CN202100442U - Seal short joint for oil well pump - Google Patents

Abstract

The utility model relates to a seal short joint for an oil well pump, mainly comprising a seal short joint body, an annular knife rest, an annular blade and an annular compression spring. The seal short joint is characterized in that the annular knife rest is arranged at the periphery of a ring body of the seal short joint body, an annular hairline is arranged in the middle of the annular knife rest, and the annular blade is arranged in the hairline; and an annular spring ring is contacted with the annular blade to be embedded into the hairline and arranged at the inner layer of the annular blade. The pressure gradient of an oil film at a seal interface is sharply enlarged and steepened due to the structure of an annular knife, so that the leakage rate of liquid in the annular hairline during one stroke of a plunger piston is nearly zero; and contact force between the annular knife of the seal short joint and the wall surface of a pump barrel is always kept at a steady value due to the annular spring ring, so that the service life of the seal short joint is longer than that of the existing elastic seal ring.

Description

A kind of oil well pump is with the sealing short circuit

Technical field

The utility model relates to the downhole tool that uses in a kind of petroleum gas oil well, and particularly a kind of oil well pump is with the sealing short circuit.

Background technique

Diaphragm type sand control card oil well pump can effectively solve sand production and cause pump wearing and tearing oil return and sand to block plunger two big technical barriers.The diaphragm type sand-proof oil-well pump must guarantee that all there is liquid on the barrier film both sides when work, and the diaphragm cavity at plunger two ends is communicated with through annular space, and the pressure reduction that the annular space two ends produce when down stroke is less than in upstroke being the pressure reduction that produces; In a stroke, the cleaning liquid measure increases in the diaphragm cavity of plunger lower end, and the cleaning liquid measure reduces in the diaphragm cavity of plunger upper end.If do not take necessary sealing technique, this equilibrium system will be destroyed.In addition, downhole pump is changed the sealing short circuit and need be played pump.Therefore the life-span that is used for the Sealing of diaphragm type sand-proof oil-well pump must be consistent with the barrier film operating life.

In existing sealing technique, the pressure gradient that the contact pressure of the seal interface of seal ring is distributed in low voltage side is not equal on high-tension side pressure gradient, when setting in motion; The oil film that sticks on the pump barrel wall is carried to the convergence slit; The hydrodynamic effect causes the pressure at pressure ratio annular space two ends of this part oil film big, and the surface crater that oil film is pressed against elaxtic seal goes out, along with motion is carried out; Oil film is passed to form to next one hole successively from a hole and is leaked; In a reciprocating stroke, can produce leakage, final failure barrier film equilibrium system.In addition, seal ring provides the sealing pretightening force, and it is bigger that it begins pretightening force, the seal ring rapid wearing; Along with service wear, pretightening force reduces fast, and until inefficacy, the bulk life time of sealing short circuit falls short of.The oil well pump space is narrow and small, and the volume and the structure of sealing short circuit are restricted.Chinese patent publication number: CN 2391029Y; August 9 2000 notice of authorization day; The name of utility model patent is called strong elastic sand control card oil well pump, this application case disclose " the plunger body skin of this pump be by seal ring and lining mutually embedding form a plurality of assembled arrangement, seal ring adopts composite elastic material to process; seal by the expansion principle ", this scheme sealing effect difference and wear-resisting time lack; Chinese patent publication number: CN100376794C, on March 26 2008 notice of authorization day, the name of patent of invention is called the anti-thick sand control fluid power feedback oil well pump of belt length plug ring envelope and oil-feed sand setting passage; This application case discloses " long plug ring envelope seal assembly set gradually some roads strike-off ring and metal ring and nonmetallic ring "; The wearing and tearing back principle of compensation automatically all is that elastomer recovers distortion, and sealing effect and wear resistance all are not suitable for the sealing of diaphragm type sand-proof oil-well pump, secondly; The leather cup of machinery self sealing plunger pump is close to the pump barrel inwall; Because wearing and tearing can appear in leather cup and pump barrel inwall Long contact time, leather cup, the life-span of plunger is short.

The model utility content

The utility model technical problem to be solved be to existing technology not enough and provide a kind of can be in the diaphragm type oil well pump proper functioning, leakage rate approach zero, the oil well pump of long service life is with the sealing short circuit.

The utility model solves the problems of the technologies described above the technological scheme of being taked:

A kind of oil well pump mainly comprises sealing short circuit body, annular knife rest, annular blade, annular compression spring with the sealing short circuit; It is characterized in that: described sealing short circuit body ring body periphery is provided with annular knife rest, is provided with a ring-type finedraw in the middle of the said annular knife rest, and said annular blade is arranged in the finedraw; Said annular elastomeric spring coil and annular blade are embedded in the finedraw in contact and are positioned at the internal layer of annular blade.

