Linkage mechanism of limit switch and pneumatic valve positioner

Abstract

The utility model provides a linkage mechanism of a limit switch and a pneumatic valve positioner, which comprises a metal support, the pneumatic valve positioner, the limit switch and a connecting rod, a step portion of a transmission shaft of the positioner is connected with a first transmission plate through a first clamp spring, and one end of the first transmission plate is hinged with one end of the connecting rod. A limiting switch base is arranged on the other side of the inner cavity of the metal support, a limiting switch transmission shaft is arranged in the limiting switch base, the step portion of the limiting switch transmission shaft is connected with a second transmission plate through a second clamping spring, and the second transmission plate is hinged to the other end of the connecting rod. According to the technical scheme, the integral support is adopted, namely, the metal support is of an integral structure and is not divided into two parts, the structure is simple, strength is high, deformation is not prone to occurring in the machining process, bolts do not need to be screwed between the two supports, and assembling is simplified; torque is transmitted through the positioner transmission shaft, the positioner base does not participate in transmission, transmission through several sheets in the prior art is avoided, and reliability is greatly improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of valve control, and relates to a linkage mechanism of a limit switch and a pneumatic valve positioner. Background Technique

[0002] When the control system needs to know the precise valve position, a limit switch is generally installed. Moreover, since the valve position can be monitored in real time, the safety of the system can be improved; in order to ensure a certain valve control accuracy and improve the flow characteristics, a positioner is installed on the basis of the limit switch. To install both the positioner and the limit switch on the pneumatic actuator of the valve, a special device for the linkage between the two is required. While the positioner controls the valve, it needs to feedback the valve position to the limit switch so that the control system knows whether the valve is open or closed; the transmission structure of the existing technical solutions (as Figure 4 shown) is relatively complex. The bracket is divided into two parts, and the structure of each bracket is relatively complex. The structure of one of the brackets is in the shape of "匚", and the two brackets need to be bolted together; the transmission parts between the positioner and the actuator are also divided into two parts, namely the base and the transmission shaft; the connecting rod is designed in three parts, and in order to assemble it, threads need to be machined.

[0003] Disadvantages of the Existing Technical Solutions

[0004] (1) The bracket structure is complex, with low stiffness, easy to deform, not easy to drill holes, and high assembly cost. The bracket is divided into two parts, and the structure of each bracket is relatively complex. The structure of one of the brackets is in the shape of "匚", so the overall stiffness of such a structure is relatively low. It is easy to deform under the influence of the cutting force during drilling, and it is difficult to ensure that the installation plane of the limit switch remains horizontal and is prone to tilt, which is not conducive to the correct installation of the limit switch. The two brackets also need to be bolted together, increasing the assembly cost.

[0005] (2) The transmission parts between the positioner and the actuator have a complex structure and unreliable transmission. The transmission parts between the positioner and the actuator are also divided into two parts, namely the base and the transmission shaft, which is obviously unreasonable. When the valve moves, there will be torque passing through the thin sheet of the transmission shaft, and since there is a through hole in the transmission shaft, the thin sheet is divided into 4 pieces, so the stiffness is obviously very low, and it is easy to fatigue and fail during long-term torque transmission. The connecting rod is designed in three parts and requires machining of threads, increasing unnecessary manufacturing difficulty. The bearing is completely unnecessary. In practice, it shows that the torque for opening and closing the valve is completely sufficient to overcome the resistance and drive the transmission shaft. Summary of the Invention

[0006] The purpose of the utility model is to provide a linkage mechanism of a limit switch and a pneumatic valve positioner to solve the problems raised in the above background technique.

[0007] The purpose of the utility model can be achieved through the following technical solutions: a linkage mechanism of a limit switch and a pneumatic valve positioner, comprising a metal bracket, a pneumatic valve positioner, a limit switch and a connecting rod, the top two sides of the metal bracket are respectively threadedly fastened with the pneumatic valve positioner and the limit switch by bolt fasteners, a positioner base is arranged on one side of the inner cavity of the metal bracket, a positioner connecting shaft is arranged on the top of the positioner base, a step portion of the positioner connecting shaft is connected to a first transmission plate through a first retaining spring, one end of the first transmission plate is hinged to one end of the connecting rod, a limit switch base is arranged on the other side of the inner cavity of the metal bracket, a limit switch transmission shaft is arranged inside the limit switch base, the step portion of the limit switch transmission shaft is connected to a second transmission plate through a second retaining spring, and the second transmission plate is hinged to the other end of the connecting rod.

