JPS6381511A - Control mechanism for actuator - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control mechanism for an electric actuator used to control a valve via an electric motor drive forming part of the actuator. The invention is particularly designed to deliver an operating torque of 3 Nm, even on the small end, and 120 Om on the large end.
The present invention relates to a relatively large actuator capable of producing an operating torque of Nm. Such actuators are used, for example, in the thermal and hydraulic power generation industry, or in the marine, water and chemical processing industries, for oil and gas extraction,
It is widely used as a valve actuator for other uses.

[Prior Art] Such a valve actuator comprises -m, a gear system,
an output shaft driven by a reversing electric motor, e.g. via a gearing system consisting of a worm and a worm wheel; It can be rotated in the direction of

For such valve actuators, it is necessary to configure, monitor, and control the operation of the actuator.

The basic control elements are the position of the actuator,
namely, valve position and actuator torque. The position of a valve is typically determined by counting the number of revolutions, or fractions of a revolution, of a passive shaft that is geared to the output shaft (referred to as the "post") of its actuator. The torque developed on the actuator's output shaft, or column, is typically also determined by a mechanical device. The torque is also determined from the current that is related to the motor's torque. Examples of such mechanisms are shown in US Pat. No. 4,288,665 and British Patent No. 2,101,355.

``Problem Solved by the Invention'' One difficulty with these mechanical or electro-mechanical mechanisms is that the protective cover must be removed in order to adjust the actuator travel and torque settings. This exposes the mechanism to an environment in which dust and moisture can enter the working parts of the actuator.Another difficulty is that the cover is exposed to the presence of potentially explosive gas mixtures. This is because there is a dangerous situation in which it is not possible to remove the ``sparking'' electrical element, which if removed would expose the ``sparking'' electrical element to the explosive mixture.

Furthermore, these current designs do not reduce the number of people who adjust their settings other than by locking and keying the actuator covers.

One aim of the invention is therefore to overcome the aforementioned drawbacks.

SUMMARY OF THE INVENTION The present invention provides a control mechanism for an electric actuator used to control a valve via an electric motor drive forming part of the actuator. configures and monitors actuator operation,
It consists of a control electronic device that has an interface with the outside of the actuator so that the actuator can be monitored and configured without removing the cover from the actuator.

The invention also includes an electronic control unit within the cover of the actuator and a battery-powered power supply for the control unit, and further includes a wake-up/sleeve circuit that preserves battery life. Basically, all circuits in the control unit are closed except when the energized state is maintained.
The "5LEEP" state starts when the external power supply to the actuator is cut off and the actuator does not move, and the subsequent movement of the actuator causes the wake-up/sleep circuit to enter the "wake-up state". The present invention seeks to provide a control mechanism for an electric actuator used to control a valve via an electric motor drive forming part of the actuator, characterized in that

Further, the present invention includes an electronic control unit in the actuator and a position indicating device that provides a series of pulse signals to the control unit to indicate the position of the actuator, and the position indicating device is driven synchronously with the actuator. The present invention seeks to provide a control mechanism for an electric actuator used to control a valve via an electric motor drive forming part of the actuator, characterized in that it consists of a rotary electrometer.

[Function] Since the present invention is configured as described above, according to the first invention, the actuator can be monitored and set without removing the cover from the actuator.

One major difficulty in replacing electrical, mechanical setting and switch operation systems with electronic systems using solid-state logic elements is that the actuators cannot be rotated by hand, e.g. when mains power is not available. As with the time position monitor, it is necessary to enable the assistance of an internal battery to handle the power needs of the circuit.

According to the second invention, the present invention is such that when the external power supply is cut off and the output shaft of the actuator, that is, the columnar body is not manually rotated, the demand from the power from the auxiliary battery is minimized. Provides a control circuit for a battery that has been developed.

