaxially to reduce the problem of stroke deviation caused by non-uniform magnetic field density.

The utility model discloses in, moving magnetic driver 70 has the stroke short, the response is fast, efficient, small and the characteristics that thrust is big, when actually implementing, when letting in change electric current to solenoid 72 and forming alternating magnetic field, alternating magnetic field produces attraction and repulsion respectively to the permanent magnet 76 of N, S magnetic pole polarity, then under alternating magnetic field' S effect, permanent magnet 76 is the up-and-down oscillatory motion along interior yoke 74 with mounting bracket 75 together to via linking post 40 drive flexible membrane module 10 and do the up-and-down oscillatory motion with frequency, with the amplitude together.

As shown in fig. 1 and 9, the outer cover of the moving magnet actuator 70 is provided with an outer cover 60, the outer cover 60 covers the moving magnet actuator 70 and the connection portion between the upper pump body 31 and the lower pump body 32, the outer cover 60 extends to be flush with the lower end surface of the lower pump body 32 and then is welded to the lower pump body 32 to enhance the sealing performance between the upper pump body 31 and the lower pump body 32, wherein:

an outer boss 311 is arranged on the periphery of the upper pump body 31 around the blood inlet pipe 310, an inner boss 61 is arranged in the outer cover 60 opposite to the outer boss 311, an inner yoke 74 is sleeved and fixed on the circumferential side walls of the outer boss 311 and the inner boss 61, and a stator core 71 wound with an electromagnetic coil 72 and a mounting frame 75 embedded with a permanent magnet 76 are positioned in an annular cavity 64 formed between the outer cover 60 and the upper pump body 31; the fastening screw 65 passes through the screw hole 63 of the inner boss 61 and then is screwed into the screw hole 312 of the outer boss 311, so that the outer cover 60 is screwed and fixed to the upper pump body 31 by the fastening screw 65. As shown in fig. 9, the housing 60 has an opening 62 corresponding to the blood inlet tube 310 for the blood inlet tube 310 to pass through.

The cable connected to the electromagnetic coil 72 is led out to the outside through the stator core 71 and the cover 60 and connected to the relevant power supply device.

As shown in fig. 1, 4, 5 and 7, the diversion disc 50 is fixed to the upper pump body 31 by a plurality of fixed beams 33, and a plate spring 34 is disposed in each fixed beam 33 and penetrates through the fixed beams 33 together, wherein: the plate spring 34 comprises an annular belt part 341 for passing through the fixed beam 33, the belt part 341 is provided with an elastically deformable annular limiting part 340, and the limiting part 340 is positioned outside the fixed beam 33; after the limiting portion 340 is sleeved on the linking column 40, one side of the limiting portion 340 is fixedly connected with the convex ring 41 on the linking column 40.

Fig. 5 shows the case of designing 3 fixed beams 33 evenly distributed along the axis of the upper pump body 31, the number of the fixed beams 33 is not limited, but too much increases the resistance to the flow of blood.

In the present invention, the plate spring 34 is made of a well-known metal material with elasticity, and the limiting portion 340 is used to limit the amplitude of the up-and-down oscillation of the linking column 40.

The utility model discloses a design has 3 condition of interlocking post 40, spiro union between the metal connecting seat 121 of interlocking post 40 and flexible membrane module 10, fixed connection (like the spiro union etc.) between interlocking post 40 and the mounting bracket 75.

In practice, the diameter of the hole through the upper pump body 31 for the interlock post 40 should be as small as possible to reduce the likelihood of blood flow through the hole.

As shown in fig. 4, the upper pump body 31 and the lower pump body 32 are both of an axisymmetrical structure, the upper pump body 31 and the lower pump body 32 are assembled together in a manner of screwing the internal thread and the external thread, and the coaxiality of the upper pump body and the lower pump body should be ensured when the upper pump body and the lower pump body are fastened and installed.

The utility model discloses in, the parts that need contact with blood such as the upper pump body 31, the lower pump body 32, linkage post 40, flow guide plate 50 all should be made for the titanium alloy material that has good blood compatibility to improve blood compatibility.

In use, blood inlet tube 310 is used to connect to the left ventricular apex and blood outlet tube 320 is connected to the aorta via a graft. The electromagnetic coil 72 is energized with a changing current to form an alternating magnetic field, and the alternating magnetic field generates attraction and repulsion on the permanent magnets 76 with different magnetic poles of N and S, so that the permanent magnets 76 and the mounting frame 75 make oscillating motion on the inner magnetic yoke 74 under the action of the alternating magnetic field, and then the flexible membrane 11 is driven by the linking column 40 and the metal ring 12 (or the metal connecting seat 121) to make oscillating motion with the same frequency and amplitude (the oscillation amplitude is about 1 mm) in the narrow flow channel 80. Therefore, the flexible membrane 11 generates wave motion along its radial direction while performing oscillation motion, similar to the flapping effect of the fin on the tail of a fish, so that the flexible membrane 11 converts the deformation energy generated by the flexible membrane into pressure potential energy for blood, and the blood flowing into the blood inlet pipe 310 is pumped to the blood outlet pipe 320 by the wave motion of the flexible membrane 11 and the flow guide effect of the flow guide cone 51 and the flow guide opening 110.

The above description is the preferred embodiment of the present invention and the technical principle applied by the preferred embodiment, and for those skilled in the art, without departing from the spirit and scope of the present invention, any obvious changes based on the equivalent transformation, simple replacement, etc. of the technical solution of the present invention all belong to the protection scope of the present invention.