[0008] In the above-mentioned linkage mechanism of the limit switch and the pneumatic valve positioner, the bottom of the positioner connecting shaft is provided with an actuator accessory interface correspondingly connected to the positioner base.

[0009] In the above-mentioned linkage mechanism of the limit switch and the pneumatic valve positioner, the positioner connecting shaft and the limit switch transmission shaft respectively pass through the metal bracket and are transmission-connected with the pneumatic valve positioner and the limit switch.

[0010] In the above-mentioned linkage mechanism of the limit switch and the pneumatic valve positioner, the metal bracket is fastened to the positioner base and the limit switch base by bolts.

[0011] In the above-mentioned linkage mechanism of the limit switch and the pneumatic valve positioner, both ends of the connecting rod are provided with hinge joint mounting holes with a diameter of five millimeters.

[0012] Compared with the prior art, the linkage mechanism of the limit switch and the pneumatic valve positioner of the utility model has the following advantages: the technical solution adopts an integral bracket, that is, the metal bracket is an integral structure and is not divided into two, with a simple structure and high strength, and is not easy to deform during processing. There is no need to tighten bolts between the two brackets, which simplifies assembly; the torque is transmitted through the positioner connecting shaft, and the positioner base does not participate in the transmission, especially it is not transmitted through several thin sheets like the prior art solution, which greatly improves the reliability; the connecting rod of the linkage part between the positioner and the limit switch adopts an integrated design, which avoids thread processing, reduces the processing difficulty, and improves reliability; the limit switch transmission shaft of the technical solution does not have a bearing at the bottom, and the valve torque is very large. Practice shows that the torque can be smoothly transmitted without a bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The utility model is a schematic diagram of the structure of the linkage mechanism of the limit switch and the pneumatic valve positioner.

[0014] Figure 2 It is a linkage mechanism of the utility model limit switch and pneumatic valve positioner Figure 1 Schematic diagram of the top view structure.

[0015] Figure 3 The utility model is a schematic diagram of the structure of the limit switch and the linkage mechanism connecting rod of the pneumatic valve positioner.

[0016] Figure 4 It is a structural diagram of the linkage mechanism of the prior art.

[0017] In the figure, 1. metal bracket; 2. pneumatic valve positioner; 3. limit switch; 4. actuator accessory interface; 5. positioner base; 6. positioner connecting shaft; 7. first transmission plate; 8. first retaining spring; 9. limit switch base; 10. limit switch transmission shaft; 11. second transmission plate; 12. second retaining spring; 13. connecting rod. DETAILED DESCRIPTION

[0018] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0019] like Figure 1 , Figure 2 and Figure 3 As shown, the linkage mechanism of the limit switch and the pneumatic valve positioner of the utility model;

[0020] Embodiment: It includes a metal bracket 1, a pneumatic valve positioner 2, a limit switch 3 and a connecting rod 13. The top two sides of the metal bracket 1 are threadedly fastened with the pneumatic valve positioner 2 and the limit switch 3 by bolt fasteners respectively. A positioner base 5 is arranged on one side of the inner cavity of the metal bracket 1, and a positioner connecting shaft 6 is arranged on the top of the positioner base 5. The step portion of the positioner connecting shaft 6 is connected to the first transmission plate 7 through the first retaining spring 8, and one end of the first transmission plate 7 is hinged to one end of the connecting rod 13. A limit switch base 9 is arranged on the other side of the inner cavity of the metal bracket 1, and a limit switch transmission shaft 10 is arranged inside the limit switch base 9. The step portion of the limit switch transmission shaft 10 is connected to the second transmission plate 11 through the second retaining spring 12, and the second transmission plate 11 is hinged to the other end of the connecting rod 13.

[0021] Wherein: the positioner connecting shaft 6 and the limit switch transmission shaft 10 of the present technical solution pass through the metal bracket 1 respectively and are transmission-connected with the pneumatic valve positioner 2 and the limit switch 3 .

[0022] In this embodiment, in order to better connect with the accessories of the pneumatic actuator so that the torque can be transmitted to the pneumatic valve positioner 2, the bottom of the positioner connecting shaft 6 is provided with an actuator accessory interface 4 corresponding to the positioner base 5.

