Plastic stop valve

Abstract

The invention relates to a plastic stop valve. The plastic stop valve is provided with a valve cover, a valve clack, a valve rod and a plastic valve body, the valve rod penetrates through the valve cover, a valve seat is arranged in the plastic valve body and provided with a valve seat opening, the valve seat opening is opposite to the valve clack located at the bottom of the valve rod, the two ends of the plastic valve body are provided with a flow inlet and a flow outlet respectively, and the flow inlet and the flow outlet are communicated with the valve seat opening. The top of the plastic valve body is provided with a valve cover connecting port matched with the valve cover, the valve cover is connected with the valve cover connecting port, the valve seat is made of polyolefin materials, the portion, making contact with the valve seat, of the valve clack is made of metal materials, the valve clack is provided with a circular truncated cone, the circular truncated cone is provided with a valve clack sealing face, and the valve clack sealing face is connected with the valve seat. The valve clack sealing face is a conical sealing face, the conical sealing face is a side face of a circular truncated cone, and the cone angle of the conical sealing face ranges from 15 degrees to 50 degrees. The product can bring more comfortable hand feeling and tighter sealing effect.

Description

Technical Field

[0001] The invention relates to a plastic stop valve. Background Art

[0002] The plastic stop valve used in conjunction with polyolefin plastic water supply pipes (PPR, PP, PE and their steel-plastic composite pipes) has the advantage of not polluting water sources. The existing plastic stop valve has a valve cover, a valve disc, a valve stem and a plastic valve body. The valve stem passes through the valve cover, and a valve seat is arranged in the plastic valve body. The valve seat has a valve seat opening opposite to the valve disc located at the bottom of the valve stem. The valve seat and the valve disc cooperate to form a sealing pair for sealing the above-mentioned valve seat opening. As for this sealing pair composed of the valve seat and the valve disc, the selection of the materials used needs to fully consider the manufacturing process, manufacturing cost, service life and other factors of the plastic stop valve. The valve seat of the existing plastic stop valve is made of polyolefin material, and the contact part of the valve disc with the valve seat is played by a rubber sheet. The sealing pair thus formed has the defects of poor wear resistance and easy to fall off, which affects the service life of the product. To this end, the applicant provides a plastic stop valve body in the Chinese utility model patent application No. 200420032750.9, the feature of which is that the valve seat is formed by a valve seat insert embedded in the plastic valve body. The valve seat insert can be made of a metal material (such as copper alloy, etc.), that is, a metal valve seat insert; the valve seat insert can also be made of a plastic material such as polyoxymethylene or nylon, ultra-high molecular weight polyethylene, that is, a plastic valve seat insert; in addition, other wear-resistant materials can also be used to make the above-mentioned valve seat insert. Since an independent valve seat insert is specially provided in the technical solution, the wear resistance of the plastic stop valve body at the valve seat part can be better, which is conducive to enhancing the sealing performance of the plastic stop valve and ensuring that the product has a sufficiently long service life. However, it is undeniable that: although the use of an independent valve seat insert can ensure the wear resistance of the valve seat part, it increases the manufacturing difficulty of the plastic stop valve, correspondingly increases the manufacturing cost of the plastic stop valve, and still cannot solve the problem of the rubber sheet on the valve disc falling off.

[0003] Therefore, Chinese invention patent 200610059024.X proposes a manufacturing scheme for a plastic stop valve, which provides a plastic stop valve that is relatively simple to manufacture and can ensure the sealing performance and service life of the product by optimizing the materials of the valve seat and valve disc in the plastic stop valve.

