JPH0512591B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to, for example, a valve opening/closing control device, etc.
Detects fluctuations in load torque when opening/closing a valve, and if there is an abnormality in the load torque, stops valve opening/closing midway through, checks the history of load torque, and calculates maintenance/inspection timing for the valve opening/closing control device. The present invention relates to a method and device for monitoring load torque fluctuations, which enables the monitoring of load torque fluctuations.

[Conventional technology]

Conventional valve opening/closing control devices detect that when a load torque exceeding a predetermined value occurs when opening/closing a valve, it is recognized as an abnormal situation, and the driving force for opening/closing the valve is cut off to protect the valve. ing.

3 and 4 show an example of a conventional valve opening/closing control device of this type.

1 is a valve body of a wedge gate valve, 2 is a valve drive shaft, and 3 is a worm wheel integrated with a nut 5 that is screwed into a male thread 4 provided at the upper end of the valve drive shaft 2.

6 is a motor as a driving source for the valve; 7 is a motor as a driving source for the valve;
The left-right main drive shaft 11 is driven at a reduced speed by the motor 6 via gears 8 and 9 and has a spline shaft 10 in the center, and its inner hole meshes with the spline shaft 10 so that it cannot rotate and the axis This is a worm that is movable in the direction and meshes with the worm wheel 3.

A sleeve shaft 12 with a slightly smaller diameter is connected to the right end of the worm 11, and a ring groove 14 with a slightly larger diameter is provided at the right end of the sleeve shaft 12, which is sandwiched between flanges 13, 13.

The parts of the main drive shaft 7 protruding from both left and right ends of the worm 11 are provided with flanges 15 and 15, respectively.
Torque springs 17 and 18 are compressed between the left flange 15 and the left end surface of the worm 11, and between the right flange 16 and the flange 13 near it.

The upper end of the swing arm 19 is engaged with the annular groove 14 . The lower end of a movable contact 22 of a torque switch 21 is fixed to the front end of a rotation shaft 20 in the front-rear direction at the lower end of the swing arm 19, and fixed contacts 23 are mounted on both sides of the upper part of the movable contact 22 at a slight distance. , 24 are provided.

The left end of the main drive shaft 7 is a worm 25, and this worm 25 is connected to a worm wheel 2 provided on an input shaft 27 of a limit switch 26.
It meshes with 8.

Figure 4 shows a time chart of the valve opening/closing control device. When the valve is driven in the closing direction, time elapses from right to left in the diagram, and when the valve is driven in the opening direction, time elapses from left to right in the diagram. shall be.

Torque characteristics are determined by both torque springs 17 and 18.
When the worm 11 is pressed in an equilibrium state, the 0 point is set, and when the valve body 1 is driven to close, the load torque of the valve body 1 causes the
When the worm 11 moves in the axial direction, the pressing force of the right torque spring 18 is positive, and when driven to open, the load torque of the valve body 1 causes
The pressing force of the left torque spring 17, which is pressed by the movement of the worm 11 in the axial direction, is shown as negative.

The pressing force of the torque springs 17 and 18 is generated according to the load torque, and this pressing force is proportional to the amount of movement of the worm 11. The amount of movement of the worm 11 is converted into a rotation angle of the rotation shaft 20 of the swing arm 19 and transmitted to the torque switch 21.

The torque switch 21 switches the motor 6 when the movable contact 22 and the left or right fixed contacts 23, 24 are closed.
This limit operating point is adjusted by changing the distance from the movable contact 22 to the fixed contacts 23, 24. The positive and negative dashed lines in FIG. 4 indicate the limit motion point.

Items that require a constant seat pressure when closing, such as wedge gate valves, are stopped when the required seat pressure is obtained at the limiting operating point of the torque switch 21, and when the seat pressure exceeds this seat pressure during the closing operation. When load torque is generated, the closing operation is stopped and
Make sure to protect the valve.

The limit switch 26 is configured to operate in a fully closed position, a fully open position, and an intermediate position by a plurality of limiting operating points provided according to the rotational speed of the main drive shaft 7 at an absolute value level.

