CN101413584A - Non-contact type mechanical dynamic seal - Google Patents

Abstract

The invention provides a non-contact mechanical movable sealing, which is characterized in that the sealing consists of a movable ring and a fixed ring which are made of steel; the sealing surfaces of the movable ring and the fixed ring are flat and have the average value of the surface roughness at 0.2-0.4 microns after being polished; the sealing surface of the movable ring is coated by a TiO2 coating with uniform circumferential spacing; the circumferential width of the area of the same circumference of the movable ring sealing surface is provided with where the TiO2 coating is arranged is 1.0-2.0 times of the circumferential width of the area where the coating is not arranged; the thickness of the TiO2 coating is 0.08-0.15mm; the clearance value of the movable ring and the fixed ring is 0.05-1.00 microns. The sealing does not need to process the geometrical shape on the sealing surface, the sealing surface has a simple structure, easy processing and low cost; the sealing force or the external load has large change range; the sealing has small leakage quantity, low friction coefficient, extremely light abrasion, long service life, low energy dissipation, good anti-leakage performance, excellent sealing stability and anti-interference capability.

Description

A kind of non-contact type mechanical dynamic seal

Technical field

The present invention relates to a kind of mechanical dynamic seal, particularly a kind of non-contact type mechanical dynamic seal.

Background technique

Mechanical dynamic seal is to solve between moving parts and stationary components the technology that concerns problem, prevents liquid excessive bleed from slit, dynamic and static mating face.It need reach tribological property index and sealability index, make friction surface between Sealing (or sealing medium) and part have low friction factor, strong wear-resistant ability, liquid is run off from its friction surface be no more than that regulation requires and as much as possible little.Therefore, it comprises two technology: tribology technology and leak sealing technology.Passing judgment on mechanical dynamic seal should carry out from this two aspects technical performance index.

The mechanical dynamic seal that mechanical field uses now divides two big classes: contact-type mechanical dynamic seal and non-contact type mechanical dynamic seal.Moving parts directly contacts with stationary components or Sealing in the contact-type mechanical dynamic seal, forms the friction engageable surface of no fluid lubrication.Dynamic and static mating face friction factor of this sealing is big, wear extent is bigger, therefore this sealing life shorter, and its leak sealing differs and reserves.Common contact-type mechanical dynamic seal has:

(1) felt collar oil sealing

On stationary components, leave dovetail groove, felt is circularized (when size is little) or band shape (when size is big) by metric system, be placed in the dovetail groove to contact with the moving parts driving fit; Perhaps gap is placed the felt collar oil sealing on stationary components, is pressed on the felt collar oil sealing with the another one part then, with the closed intensity of adjustment felt and moving parts, thereby improves sealing effect.This sealing configuration is simple, but friction factor is big, wearing and tearing are more remarkable, and the life-span is shorter, generally only is used for the less occasion of Sliding velocity.

(2) lip-type packing

On stationary components, place a lip-type packing, tightly be enclosed within on the moving parts by the fastening effect of the elastic force of the rubber that bent and the garter spring that adds, so that seal with oil resistant rubber system.The direction of lip-type packing sealing lip will be towards the position of sealing.The Sliding velocity that this sealing is suitable for is big slightly, but normal require the moving parts surface that contacts with lip-type packing through cure process with the raising wear resistance.This sealing still has the shortcoming that friction factor is big, wearing and tearing are remarkable, the life-span is short.

(3) seal ring

Seal ring is a kind of annular seal that has breach, and it is placed in the annular groove of sleeve, and sleeve rotates with moving parts, and seal ring is held together the back elasticity that is had by breach by pressure and pushes against on the inner hole wall of stationary components, can play the effect of sealing.Each contact surface must be through cure process and polishing.When seal ring is made by the wear resisting cast iron that contains chromium, can be used for Sliding velocity less than the 100m/s part.Also available tin bronze is made seal ring, but Sliding velocity should be not more than 60m/s.Compared with preceding two kinds of sealings, this seal friction coefficient is less, wearing and tearing are light, the life-span is longer.