[0004] In the scheme of Chinese invention patent 200610059024.X, although metal material is selected as the material of the contact part between the valve disc and the valve seat, a plastic stop valve with simple and convenient manufacturing, satisfactory wear resistance and sealing performance of the valve seat and long product service life is obtained. However, when the valve is closed, that is, when the valve disc contacts the valve seat, there is a "hard" feeling. That is to say, when the valve disc contacts the valve seat, the rubber sheet on the valve disc has a certain elasticity before, and the rubber sheet contacts the valve seat. When the sealing is completed, further pressure can be applied by rotating the handle to make the contact part of the rubber sheet and the valve seat deform under pressure, which not only brings a more comfortable hand feel, but also can bring a tighter sealing effect. When the metal material of the valve disc contacts the valve seat, the metal material is "harder" than the rubber sheet and cannot be deformed under pressure. When the metal material contacts the valve seat to complete the sealing, although the valve seat is made of plastic material, the deformation range is also "smaller" than the rubber sheet. That is, although the valve seat made of plastic material will be deformed by the extrusion of the metal material, the deformation range can be ignored. The result is that when the seal is completed, the part where the metal material of the valve disc contacts the valve seat cannot be further pressured by the user's normal force to rotate the handle to make it "largely" deformed like a rubber sheet, so that the contact cannot be closer or more complete. In other words, the solution of Chinese invention patent 200610059024.X cannot further apply pressure by rotating the handle to bring a more comfortable feel and a tighter sealing effect.

[0005] Therefore, it is necessary to make further improvements to the existing plastic stop valve. Summary of the invention

[0006] The purpose of the present invention is to provide a plastic stop valve which is relatively simple to manufacture and has a more comfortable feel and a tighter sealing effect while ensuring the sealing performance and service life of the product by further optimizing the valve disc in the plastic stop valve.

[0007] The basic concept of the present invention is:

[0008] According to the "Practical Valve Design Manual" published by the Machinery Industry Press / Edited by Lu Peiwen, 4th edition, 2020.5, the 4th edition was first printed in August 2020. Chapter 6 Valve Structural Elements, Chapter 6.3 Conical Sealing Surface Dimensions. That is, page 1276 of the "Practical Valve Design Manual", 6.3 Conical Sealing Surface Dimensions, records: Structural type and size of the conical sealing surface... (as shown on page 1276 of the "Practical Valve Design Manual"). The... indicates that the cone angle of the conical sealing surface is 60°. Therefore, the applicant believes that those skilled in the art, in accordance with the teachings of the prior art, reasonably concluded that the cone angle of the conical sealing surface should be 60°.

[0009] Although the above-mentioned Practical Valve Design Manual does not explicitly exclude plastic valve seats, the valve disc and valve seat of the stop valve design scheme recorded in the manual are made of metal. (The valve seat can be a metal valve seat installed separately)

[0010] The closure of existing metal valves is achieved by the cooperation of the valve disc and the valve seat. In the long-term cooperation, the metal valve disc and the metal valve seat will wear each other and cause damage. Any deformation of either will cause the seal to fail.

[0011] The closing of the stop valve with metal valve disc and plastic valve seat is also achieved by matching. However, the opening of the plastic valve seat is easily out of round due to the influence of environment and temperature. In actual use, the metal valve disc squeezes the plastic valve seat, causing the opening of the plastic valve seat to deform to adapt to the metal valve disc, thereby achieving sealing.

[0012] That is to say, the plastic valve seat is deformed by the influence of climate and other environmental factors, and this deformation affects the sealing quality.

[0013] Under normal circumstances, the plastic valve seat will not cause damage to the metal valve disc. On the contrary, when the stop valve is closed, the metal valve disc squeezes the plastic valve seat, which can deform the plastic valve seat and make the plastic valve seat adapt to the metal valve disc through deformation. This deformation is beneficial to the sealing of the valve disc and the valve seat. Changing the angle of the valve disc can better deform the valve seat, which is more conducive to sealing. This deformation is divided into two parts, one is elastic deformation and the other is plastic deformation. Both deformations are beneficial to sealing.

[0014] In other words, as long as it is handled properly, every squeeze of the valve disc on the valve seat is a repair of the seal.

[0015] The correct selection of the angle of the metal valve disc (i.e. the cone angle of the conical sealing surface of the metal valve disc) is creative. Because if the angle of the metal valve disc (i.e. the cone angle of the conical sealing surface of the metal valve disc) is too sharp, there are two disadvantages. One is that it may pass through the opening of the plastic valve seat, and the other is that the stroke of the valve disc is increased. If the angle of the metal valve disc is too blunt, it will make it difficult for the opening of the plastic valve seat to deform and cannot adapt to the metal valve disc well. Therefore, the angle of the metal valve disc needs to be selected so that the opening of the plastic valve seat can be deformed appropriately, but it will not easily pass through the opening of the valve seat, so as to achieve more effective sealing.