Claims

1. A moving-magnet external-drive type blood left ventricular blood pump capable of pumping blood through fluctuation is characterized in that: it includes the pump body that the lock formed about the last pump body and the lower pump body, the top of going up the pump body is equipped with the blood inlet pipe, the bottom of the lower pump body is equipped with the blood outlet pipe, the blood inlet pipe is relative about with the blood outlet pipe and the pipe diameter of blood inlet pipe is greater than the pipe diameter of blood outlet pipe, an inner chamber fixed mounting flow guide disc of the pump body and unsettled flexible membrane subassembly that is equipped with between flow guide disc and blood outlet pipe, the outside cover of the blood inlet pipe of going up the pump body is equipped with the moving magnet driver, the flexible membrane subassembly is connected with the moving magnet driver through the interlock post that passes the setting of the last pump body, wherein: under the action of an alternating magnetic field generated by the moving magnetic driver, the flexible membrane of the flexible membrane component is driven by the linkage column to do up-and-down oscillating motion, and meanwhile, the flexible membrane generates wave motion along the radial direction of the flexible membrane so as to pump blood flowing in from the blood inlet pipe to the blood outlet pipe and flow out.

2. The dynamic-magnetic externally-driven wave-pumping blood left ventricular blood pump of claim 1, wherein:

the flexible membrane subassembly includes circular flexible membrane, and the center of flexible membrane is equipped with a water conservancy diversion mouth, and the diameter of water conservancy diversion mouth equals the internal diameter of blood outlet pipe, the circumference border of flexible membrane is embedded to have a becket, be equipped with on the becket be used for with the metal connecting seat of linkage column connection, when metal connecting seat stretches out the flexible membrane, the lateral wall of metal connecting seat is wrapped up by the flexible membrane of extension.

3. The dynamic-magnetic externally-driven wave-pumping blood left ventricular blood pump of claim 2, wherein:

the peripheral edge part of the flexible membrane embedded with the metal ring is thick outside and thin inside, and the thickness of the rest part is uniform and twice of the thickness of the metal ring, wherein: the metal ring with the metal connecting seat and the flexible membrane are integrally formed in an injection molding mode.

4. The dynamic-magnetic externally-driven wave-pumping blood left ventricular blood pump of claim 2, wherein:

the end face of the flow guide disc, which faces the flexible film, is provided with a flow guide cone, and the flow guide cone is arranged opposite to the flow guide opening and the blood outlet pipe on the flexible film.

5. The dynamic-magnetic externally-driven wave pumping blood left ventricular blood pump of claim 4, wherein:

the inner end face of the lower pump body is convexly provided with a platform, an annular groove is formed between the platform and the inner side wall of the lower pump body, and the annular groove is opposite to the metal ring of the flexible membrane assembly.

6. The dynamic-magnetic externally-driven wave-pumping blood left ventricular blood pump of claim 2, wherein:

move the magnetic drive and establish including the cover go up the pump body go up the outer tube-shape inner yoke of blood inlet pipe, the outer circumference lateral wall of inner yoke on the activity overlap be equipped with be used for with the tube-shape mounting bracket that the linkage post is connected inlays on the lateral wall of mounting bracket and is equipped with a plurality of annular permanent magnets, magnetic pole polarity between the upper and lower adjacent permanent magnet is opposite, a tube-shape stator core around the permanent magnet setting, stator core is formed with two wire casings towards the inboard of permanent magnet, the winding has solenoid in each wire casing, the winding has the stator core of solenoid and inlays to have the clearance that is less than 1mm between the mounting bracket that is equipped with the permanent magnet.

7. The dynamic-magnetic externally-driven wave-pumping blood left ventricular blood pump of claim 6, wherein:

stator core forms by the last iron core of annular lid form, annular middle iron core and the lower iron core of annular lid form concatenation from top to bottom, and middle iron core and last iron core, down form one between the iron core respectively the wire casing, wherein: when the electromagnetic coil is wound in the wire slot, the electromagnetic coil is covered by the coil cover.

8. The dynamic-magnetic externally-driven wave pumping blood left ventricular blood pump of claim 6, wherein:

the outer mask of the movable magnetic driver is provided with an outer cover, the outer cover covers the movable magnetic driver and the connecting part between the upper pump body and the lower pump body, wherein:

the periphery of the upper pump body is provided with an outer boss around the blood inlet pipe, an inner boss is arranged in the outer cover opposite to the outer boss, and the inner yoke is sleeved and fixed on the circumferential side walls of the outer boss and the inner boss; the fastening screw penetrates through the screw hole on the inner boss and then is in threaded connection with the screw hole on the outer boss, so that the outer cover is in threaded connection and fixation with the upper pump body through the fastening screw.

9. The dynamic-magnetic externally-driven wave pumping blood left ventricular blood pump of claim 2, wherein:

the flow guide disc is fixed with the upper pump body through a plurality of fixed beams, and a plate spring is arranged in each fixed beam in a penetrating mode, wherein: the plate spring comprises an annular belt part which is used for penetrating through the fixed beam, the belt part is provided with an annular limiting part which can elastically deform, and the limiting part is positioned outside the fixed beam; after the limiting part is sleeved on the linkage column, one side of the limiting part is fixedly connected with the convex ring on the linkage column.