(4) rotating ring, stationary ring contact seal

Make rotating ring and stationary ring.Rotating ring is contained on the moving parts, and stationary ring is contained on the stationary components.The sealing force generation driving fit that rotating ring and stationary ring rely on spring etc. to provide contacts, and makes its surface of contact play sealing effect.Rotating ring, stationary ring need to be made by the less high-abrasive material of friction factor, and the mating face is often through sclerosis and high finishingness processing.The wearing and tearing of this sealing, life-span and leak sealing ability are relevant with the sealing force that spring etc. provides.It generally has stronger leak sealing ability and low coefficient of friction and wear-resistant, is used for important events.This is a kind of important contact-type motive sealing.

Do not take place directly to contact between moving parts and stationary components in the non-contact type mechanical dynamic seal, in their gap, be full of fluid or gas to realize fluid film or gas film lubrication.This seal friction coefficient is little, wearing and tearing are very light, the life-span is long, and its leak sealing is also fine, is a kind of important sealing technique.It represents the developing direction of mechanical sealing technology.Common important non-contact type mechanical dynamic seal has:

(1) single-row fluid dynamic pressure groove non-contact mechanical seal

This sealing can realize that " two-way " hangs down leakage sealed function, and friction factor is little, and it is very light to wear and tear, and energy consumption is low, and moving parts can two-wayly rotate.It has good sealing stability and anti-external interference ability, is applicable to high PV value turbomachinery.

(2) biserial fluid dynamic pressure groove upstream pumping mechanical seal in the same way

This sealing can realize low leakage sealed function, and friction factor is little, and it is very light to wear and tear, and energy consumption is low, has good anti-solid particle ability.It is applicable to carries the high rotator type pump that contains solid particle medium.

(3) biserial intersection dynamic pressure groove upstream pumping mechanical seal

This sealing can realize low leakage sealed function, and friction factor is little, and it is very light to wear and tear, and energy consumption is low, has good selflubricating ability and good starting performance.It is applicable to the rotor pump of carrying clean fluid or is in rotary type fluid machine under the frequent start-stop state.

(4) biserial reverse dynamic pressure tank non-contact mechanical seal

This sealing can realize the low leakage sealed function of process gas or liquid, and friction factor is little, and it is very light to wear and tear, and energy consumption is low, has good seal operation stability (higher fluid film rigidity), can be used as gas film sealing or liquid film seal.It is applicable to turbine gas compressor, blower, all kinds of light hydrocarbon pump, carries volatile medium class pump etc.

(5) laser beam machining micro-pore face mechanical seal

This is the advanced person's that gets up of a kind of developed recently a sealing technique.On moving parts or stationary components seal face, process the small hole of intensive size with laser, in the sealing surface gap of moving parts and stationary components, be full of fluid, when moving parts and stationary components generation relative movement, rely on the microcosmos geometric shape of aperture on the sealing surface, it is lubricated and fluid film thickness is very little that sealing surface is in fluid film.This seal friction coefficient is little, wearing and tearing are very light, the life-span is long, has good leak sealing.Its applicable situation is extensive.

Because low coefficient of friction, very light wearing and tearing, long lifetime and good leak sealing, non-contact type mechanical dynamic seal obtains application more and more widely in practice, is subjected to engineers and technicians' attention, becomes the important directions of sealing technique development.The application of this sealing makes sealability obtain substantive the improvement.The appearance of new non-contact type mechanical dynamic seal is the impressive progress of mechanical sealing technology development.

Summary of the invention

Technical problem to be solved by this invention is at the deficiencies in the prior art, and a kind of have low coefficient of friction, very light wearing and tearing, long lifetime and the good non-contact type mechanical dynamic seal of leak sealing are provided.

Technical problem to be solved by this invention is to realize by following technological scheme.The present invention is a kind of non-contact type mechanical dynamic seal, is characterized in, it is made up of the rotating ring and the stationary ring of steel; The sealing surface of rotating ring and stationary ring is smooth plane, and through polishing processing, surface roughness average is 0.2～0.4 micron; On the sealing surface of rotating ring, be coated with the uniform TiO in circumferential interval ₂Coating is provided with TiO on the same circumference of rotating ring sealing surface ₂The regional circumferential width of coating is not establish 1.0～2.0 times of regional circumferential width of coating, preferred 1.5 times; TiO ₂The thickness of coating is 0.08～0.15 millimeter, preferred 0.1 millimeter; The gap width of rotating ring and stationary ring is 0.05～1.00 micron.