[0016] Regarding increasing the stroke of the metal valve disc, the explanation is as follows:

[0017] During the valve closing process, the metal disc will go through the following stages: approaching the plastic seat opening, contacting the plastic seat opening, entering the plastic seat opening, squeezing the plastic seat opening to deform it, etc. For the same deformation of the plastic seat opening, the smaller the angle of the metal disc, that is, the sharper the metal disc, the longer the stroke.

[0018] In summary, based on the sealing pair of the metal valve disc and the plastic valve seat, the selection of the angle of the metal valve disc (i.e. the cone angle of the conical sealing surface of the metal valve disc) has the creativity stipulated in Article 22, Paragraph 2 of the Patent Law.

[0019] On this basis, the present invention adjusts the cone angle of the conical sealing surface to 15° to 50°. In this way, the processing difficulty of the valve disc remains basically unchanged, but the entire valve disc appears to be more "sharp", which allows the user to rotate the handle with normal force to drive the valve disc downward to close the valve seat, so that the conical sealing surface of the valve disc completes the seal with the valve seat, and can further rotate the handle to allow the valve disc to drill into the valve seat opening a short distance more easily, so that the contact surface of the conical sealing surface of the valve disc and the valve seat is more closely and fully contacted, thereby bringing a tighter sealing effect, and can bring a similar feel as when the rubber valve disc is squeezed and deformed in the prior art.

[0020] When the user rotates the handle to allow the valve disc to easily drill into the valve seat opening a short distance, the drilling process will make the contact surface of the valve disc conical sealing surface and the valve seat more closely and fully contacted. Correspondingly, the force of rotating the handle will increase due to the closer and more fully contacted contact surface, until the normal hand strength of an ordinary user, so this process has a certain "stroke", which depends on the deformation of the valve seat plastic material. Over time, the plastic will creep, and then this "stroke" will change again, but also within a very small range. Because even if the plastic creeps, the user rotates the handle to allow the valve disc to drill into the valve seat opening a short distance again (about 0.2 to 0.5 mm), the contact surface of the valve disc conical sealing surface and the valve seat will be closely and fully contacted again to achieve a tighter sealing effect.

[0021] The cone angle of the conical sealing surface of the valve disc described in the present invention is adjusted to 15° to 50°, which not only satisfies the user's feeling of "stroke" when rotating the handle, that is, brings a more comfortable hand feel, but also makes the contact surface of the conical sealing surface of the valve disc and the valve seat closer and more fully contact, thereby achieving a tighter sealing effect.

[0022] Specifically, the plastic stop valve of the present invention comprises a valve cover, a valve disc, a valve stem and a plastic valve body, wherein the valve stem passes through the valve cover, a valve seat is arranged in the plastic valve body, the valve seat has a valve seat opening, the valve seat opening is opposite to the valve disc located at the bottom of the valve stem, the two ends of the plastic valve body respectively have an inlet and an outlet connected to the valve seat opening, the top of the plastic valve body has a valve cover connecting port matched with the valve cover, the valve cover is connected to the valve cover connecting port, the valve seat is made of polyolefin material, the contact part of the valve disc with the valve seat is made of metal material, the valve disc has a truncated cone, the truncated cone has a valve disc sealing surface, the valve disc sealing surface is a conical sealing surface, the conical sealing surface is the side of the truncated cone, and the cone angle of the conical sealing surface is 15° to 50°.

[0023] The cone angle of the conical sealing surface of the present invention is 15° to 50°, that is, it can be between 15° and 45°, between 15° and 40°, between 15° and 35°, and between 20° and 35°. Of course, the cone angle can also be 30°. Further preferably, the cone angle of the conical sealing surface of the present invention can also be between 20° and 50°, between 25° and 50°, between 30° and 50°, between 35° and 50°; between 20° and 45°, between 25° and 45°, between 30° and 45°, between 35° and 45°; between 20° and 40°, between 25° and 40°, between 30° and 40°, between 35° and 40°. After experiments, the applicant found that as long as the cone angle of the conical sealing surface is 5° less than 60°, the sealing effect will be significantly improved. In other words, the closing torque is reduced.