One of the problems with electronic devices is the inexpensive and convenient way to generate the pulse signals that guide the valve position. According to a third invention, such a pulse signal is emitted by a rotating optical shutter disc or a rotating electrometer. This optical disc,
Or the rotary contact of the electrometer is driven synchronously with the actuator. Rotation of the shutter disk generates a series of pulses by blocking the light beam to the optical detector, and by counting those pulses it indicates the shaft position and thus the valve position. In the case of an electrometer, a short break in the output voltage from an electrometer when it flows from the end of one stroke to the beginning of the next stroke.
is used to generate one pulse for each revolution of the passive shaft, and the analog value of the amplitude of the sawtooth waveform at any time is used as an indication of the angular position of the shaft within the revolution. Ru.

Advantageously, the electronic devices provide one or more levels of monitoring and/or configuration functionality, so for dispatched service engineers their monitoring and configuration equipment is useful for dedicated personnel involved in actuator operation. The level of inspection and/or configuration is higher than that of monitoring and configuration devices.

The monitoring and configuration device thus includes a monitoring and configuration unit that is hand-held or mounted on the outside of the cover of the actuator or connected to a remote location by a wire. In such units, particularly if hand-held, a keyboard and internal controls are included and the actuators are configured to read or write a unique sequence of characters on the keyboard before being reset, or by other means. to enter the monitoring and configuration unit. Mechanical keys can also be used for this purpose. The coding is also such that only one group of actuators is monitored and reset by the selected monitoring and configuration unit, and vice versa.

Communication through the interface device is by electromagnetic radiation (including radiation in the visible and infrared ranges), and the energy level of that communication is such that upon removal of the cover,
Such monitoring and configuration operations are performed in an environment that is so hazardous as to expose the sparking element to an explosive environment. In such cases, windows for electromagnetic radiation, i.e. inlet and outlet devices, must be provided, which are in contact with the internal pressure to which the actuator housing and the monitoring and setting unit are normally exposed in the event of an internal gas explosion. Instead of expensive explosion-proof windows, explosion-proof bulkheads should be installed behind the windows, and only necessary and non-hazardous materials should be used between the bulkheads and windows. It can also be placed between the two.

The aforementioned monitoring and configuration units are designed to be considered inherently safe when operating in hazardous environments. If the monitoring and configuration unit is battery-powered, the battery is housed within an explosion-proof enclosure and the remaining circuitry, etc., which is considered inherently safe, is housed within a non-explosion-proof enclosure. , the battery is encased with a resistor that has a high resistance value, so the wires exiting the encased assembly require less current to cross that resistor and reduce the potential of the battery. Therefore, even in the case of a short circuit, no spark will be generated.

This monitoring and configuration unit also incorporates additional equipment such that the actuator can be started, reversed, or stopped by issuing further code signals from the unit across the interface. You can also prepare.

[Example] An exemplary system incorporating certain aspects of the invention will now be described by way of example with reference to the accompanying drawings.

If we refer to Figure 1 here, the boundary (1) defined by the two-dot chain line
The components of the actuator are schematically shown in the boxed area. Electrical power enters from the terminal block (2) and is sent to the motor control unit (3), which in the usual way for controlling a reversing electric motor (4), such as a three-phase induction motor, for example. It consists of contactors, relays, etc. arranged in The conductor from the contactor of the motor control unit <3) leads to the reversing motor (4) and is connected to the worm shaft (5) of the gearbox of the actuator of this reversing motor (4).

The worm (6) is integrally formed with the worm shaft (5) and meshes with the output worm wheel (7).
) sequentially connects the actuator's output shaft, that is, the ``column body'' (8
) to drive. Such a drive method is described in British patent specification no. Selectively actuated to connect to the driver.

The armature of the motor (4) is axially movable by a limited amount and is held centrally relative to the actuator frame by a spring back assembly (9). This assembly is designed such that when torque is applied to the output shaft (8), the armature moves to compress one or the other of the two sets of springs. Thus, the worm from that central position! The axial movement of M (5) is the magnitude of the axial force applied to that shaft, and thus the output shaft (8).
The torque is determined by the magnitude of the torque at the worm wheel (7), which torque is the product of the axial force and the pitch radius of the worm wheel (7). Axial movement of the ohmic shaft (5) is arranged to move the lidar of the electrometer (10), either directly as shown, or via a cam and follower.