The present invention is the non-contact type mechanical dynamic seal of no sealing surface geometrical shape processing.In rotating ring and stationary ring gap, be full of certain fluid (working medium needs sealed fluid flow) during work, when rotating ring and stationary ring relatively rotate, promptly form the fluid lubrication film in rotating ring and the stationary ring gap and that sealing surface is obtained is fine lubricated.Because rotating ring and stationary ring gap width are very little, fluid is very little in the leakage rate of sealing surface.

Theoretical according to slippage fluid film carrying, can push away to such an extent that the formation condition of this sealing is:

${\mathrm{\&tau;}}_s<\frac{\mathrm{u\&eta;}}{h},$ ${\mathrm{\&tau;}}_{s1}>1.5455\frac{\mathrm{u\&eta;}}{h}-0.5455{\mathrm{\&tau;}}_s,$ ${\mathrm{\&tau;}}_{\mathrm{<figure-callout\; id="3"\; label="s"\; filenames="A200810235470E00131.png,A200810235470E00142.png"\; state="\{\{state\}\}">s</figure-callout>}3}>1.8176\frac{\mathrm{u\&eta;}}{h}-0.5455{\mathrm{\&tau;}}_s---\left(1\right)$

Be mainly along the mobile requirement of the circumferential one dimension of sealing surface at sealing surface according to fluid, sealing configuration size of the present invention should satisfy following requirement:

$\frac{d_2-d_1}{2l}\&GreaterEqual;2---\left(2\right)$

Herein, τ _sBe fluid-encapsulated and TiO ₂Interface shear strength between coating, τ _S1Be fluid-encapsulated and the rotating ring sealing surface on do not establish interface shear strength between coating area, τ _S3Be fluid-encapsulated and the stationary ring sealing surface between the interface shear strength, η is a fluid viscosity, h is rotating ring and stationary ring sealing surface gap width, u is the average Sliding velocity of dynamic and static interannular, d ₁, d ₂Be respectively the internal diameter and the external diameter of dynamic and static ring, l is TiO on the rotating ring sealing surface ₂Coating area average circumferential width and adjacent (one) do not establish coating area average circumferential width sum.U and l are calculated by following formula respectively:

$u=\frac{\mathrm{\&omega;}(d_1+d_2)}{4}---\left(3\right)$

$l=\frac{\mathrm{\&pi;}(d_1+d_2)}{2N}---\left(4\right)$

Herein, ω is the rotational angular velocity of rotating ring with respect to stationary ring, and N is TiO on the rotating ring sealing surface ₂The coating area number.Consider the uniformity of dynamic and static interannular Sliding velocity on the sealing surface, d ₁, d ₂Satisfy relation d ₁=(0.90～0.95) d ₂

Theoretical according to slippage fluid film carrying, can push away to such an extent that the present invention's bearing capacity of sealing whole sealing surface is:

$w=0.4037{(d_1+d_2)}^2(d_2-d_1)(\frac{\mathrm{u\&eta;}}{h^2}-\frac{{\mathrm{\&tau;}}_s}{h})\frac{1}{N}---\left(5\right)$

With whole sealing surface radially leakage rate be:

$Q=0.2692\frac{{\mathrm{\&rho;h}}^3{(d_1+d_2)}^2}{\mathrm{\&eta;}(d_2-d_1)N}(\frac{\mathrm{u\&eta;}}{h^2}-\frac{{\mathrm{\&tau;}}_s}{h})---\left(6\right)$

It is example that following inventor does fluid-encapsulated with hydraulic oil YA-N32, uses above-mentioned formula (1)-(6) and calculates, and draws the sealing surface bearing capacity and the leakage rate data of the present invention's sealing.

Fluid-encapsulated is hydraulic oil YA-N32, its density p=890kg/m ³, viscosities il=0.03Pas, TiO on it and the sealing surface ₂The interface shear strength is τ between coating _s=0.1MPa gets d ₂=55mm, d ₁=48mm, N=100, h=0.5 μ m.