[0024] Since the valve stem and the valve disc are movably connected, this connection allows the valve disc to move in a small range relative to the valve stem. When the valve is closed, the small end of the valve disc enters the valve seat opening. During the valve closing process, the valve disc with a taper can automatically align and smoothly enter the valve seat opening when it cooperates with the valve seat opening. However, in the present invention, the cone angle of the valve disc cone is reduced, that is, when the diameter of the large end of the cone of the valve disc and the height of the cone remain unchanged, the small end of the cone of the valve disc becomes larger. The applicant is worried that the valve disc will not be able to smoothly enter the valve seat opening, so a guide section can be provided at the small end of the cone. That is to say, the cone of the valve disc described in the present invention can be divided into two sections, one section is a sealing section; the other section is a sealing guide section. When the cone of the valve disc is divided into two sections, the large end is a sealing section, and the small end is a sealing guide section. The two sections are a whole and have a smooth transition. As long as the cone angle of the small end section is smaller than the cone angle of the large end section, it can play a guiding role.

[0025] The side of the sealing section is a conical sealing surface, and the side of the sealing guide section is a valve flap sealing guide surface. The valve flap sealing guide surface is a conical guide surface, and the conical guide surface is closer to the valve seat opening than the conical sealing surface. That is, when the user rotates the handle to close the stop valve of the present invention, the conical guide surface first enters the valve seat opening to play a guiding role, and then the conical sealing surface enters the valve seat opening to form a seal with the contact surface of the valve seat. The conical sealing surface and the conical guide surface have different cone angles. The cone angle of the conical sealing surface can be 15° to 50°, and the cone angle of the conical guide surface can be 60° to 90°.

[0026] That is to say, the valve flap may also have a valve flap sealing guide surface, and the valve flap sealing guide surface is a conical guide surface, and the conical guide surface is also the side of a truncated cone. The conical guide surface is located on the side close to the small end of the truncated cone, and the cone angle of the conical guide surface can be 60° to 90°, as long as the conical guide surface can smoothly guide the conical sealing surface of the valve flap into the valve seat opening.

[0027] In this way, when the user rotates the handle to make the conical sealing surface of the valve disc contact the valve seat, even if there is looseness caused by the matching gap between the valve stem and the valve disc, the conical guide surface can effectively guide the conical sealing surface of the valve disc to align with the valve seat opening and smoothly enter the valve seat opening, thereby allowing the conical sealing surface and the contact surface of the valve seat to fully contact.

[0028] In the present invention, the polyolefin material for making the valve seat can be polyethylene material, polypropylene material, polybutylene material, etc. Of course, when necessary, fillers, dyes and other additives can be added to the above polyolefin material in appropriate amounts. That is to say, the above polyolefin material described in the present invention does not specifically refer to polyolefin materials with a purity of 100%. In addition, in addition to the valve seat being made of polyolefin material, the present invention also recommends that the entire valve body be made of polyolefin material, which is conducive to simplifying the production of the valve body and reducing the production cost of the product. In the present invention, the contact part of the valve disc with the valve seat is made of metal material, and the metal material used can be copper or copper alloy, stainless steel, aluminum alloy and other metal materials that are not easy to rust. When copper alloy is selected, the copper alloy can be aluminum brass or aluminum bronze, manganese brass and the like.

[0029] In the present invention, only the portion of the valve flap that contacts the valve seat may be made of metal material, or the entire valve flap may be made of metal material.

[0030] It has been verified in practice that in plastic stop valves with smaller diameters, copper alloy materials can be directly used to make the contact part between the valve disc and the valve seat. However, in plastic stop valves with larger diameters, the strength of copper alloy materials will be insufficient and the price will be too high. In this case, stainless steel such as 1Cr13, 2Cr13 and 3Cr13 and other metal materials with higher strength and no corrosion should be selected to make the contact part between the valve disc and the valve seat.

[0031] In the present invention, the valve cover connection port can be a hot-melt connection port with a plastic surface. The valve cover connection port can be hot-melt connected to the valve cover in a hot-melt socket connection manner.

