Low temperature major diameter magnetic fluid seal device
Technical field
The invention belongs to the mechanical engineering technical field of sealing technology, be specially adapted in the fields such as military project, boats and ships, navigation, space flight and aviation temperature under-40 ℃, the sealing diameter of axle is greater than vacuum seal or the positive seal of 160mm.
Background technique
Magnetic liquid is to follow development in science and technology and a kind of new function material of occurring, has the magnetisable performance of magnetic material and the mobile performance of liquid.Since when the dynamic seal (packing) of the handkerchief skin sixties slow (Papell), at first preparing and used magnetic liquid at the research suit, it has obtained day and night deep research in short 30 years of development courses, and be widely applied to various fields such as machinery, electronics, aviation, medicine, wherein use and to count the magnetic liquid rotation axis seal than ripe, many companies have produced product, in these products, the diameter of seal shaft is 5~40mm, and seal temperature is between 0~20 ℃.But in the reality, require the magnetic liquid long-term work under-40 ℃, and require the sealing diameter of axle to reach 160mm at some special dimension.Under this temperature, the viscosity of magnetic liquid will change a lot, and it is big to add the diameter of axle, make the running shaft starting torque too big so that usually destroy power-driven system, so the moment of torsion when reducing to start just becomes the problem that presses for solution as far as possible.
Summary of the invention
Technical problem to be solved by this invention is, the method of existing magnetic fluid sealing can not be applicable to low temperature major diameter condition, therefore, provides a kind of low temperature major diameter magnetic fluid seal device, make that the large diameter seals driving torque drops to 3kgm from 7kgm under the cryogenic conditions, satisfy actual demand.
Technological scheme of the present invention: the physical parameter that designs magnetic liquid sealing structure and selection magnetic liquid according to low temperature, major diameter condition.
Low temperature major diameter magnetic fluid seal device comprises: little end cap, bearing, pole shoe, overcoat, axle sleeve, permanent magnet, magnetic liquid, rubber seal, adjusting pad, big end cap, screw.Earlier rubber seal is embedded in the pole shoe during installation, then bearing, pole shoe, permanent magnet, pole shoe, bearing successively near overcoat inner convex platform right side; After magnetic liquid injected sealing tooth on the axle sleeve equably, the bearing that has installed above packing into, pole shoe, permanent magnet, pole shoe, bearing inside, with screw little end cap is fixed on the axle sleeve, then will regulate pad and be contained in the bearing right side successively with big end cap, at last with continuous overcoat of screw and big end cap, compress mutually between so little end cap, bearing, pole shoe, permanent magnet, pole shoe, bearing, adjusting pad, the big end cap, make the seal arrangement axial restraint.Thereby magnetic liquid is adsorbed under the effect in magnetic field in the gap of sealing tooth, forms reliable sealing.
Use the base load liquid of magnetic liquid to select high-quality burning oil or silicate lipid or two lipids for use among the present invention, they still have good flowability in the time of-40 ℃, and the particle diameter of magnetic-particle satisfies low temperature and uses less than 5nm in the magnetic liquid.
The invention has the beneficial effects as follows, because axle sleeve is provided with the tooth profile parameter of sealing tooth and optimization, the particle diameter of selecting the base load liquid of high-quality burning oil or silicate lipid or two lipids and magnetic-particle for use is less than 5nm, major diameter magnetic fluid sealing when having realized-40 ℃, driving torque is reduced, and leak-down rate is lower than 10
-11Palm
3/ s, long service life, and also assembly method is simple, has overcome the drawback of original sealing.