[0023] In this embodiment, in order to improve the firmness of the installation, the metal bracket 1 is fastened to the positioner base 5 and the limit switch base 9 by bolts.

[0024] In this embodiment, in order to facilitate the hinge connection between the connecting rod 13 and the first transmission plate 7 and the second transmission plate 11, hinge joint mounting holes with a diameter of five millimeters are provided at both ends of the connecting rod 13.

[0025] Working principle: When the valve is actuated, the torque is transmitted to the positioner connecting shaft 6 through the accessory interface on the pneumatic actuator, and then transmitted to the pneumatic valve positioner 2 and the first transmission plate 7 through the positioner connecting shaft 6. The first transmission plate 7 is transmitted to the second transmission plate 11 through the connecting rod 13, and the second transmission plate 11 is transmitted to the limit switch transmission shaft 10. The limit switch transmission shaft 10 is finally transmitted to the limit switch 3, realizing the linkage of the pneumatic valve positioner 2 and the limit switch 3, so as to monitor the opening and closing status of the valve in real time, and the control system in turn uses the pneumatic valve positioner 2 to accurately control the valve.

[0026] Pneumatic Valve Positioners and Limit Switches:

[0027] The lower part of the positioner connecting shaft 6 is directly connected to the actuator accessory interface 4, and the upper part passes through the positioner base 4 and is connected to the pneumatic valve positioner 2, and then is limited by the positioner base 5 to prevent the positioner connecting shaft 6 from being separated from the actuator accessory interface 4 during use, and the positioner base 5 is fixed to the pneumatic actuator with bolts; in actual production, a certain gap is left between the positioner base 5 and the positioner connecting shaft 6, and also between the accessory interface and the positioner base 5, so that normal transmission is not affected; similarly, the lower part of the limit switch transmission shaft 10 is limited by the limit switch base 9, and similarly there is a gap between the limit switch transmission shaft 10 and the limit switch base 9 that does not affect transmission.

[0028] The contents not described in detail in this specification belong to the prior art known to the professional and technical personnel in this field. The specific embodiments described in this article are only used to illustrate the spirit of the utility model. The technicians in the technical field of the utility model can make various modifications or supplements to the specific embodiments described or replace them in a similar way, but they will not deviate from the spirit of the utility model or exceed the scope defined by the attached claims.

Claims

1. A linkage mechanism of a limit switch and a pneumatic valve positioner, comprising a metal bracket (1), a pneumatic valve positioner (2), a limit switch (3) and a connecting rod (13), characterized in that: The top sides of the metal bracket (1) are respectively threadedly fastened with the pneumatic valve positioner (2) and the limit switch (3) by bolt fasteners; a positioner base (5) is arranged on one side of the inner cavity of the metal bracket (1); a positioner connecting shaft (6) is arranged on the top of the positioner base (5); a step portion of the positioner connecting shaft (6) is connected to a first transmission plate (7) by a first retaining spring (8); one end of the first transmission plate (7) is hinged to one end of a connecting rod (13); a limit switch base (9) is arranged on the other side of the inner cavity of the metal bracket (1); a limit switch transmission shaft (10) is arranged inside the limit switch base (9); a step portion of the limit switch transmission shaft (10) is connected to a second transmission plate (11) by a second retaining spring (12); the second transmission plate (11) is hinged to the other end of the connecting rod (13).

2. The linkage mechanism of the limit switch and the pneumatic valve positioner according to claim 1, characterized in that: The bottom of the positioner connecting shaft (6) is provided with an actuator attachment interface (4) correspondingly connected to the positioner base (5).

3. The linkage mechanism of the limit switch and the pneumatic valve positioner according to claim 1, characterized in that: The positioner connecting shaft (6) and the limit switch transmission shaft (10) respectively pass through the metal bracket (1) and are transmission-connected to the pneumatic valve positioner (2) and the limit switch (3).

4. The linkage mechanism of the limit switch and the pneumatic valve positioner according to claim 1, characterized in that: The metal bracket (1) is fastened to the positioner base (5) and the limit switch base (9) by bolts.

5. The linkage mechanism of the limit switch and the pneumatic valve positioner according to claim 1, characterized in that: Both ends of the connecting rod (13) are provided with hinge joint installation holes with a diameter of five millimeters.

Images