CN202451895U

CN202451895U - Stop check valve

Info

Publication number: CN202451895U
Application number: CN2011205351449U
Authority: CN
Inventors: 季克寅
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-12-20
Filing date: 2011-12-20
Publication date: 2012-09-26
Anticipated expiration: 2021-12-20

Abstract

The utility model relates to a stop check valve, which comprises a valve body, wherein a fixed valve seat and a valve flap are arranged in the valve body, the valve flap and the valve seat commonly form a valve sealing pair, a guide surface realizing the guide effect on the upward and downward moving of the valve flap is arranged on the inner wall of the valve body, and the outer side wall of the valve flap is in clearance fit with the guide surface. The stop check valve has the advantages that the structure is simple, the requirement on the processing precision is lower, the processing is easy, the cost is low, in addition, the guide performance is good, the positioning of the valve flap is accurate, the valve flap can stably and smoothly complete the check effect, in addition, the sealing performance of the valve is good, the leakage cannot easily occur, the medium flowing in a valve passage is stable, the abrasion of the valve is small, and the service life is long.

Description

Stop check valve

Technical Field

The utility model relates to a valve, especially a stop check valve with stop function and non return function.

Background

As shown in fig. 1, the existing check valve includes a valve body 1, a valve seat 5, a valve flap 7, a valve flap positioning rod 2, a shaft sleeve 3, a valve rod and a valve cover, the valve flap is disposed in a middle cavity 9 always communicated with an outlet 8 of the valve, the valve flap and the valve seat are respectively provided with a conical sealing surface and are mutually matched to form two sealing surfaces of a conical sealing pair 6, the sliding fit position of the valve rod and the valve cover, the sliding fit position of the valve flap positioning rod and the shaft sleeve, and the joint position of the two sealing surfaces of the conical sealing pair relate to three positions, the requirements on form and position accuracy, particularly coaxiality, of the associated parts are high, not only the processing cost is high, but also the processing is very difficult, for example, for the shaft sleeve, because the shaft sleeve is usually directly cast with the valve seat as a whole, the processing of an inner hole of the shaft, the tightness of the fit between the two sealing surfaces is necessarily affected, thereby affecting the sealing performance and consequently reducing the non-return performance.

In addition, in practical use, the form and position accuracy is difficult to guarantee, so that unsmooth opening and closing of the valve is easily caused, and particularly when the valve is applied to a non-return state, the influence is more obvious because medium pressure and the self weight of the valve clack are used as main power.

Therefore, the above-mentioned multipoint positioning structure of prior art not only processing cost is high, still can not guarantee good location guiding performance, appears the inaccurate, not tight condition of sealing of location easily, leads to the ubiquitous location guiding performance of valve clack of current check valve shortcoming such as poor, the non return performance is poor.

In addition, the sleeve arranged at the drift diameter of the valve seat and the connecting rib 4 for fixing the sleeve on the valve seat can influence the flow of the medium and reduce the flow capacity of the valve.

SUMMERY OF THE UTILITY MODEL

In order to overcome the above-mentioned defect of prior art, the utility model aims to provide a stop check valve, the utility model discloses a stop check valve can adopt very simple structure to guarantee the location and the direction performance of valve clack, can effectively reduce the processing degree of difficulty and the processing cost of valve, and can guarantee smooth and easy, the stability that the valve clack reciprocated in-service use, and can guarantee good valve seal effect, consequently can improve the non return performance of valve correspondingly.

The utility model adopts the technical proposal that:

the stop check valve comprises a valve body, wherein a fixed valve seat and a valve clack jointly forming a valve sealing pair with the valve seat are arranged in the valve body, a guide surface for guiding the valve clack to move up and down is arranged on the inner wall of the valve body, and the outer side wall of the valve clack is in clearance fit with the guide surface.

Preferably, the gap between the outer side wall of the valve flap and the guide surface may be 1mm to 4mm, preferably 2mm to 3 mm.