Press such scheme, said annular knife rest is made up of main fixing frame and secondary fixing frame; Said main fixing frame is that the cross section is L shaped annulus; Said secondary fixing frame is that one jiao on interior ring is removed a part and cross section is tetragonal annulus.

Press such scheme; Said finedraw is the slit that main fixing frame and secondary fixing frame clamping constitute; The outer end of finedraw moves horizontally the outer slit of opening for holding annular blade, and the inner of finedraw is the termination handle of a knife that can hold annular blade and annular compression the spring rectangle and the circular joining hole of relative backup campaign in the horizontal direction.

Press such scheme, said annular blade is circumferential annular blade, by the sheet rectangle reel form and two coiling limits overlapped; Lap accounts for 1/5th to 1/2nd of total circumferential length.

Press such scheme, said annular compression spring is connected to form by the two ends of compression helical spring.

Compared with prior art, the utlity model has following beneficial effect:

(1) pressure gradient of through the cutting ring structure oil film being located in the seal interface sharply strengthens steepening, thereby realizes in the annular space that the leakage rate of liquid is almost nil in stroke of plunger.

Under pressure at two ends magnitude relationship generation alternate situation, oil well pump uses the sealing short circuit can guarantee that also the annular space leakage rate is zero, good sealing effect; And the self structure of other seal ring has determined it that certain leakage rate is arranged under this complex situations.

For conventional elastic sealing ring, during the plunger to-and-fro motion, sealing is to realize by the elastomeric flow dynamic pressure effect that seals oil film between short circuit and the pump barrel wall.The motive sealing of annular space and lubrication mechanism depend on that the pump barrel wall brings the behavior of seal interface oil film into.Can know that through analyzing a stroke H will produce clean leakage rate and be:

$Q=\mathrm{\&pi;dH}(h_0-h_i)=\mathrm{\&pi;<figure-callout\; id="2"\; label="dH"\; filenames="HDA0000066082790000011.png"\; state="\{\{state\}\}">dH</figure-callout>}\sqrt{\frac{2\mathrm{\&eta;}}{9}}\&CenterDot;[\sqrt{\frac{u_0}{{\mathrm{\&omega;}}_G}}-\sqrt{\frac{u_i}{{\mathrm{\&omega;}}_E}}]$

In the formula, h is the annular space height, and d is a plunger diameter, and η is the viscosity of liquid film, u ₀Be upstroke speed, u _iBe down stroke speed, ω _GAnd ω _EBe respectively upstroke or down stroke maximum pressure gradient, follow-up identical.If the numerical value in the bracket is zero or is negative, then realized zero leakage.Promptly when upstroke, keeping low leakage rate, to require contact pressure to be distributed near extreme direction on the plunger steeper, has bigger pressure gradient, and extreme direction has less pressure gradient under plunger; And when down stroke, it is steeper to require contact pressure to be distributed near the plunger lower end, has bigger pressure gradient, has less pressure gradient in plunger upper end and maximum pressure gradient depends primarily on the structure and material of Sealing.For elastomeric seals, under plunger pressure at two ends magnitude relationship generation alternate situation, can not satisfy above two requirements simultaneously.

But; An endless knife is set in the middle of sealing surface; In upstroke and down stroke; Maximum pressure gradient and contact pressure distribution curve steepest point be all in the centre, that is:

In the formula, u ₀Be upstroke speed, u _iBe down stroke speed, ω _GAnd ω _EBe respectively upstroke or down stroke maximum pressure gradient.Therefore, the leakage rate through the sealing short circuit is zero; In addition; Fluid only is decided by the greatest gradient of fluid pressure distribution curve through the amount of sealing short circuit surface of contact, and promptly pressure distribution curve is steep more, and oil slick thickness is more little; Near knife rest pressure gradient maximum, endless knife is set again, can confirms that the pressure gradient in the seal clearance is:

$\frac{\mathrm{dp}}{\mathrm{dx}}=\frac{6\mathrm{\&eta;U}}{h_0^2}$

P is fluid (x direction) pressure radially in the annular space in the formula, and the annular space height is h ₀, plunger travelling speed U, viscosities il; Pressure is the linear increase of journey along the gap, and with respect to knife rest thickness, the thickness of the edge of a knife is less; Making whole seal contact pressure be distributed in knife-edge part increases suddenly; Reach maximum value at the edge of a knife, further increase the gradient of the pressure distribution curve at this place, make the annular space leakage rate still less.

(2) use the ring-spring circle to guarantee that the cutting ring of sealing short circuit and the contact force of pump barrel wall are always a steady state value, thereby guarantee the long service life of the working life of sealing short circuit than existing elastic sealing ring.