It is obvious that other forms of electrical transducers, such as Hall effect devices, could be used to detect and measure worm shaft movement. t derived from an electrometer (10) or equivalent device.

(electronic control unit whose actuator is the actuator)
(11).

The output shaft (8) carries a skew gear (12) which meshes with a passive skew pinion (13) mounted on the signal shaft (14), on which the shutter disc (15 ) is installed and this disk (15
) is equipped with a slot (16), so when the disk rotates, the photosensitive bag M (18
) alternately blocks and passes the rays of light.

Shutter disks and other components (15) (18
)(17) The purpose of (18) is to act as a pulse generator that emits pulses related to the rotation of the output shaft (8) of the actuator. These pulses are sent to the actuator's electronic control unit (11). By using shutter disc and light beam system,
Two rows of slots and two rays can be used.

One light beam, ie, one slot row, can be displaced by a portion of the pitch of the slots. This allows the direction of movement, ie, clockwise or counterclockwise, to be detected.

The system can also be designed such that a partial rotation identification encoder, ie an increment identification encoder, can identify partial rotations of the output shaft (8). Other types of shaft-driven pulse generators may be used, such as gear- or inductor-actuated switches.

Another particularly effective alternative is, for example, the use of a continuous rotary electrometer with a rotating contact connected to the skew axis (14). A break between the beginning and end of the electrometer's trajectory along which the contact moves
is used as the reference position.

The electrometer generates a sawtooth voltage, and depending on whether it is a decreasing or increasing voltage from the reference position, the direction of rotation of the actuator, i.e. the direction of the valve ``opening'' or ``opening'', is determined. passes through a break in the trajectory, representing one rotation of the skew axis (<14).The analog value of the sawtooth voltage at any time represents the angular position of the skew axis (14) with respect to the reference position.

The skew axis (14
) rotation pulses can be counted.

It will be appreciated that the use of an electrometer as described above to indicate position is independent of the speed of the actuator motor.

Yet another option is to take the signal directly from the actuator column, for example by using an inductive coupling in conjunction with a magnetic device provided on the column.

The child control unit (11) has a microprocessor and its associated power supply and circuitry so that the position and torque of the output shaft (8) can be determined and adjusted to a plurality of preset positions and values. By comparing and sending a signal to the motor control unit (3), a monitor signal or a limit position or limit torque value at which the actuator needs to be stopped is generated.

The monitoring of the shaft position and torque, as well as the intermediate position, limit position, limit torque, or reset, is achieved by interfacing signals from the electronic control unit (11) using infrared or other radiating devices. Doorway (1
9) Handheld programming unit (20) through
This is achieved by sending the This programming unit has input and output ports (21) and a battery (2).
2), reading display panel (23), and keypad (2).
4) and associated circuitry so that the actuator status is monitored and limit settings, torque settings, etc. are adjusted after a release code is entered through the keypad.

It may also be provided with an LCD (liquid crystal display) or LED (light emitting diode) reading unit (29), which accepts its input from the control unit (11) and instantaneously indicates the position of the actuator, etc.

The terminal block (2) usually present on the actuator has a number of terminals through which electrical control signals are sent to the actuator. Electric control unit (11)
The actuator can be set and monitored by using e.g. electrical wires.

This is done by a coded signal sent from the wholesale desk through the terminals on the terminal block, which connects the actuator to the remote end. A fiber optic link may also be provided between the block and the remote control desk.

In case of a hazardous environment, both the actuator and the programming unit can be equipped with an explosion-proof housing, and the vents (19) (20) are also configured to the same explosion-proof standards as that housing.

In order to maintain the power supply to the electronic control unit (11) when the main power supply to the actuator is cut off, a small battery (25) is provided in the actuator housing. A charging circuit provided by a power supply, a primary battery equipped with a solar cell, or a rechargeable unit.