Preferably, an annular valve seat sealing surface is arranged on the valve seat, a circular or annular valve clack sealing surface is arranged on the valve clack, the valve seat sealing surface and the valve clack sealing surface jointly form two sealing surfaces of the valve sealing pair, the outer diameter of the valve clack sealing surface is larger than that of the valve seat sealing surface, and when the valve clack sealing surface is annular, the inner diameter of the valve clack sealing surface is smaller than that of the valve seat sealing surface.

The stop check valve further comprises a valve rod driving the valve clack to move up and down, the valve clack comprises a cylindrical valve clack body with a closed lower end and an open upper end and a valve clack top cover connected to the upper end of the valve clack body in a threaded mode, a central through hole is formed in the valve clack top cover, the tail end of the lower portion of the valve rod is in sliding fit with the central through hole, an axial limiting device capable of limiting the valve rod to be separated from the valve clack is arranged at the lower end of the valve rod, and an ascending limiting boss used for limiting the ascending stroke upper limit of the valve.

The specific setting mode of the axial limiting device can be as follows: (1) the axial limiting device is an end limiting boss arranged at the tail end of the valve rod; or, (2) the axial limiting device comprises an annular groove arranged on the outer cylindrical surface of the valve rod and a retaining ring embedded into the groove at the inner side edge, and the retaining ring is formed by combining a plurality of sector annular retaining blocks.

Preferably, in any one of the above check valves, a guided protrusion is provided on an outer side surface of the valve flap main body and/or the valve flap top cover, an outer surface of the guided protrusion forms an outer side wall of the valve flap, and the number of the guided protrusions is one or more.

The utility model has the advantages that:

the stop check valve of the utility model realizes the positioning and guiding of the valve clack by matching the lateral wall of the valve clack with the guide surface of the inner wall of the middle cavity, not only saves the positioning rod of the valve clack and the shaft sleeve matched with the positioning rod of the valve clack, simplifies the structure of the valve, but also only needs to process most of the inner wall of the middle cavity of the valve into a straight cylinder to be matched with the lateral wall of the valve clack, greatly simplifies the processing technology, reduces the processing difficulty and the processing cost, and ensures good positioning and guiding effects;

the arrangement of structures such as a valve clack positioning rod, a shaft sleeve and a connecting rib for fixing the shaft sleeve is omitted, so that the circulation of a medium in the valve is facilitated, and the turbulence of the medium and a series of adverse effects on the valve caused by the turbulence of the medium are reduced;

additionally, because the utility model discloses a plane seal is vice, and the sealed external diameter of the sealed face on the valve clack than the disk seat is big and the internal diameter is little, even small skew has taken place at the horizontal direction to the valve clack, still can guarantee that the valve has good sealed effect.

Drawings

FIG. 1 is a schematic view of a prior art check valve;

fig. 2 is a schematic structural diagram of the stop check valve of the present invention (working state one);

fig. 3 is a schematic structural view of the check valve of the present invention (working state two);

fig. 4 is a schematic structural view of the check valve of the present invention (working state three);

fig. 5 is a schematic structural view of the check valve of the present invention (operating state four);

fig. 6 is a schematic structural view of the check valve of the present invention (working state five);

fig. 7 is a schematic structural view (six operating states) of the check valve of the present invention;

FIG. 8 is a schematic view showing the fitting relationship between the guide surface of the inner wall of the valve body and the outer side wall of the valve flap according to an embodiment of the check valve of the present invention (the cross-sectional position is the same as the A-A position shown in FIG. 2);

fig. 9 is a schematic view showing the fitting relationship between the guide surface of the inner wall of the valve body and the outer side wall of the valve flap according to another embodiment of the check valve of the present invention (the cross-sectional position is the same as the position a-a shown in fig. 2).

Detailed Description

For a better understanding of the present invention, reference will now be made in detail to the present invention as illustrated in the accompanying drawings.

Referring to fig. 2 to 9, the utility model provides a stop check valve, including valve body 1, be equipped with fixed disk seat in the valve body and with the disk seat constitutes the valve clack 5 of valve seal pair 4 jointly, the valve clack can be located the lumen 6 that is linked together with the export of valve all the time, be equipped with the spigot surface that is used for reciprocating the play guide effect to the valve clack on the valve body inner wall, the spigot surface is usually located on the lumen inner wall of lumen to be parallel with valve rod 14.

Preferably, the guide surface is a part of a cylindrical surface, the central angle of an arc of which the cross section outline is positioned is 180-270 degrees, preferably not less than 220 degrees, namely the guide surface on the inner wall of the middle cavity occupies 180-270 degrees of cylindrical surface of the inner wall of the middle cavity, preferably not less than 220 degrees of cylindrical surface, so as to ensure that the guide surface forms effective surrounding on the outer circumferential surface of the valve clack, improve the positioning and guiding precision, and can avoid the problems of inaccurate positioning, unstable guiding, untight sealing and the like caused by vibration, swing and the like of the valve clack in the motion process, at the same time, in order to ensure effective guidance, the guide surface is usually machined to be parallel to the travel path of the valve flap (usually parallel to the valve stem), the inner wall which is generally in a straight cylinder shape is convenient to process, the processing precision is easy to ensure, and accordingly the positioning and guiding performance is improved.

When the non-return function of the stop check valve is opened, that is, the valve flap is in a position where the non-return function can be automatically realized, preferably, when the valve flap is in any position where the non-return function can be realized, the surrounding angle of the guide surface to the guided surface is not less than 180 degrees, more preferably not less than 220 degrees, or the continuous gap angle of the outer side wall of the valve flap, which is not surrounded by the guide surface, is not more than 180 degrees, preferably not more than 140 degrees, preferably at least 90 degrees, is reserved, and the gap position preferably directly faces the valve outlet, so that the communication between the middle cavity and the valve outlet is ensured, and the adverse influence on the flow of the medium is avoided.

The utility model discloses an embodiment, the spigot surface is located same face of cylinder, both can be continuous curved surface, also can be the curved surface that constitutes by the combination of the curved surface of multi-disc discontinuous setting to guarantee smooth and easy, the stability of direction.

Preferably, the guide surface adjacent to the valve cover 8 is a part of a cylindrical surface, surrounds the outer side of the outer side wall of the valve clack, and surrounds the circumferential angle alpha not less than 180 degrees, preferably substantially in a C shape, and has an angle of 180-270 degrees.

Preferably, the specific arrangement mode of the guide surface can be any one of the following modes:

(1) the guide surface is a continuous curved surface;

(2) the inner wall of the valve body is provided with a plurality of transverse guide bosses, curved surfaces where the top surfaces of the transverse guide bosses are located form the guide surfaces together, and the intervals between the transverse guide bosses are equal or unequal;

(3) a plurality of longitudinal guide bosses 18 are arranged on the inner wall of the valve body, curved surfaces where the top surfaces of the longitudinal guide bosses are located form the guide surfaces together, and the intervals between the longitudinal guide bosses are equal or unequal;

(4) the valve body is characterized in that a plurality of criss-cross guide bosses are arranged on the inner wall of the valve body, curved surfaces where the top surfaces of the guide bosses are located jointly form the guide surfaces, and the intervals between the guide bosses extending in the same direction are equal or unequal.

The clearance between the lateral wall of valve clack and the spigot surface can be 1mm ~ 4mm, preferably 2mm ~ 3mm to when guaranteeing that the valve clack can stabilize the direction, can also avoid the friction between the two, make the valve clack can quick non return, improve the non return performance of valve, and, avoid the wearing and tearing on spigot surface and valve clack, improve life.

Preferably, the valve seat is provided with an annular valve seat sealing surface, the valve clack is provided with a circular or annular valve clack sealing surface, and the valve seat sealing surface and the valve clack sealing surface jointly form two sealing surfaces of the valve sealing pair.

Preferably, the outer diameter of the valve flap sealing surface is larger than that of the valve seat sealing surface, and when the valve flap sealing surface is in a circular ring shape, the inner diameter of the valve flap sealing surface is smaller than that of the valve seat sealing surface, so that effective sealing of the valve can be guaranteed even if the valve flap slightly deviates on a horizontal plane relative to the valve seat.