One limiting operating point of the limit switch 26 is
It is a rotation counter type equipped with multiple intermittent feed gears.

[Problem that the invention seeks to solve]

In the conventional valve opening/closing control device described above, when controlling a wedge gate valve, it is not possible to reduce the load torque limit operating value at the time of valve closing operation to the required seat pressure or less, and Even during operation, the wedge gate pullout force cannot be lowered to less than the wedge gate's pulling force at the initial stage of opening the valve, and it is not possible to respond to minute changes in the load torque due to impurities or the like during the operation.

Furthermore, if the load torque increases due to impurities just before the valve closes, the valve is determined to be fully closed even though it is not fully closed, and the operation is terminated.

In such a case, it is possible to detect an abnormal situation based on the fully closed operating point of the limit switch 26, but it is difficult to precisely align the two limiting operating points with one fully closed operating point. be. Further, in order to give priority to obtaining the seat pressure, the limiting motion point when closing the valve is set on the torque switch 21 side.

Further, if the fully closed point is defined as the point where a constant seat pressure is obtained, this fully closed point may change over time due to wear of the seat or transmission mechanism, and the fully closed point of the limit switch 26 is Since the initial settings are made at the absolute value level, the fully closed operating points of the torque switch 21 and the limit switch 26 will differ over time.

Furthermore, for each intermediate operating point X, Y of the limit switch 26, each time the operating point is increased by one, the number of limiting contacts provided at the final stage of the gear train formed by the intermittent feed gear must be increased by one set, and , the added gear train must be precisely adjusted to the operating point.

Adjustment of the operating point of this limit switch 26 is as follows:
It is desirable that the fully closed point, fully open point, and intermediate points X and Y are determined based on the actual operating state of the valve. Further, the intermediate operating point is often modified after initial setting to selectively adjust the optimum value depending on the usage status of the valve.

In this way, when the setting value of the intermediate point is changed from the initial setting value, in order to replace the limit switch 26 due to contact wear, etc., it is necessary to set the new limit switch 26's intermediate point X, Y in advance. It is not possible to reset the initial values at the time of installation.

Therefore, it is necessary to read the relative values of each intermediate point X and Y from the fully closed point or fully open point of the limit switch 26 that was removed for replacement, and reset it to the new limit switch 26. For the replacement work,
It requires a lot of effort and skill.

[Means for solving problems]

According to the present invention, between the power transmission mechanism connected to the power source and the power transmission mechanism connected to the load,
A variable transmission force coupling mechanism that changes the elastic coupling force according to the load torque is provided, and the elastic coupling force of the variable transmission force coupling mechanism is converted into an electrical value, and the electrical value is transferred to either the power source or the load. The load torque characteristics in the movable range of the load are determined in correspondence with key electrical values in the power transmission mechanism connected to the By detecting this, the above problem can be solved.

In addition, there is a power transmission mechanism connected to a power source, a power transmission mechanism connected to a load, and a variable transmission force coupling mechanism that is interposed between both power transmission mechanisms and changes the elastic coupling force according to the load torque. , a torque value detection means connected to a part of the variable transmission force coupling mechanism whose position changes according to its elastic coupling force and converts the position of the part into a torque value signal, and either a power source or a load. A rotation amount detection means is connected to the power transmission mechanism and converts the movement of the power transmission mechanism at an appropriate position into a numerical signal, and the numerical signals of the torque value detection means and the rotation amount detection means are associated with each other to determine the load variable range. a calculation means for calculating load torque characteristic data; a reference value memory in which a reference value of load torque is recorded in advance; and a reference value read from the reference value memory and compared with a plurality of the load torque characteristic data. The above-mentioned problem is solved by a load torque fluctuation monitoring device in a driving force transmission mechanism characterized by comprising means for.

[Effect]

Characteristic data of load torque in the drive range of a driven body such as a valve body is obtained every time the driven body is operated, and the characteristic data is used to calculate the characteristic data of load torque from the time when the characteristic data was installed to the present. Since the load torque variation is determined by comparing with the history and the initial value, an accurate abnormal state can be detected regardless of the position where the driven body is being driven.