In order to save battery life, it is effective to arrange only the basic circuits of the control unit (11) in the energized state when main power is not available, thereby preserving the battery life. That's true.

However, two problems arise when the actuator is in this "stop" condition. The first is the need to inspect the actuator and change control and torque settings when mains power is not available. This is done by arranging the programming unit with a code signal and using the actuator's battery power to normally suspend the actuator's electronic control unit (11) as long as the programming unit outputs and inputs signals from the actuator. This is achieved by energizing the circuits in the state and causing them to hold.

second, mechanically overriding the electric drive;
The output shaft (8) can be rotated by means of the handle (26). This causes the electronic counting mechanism <16) (17) etc. to lose its reference when the main power supply is cut off and the circuit is in a "dormant" state.

To overcome this problem, it is necessary to include a motion detection circuit to energize the battery.

One way to achieve this is to include a gear (27) attached to the signal shaft (14) and operating a switch (28). As shown in Figure 2, the switch (28)
is arranged in a "wake-up" circuit so as to use the battery power supply to activate normally dormant circuits of the electronic control unit (11).

Referring to FIG. 2, this "wake-up" circuit operates as follows: When the actuator moves, the switch (28) is activated by the gear (27) (FIG. 1) to close its two contacts. The output labeled '5TATE' in Figure 2 is used to monitor the position of switch (28).

When the actuator is at rest, the switch closes the contact (2
8a) or (28b). When one of the outputs Q and Q of the bistable (31) is high (HIGH), the other is low (LOW). For example, when the actuator is at rest and the contactor (28a) is in contact as shown in FIG. 2, if the output Q of the bistable (31) is high (HIGH), no action is performed. However, if the output Q is low, the inputs (S) and (R
) by the set signal and reset signal A (HI
GH).

In this way, the contactor is controlled by the set (S) and reset (R) inputs from the microprocessor to set the bistable (31) to HIGH.
Connected to the output. Thus, the microprocessor
Look at the “S T A T E” signal. If it is high (
If it is HIGH) then nothing changes, but if it is LOW (LO
W), the bistable (31) is switched using the set input and reset input. Once this is achieved, the "'5L" to the bistable (33)
The EEP" input goes LOW and the microprocessor is in its standby mode in which the circuitry draws minimum power. When the microprocessor is in this standby mode, the pathet ' of bistables (31) (33)
The ``reset'' and ``sleeve'' inputs are pulled to the high (HIGf() state by the pull-up resistor (34), so that the bistables (31) (33) are held in their required state, so that the wake The up circuit has no risk of malfunction. When the actuator moves again, the switch moves from the contacted contact, e.g. (28a) to the other contact (28b), and the switch <
28) is connected to the low output from bistable (31).

This sets the ``wake-up'' output of the bistable (33) high, bringing the microprocessor out of its standby mode. Resistor (35
) sends a limited level voltage to the "5TATE" line when the switch is between contacts (28a) and (28b), i.e. when it is not in contact with either contact, the switch (28) Used to hold the input to the bistable (33) high when between the contacts.

It is advantageous to have multiple levels of wake-up commands originating from the aforementioned handle or from the monitor and configuration unit. These levels are the lowest levels at which an LED (light emitting diode) or LCD (liquid crystal display) can be illuminated on the panel (29) to indicate valve position or one or two other valve conditions. It is.

At other levels, access is provided to change valve settings and, ultimately, additional monitoring and setting equipment required by the service engineer.

During normal electric motor operation of the actuator, the switch (28) is lifted off the gear (27) to avoid wear on the gear (27) and the switch (28).
A solenoid can be provided. This solenoid is
Automatically energized by mains power supply to actuator. Instead of such gears and switches, non-contact motion detection devices can also be provided, such as variable capacitance, inductance devices or magnetic devices.

The number of monitoring and control functions handled by the programming unit is varied by providing a key inserted into the unit that disables the functions and provides access to these normally prohibited functions. be able to. These special access keys are usually
It is kept by the dispatch engineer, i.e., the service engineer. A password can also be stored in the programming unit's keypad.

so that actuators that perform critical operations in complex locations cannot be inspected and/or reset unless a special key is inserted into the programming unit.
It is also possible to provide a lockout key for the actuator.

