JPS5868580A - Abnormality-diagnosis device for valve - Google Patents

Abstract

PURPOSE:To diagnose the abnormality of a valve due to a delay of operation caused by a frictional force between a valve rod and a gland packing or the like, by a method wherein air is supplied to a driving member for the valve rod, and the pressure of air and the displacement of the rod are detected, in pneumatically operated type control valve. CONSTITUTION:In a pneumatically operated type control valve 10, leakage of a fluid flowing through the interior of a valve box 1 is prevented by the gland packing 5 provided between the box 1 and the valve rod 3. However, when foreign matter enters between the packing 5 and the rod 3, sliding of the rod 3 by the driving member 7 comes to lack smoothness, and there is a fear of damaging the controlling property of the control valve 10. To avoid this problem, a control signal 11 is appropriately provided so that air is fed into the driving member 7 by a pneumatic booster 13. Signals from a pressure gauge 15 fitted to the member 17 and a valve lift measurer 19 fitted to the valve rod 3 are taken into an abnormality-diagnosing device 17, and the abnormality of the control valve 10 is diagnosed in terms of the supply of air and the delay of the operation of the valve rod 3 caused by the frictional force acting between the rod 3 and the packing 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called diagnostic device for detecting abnormal operation of a valve, particularly a pneumatic control valve.

For air-operated control valves, as shown in FIG.

Although the tarsid bash 5 provided between the valve body 1 and the valve stem 3 prevents leakage of the fluid flowing inside the valve body 1, it is possible for foreign matter to get in between the ground ballast 5 and the valve stem 3. If there is a,
The sliding movement of the valve stem 3 by the drive member 7 may not be smooth, and there is a danger that the controllability of the control valve 1o may be impaired. Similar problems also occur due to deformation of the valve stem 3 and gland pad 5.

The present invention was developed in view of the above-mentioned problem, and includes a pressure gauge on the drive member that receives air as the drive fluid, and a displacement detector that detects the operation of the valve stem. This system is used to diagnose valve abnormalities based on delays in air supply and valve stem operation.

Hereinafter, the present invention will be explained based on a practical example from Myanmar.

In FIG. 2, the control valve 1o is shown schematically, but is the same as that in FIG.

In FIG. 2, an air intensifier 13 receiving a control signal 11
is in communication with the drive member 7, and a pressure gauge 15 attached to the drive member 7 is in communication with an abnormality diagnostic device 17. A displacement detector, that is, a valve lift gauge 19 attached to the valve stem 3 is also connected to the abnormality diagnostic device 17.

In the structure described above, when the control signal 11 is applied, the air amplifier 13 sends air to the drive member 7 so as to maintain the valve lift corresponding to the control signal 11. The amount of lift of the valve rod 3 is adjusted by the air pressure of the drive member 7. A sealing member, ie, a gland shield 5, is connected to the control valve 1.
This is to confine the fluid, which is a controlled amount of 0, to 5 to prevent it from leaking outside. Signals from the pressure gauge 15 and valve lift gauge 19 are taken into an abnormality diagnostic device 17 to diagnose an abnormality in the control valve 10.

Next, details of the diagnosis will be explained with reference to FIGS. 2 and 3.

When a 5-ins wave is input to the control signal 11, the pressure of the drive member 7 and the movement of the valve stem 3 (valve lift) become K as shown in FIG. In other words, control (valve #5 follows No. 1 11 with a delay time ΔT. This phenomenon is caused by the frictional force acting between valve 4I3 and tarashidobawa middle 5).

Acting in the opposite direction to the direction in which the valve stem 3 moves (.If the magnitude of the frictional force is F and the pressure change in the drive member 7 until the valve stem 5 stops moving and starts moving is ΔP, then The following relational expression holds true.

F==dΔP(1) where d is a parameter determined from the effective area of the drive member 7. Therefore, by measuring the pressure change ΔP, the frictional force acting between the valve stem 3 and the tarland password 5 can be determined.

The abnormality diagnostic device 7 receives a signal from a pressure gauge 15 that measures pressure;
Using the signal from the valve lift meter 19 that measures the valve lift of the valve stem 3, and based on the above principle, calculate the pressure change ΔP in the drive member 7 until the valve body, that is, the valve stem 6 starts to move from a stationary state. , the frictional force F is determined from the above equation (1). moreover.

For the preset upper limit of allowable friction force FMAXK.

F　＞　F　MAX If so, it is determined that the valve is abnormal.

According to the two embodiments as described above.

By detecting the pressure within the drive member 7 that drives the valve stem 3 and the movement of the valve stem 3, it is possible to diagnose whether there is an abnormality in the control valve 10.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a control valve, FIG. 2 is a diagram illustrating an embodiment of the present invention, and FIG. 3 is a diagram illustrating one operation. 1... Valve box, 6... Valve stem, 5...
... Jirashidopa so+n. 7... Drive member, 15... Pressure gauge. 17...Abnormality diagnostic device, 19...Valve lift meter, #12 Diagram ``Zυ■

Claims (1)

[Claims] An abnormality connected to a pneumatic drive comprising a valve stem that slidably penetrates the valve body, a driving member attached to the outer end of the valve stem, and a sealing member provided between the valve stem and the valve body. A valve abnormality diagnosis device having a diagnostic device.