In addition, since the load torque characteristic data is a table of position data related to the drive range of the driven body and load torque data at that position, a large number of intermediate operating points can be arbitrarily determined from the position data in the drive range during operation. The load torque limit value can be arbitrarily set depending on the position or range.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. Mechanical parts in the figure are the same as the conventional mechanism shown in FIG. 3, and therefore are given the same reference numerals.

In the mechanical part of FIG. 1, a motor 6, a gear 8,
9 and the main drive shaft 7 form a power transmission mechanism A.

Further, the valve body 1, the valve drive shaft 2, the male screw 4, the nut 5, and the worm wheel 3 form a power transmission mechanism B connected to the valve body 1, which is a load.

Between the two power transmission mechanisms A and B, the worm wheel 3 is engaged, the main drive shaft 7 is fitted non-rotatably and movably in the axial direction, and torque springs are provided at both ends in the axial direction. 17,18
A variable transmission force coupling mechanism C is provided, which includes a worm 11 provided with a worm 11 and a mechanism around the worm 11.

The elastic coupling force of the variable transmission force coupling mechanism C changes depending on the load torque.

In the present invention, as this torque value detection means, the amount of lateral movement of the worm 11 is determined by the swing arm 1.
Torque encoder 30 connected to rotating shaft 20 of 9
is used.

The torque encoder 30 is an absolute rotary encoder that measures the rotation angle (θ) of the rotating shaft 20, and the rotation angle (θ) is proportional to the amount of movement of the worm 11, and
The forward and reverse rotation angles (θ ₁ ) (θ ₂ ) of the torque springs 17 and 18 from the equilibrium point are
8 and 17, that is, proportional to the load torque.

A worm wheel 28 meshed with a worm 25 formed on the main drive shaft 7 is integrated with an input shaft of a rotation amount detection means, that is, a valve opening/closing degree encoder 31.

The valve opening/closing degree encoder 31 is also an absolute type rotary multi-rotation encoder, and this encoder 31 can measure the amount of rotation of the main drive shaft 7 at an absolute level to know the opening degree of the valve body 1.

Both the torque encoder 30 and the valve opening/closing degree encoder 31 are means for digitally measuring the amount of rotation; Good too. Alternatively, the amount of rotation may be converted into linear motion and then transmitted to the linear position detection means.

The torque encoder 30 has a variable angle (θ ₁ ) provided between the rotating shaft 20 and the input shaft of the encoder 30.
(θ ₂ ) is increased by increasing the resolution.
In the range of variable angles (θ ₁ ) (θ ₂ ), a 4- to 6-bit binary code with positive and negative signs is output.

The valve opening/closing degree encoder 31 is designed to indicate the range from fully closed to fully open of the valve with a resolution of about 7 to 8 bits.

The valve opening/closing degree encoder 31 may be connected to an appropriate position of the power transmission mechanism B to which the valve body 1 is connected, and the direct movement amount of the valve body 1 may be measured at an absolute value level.

Each digital electric signal e ₁ , e ₂ output by the torque encoder 30 and the valve opening/closing degree encoder 31
is taken into a microcomputer (hereinafter abbreviated as CPU) 35, which is a calculation means, via interfaces 33 and 34.

The CPU 35 is equipped with a read-only memory ROM that records the work procedures described below and programs for controlling other functions, as well as a calendar clock unit that calculates date and time. Since it is well known, its explanation and illustration will be omitted.

Each time the valve body 1 is driven to open or close, the CPU 35
The signal _e2 output by the valve opening/closing degree encoder 31 is taken as an address signal a, the signal _e1 output by the torque encoder 30 is taken in as data d corresponding to the address signal a, and is stored in the working memory 36, which is a recording means. write to.

A signal _e2 outputted by the valve opening/closing degree encoder 31,
What is simultaneously associated with the signal _e1 outputted by the torque encoder 30 is characteristic data of the load torque corresponding to the opening degree of the valve. Below, signal e ₂ and signal
A table format in which e ₁ is associated with the entire signal e ₂ is referred to as load torque data.