(1) (during rotation speed n=800r/min), the sealing surface bearing capacity and the leakage rate that obtain are respectively w=17.6kN, Q=8.9 * 10 as ω=83.8rad/s ^-7Kg/s (=3.2g/h).

(2) (during rotation speed n=705r/min), the sealing surface bearing capacity and the leakage rate that obtain are respectively w=8.4kN, Q=4.2 * 10 as ω=73.8rad/s ^-7Kg/s (=1.52g/h).

(3) (during rotation speed n=667.5r/min), the sealing surface bearing capacity and the leakage rate that obtain are respectively w=4.8kN, Q=2.4 * 10 as ω=69.9rad/s ^-7Kg/s (=0.87g/h).

(4) (during rotation speed n=630r/min), the sealing surface bearing capacity and the leakage rate that obtain are respectively w=1.2kN, Q=6.1 * 10 as ω=66.0rad/s ^-8Kg/s (=0.22g/h).

(5) (during rotation speed n=619r/min), the sealing surface bearing capacity and the leakage rate that obtain are respectively w=0.12kN, Q=6.1 * 10 as ω=64.9rad/s ^-9Kg/s (=0.02g/h).

The conventional method of Seal Design of the present invention is: the known conditions of design provides the inner diameter d of required sealing surface bearing capacity w, sealing surface radial leakage amount Q allowable, fluid-encapsulated and ρ, η value, dynamic and static ring ₁And outside diameter d ₂, rotating ring is with respect to the rotational speed omega of stationary ring, determines on seal clearance h value, required fluid and the rotating ring sealing surface interface shear strength τ between coating _sCoating area is counted N on value and the required rotating ring sealing surface.According to the design known conditions, can set up equation respectively by formula (5), (6), these two equations of simultaneous solution can get h value and (u η/h ²-τ _s/ h)/the N value.Get suitable τ _sValue is calculated the N value.

The design example explanation:

Design known conditions: d ₁=48mm, d ₂=55mm, ω=78.5rad/s (rotation speed n=750r/min), ρ=890kg/m ³, η=0.03Pas, w=0.5kN, Q=0.1g/h (=2.8 * 10 ^-8Kg/s), require to determine: h, τ _sWith the N value.

Design is found the solution: according to known conditions, descended equation respectively by formula (5), (6):

$0.4037\&times;{103}^2\&times;{10}^{-6}\&times;7\&times;{10}^{-3}\&times;(\frac{\mathrm{u\&eta;}}{h^2}-\frac{{\mathrm{\&tau;}}_s}{h})\frac{1}{N}=0.5\&times;{10}^3---\left(7\right)$

$\frac{0.2692\&times;890\&times;{\mathrm{<figure-callout\; id="3"\; label="h"\; filenames="A200810235470E00131.png,A200810235470E00142.png"\; state="\{\{state\}\}">h</figure-callout>}}^3\&times;{103}^2{\&times;10}^{-6}}{0.03\&times;7\&times;{10}^{-3}}(\frac{\mathrm{u\&eta;}}{h^2}-\frac{{\mathrm{\&tau;}}_s}{h})\frac{1}{N}=2.8\&times;{10}^{-8}---\left(8\right)$

The above-mentioned equation of simultaneous solution: h=0.516 μ m, (u η/h ²-τ _s/ h)/N=1.668 * 10 ⁷N/m ³Get τ _s=0.116MPa then gets N=168.

Principle of the present invention below is described.