Preferably, half of the difference between the outer diameter of the valve flap sealing surface and the outer diameter of the valve seat sealing surface is not smaller than the gap between the outer side wall of the valve flap and the guide surface, and when the valve flap sealing surface is circular, half of the difference between the inner diameter of the valve seat sealing surface and the inner diameter of the valve flap sealing surface is preferably not smaller than the gap between the outer side wall of the valve flap and the guide surface, so as to avoid sealing failure caused by slight deviation when the valve flap is matched with the valve seat.

Preferably, the valve clack includes that the lower extreme is sealed, the open tube-shape valve clack main part in upper end and threaded connection be in the valve clack top cap of the upper end of valve clack main part, the internal thread of valve clack main part with the external screw thread of valve clack top cap matches threaded connection, perhaps, the external screw thread of valve clack main part with the internal thread of valve clack top cap matches threaded connection, preferably the former to guarantee threaded connection's stability.

The valve clack top cover can be provided with a central through hole, the lower end of the valve rod is in sliding fit with the central through hole, the lower end of the valve rod is provided with an axial limiting device capable of limiting the valve rod to be separated from the valve clack, and preferably, the stroke of the lower end of the valve rod in the valve clack body is not less than half of the whole length of the valve clack so as to ensure proper non-return stroke.

The valve rod can be provided with or not with an upward limiting boss for limiting the upward travel upper limit of the valve rod, and the central through hole of the valve clack top cover can be in sliding fit with the upward limiting boss.

The specific setting mode of the axial limiting device can be as follows:

the axial limiting device is an end limiting boss arranged at the tail end of the valve rod, and the outer cylindrical surface of the end limiting boss can be in sliding fit with the inner cylindrical surface of the valve clack main body; or,

the axial limiting device comprises a groove arranged on the outer cylindrical surface of the valve rod or the outer cylindrical surface of the upper limiting boss and a limiting stop partially embedded in the groove, for example, the limiting stop can be a check ring embedded in the groove at the inner side edge, and the check ring can be formed by combining a plurality of fan-shaped annular stops. The plurality of the fan-shaped stop blocks can be mutually independent or fixedly connected and combined into the retainer ring. For example, the two semicircular fan ring stoppers with the same specification are butted.

The limit stop can be one or a plurality of fan-shaped annular stops with central angles not larger than 180 degrees, the inner cylindrical surface of each fan-shaped annular stop is matched with the bottom surface of the groove, and the outer cylindrical surface of each fan-shaped annular stop protrudes out of the cylindrical surface of the valve rod or the upward limit boss and is in sliding fit with the inner cylindrical surface of the valve clack main body.

The valve gap can sealed fixed connection in the valve body top, for example, valve gap and valve body flange joint to it is fixed through well flange fastening bolt 9, still be equipped with between valve gap and the valve body and be used for the sealed well flange seal 7 between the two, the upper end of valve rod by wear to come out in the valve gap hole of valve gap, the valve rod with at least one section hole sliding fit in the valve gap hole.

The valve cover hole can be provided with a packing box, wherein packing 10 used for sealing between the valve cover and the polished rod section of the valve rod is filled in the packing box, the top of the packing is provided with a packing gland 11 used for compressing the packing, and the packing gland is fixedly connected with the valve cover through a packing gland compression bolt 12.

The top of the valve cover can be further connected with a valve rod guide piece through a support fixedly connected with the valve cover, a valve rod nut 13 is fixed in the valve rod guide piece, the valve rod nut is provided with an internal thread matched with the external thread of the screw rod section of the valve rod, preferably, the internal thread of the valve rod nut and the external thread of the screw rod section are trapezoidal threads matched with each other, and therefore stable transmission of driving torque is guaranteed.

The upper end fixedly connected with valve drive of valve rod, valve drive includes hand wheel 15, the hand wheel cup joint in on the toper section on the top of valve rod to through with valve rod threaded connection's hand wheel nut 16 compresses tightly and is fixed in on the valve rod.

The inlet 3 and outlet 2 of the valve may be provided with an inlet flange and an outlet flange, respectively, for mounting the valve.

In any of the above check valves, the outer side surface of the valve flap main body and/or the valve flap top cover is provided with a guided boss 17, and the outer surface of the guided boss forms the outer side wall of the valve flap and is matched with the guide surface for guiding the valve flap.

The number of the guided bosses may be one or several.

The guided boss can be a circular guided boss or a long-strip-shaped guided boss.

The annular guided boss is an annular boss which protrudes outwards on the outer cylindrical surface of the valve clack body and extends along the circumferential direction of the outer cylindrical surface.

When the number of the circular guided bosses on the valve clack main body is one, the circular guided bosses are arranged at one end close to the sealing surface of the valve clack, and when the number of the circular guided bosses is more than one, the circular guided bosses are uniformly or non-uniformly distributed on the outer side wall of the valve clack main body so as to ensure good positioning and guiding performance and reduce the deviation, swing and the like of the valve clack in the stroke.

Preferably, the total length of the circular ring-shaped guided boss is not less than one third of the whole length of the valve flap, so as to ensure the stability of guiding.

Preferably, the valve flap top cover can be a T-shaped nut, and the outer diameter of the big head end of the T-shaped nut is the same as or similar to the outer diameter of the guide boss, preferably the same as the outer diameter of the big head end of the T-shaped nut, so that one guide boss of the valve flap is used for guiding the valve flap.

The long-strip-shaped guided boss is a long-strip-shaped boss which protrudes outwards on the outer cylindrical surface of the valve clack body and/or the valve clack top cover and extends linearly along the longitudinal direction of the outer cylindrical surface.

And the plurality of elongated guided bosses are uniformly or non-uniformly distributed on the outer cylindrical surface of the valve clack body and/or the valve clack top cover.

When the guide surface and the outer side wall of the flap are both non-continuous curved surfaces, the guide surface and the outer side wall of the flap are preferably arranged crosswise, for example, when the guide surface is formed by the top surfaces of a plurality of transverse guide projections, the outer side wall of the flap is preferably formed by a plurality of elongated guided projections, when the guide surface is formed by the top surfaces of a plurality of longitudinal guide bosses, the outer side wall of the valve flap is preferably formed by a plurality of circular guided bosses, and particularly when the latter is adopted, the gaps between the longitudinal guide bosses not only facilitate the circulation of the medium, and when the medium flows back, the reverse flow medium can apply downward thrust to the valve clack, the circular guided boss on the valve clack can receive the thrust of the reverse flow medium, can provide certain backflow resistance for the backflow medium, and is favorable for improving the non-return performance of the valve.

The main work flow of the check valve of the present invention may be (only described by taking the medium introduced into the check valve shown in the embodiments of fig. 2 to 7 as an example, wherein the pressure of the introduced medium is sufficient to overcome the valve flap self gravity to jack up the valve flap):

(1) opening and closing of a valve operating in the blocking state: the hand wheel is rotated in the positive direction, so that the valve rod presses the valve clack against the valve seat, the valve is in a stop state (shown in figure 2), a medium can enter a valve cavity (which can be called as a lower valve cavity) through an inlet of the valve, when the valve needs to be opened, the hand wheel is rotated in the reverse direction to drive the valve rod to rotate and rise, the pressure of the valve rod on the valve clack is reduced until the pressure disappears, the valve clack is jacked up by the medium under the medium pressure, the valve is opened, the medium in the lower valve cavity enters an upper valve cavity through a valve seat drift diameter of the valve seat, the opening degree of the valve is increased (shown in figure 3) along with the continuous rising of the valve rod, the medium flow in the valve seat drift diameter is increased, if the medium flow in the valve cavity is enough, the valve clack can almost keep rising synchronously with the valve rod under the medium pressure, when, when the valve needs to be closed, the hand wheel is rotated in the forward direction to drive the valve rod to descend until the valve rod applies pressure to the valve clack again (as shown in fig. 5), the valve clack descends under the pressure of the valve rod until the valve is closed (as shown in fig. 2), and at the moment, the sealing positive pressure between the sealing pairs is usually applied by the valve rod;