The CPU 35 has a reference value memory 37 in which a load torque reference value is recorded for comparison with the new load torque characteristic data on the work memory 36, and a means for recording the history of the load torque characteristic data, that is, an IC card 38. It is equipped with

The reference value memory 37 includes load torque characteristic data immediately before the current valve driving time, average load torque characteristic data obtained by averaging the load characteristics during multiple valve driving times, initial load torque characteristic data at the time of valve installation,
Abnormal load torque characteristic data in cases where an abnormal load has occurred, and other load torque characteristic data of various types and periods required for determining abnormal loads, are recorded and held or read from the IC card 38. recorded.

The reference value memory 37 is equipped with a backup battery 39 in order to record important data used for determining various types of abnormal loads.

Load torque characteristic data obtained each time the valve body 1 is opened and closed is recorded in the IC card 38 together with date and time data from a calendar clock unit built into the CPU 35. However, if it matches or approximates the previous load torque characteristic data, average load torque characteristic data, or standard load torque characteristic data, the recording of the load torque characteristic data is omitted and only the number of operations is updated. Ru.

Furthermore, when recording the load torque characteristic data, it is also possible to increase the data storage capacity by recording only deviation values from the various reference values or singular values.

This IC card 38 records the entire history of dynamic load torque fluctuations of the entire valve opening/closing drive device, and during maintenance and inspection, by analyzing the recorded data of the IC card 38, it is possible to check the valve body 1, valve seat, etc. degree of wear,
Alternatively, it is possible to know the degree of wear of the drive system, and to calculate the exact timing for maintenance inspections and parts replacement.

FIG. 2 shows a time chart of both the output signals e ₁ and e ₂ of the torque encoder 30 and the valve opening/closing degree encoder 31. The time elapsed between the valve opening and the valve closing is as follows.
As in Figure 4, it is oriented in the opposite direction.

The curve indicated by the dotted line in FIG. 2 is a limited operating dynamic characteristic curve that stops the motor 6 when the load torque fluctuation exceeds a certain value. The sensitivity is high in areas where the torque is high, and the sensitivity is low in areas where high load torque is applied.

Immediately after the value of the signal e ₁ of the torque encoder 30 is taken into the work memory 36, the load torque fluctuation is calculated by the signal e ₂ of the valve opening/closing encoder 31 at that time.
Based on the address signal a of , the data d at the same address in the reference value memory 37 is read out, and the load torque data at the same address part of the load resistance data d and the reference load torque characteristic data is read out from the reference value memory 37.
It is obtained by subtracting d' by a subtraction routine of the CPU 35, which is a comparison means.

Since the calculation speed of the CPU 35 at this time is sufficiently faster than the step speed of the address signal a, the detection result of the load torque fluctuation is reflected in the control of the motor 6 in real time. Note that the motor 6 is
It is controlled by the CPU 35 via an interface 40 and a motor drive control device 41.

When the load torque fluctuates due to impurities when the valve is closed, as shown by the two-dot chain line, the rate of change is high for a hard object H, and the rate of change is low for a soft object S. appears low. In the case of a soft material, if a force above a certain level is applied, it is often cut and removed without damaging the valve body 1.

If both hard and soft impurities are controlled by the limit value shown by the dotted line, the soft objects, which were not restricted in the past, will be restricted, and the number of stopping operations will increase compared to the past.

However, the hardness or softness of the impurities is determined by calculating the differential value of the load torque fluctuation, and if a high rate of increase is shown and the object is determined to be hard, the motor is immediately stopped.

In addition, if the load torque fluctuates but the rate of increase is low and the object is determined to be soft, the limit value is raised to a predetermined relatively large torque so that the impurities are naturally removed. It can also be done.

The occurrence of an abnormality due to such impurities and the maximum value of load fluctuation at that time are recorded in the IC card 38.

The above-mentioned old and new load characteristic data can be displayed on the display section 42 or transmitted to the central control system 44 via the communication line interface 43, if necessary.

In addition, in the valve closing portion where the load torque is constantly large, the CPU 3 controls the motor drive control device 41 so as to increase the output torque of the motor 6 itself.
By controlling with 5, compared to conventional motors,
A one class smaller motor can be used.

The intermediate point between the valve fully closed and fully opened can be divided into fine sections according to the resolution of the valve open/close encoder 31, and many stopping points of the valve can be set in the intermediate part, and the value of the set point and the logic of other conditions can be divided. It is also easy to perform a product or a logical sum to change the intermediate stopping point to another location, or to output a required control signal.

〔Effect of the invention〕

According to the present invention, the load torque characteristics in the moving range of the driven body are obtained each time the driven body is driven, so only the fluctuation component can be detected, excluding the steady load torque component. can be monitored with high sensitivity.

Further, since the load torque characteristic referred to for determining the load torque fluctuation can be updated to the latest one, gradual fluctuations in the load torque due to wear of mechanical parts or the like are also eliminated.

It is easy to average, integrate, extract unique parts, and store the load torque characteristics obtained for each drive. It is possible to calculate the degree of

Furthermore, installation adjustment is much easier than with conventional torque switches and limit switches.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a time chart of the main electrical signals in FIG. 1, and FIG. 3 is a perspective view showing an example of a conventional valve opening/closing control device. , FIG. 4 is a time chart showing the relationship between the opening/closing signals of the torque switch and limit switch shown in FIG. 3 and the load torque. 1... Valve body, 2... Valve drive shaft, 3... Worm wheel, 4... Male thread, 5... Nut, 6... Motor,
7... Main drive shaft, 8, 9... Gear, 10... Spline shaft, 11... Worm, 12... Sleeve shaft, 1
3... Flange, 14... Annular groove, 15, 16... Flange, 17, 18... Torque spring, 19... Swing arm, 20... Rotating shaft, 21... Torque switch,
22...Movable contact, 23, 24...Fixed contact, 25...
Worm, 26... Limit switch, 27... Input shaft, 28... Worm wheel, 30... Torque encoder, 31... Valve opening/closing degree encoder, 33, 34
...Interface, 35...CPU, 36...Working memory, 37...Reference value memory, 38...IC card,
39... Backup battery, 40... Interface, 41... Motor drive control device, 42... Display section,
43...Communication line interface, 44...Central control system, A, B...Power transmission mechanism, C...Transmission force variable coupling mechanism.

Claims (1)

[Claims] 1. A variable transmission force coupling mechanism is provided between a power transmission mechanism connected to a power source and a power transmission mechanism connected to a load, and the transmission force variable coupling mechanism changes the elastic coupling force according to the load torque. The elastic coupling force of the variable transmission force coupling mechanism is converted into an electrical value, and the electrical value is correlated with the electrical value of the key point in the power transmission mechanism connected to either the power source or the load, and the load is adjusted. A method for monitoring load torque fluctuations in a driving force transmission mechanism, characterized in that load torque fluctuations are detected by determining load torque characteristics in a movable range and comparing the load torque characteristics with a reference value stored in advance. . 2. A power transmission mechanism connected to a power source, a power transmission mechanism connected to a load, and a variable transmission force coupling mechanism that is interposed between both power transmission mechanisms and changes the elastic coupling force according to the load torque. , a torque value detection means connected to a part of the variable transmission force coupling mechanism whose position changes according to its elastic coupling force and converts the position of the part into a torque value signal, and a torque value detection means of either the power source or the load. A rotation amount detection means is connected to the power transmission mechanism and converts the movement of the power transmission mechanism at an appropriate position into a numerical signal, and the numerical signals of the torque value detection means and the rotation amount detection means are correlated with each other to determine the load variable range. a calculation means for calculating load torque characteristic data; a reference value memory in which a reference value of load torque is recorded in advance; and a reference value read from the reference value memory and compared with a plurality of the load torque characteristic data. 1. A load torque fluctuation monitoring device in a driving force transmission mechanism, comprising: means.