According to the interface sliding theory of setting up before, in the sealing of the present invention's design, under operating conditions, because TiO on the rotating ring sealing surface ₂Interface shear strength a little less than coating and fluid-encapsulated, fluid-encapsulated at TiO ₂Slippage on the coating surface, (reaching this interface shear strength by this fluid-encapsulated at the interface shearing stress causes), and owing to higher interface shear strength between the interregional higher interface shear strength of not establishing coating on fluid-encapsulated and the rotating ring sealing surface and fluid-encapsulated and stationary ring sealing surface, slippage does not take place in fluid-encapsulated zone of not establishing coating on the rotating ring sealing surface, fluid-encapsulated slippage does not take place on whole stationary ring sealing surface yet.Like this, TiO on the rotating ring sealing surface ₂Fluid flow is less than not establishing fluid flow between coating area and stationary ring sealing surface on the rotating ring sealing surface between coating and stationary ring sealing surface.According to the inventive method, when dynamic and static interannular relatively rotated, if no pressure generation in the fluid film in the dynamic and static czermak space, flowing of then dynamic and static interannular fluid was Couette mobile (seeing fluid mechanics).This flowing only caused by the speed of related movement between dynamic and static ring surface that its flow is ρ uh (1-ε)/2, and ρ is a fluid density herein, and ε is interface sliding rate (h is the gap width of dynamic and static ring).For TiO on the rotating ring sealing surface ₂Fluid between coating and stationary ring sealing surface, 0＜ε＜1; For not establishing fluid between coating area and stationary ring sealing surface, ε=0 on the rotating ring sealing surface.Like this, according to top described, the Couette traffic flow of not establishing fluid between coating area and stationary ring sealing surface on the rotating ring sealing surface is than TiO on the rotating ring sealing surface ₂The Couette traffic flow of fluid wants big between coating and stationary ring sealing surface.If in the dynamic and static czermak space in the fluid film no pressure produce, the flow of fluid can not balance in the then dynamic and static czermak space, the mobile condition that does not satisfy continuous-flow of fluid.This obviously is unpractical.For the flow that makes fluid on the dynamic and static czermak space middle section equates everywhere, satisfy fluid continuous-flow condition, necessary build-up pressure in the fluid film in the dynamic and static czermak space produces pressure gradient mobile (be that Poiseuille flows, see fluid mechanics).Like this, fluid mobile in dynamic and static czermak space could satisfy continuity condition.In other words, in the sealing of the present invention design, because the continuity requirement that fluid flows, must build-up pressure in the fluid film in the dynamic and static czermak space, this pressure is used for balanced seal power or extraneous load.Like this under sealing force or the extraneous loading with regard to kept fluid film on sealing surface existence and that sealing surface is obtained is good lubricated.On the other hand, because dynamic and static czermak space value very little (less than 1 micron), fluid is very little along sealing surface leakage rate radially.The present invention that Here it is seals the mechanism of low coefficient of friction, very light wearing and tearing, long lifetime, good leak sealing.

The sealing surface bearing capacity of the present invention sealing and leakage rate data can experimentize and measure with the experimental technique of routine and determining method.

Compare with existing non-contact type mechanical dynamic seal, the present invention has the following advantages:

(1) do not need sealing surface is carried out geometrical shape processing.

(2) sealing surface is smooth plane, and is simple in structure, easy processing.

(3) the sealing surface processing cost is low, the work efficiency height.

(4) sealing force or extraneous load change scope are big, and leakage rate is little.

(5) moving parts (rotating ring) can two-wayly rotate, and can realize that " two-way " hangs down leakage sealed function.

(6) friction factor is low, and it is very light to wear and tear, and the life-span is long, and energy consumption is low, and leak sealing is good.

(7) have good sealing stability and anti-external interference ability.Applicable situation is extensive.

Description of drawings

Fig. 1 is a kind of structural representation of the present invention.

Fig. 2 is the plan view of Fig. 1.

Fig. 3 removes the left view of (rotating ring) behind the stationary ring for Fig. 1.

Fig. 4 is the sealing surface schematic representation of rotating ring.

Embodiment

Following with reference to accompanying drawing, further describe concrete technological scheme of the present invention, so that those skilled in the art understands the present invention further, and do not constitute restriction to its right.

Embodiment 1.With reference to Fig. 1-4.A kind of non-contact type mechanical dynamic seal, it is made up of the rotating ring 1 and the stationary ring 2 of steel; The sealing surface 4 of rotating ring 1 and stationary ring 2 is smooth plane, and through polishing processing, surface roughness average is 0.2 micron; On the sealing surface 4 of rotating ring 1, be coated with the uniform TiO in circumferential interval ₂Coating 3 is provided with TiO on the same circumference of rotating ring 1 sealing surface 4 ₂The regional circumferential width of coating 3 is not establish 1.0 times of regional circumferential width of coating, TiO ₂The thickness of coating 3 is 0.08 millimeter; The gap width of rotating ring 1 and stationary ring 2 is 0.05 micron.