[0032] During the injection molding process, the valve body shrinks and deforms, and this deformation makes the consistency of the valve body not very good. In other words, due to shrinkage, there are some differences in the geometric dimensions of each valve body, and this difference brings some difficulties to the subsequent assembly. Therefore, the subsequent assembly can be "grouped assembly". In other words, after the valve body is injection molded, it is grouped according to the geometric dimensions of the valve body and the assembly needs. In this way, the consistency of the valve body in each group is improved. Then assemble.

[0033] In the present invention, a downwardly concave portion lower than the lower wall of the inlet flow channel may be provided in the flow channel below the valve seat, and the bottom of the downwardly concave portion is formed by a bottom cover integrally spliced ​​and connected with the plastic valve body.

[0034] In the present invention, the outer edge side wall of the bottom cover can be matched with and fixedly connected to the inner side wall of the downwardly concave portion of the plastic valve body.

[0035] In the present invention, the inlet and outlet can be respectively a hot-melt socket-type inlet and a hot-melt socket-type outlet, the inner walls of which are made of plastic material.

[0036] It is worth noting that the applicant conducted tests in accordance with the JB / T8859--2004 standard of the People's Republic of China "Static Pressure Life Test Procedure for Stop Valves". When the valve seat is made of polypropylene material and the valve flap with a conical sealing surface is made of cast aluminum brass copper alloy or stainless steel, the plastic stop valve can be used normally without leakage when the number of opening and closing times of the stop valve reaches 100,000 times. After that, the plastic stop valve was disassembled and the valve seat was sliced ​​and tested, and no damage was found. Compared with ordinary metal valves, this is already a very excellent quality.

[0037] Compared with the above-mentioned existing similar products, the plastic stop valve of the present invention can bring a more comfortable feel and a tighter sealing effect. In other words, the closing torque is smaller.

[0038] The content of the present invention is further described in conjunction with the following examples, but the content of the present invention is not limited to the content involved in the examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the plastic stop valve in Example 1.

[0040] Figure 2 yes Figure 1 Schematic diagram of the valve disc structure of the plastic stop valve.

[0041] Figure 3 yes Figure 1 Schematic diagram of the valve disc structure of the plastic stop valve.

[0042] Figure 4 yes Figure 1 Schematic diagram of the contact seal between the valve disc and the valve seat of the plastic stop valve.

[0043] Figure 5 yes Figure 1 Schematic diagram of the contact seal of the valve disc of the plastic stop valve drilled into the valve seat with a 0.5 mm opening.

[0044] Figure 6 Schematic diagram of the valve body structure of the plastic stop valve in Example 2.

[0045] Figure 7 It is a schematic diagram of the appearance structure of the valve body of the plastic stop valve in Example 2.

[0046] Figure 8 yes Figure 7 Schematic diagram of direction A.

[0047] Fig. 9 yes Figure 7 Schematic diagram of direction B.

[0048] Fig.10 yes Figure 7 Schematic diagram of CC cross-section.

[0049] Fig.11 Schematic diagram of the valve disc structure used in the plastic stop valve in Example 2.

[0050] Fig.12 Schematic diagram of the valve disc structure used in the plastic stop valve in Example 2.

[0051] Fig.13 Schematic diagram of the valve flap structure of the plastic stop valve in Example 3.

[0052] Fig.14 Schematic diagram of the valve flap structure of the plastic stop valve in Example 3.

[0053] Fig.15Schematic diagram of the valve flap structure of the plastic stop valve in Example 4.

[0054] Fig.16 Schematic diagram of the valve flap structure of the plastic stop valve in Example 5.

[0055] Fig.17 Schematic diagram of the valve flap structure of the plastic stop valve in Example 6.

[0056] Fig.18 Schematic diagram of the valve flap structure of the plastic stop valve in Example 7.

[0057] Fig.19 Schematic diagram of the contact seal between the valve disc and the valve seat of the plastic stop valve in Example 7.

[0058] Fig. 20 Schematic diagram of the valve flap structure of the plastic stop valve in Example 8.

[0059] Fig.21 Schematic diagram of the valve flap structure of the plastic stop valve in Example 9.

