原文:
由于现在的控制方式和手段越来越多,在实际工业生常和工业控制中,用来控制气动执行机构的方法也很多,常用的有以下几种。
(一)基于单片机开发的智能显示仪控制
智能显示仪是用来监测阀门工作状态,并控制阀门执行期工作的仪器,它通过两路位置传感器监视阀门的工作状态,判断阀门是处于开阀还是关阀状态,通过编程记录阀门开关的数字,并且有两路与阀门开度对应的4~20mA输出及两足常开常闭输出触点。通过这些输出信号,控制阀门的开关动作。根据系统的要求,可将智能阀门显示仪从硬件上分为3部分来设计:模拟部分、数字部分、按键/显示部分。
1、模拟电路部分主要包括电源、模拟量输入电路、模拟量输出电路三部分。
电源部分供给整个电路能量,
包括模拟电路、数字电路和显示的能源供应。为了实现阀门开读的远程控制,需要将阀门的开度信息传送给其他的控制仪表,同时控制仪表能从远方制定阀门为某一开度,系统需要1路4~20mA的模拟量输入信号和1~2路4~20mA的模拟量输出信号。模拟量输入信号通过A/D转换变成与阀门开度相对应的数字信号后送给数字部分的单片机,在单片机中对它进行滤波处理后就可以输出了。阀门的开度信息通过D/A转换后变成模拟信号输出,用来接显示仪显示阀门开度或连接其他的控制设备。在本设计系统中,所有的数字量数据均采用串行的输入输出方式,为了节省芯片资源和空间,输入的4~20mA的模拟量在转化为数字量时,采用已有的4路DA芯片与单片机的系统资源相结合作8位的AD使用。
2、数字电路部分主要包括:单片机、掉电保护、两路监测脉冲输入信号、两路常开常闭转换触点输出。
在设计方案中选用目前普遍使用的51系列单片机AT89C4051。AT89C4051是一款低电压、高性能的CMOS8位微控制器,它具有4K字节的可擦除、可重复编程的只读闪存。通过在单芯片内复合一个多功能的8位CPU闪存,在性能、指令设定和引脚上与80C51和80C52xx兼容。
考虑到在系统掉电或重新启动时,需要保持先前在仪表中设置的一些阀门参数,而单片机中的数据存储器不具备掉电存储功能,所以在片外扩展了一个具有掉电保存功能的芯片X5045。X5045是一种集看门狗、电源监控和串行EEPROM3种功能于一身的可编程电路,这种组合设计可以减少电路对电路板空间的需求,X5045中的看门狗为系统提供了保护,当系统发送故障而超过设定时间时,电路中的看门狗将通过RESET信号向CPU作反应。X5045提供了三个时间值供用户选择使用。它所具有的电压监控功能还可以保护系统免受低电压的影响,当电源电压降到允许范围以下时,系统将复位,直到电源电压返回到稳定值为止。X5045的存储器与CPU可通过串行通信方式接口。共4069位,可以按512×8个字节来放置数据。
X5045的管脚排列,它共有8个引脚,各个引脚的功能如下:
CS:电路选择端,低电平有效;
SO:串行数据输出端;
SI:串行数据输入端;
SCK:串行时钟输出端;
WP:写保护输入端,低电平有效;
RESET:复位输出端;
Vcc:电源端;
Vss:接地端。
INA为输入信号,是由光电传感器采集到的阀门脉冲信号(<10ma)。该信号经旁路电容滤波后送入光耦,转换成了输出的out电压信号送入单片机。输出的电压可直接进入单片机的i 口。在控制中,要求a、b两路脉冲都接收到的时候,才认为是由信号输入,ab为正转,ba为反转。只有一路信号输入时不计数。="" 两路常开、常闭转换触点输出。用来连接电磁阀,通过控制电磁阀的吸合来控制气动执行机构作相应的开阀或关阀动作。="" 3、显示部分主要包括:单片机、4位led显示、3只状态指示灯(自动、正转、反转)、3只按键(mode/set键、上键、下键)。="">10ma)。该信号经旁路电容滤波后送入光耦,转换成了输出的out电压信号送入单片机。输出的电压可直接进入单片机的i>用来控制4位LED显示,且同数字部分的单片机进行通讯,还要对控制仪的模式做相应的选择和控制。显示仪上设计有3只状态指示灯用来显示执行机构的状态:正转、反转、自动;3只按键:MODE/SET键、上键、下键,控制执行机构的工作模式和一些参数的初始化。这3部分通过接口连接,构成一个完整的控制系统,可以对一些类似气动马达等的执行机构进行控制。在实际应用中基本实现了预先要求的各种性能指标。
(二)利用PLC来控制的系统
PLC在控制系统中的应用越来越广泛,由于本方案是在OMRON的PLC上面作的开发,所以以OMRON的PLC来作介绍。
硬件组成:1台计算机,1套PLC(包括CPU,I/O模块,ID212,OC224,AD003模块),2个继电器,2个电磁阀,1个气动阀门执行器。
其组成原理为:由PC机通过RS-232串口通讯连接OMRON的PLC,对PLC进行编程和监控。PLC的I/O模块分别接入输入、输出信号,其中输入模块连接到阀门上的两个位置传感器,通过PLC的输入模块ID211的指示灯亮的先后顺序来显示阀门的开关状态。输入模块接收两路阀门检测脉冲输入,即脉冲A与脉冲B。在运行状态下,脉冲A输入时指示灯A亮,脉冲B输入时指示灯B亮。输入顺序为AB,表示开阀。输入顺序为BA表示关阀。阀门检测脉冲A和B信号必须部分叠加,否则不能正常检测阀门开度。
通过PLC的输出模块OC225控制两个继电器,继电器具有两组常开常闭输出触点,1组为开阀输出触点,1组为关阀输出触点。开阀时,当阀门开度大于或等于所设阀门限位值时开阀输出触点动作,阀门开度小于所设阀门限位值时开阀输出触点动作,发明开度小于所设阀门限位值时开阀输出触点复位。关阀时,当阀门关到零位且21s内无脉冲输入时关阀输出触点动作;若21s内有脉冲输入,则延时21s关阀输出触点动作。通过继电器的吸合来控制两个电磁阀的开关,电磁阀打开后,便可以控制气动阀门执行器使得阀门做相应的开阀或关阀动作。同时接近传感器把阀门的开关情况再传送到PLC中,并同要求的阀门开度作比较,直到符合要求为止。
自动归零与自动调满:控制系统具有自动归零与自动调满功能,当阀门开度小于归零范围值或阀门开度距满量程小于满度调节范围值,且时间大于或等于所设值稳定时间值时,PLC自动控制阀门进行归零或自动调满。
在实验中,由阀门上的位置传感器计算阀门的开度。
当阀门先离开A传感器,后离开B传感器时,表示阀门在关阀。当阀门先离开B传感器,后离开A传感器时,表示阀门在开阀。传感器接收到的是一个脉冲信号,通过位置传感器的采集信号来记下阀门的开关状态。
在上位机中用编程软件CX-programmer编写梯形图,然后把梯形图下载到PLC中运行,在上位机的组态软件中进行控制和监控,阀门开关量的多少可由组态软件界面输入的圈数值确定。组态界面做好后,开阀、关阀、停止、总开关等控件的控制和动作可以直接在组态界面中很直观形象地进行操作。
气动阀门执行器工作原理
利用压缩空气推动执行器内多组组合气动活塞运动,传力给横梁和内曲线轨道的特性,带动空芯主轴作旋转运动,压缩空气气盘输至各缸,改变进出气位置以改变主轴旋转方向,根据负载(阀门)所需旋转扭矩的要求,可调整气缸组合数目,带动负载(阀门)工作。
两位五通电磁阀通常与双作用气动执行机构配套使用,两位是两个位置可控:开-关,五通是有五个通道通气,其中1个与气源连接,两个与双作用气缸的外部气室的进出气口连接,两个与内部气室的进出气口接连,具体的工作原理可参照双作用气动执行机构工作原理。
“ Pneumatic valve actuator control methods and working principle ”是由提供的阀门行业新闻,译文仅供参考。另外,中国气动阀门网还提供相关产品搜索: 、 、 、 、 、 、 、 、 、 等。
译文:
As the ways and means of control is now more and more often in the actual industrial hygiene and industrial control, used to control the pneumatic actuators are also many methods commonly used are the following.
(A) Based on Single Chip Smart display instrument control
Smart indicator is used to monitor the working status of the valve and control valve actuator apparatus of the work it through two-way valve position sensor to monitor the working status, determine the valve is in a valve open or closed valve state, recorded by programming valve switch figures, and the two Road and valve opening corresponding to the 4 ~ 20mA output and two-legged normally open normally closed output contacts. Through these output signals to control the switching valve. According to the requirements of the system can be smart valve indicator from the hardware design is divided into three parts: analog and digital parts, buttons / display part.
1, analog circuit section includes power, analog input circuitry, analog output circuit of three parts.
Part of the circuit power supply energy, including analog circuits, digital circuits and display of energy supply. In order to achieve the remote control valve opening time, opening the valve needs to send information to other control instruments, and control instruments to develop the valve for a distance from the opening, the system needs a way Analog 4 ~ 20mA input signal and 1 ~ 2 Way 4 ~ 20mA analog output signal. Analog input signal through the A / D converter and the valve opening into a corresponding digital signal sent to digital part of the microcontroller, the microcontroller it can filter the output after the. