JPH0721731B2 - Positioning control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a positioning control device that performs position control at an arbitrary position of a certain stroke, such as a valve opening of a motor-operated valve, and in particular, a dead zone for a set position. Regarding what is provided.

[Prior Art] As a valve used in various plants such as a chemical plant and a desalination plant and an air conditioner, an electronic control valve using an electric valve actuator is used instead of an air control valve. The electric drive section as a valve actuator in this type of electronic control valve is configured as shown in FIG. 4, and for example, the valve opening setting signal Ei input from the controller 3 or the like is a feedback signal from the potentiometer 2.
When it becomes larger than Ef, its deviation E ₁ (Ei−Ef) increases,
Becomes greater than the dead band setting signal Ed output from the dead zone setting unit 4, the output of comparator A ₁ is turned ON from OFF, the relay R ₁ is excited, the output contact is turned ON, capacitor motor 5 in the forward direction It is designed to rotate. The signal of the feedback mechanism connected to the motor output shaft increases, and when the deviation E ₁ decreases and enters the dead zone Ed, the motor 5 stops. If the setting signal Ei is small, the deviation E ₂ (Ef−Ei)
Thus, the comparator A ₂ is turned on, the motor 5 is reversely rotated in the direction of decreasing the feedback signal, and the motor 5 is controlled to stop when the deviation E ₂ falls within the dead zone.

[Problems to be Solved by the Invention] A motor used for a drive unit for position control has inertia,
Even if it reaches the set position and the output of the position controller is turned off, it coasts to some extent. Therefore, the dead zone is provided as described above to prevent hunting in consideration of the amount of coasting.

However, if the dead zone is provided, there is a problem that the setting accuracy is deteriorated accordingly. For example, in the case of a motor-operated valve, even if the setting is 0%, that is, the valve is set to fully closed, there is a dead zone, so the valve opening does not become 0% and liquid may leak. Explaining this situation, as shown in FIG. 6 which is an enlarged view around the setting 0% in FIG. 5 showing the follow-up relationship between the setting input signal and the valve opening, the valve opening is reduced by lowering the setting input. 11,12,1
Despite following like 3,14,15, even if the setting input is 0%, the valve opening is A because it enters the dead zone range.
It cannot be lowered below the point. On the other hand, in FIG. 7 in which the follow-up state in the vicinity of the setting of 100% is enlarged, even if the setting is 100%, it becomes impossible to raise from the point B.

Therefore, the present invention provides a positioning control device such as a motor-operated valve that can forcibly control the valve opening degree to 0% or 100% with respect to a set input 0% or 100% instruction even if a dead zone is provided. The purpose is to do.

[Means for Solving the Problems] The present invention adopts the following configurations in order to solve the above problems.

That is, the positioning control device according to the present invention compares a feedback signal from a detector or the like that detects the stroke position of an actuator with a setting signal input from a setting means such as a controller, and controls the deviation target signal based on these deviation signals. Position control of the actuator
A positioning control device that controls the actuator to stop driving when the deviation signal enters a preset dead band, so that the actuator is continuously driven within the set dead band independently of the feedback control. A control means for controlling is provided.

[Operation] When the deviation signal enters the set dead zone by the feedback control, the driving of the actuator is stopped, but by the control means provided independently of the feedback control,
For example, the actuator to be controlled is 0% of the set input signal.
Or it is continuously driven so as to follow the 100% instruction.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention. A positioning control device 1 for controlling the valve opening of a motor-operated valve is provided on an output shaft of a condenser motor 5 which is a drive unit of the motor-operated valve. The feeder back signal Ef output from the potentiometer 2 and the setting signal Ei set by the controller 3 are input. Both of these signals are the same as the conventional ones, and as a deviation signal E ₁ or E ₂ , a dead zone setting signal Ed set by the dead zone setting device 4 and a comparator.
Compared with A ₁ or A ₂ . Deviation signal E ₁ is dead zone setting signal
When it is larger than Ed, the output of comparator A ₁ turns ON and the relay
R ₁ is excited, the output contact is turned on, and the capacitor motor 5 rotates in the forward direction. When the rotation of the motor 5 progresses, the feedback signal Ef increases, and the deviation signal E ₁ decreases and enters the dead band, the motor stops. Also, the deviation signal E ₂ is Ed
When it is larger than this, the relay R ₂ is excited, the motor 5 rotates in the opposite direction, and the motor stops when it enters the dead zone.

By the way, in the present embodiment, even if the deviation signal further enters the dead zone, the valve opening of the motor-operated valve is continuously driven so as to be 0% (fully closed) and 100% (fully open) according to the setting instruction. That is, transmitters 6 and 7 for transmitting a 100% setting signal and a 0% setting signal of the valve opening, which are independent of the setting signal Ei from the controller 3, are provided. The 100% setting signal output from the 100% transmitter 6 is sent to the comparator A ₃ together with the setting signal Ei from the controller _3.
The 0% setting signal input to the comparator A ₄ and output from the 0% oscillator is input to the comparator A ₄ . Setting signal Ei of comparator A ₃ is Ei
≧ 100%, the comparator A ₄ outputs when the condition of Ei ≦ 0% is satisfied. The output from the comparator A ₃ is input to the OR circuit 8 together with the output from the comparator A _{1 and} to the AND circuit 9 together with the output from the comparator A ₂ . The output from the comparator A ₄ is ORed together with the outputs from the OR circuit 8 and the AND circuit 10 and the AND circuit 9.
Input to circuit 11. Relays R ₁ and R ₂ are AND circuit 10 and OR circuit 1
Each of the outputs of 1 is excited to turn on the output contact and rotate the motor 5 in the opposite direction.

The operation of the logic circuit formed by these gates will be described. When the setting signal Ei of the controller 3 is set to Ei <100% in the opening direction of the motor-operated valve, the deviation signal is set as described above.
E ₁ is compared with the dead zone signal Ed, the gate is opened so that the relay R ₁ is excited by the output from the comparator A _1, and the motor 5 is normally rotated to the set valve opening. Ei is Ei ≧ 100%
When set to, the deviation signal E ₁ enters the dead band and the comparator A ₁
However, the output of the comparator A ₃ is turned on, the gate is opened so that the relay R ₁ is excited and the relay R ₁ is excited, and the motor 5 is rotated in the forward direction to the position where the electric valve is fully opened. On the contrary, Ei
When is set to 0%, the output of comparator A ₂ is turned off, but the output of comparator A ₄ is turned on and the gate is opened so that relay R ₂ is excited, and the motorized valve is fully opened. Reverse the motor 5 to the position.

In this way, the motor 5 rotates in the fully opening direction and the fully closing direction of the valve regardless of the set dead zone. When the valve reaches the fully open or fully closed position due to the rotation of the motor, the valve plate hits the valve seat and overload is applied.This causes the overload switch TL ₁ or TL ₂ to operate, cutting off the power supply to the motor. The leaning motor 5 is configured to stop.

FIGS. 2 and 3 show how the valve opening degree in the vicinity of the set 0% or the set 100% follows when the set signal Ei is increased or decreased. That is, when the setting input is lowered from 14 to 15 near 0%, the motor 5 is driven at the time of the setting input 15 beyond the dead zone, the valve opening degree starts to decrease, and the dead zone is entered again. However, the valve opening from 5 due to the coasting of the motor
It goes down to 16 and stops. Further, when the input is reduced from 16 to 17, the valve opening degree is reduced from 17 to 18. When the input is reduced from 18 to 19 and the set input is 0%, the valve opening reaches 20 (valve opening 0%) regardless of the dead zone range.

As described above, in the apparatus according to the embodiment of the present invention, even in the positioning control provided with the dead zone, if the valve opening is set to 0% or 100%, 0% (fully closed position) 100% ( Reach full open position). This relationship indicates that even if the relationship between the setting signal and the feedback signal is slightly deviated, the relationship is always satisfied at the 0% and 100% positions. Therefore, the zero adjustment and the span adjustment of the setting signal and the feedback signal are allowed without problems even if they are not strictly performed.

In the above embodiment, the means for controlling the motor drive to the fully closed position and the fully open position regardless of the dead zone was implemented by hardware, but when the position controller itself is configured by a CPU, the above control function is implemented by software. It can also be executed.

Further, in the above embodiment, the 0% oscillator is used in order to effectively close the motor-operated valve. However, if configured as a 10% oscillator, for example, the valve should be fully closed when the set input is 10% or less. It can also be operated.

[Effects of the Invention] As is clear from the above description, according to the positioning control device of the present invention, even when performing position control with a dead zone within a certain range, it is possible to control from 0% to 100% position in the set range. When driving an electric valve, etc., the valve can be completely closed to prevent the occurrence of fluid leakage. Obviously, this positioning control device can be used to control the operating positioning of devices other than valves.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG.
FIG. 3 and FIG. 3 show setting signals 0% and 10 in the embodiment.
Setting signal and feedback signal (valve opening) near 0%
FIG. 4 is a block diagram showing a configuration of a conventional example, FIG. 5 is a diagram showing a tracking relation between a setting input signal and a feedback signal, and FIGS. 6 and 7 are setting diagrams in the conventional example. It is a figure which expands and shows the tracking relationship of 0% and 100% of setting of an input signal and a feedback signal. 1 ... Positioning control device, 2 ... Potentiometer, 3 ... Controller, 4 ... Dead band setting device, 5 ... Motor, 6 ... 100% transmitter, 7 ... 0% transmitter

Claims (1)

[Claims] 1. A position control of an actuator to be controlled by comparing a feedback signal from a detector or the like for detecting a stroke position of an actuator with a setting signal input from a setting means such as a controller and using these deviation signals. A positioning control device that controls the actuator to stop driving when the deviation signal enters a preset dead band, and the actuator is continuously driven within the set dead band independently of the feedback control. The positioning control device is provided with a control means for controlling so as to be performed.