The elastic sealing ring of uses such as existing combined plunger anti-sticking oil well pump is to rely on the elastic expansion of self to realize automatic compensate for wear amount, and contact force is big in advance, quick abrasion.

And use in the sealing short circuit at this oil well pump; The preparatory contact force of annular knife rest and the annular edge of a knife and the borehole wall is to be provided by the annular compression spring that embeds in the finedraw; Can select the annular compression spring according to only preparatory contact force size, make the edge of a knife and pump barrel wall between leakage rate be zero, guarantee that simultaneously the contact force between the edge of a knife and pump barrel wall is not excessive; The wear extent of endless knife is fit to, and makes the longer service life of whole sealing short circuit.

Description of drawings

Fig. 1 is the structural representation of oil well pump with the sealing short circuit;

Fig. 2 is the cross-sectional structure schematic representation of oil well pump with the sealing short circuit.

Among the figure: 1, sealing short circuit body; 2, annular knife rest; 3 annular blades; 4, annular compression spring; 5, main fixing frame; 6, finedraw; 7, secondary fixing frame.

Embodiment

Below in conjunction with embodiment and accompanying drawing the utility model is described further, but does not limit the utility model.

The utility model mainly comprises sealing short circuit body (1), annular knife rest (2), annular blade (3), annular compression spring (4); It is characterized in that: described sealing short circuit body (1) ring body periphery is provided with annular knife rest (2); Be provided with a ring-type finedraw (6) in the middle of the said annular knife rest (2), said annular blade (3) is arranged on finedraw (6) lining; Said annular elastomeric spring coil (4) is embedded in the finedraw (6) in contact with annular blade (3) and is positioned at the internal layer of annular blade (3).Said annular knife rest (2) is made up of main fixing frame (5) and secondary fixing frame (7); Said main fixing frame (5) is that the cross section is L shaped annulus; Said secondary fixing frame (7) is removed a part for one jiao on interior ring and cross section is tetragonal annulus.Said finedraw (6) is the slit that main fixing frame (5) and secondary fixing frame (7) clamping constitute; The outer end of finedraw (6) moves horizontally the outer slit of opening for holding annular blade (3), and the inner of finedraw (6) is the termination handle of a knife that can hold annular blade (3) and annular compression spring (4) rectangle and the circular joining hole of relative backup campaign in the horizontal direction.

Said annular blade (3) is circumferential annular blade, by the sheet rectangle reel form and two coiling limits overlapped, lap accounts for 1/5th to 1/2nd of total circumferential length.After the part of wearing and tearing at work, annular blade (3) is the side shifting and opening outward from sealing short circuit body (1) inboard down in annular compression spring (4) effect, thus the part that the realization compensate for wear is fallen.

Said annular compression spring (4) is connected to form by the two ends of compression helical spring.Because wear extent is little, less resiliently deformable takes place said annular compression spring (4) just can be pushed against the pump barrel wall with annular blade (3), and in this process, the loss of elastic force is also little, and promptly annular blade (3) changes little to the contact force of pump barrel wall.

Below only be a kind of embodiment who realizes the utility model, based on other form of the utility model claim present principles within this scope.

Claims (6)

1. an oil well pump mainly comprises sealing short circuit body, annular knife rest, annular blade, annular compression spring with the sealing short circuit; It is characterized in that: described sealing short circuit body ring body periphery is provided with annular knife rest, is provided with a ring-type finedraw in the middle of the said annular knife rest, and said annular blade is arranged in the finedraw; Said annular elastomeric spring coil and annular blade are embedded in the finedraw in contact and are positioned at the internal layer of annular blade.

2. sealing short circuit according to claim 1 is characterized in that said annular knife rest is made up of main fixing frame and secondary fixing frame; Said main fixing frame is that the cross section is L shaped annulus; Said secondary fixing frame is that one jiao on interior ring is removed a part and cross section is tetragonal annulus.

3. sealing short circuit according to claim 2; It is characterized in that said finedraw is the slit that main fixing frame and secondary fixing frame clamping constitute; The outer end of finedraw moves horizontally the outer slit of opening for holding annular blade, and the inner of finedraw is the termination handle of a knife that can hold annular blade and annular compression the spring rectangle and the circular joining hole of relative backup campaign in the horizontal direction.

4. sealing short circuit according to claim 3 is characterized in that said annular blade is circumferential annular blade, and being reeled by the sheet rectangle forms and there is overlapped part on two coiling limits.

5. sealing short circuit according to claim 4 is characterized in that said lap accounts for 1/5th to 1/2nd of total circumferential length.

6. sealing short circuit according to claim 5 is characterized in that said annular compression spring is connected to form by the two ends of compression helical spring.

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