[0060] Fig. 22 Schematic diagram of the valve flap structure of the plastic stop valve in Example 10.

[0061] Fig.23 Schematic diagram of the valve flap structure of the plastic stop valve in Example 11.

[0062] Fig.24 It is a schematic structural diagram of the plastic stop valve in Example 12.

[0063] Fig.25 It is a schematic diagram of the contact and sealing between the valve disc and the valve seat when the plastic stop valve is closed in Example 12.

[0064] Fig.26 It is a schematic diagram of the valve flap structure of the plastic stop valve in Example 12.

[0065] Fig. 27 yes Fig.26 Schematic diagram of the cross-sectional structure. DETAILED DESCRIPTION

[0066] Example 1: Figures 1 to 5As shown, the plastic stop valve in this embodiment has a valve cover 1, a valve disc 2, a valve stem 3 and a plastic valve body 4, the valve stem 3 passes through the valve cover 1, and a valve seat 5 is arranged in the plastic valve body 4, the valve seat 5 has a valve seat opening 6, and the valve seat opening 6 is opposite to the valve disc 2 located at the bottom of the valve stem, and the two ends of the plastic valve body 4 respectively have an inlet 7 and an outlet 8 connected to the valve seat opening 6, the top of the plastic valve body 4 has a valve cover connecting port 9 matched with the valve cover 1, and the valve cover 1 is connected to the valve cover connecting port 9, the valve seat 5 is made of polyolefin material, and the contact part 10 of the valve disc 2 with the valve seat is made of metal material, the valve disc has a frustum 11, and the frustum has a valve disc sealing surface, and the valve disc sealing surface is a conical sealing surface, and the conical sealing surface is the side of the frustum, and the cone angle of the conical sealing surface is 15° to 50°.

[0067] The contact portion 10 of the valve flap 2 with the valve seat is a conical sealing surface.

[0068] In this embodiment, the cone angle of the conical sealing surface is 30°.

[0069] In this embodiment, the polyolefin material used to make the valve seat 5 is polyethylene material, the valve seat 5 is made of the same material as the plastic valve body 4 and is injection molded together with the plastic valve body, and the contact portion 10 of the valve flap 2 with the valve seat is made of a metal material, namely, cast aluminum brass copper alloy. Here, the entire valve flap is made of the copper alloy material.

[0070] In addition, the contact portion 10 of the valve flap 2 with the valve seat may be made of cast aluminum bronze type copper alloy or cast manganese brass type copper alloy, thereby forming a new embodiment. At the same time, the polyolefin material used to make the valve seat 5 may be replaced with polypropylene or polybutylene material, thereby forming a new embodiment.

[0071] In this embodiment, the valve cover connection port 9 is a hot-melt connection port with a plastic surface, the plastic surface of the valve cover connection port 9 is also made of the same material as the plastic valve body 4, and is molded together with the plastic valve body 4. The valve cover connection port 9 is hot-melt connected to the valve cover 1 in a hot-melt socket connection manner.

[0072] As mentioned above, the valve cover 1 in this embodiment is a plastic valve cover.

[0073] like Figure 5 As shown, in this embodiment, the user rotates the handle to allow the valve disc to drill into the valve seat opening by 0.2 to 0.5 mm, which can make the contact surface of the valve disc conical sealing surface and the valve seat contact more closely and fully, thereby bringing a tighter sealing effect and a more comfortable hand feel.

[0074] Example 2: Figure 6 , Figure 7 , Figure 8 , Fig. 9 , Fig.10 , Fig.11 , Fig.12 As shown, this embodiment is similar to the embodiment 1, except that a, b, c in the valve body of the plastic stop valve in this embodiment are arcs; R2 in the valve body is the radius of the arcs d, e, f. R1 is the radius of the arcs g, h, j. R1 and R2 are equal or similar. Fig.11 , Fig.12 As shown, the cone angle of the conical sealing surface of the valve disc in this embodiment is 15°.

[0075] Example 3: Fig.13 , Fig.14 As shown, this embodiment is similar to Embodiment 1, except that the cone angle of the conical sealing surface of the valve disc in this embodiment is 50°.