Leave i+ on the previous A/7'1 UC5 day P k
Although the description has been made in terms of secondary setting and control, monitoring, setting and control can be applied to other parameters as well. for example,(
a) emergency stop control; (b) selection of the direction of the motor in order to "quiet" the valve; (c) monitoring of the motor current; (cl>
Detecting and changing motor speed in variable speed actuators.

[Effects of the Invention] As explained above, according to the present invention, it is possible to move the actuator and set the torque, etc., without removing the protective cover. This prevents the ingress of dust and moisture into the working parts of the actuator and also prevents the risk of exposing sparking electrical elements to explosive gases, even in the presence of explosive scum. can.

Further, according to the present invention, when the external power supply is cut off, it is possible to minimize the power demand of the actuator control mechanism supplied from the auxiliary battery.

Furthermore, according to the present invention, a reliable pulse signal, which is a prerequisite for guiding the valve position, can be generated in an inexpensive and convenient manner.

[Brief explanation of the drawing]

FIG. 1 is a simple mechanical diagram with diagrams of the electrical and electronic block circuits involved in one embodiment of the invention, and FIG. 2 is a close-up of a portion of the circuit of FIG. It is a diagram. (2)...Terminal block (3)...Motor control unit (4)...Reversing electric motor (5)...Worm shaft (6)...Worm (7)...Worm wheel ( 8> Output shaft (9)...Spring pack assembly (10)...Electrometer (11)...Actuator electrical control unit (
12)...Skew gear (13)...Passive skew union (14)...Signal shaft (15)...Shutter disk (16)...Slot (17)...Light emitter ( 18)...Photosensitive device (19)...Interface port (20)...Programming unit (22)...
Battery (23)...Reading display panel (24)...Keypad (26)...Handle (27)
... Gear (28) ... Switch

Claims (1)

[Claims] 1. An electronic device for setting, monitoring, and controlling the operation of the actuator, and having an interface with the outside of the actuator, and monitoring and setting the actuator by removing the cover from the actuator. A control mechanism for an electric actuator used for controlling a valve through an electric motor drive forming part of said actuator, characterized in that the control mechanism can be carried out without any interference. 2. Control mechanism according to claim 1, characterized in that the interface is a contactless interface operated via electromagnetic radiation, for example infrared radiation. 3. The electronic control unit forms part of the electronic device and is built into the cover of the actuator, and the monitoring and setting unit is located outside the cover of the actuator and communicates with the electronic control unit through the interface. The control mechanism according to claim 1 or 2, characterized in that: 4. Control mechanism according to claim 3, characterized in that the monitoring and setting unit is located at a distance from the actuator and is connected to the electronic control unit by a wire. 5. The monitoring and configuration unit is a hand-held unit and is in communication with the interface by electromagnetic radiation.
The control mechanism described in Section. 6. The control mechanism of claim 5, wherein the hand-held unit includes an input/output, a readout display panel, and a keypad. 7. Contains an electronic control unit within the actuator cover and a battery-powered power supply for the control unit, as well as a wake-up/sleep circuit, which is essential to preserve battery life. The control unit is placed in a "SLEEP" state in which all circuits are closed unless the actuator is kept in an energized state, and in the "SLEEP" state, the external power supply to the actuator is cut off and the actuator does not move. The wake-up-sleep circuit is used to control the valve via an electric motor drive forming part of the actuator, characterized in that the wake-up-sleep circuit starts when the actuator changes to a "wake-up" state by subsequent movement of the actuator. Control mechanism for electric actuators. 8. The actuator has an electronic control unit and a position indicating device that provides a series of pulse signals to the control unit to indicate the position of the actuator, and the position indicating device is rotatably driven synchronously with the actuator. A control mechanism for an electric actuator used to control a valve via an electric motor drive forming part of the actuator, characterized in that it consists of a type electrometer.