Description of drawings
Fig. 1 low temperature major diameter magnetic fluid seal device structural drawing
The axle sleeve sectional drawing of Fig. 2 low temperature major diameter magnetic fluid seal device
Seal groove A, B partial structurtes enlarged view on Fig. 3 axle sleeve
The axle sleeve left view of Fig. 4 low temperature major diameter magnetic fluid seal device
Among the figure: small end lid 1, bearing 2, pole shoe 3, overcoat 4, permanent magnet 5, pole shoe 6, bearing 7, adjusting pad 8, big end cap 9, axle sleeve 10, seal groove 11, magnetic liquid 12, tapped hole 13, screw 14, rubber seal 15, through hole 16, tapped hole 17, seal groove 18, screw 19, sealing tooth 20
Embodiment
With the accompanying drawing is that the invention will be further described for embodiment:
Low temperature major diameter magnetic fluid seal device comprises: small end lid 1, bearing 2, pole shoe 3, overcoat 4, axle sleeve 10, bearing 7, pole shoe 6, permanent magnet 5, magnetic liquid 12, rubber seal 15, adjusting pad 8, big end cap 9, screw 14, screw 19.Earlier rubber seal 15 is embedded respectively in pole shoe 3 and the pole shoe 6 during installation, then bearing 2, pole shoe 3, permanent magnet 5, pole shoe 6, bearing 7 successively near overcoat 4 inner convex platform right sides; After magnetic liquid 12 injected sealing tooth 20 on the axle sleeve 10 equably, the bearing 2 that has installed above packing into, pole shoe 3, permanent magnet 5, pole shoe 6, bearing 7 inside, with screw 19 small end lid 1 is fixed on the axle sleeve 10, then will regulate pad 8 and be contained in bearing 7 right sides successively with big end cap 9, at last with screw 14 continuous overcoats 4 and big end cap 9, compress mutually between small end lid 1, bearing 2, pole shoe 3, permanent magnet 5, pole shoe 6, bearing 7, adjusting pad 8, the big end cap 9 like this, make the seal arrangement axial restraint.Thereby magnetic liquid 12 is adsorbed under the effect in magnetic field in the gap of sealing tooth 20, forms reliable sealing.
Regulate pad 8 and when assembling, adjust axial distance.
In order to assemble simple and protection sealing tooth, the sealing tooth 20 of magnetic liquid 12 is placed in design on the external cylindrical surface of axle sleeve 10, sees shown in Figure 2.
In order to realize that seal arrangement uses under greater than the 160mm condition at the diameter of axle, the tooth profile parameter of sealing tooth 20 is: facewidth 0.5mm, and tooth depth 2.5mm, A is identical with the B structure, sees shown in Figure 3.Pole shoe 3 and pole shoe 6 are 0.1mm with the gap of axle sleeve 10 external cylindrical surfaces, and the sealability that this structure is every grade can reach 0.5 barometric pressure.
The symmetrical configuration of pole shoe 3 and pole shoe 6 is established the groove of placing rubber seal 15 on external cylindrical surface, pole shoe 3 and pole shoe 6 both sides end faces respectively design a boss, and the effect of a boss is to isolate magnetic circuit, prevents that magnetic liquid 12 is adsorbed onto bearing 2 or bearing 7; Another boss is the position of fixing permanent magnet 5.Pole shoe 3 and pole shoe 6 material selection electrical pure irons.
The base load liquid of magnetic liquid is selected high-quality burning oil or silicate lipid or two lipids for use, and they still have good flowability in the time of-40 ℃, and resistance to low temperature is good, and the particle diameter of magnetic-particle is less than 5nm in the magnetic liquid.Can guarantee that like this magnetic liquid also is in colloidal state in the time of-40 ℃, viscosity is little, and the particle diameter of magnetic-particle is more little, and saturation magnetization is low more, thereby driving torque is reduced.
Tapped hole 13, through hole 16 and tapped hole 17 are in order to link to each other with other devices and to design.
Seal groove 11 and seal groove 18 are in order to use the design of sealing device.
Overcoat 4, axle sleeve 10, adjusting transfer sheet 8, big end cap 9, screw 14 and screw 19 all to be made by stainless steel material.
Permanent magnet 5 is selected Rb-Fe-B material for use.
Bearing 2 is identical with bearing 7 models.
Use-case: to diameter is that the running shaft of 180mm carries out the vacuum seal design, adopt 8 grades of pole shoe sealings, the gap of pole shoe and sleeve outer circle cylinder is 0.1mm, facewidth 0.5mm, tooth depth 2.5mm, magnetic liquid is a fat coal oil base ferroferric oxide gel, and the particle diameter of tri-iron tetroxide is 4nm, and permanent magnet is selected Rb-Fe-B material for use.This device is in the time of-40 ℃, and driving torque drops to 3kgm from 7gm, and released gas rate is less than 10
-11Palm
3/ s, and magnetic leakage free problem.
Seal arrangement is equally applicable to temperature under-40 ℃, and the sealing diameter of axle is greater than the positive seal of 160mm.