Embodiment 2.With reference to Fig. 1-4.A kind of non-contact type mechanical dynamic seal, it is made up of the rotating ring 1 and the stationary ring 2 of steel; The sealing surface 4 of rotating ring 1 and stationary ring 2 is smooth plane, and through polishing processing, surface roughness average is 0.4 micron; On the sealing surface 4 of rotating ring 1, be coated with the uniform TiO in circumferential interval ₂Coating 3 is provided with TiO on the same circumference of rotating ring 1 sealing surface 4 ₂The regional circumferential width of coating 3 is not establish 2.0 times of regional circumferential width of coating, TiO ₂The thickness of coating 3 is 0.15 millimeter; The gap width of rotating ring 1 and stationary ring 2 is 1.00 microns.

Embodiment 3.With reference to Fig. 1-4.A kind of non-contact type mechanical dynamic seal, it is made up of the rotating ring 1 and the stationary ring 2 of steel; The sealing surface 4 of rotating ring 1 and stationary ring 2 is smooth plane, and through polishing processing, surface roughness average is 0.3 micron; On the sealing surface 4 of rotating ring 1, be coated with the uniform TiO in circumferential interval ₂Coating 3 is provided with TiO on the same circumference of rotating ring 1 sealing surface 4 ₂The regional circumferential width of coating 3 be do not establish coating regional circumferential width 1.5, TiO ₂The thickness of coating 3 is 0.1 millimeter; The gap width of rotating ring 1 and stationary ring 2 is 0.65 micron.

Embodiment 4.With reference to Fig. 1-4.A kind of non-contact type mechanical dynamic seal, it is made up of the rotating ring 1 and the stationary ring 2 of steel; The sealing surface 4 of rotating ring 1 and stationary ring 2 is smooth plane, and through polishing processing, surface roughness average is 0.35 micron; On the sealing surface 4 of rotating ring 1, be coated with the uniform TiO in circumferential interval ₂Coating 3 is provided with TiO on the same circumference of rotating ring 1 sealing surface 4 ₂The regional circumferential width of coating 3 is not establish 1.2 times of regional circumferential width of coating, TiO ₂The thickness of coating 3 is 0.06 millimeter; The gap width of rotating ring 1 and stationary ring 2 is 0.10 micron.

Embodiment 5.With reference to Fig. 1-4.A kind of non-contact type mechanical dynamic seal, it is made up of the rotating ring 1 and the stationary ring 2 of steel; The sealing surface 4 of rotating ring 1 and stationary ring 2 is smooth plane, and through polishing processing, surface roughness average is 0.25 micron; On the sealing surface 4 of rotating ring 1, be coated with the uniform TiO in circumferential interval ₂Coating 3 is provided with TiO on the same circumference of rotating ring 1 sealing surface 4 ₂The regional circumferential width of coating 3 is not establish 1.8 times of regional circumferential width of coating, TiO ₂The thickness of coating 3 is 0.12 millimeter; The gap width of rotating ring 1 and stationary ring 2 is 0.80 micron.

Claims (3)

1, a kind of non-contact type mechanical dynamic seal is characterized in that, it is made up of the rotating ring (1) and the stationary ring (2) of steel; The sealing surface (4) of rotating ring (1) and stationary ring (2) is smooth plane, and through polishing processing, surface roughness average is 0.2～0.4 micron; On the sealing surface (4) of rotating ring (1), be coated with the uniform TiO in circumferential interval ₂Coating (3) is provided with TiO on the same circumference of rotating ring (1) sealing surface (4) ₂The regional circumferential width of coating (3) is not establish 1.0～2.0 times of regional circumferential width of coating, TiO ₂The thickness of coating (3) is 0.08～0.15 millimeter; The gap width of rotating ring (1) and stationary ring (2) is 0.05～1.00 micron.

2, a kind of non-contact type mechanical dynamic seal according to claim 1 is characterized in that, is provided with TiO on the same circumference of rotating ring (1) sealing surface (4) ₂The regional circumferential width of coating (3) is not establish 1.5 times of regional circumferential width of coating.

3, a kind of non-contact type mechanical dynamic seal according to claim 1 is characterized in that TiO ₂The thickness of coating (3) is 0.1 millimeter.

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