[0076] Example 4: Fig.15 As shown, this embodiment is similar to Embodiment 1, except that the cone angle of the conical sealing surface of the valve disc in this embodiment is 35°.

[0077] Example 5: Fig.16 As shown, this embodiment is similar to Embodiment 1, except that the cone angle of the conical sealing surface of the valve disc in this embodiment is 40°.

[0078] Example 6: Fig.17 As shown, this embodiment is similar to Embodiment 1, except that the cone angle of the conical sealing surface of the valve disc in this embodiment is 45°.

[0079] Example 7: Fig.18 , Fig.19 As shown, this embodiment is similar to embodiment 1, except that the valve flap in this embodiment further has a valve flap sealing guide surface, and the valve flap sealing guide surface is a conical guide surface 12, and the conical guide surface is also the side of a truncated cone, and the conical guide surface is located on the side close to the small end of the truncated cone, and the cone angle of the conical guide surface 12 is 60°.

[0080] Example 8: Fig. 20 As shown, this embodiment is similar to Embodiment 7, except that in this embodiment, the cone angle of the conical sealing surface of the valve disc is 35°, and the cone angle of the conical guide surface 12 is 90°.

[0081] Example 9: Fig.21 As shown, this embodiment is similar to Embodiment 7, except that in this embodiment, the cone angle of the conical sealing surface of the valve disc is 40°, and the cone angle of the conical guide surface 12 is 60°.

[0082] Example 10: Fig. 22As shown, this embodiment is similar to Embodiment 7, except that in this embodiment, the cone angle of the conical sealing surface of the valve disc is 45°, and the cone angle of the conical guide surface 12 is 90°.

[0083] Example 11: Fig.23 As shown, this embodiment is similar to Embodiment 7, except that in this embodiment, the cone angle of the conical sealing surface of the valve disc is 50°, and the cone angle of the conical guide surface 12 is 90°.

[0084] Example 12: Fig.24 , Fig.25 , Fig.26 , Fig. 27 As shown, this embodiment is similar to embodiment 7, except that in this embodiment, another structural form of valve flap is adopted, the cone angle of the conical sealing surface of the valve flap is 40°, and the cone angle of the conical guide surface 12 is 60°.

Claims

1. A plastic stop valve, comprising a valve cover, a valve disc, a valve stem and a plastic valve body, wherein the valve stem passes through the valve cover, a valve seat is arranged in the plastic valve body, the valve seat has a valve seat opening, the valve seat opening is opposite to the valve disc located at the bottom of the valve stem, the two ends of the plastic valve body respectively have an inlet and an outlet connected to the valve seat opening, the top of the plastic valve body has a valve cover connecting port matched with the valve cover, the valve cover is connected to the valve cover connecting port, the valve seat is made of polyolefin material, the contact portion of the valve disc with the valve seat is made of metal material, and the characteristic is that The valve flap has a valve flap sealing surface, which is a conical sealing surface. The conical sealing surface is the side surface of a truncated cone, and the cone angle of the conical sealing surface is 15° to 50°.

2. The plastic stop valve according to claim 1, characterized in that The cone angle of the conical sealing surface is between 15° and 45°.

3. The plastic stop valve according to claim 1, characterized in that The cone angle of the conical sealing surface is between 20° and 45°.

4. The plastic stop valve according to claim 1, characterized in that The cone angle of the conical sealing surface is between 15° and 40°.

5. The plastic stop valve according to claim 1, characterized in that The cone angle of the conical sealing surface is between 20° and 40°.

6. The plastic stop valve according to claim 1, characterized in that The cone angle of the conical sealing surface is between 15° and 35°.

7. The plastic stop valve according to claim 1, characterized in that The cone angle of the conical sealing surface is between 20° and 35°.

8. The plastic stop valve according to claim 1, characterized in that The cone angle of the conical sealing surface is 30°.

9. The plastic stop valve according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8, characterized in that The valve flap also has a valve flap sealing guide surface, which is a conical guide surface. The conical guide surface is also the side surface of the truncated cone, and the conical guide surface is located on the side surface close to the small end of the truncated cone.

10. The plastic stop valve according to claim 9, characterized in that The cone angle of the tapered guide surface is 60° to 90°.

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