(2) check of a valve operating in the check state: when the valve rod is in a certain position range, the valve can work under a non-return state, for example, after the valve clack is completely opened by adopting the method, the valve rod can be driven by reversely rotating the hand wheel to descend to a position (shown in figure 5) at which the valve clack independently falls and can be contacted with the valve seat and sealed, when the pressure and the flow of the medium input through the valve inlet are reduced to be insufficient for supporting the self gravity of the valve clack, the valve clack descends under the self gravity, when the medium flows backwards, the force for leading the valve clack to descend and be sealed with the valve seat (shown in figure 6) also comprises backflow medium pressure applied to the upper part of the valve clack, the valve is closed under the action of the force and is in the non-return state, at the moment, the sealing positive pressure between the sealing pairs usually comprises the self gravity and the backflow medium pressure, if the medium pressure input through, the valve clack can rise again under the action of the pressure difference between the inlet and the outlet, and the valve can be opened again.

As another working mode of the utility model, when the pressure of the medium input from the valve inlet is not enough to overcome the gravity of the valve clack to jack the valve clack, if the valve in the working state shown in FIG. 2 needs to be opened, the hand wheel is rotated reversely to drive the valve rod to rotate and rise, the pressure of the valve rod on the valve clack is reduced until the pressure disappears, the hand wheel is continuously rotated to drive the valve rod to continuously rise, when the valve rod rises to the state shown in figure 6, the valve rod applies upward tension to the valve clack, the valve clack rises under the action of the tension of the valve rod, the valve is opened, the medium in the lower valve cavity enters the upper valve cavity through the valve seat drift diameter of the valve seat, the opening degree of the valve is increased along with the continuous rising of the valve rod, the medium flow in the valve seat drift diameter is increased, when the valve stem rises to the upper limit of its travel (as shown in fig. 7), the valve stem cannot rise any further, at which point the valve opening reaches a maximum (as shown in fig. 7).

The utility model discloses a stop check valve adopts the lateral wall of lumen inner wall and valve clack to cooperate and fixes a position and lead the valve clack, has not only simplified the valve structure, and the processing of being convenient for has reduced the processing cost, has improved the positioning accuracy and the guide performance of valve clack moreover, has improved the sealing performance and the non return performance of valve to the adverse effect of guide structure to the medium flow has been reduced.

All use about from top to bottom in the drawing as the standard about, only for expressing facility to constitute the restriction to actual structure, the forward/reverse description that rotatory hand wheel used also only is in order to distinguish the difference of rotation direction when opening and closing, and does not constitute the restriction to actual structure or working method.

It will be appreciated by those skilled in the art that the present invention can also operate under a variety of other conditions, such as changes in media pressure, flow rate, etc., and will not be described in detail herein.

Claims

1. The stop check valve comprises a valve body, wherein a fixed valve seat and a valve clack jointly forming a valve sealing pair with the valve seat are arranged in the valve body, and the stop check valve is characterized in that a guide surface for guiding the up-and-down movement of the valve clack is arranged on the inner wall of the valve body, and the outer side wall of the valve clack is in clearance fit with the guide surface.

2. The check valve of claim 1, wherein the guide surface is a portion of a cylindrical surface that encircles the outer side wall of the valve flap at an angle of not less than 180 ° around the circumference.

3. The stop check valve according to claim 2, wherein the guide surface is provided in any one of the following ways:

(1) the guide surface is a continuous curved surface;

(3) the inner wall of the valve body is provided with a plurality of longitudinal guide bosses, curved surfaces where the top surfaces of the longitudinal guide bosses are located form the guide surfaces together, and the intervals between the longitudinal guide bosses are equal or unequal;

4. The check valve of claim 3, wherein the gap between the outer side wall of the flap and the guide surface is 1mm to 4 mm.

5. The check valve of claim 4, wherein the valve seat has an annular valve seat sealing surface, the valve flap has a circular or annular valve flap sealing surface, the valve seat sealing surface and the valve flap sealing surface together form two sealing surfaces of the valve sealing pair, the outer diameter of the valve flap sealing surface is greater than the outer diameter of the valve seat sealing surface, and the inner diameter of the valve flap sealing surface is smaller than the inner diameter of the valve seat sealing surface when the valve flap sealing surface is annular.

6. The stop check valve according to claim 5, further comprising a valve rod for driving the valve flap to move up and down, wherein the valve flap comprises a cylindrical valve flap main body with a closed lower end and an open upper end, and a valve flap top cover screwed to the upper end of the valve flap main body, a central through hole is formed in the valve flap top cover, the lower end of the valve rod is in sliding fit with the central through hole, an axial limiting device capable of limiting the valve rod to be separated from the valve flap is arranged at the lower end of the valve rod, and an upward limiting boss for limiting the upper limit of the upward stroke of the valve rod is arranged or not arranged on the valve rod.

7. The stop check valve according to claim 6, wherein the axial stop means is arranged in a manner that:

the axial limiting device is an end limiting boss arranged at the tail end of the valve rod; or,

the axial limiting device comprises an annular groove arranged on the outer cylindrical surface of the valve rod and a retaining ring embedded into the groove at the inner side edge, and the retaining ring is formed by combining a plurality of sector annular retaining blocks.

8. The stop-check valve as claimed in claim 7, further comprising a valve cap sealingly and fixedly connected to the upper portion of the valve body, the valve cap being flange-connected to the valve body and fixed thereto by a central flange fastening bolt, a central flange sealing member for sealing between the valve cap and the valve body being further provided between the valve cap and the valve body, the upper end of the valve stem being inserted into a valve cap hole of the valve cap, the valve stem being slidably fitted into at least one section of the valve cap hole, a packing box being provided at the valve cap hole and filled with packing for sealing between the valve cap and the polish rod section of the valve stem, a packing cap being provided at the top of the packing and adapted to press the packing, the packing cap being fixedly connected to the valve cap by a packing cap pressing bolt, a valve stem guide being further fixedly connected to the top of the valve cap by a bracket fixedly connected thereto, and a valve stem nut being fixed to, the valve rod nut is equipped with the external screw thread matched with internal thread with the screw rod section of valve rod, valve rod nut's internal thread with the external screw thread of screw rod section is the trapezoidal thread of mutually supporting, the upper end fixedly connected with valve drive of valve rod, valve drive includes the hand wheel, the hand wheel cup joint in on the toper section on the top of valve rod, and through with valve rod threaded connection's hand wheel nut compresses tightly and is fixed in on the valve rod, the entry and the export of valve are equipped with the entry flange and the export flange that are used for installing the valve respectively.

9. The stop check valve according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein the valve flap body and/or the valve flap top cover is provided on the outer side with a guided projection, the outer surface of the guided projection constituting the outer side wall of the valve flap, the number of the guided projection being one or several.

10. The stop check valve of claim 9, wherein the guided protrusion is a circular guided protrusion or an elongated guided protrusion, the circular ring-shaped guided boss is a circular ring-shaped boss which protrudes outwards on the outer cylindrical surface of the valve clack body and extends along the circumferential direction of the outer cylindrical surface, when the number of the circular guided bosses on the valve clack body is one, the circular guided bosses are arranged at one end close to the sealing surface of the valve clack, when the number of the guiding bosses is more than one, the guiding bosses are uniformly or non-uniformly distributed on the outer side wall of the valve clack body, the elongated guiding bosses are elongated bosses which protrude outwards on the outer cylindrical surface of the valve clack body and/or the valve clack top cover and extend along the longitudinal straight line of the outer cylindrical surface, and the plurality of elongated guiding bosses are uniformly or non-uniformly distributed on the outer cylindrical surface of the valve clack body and/or the valve clack top cover.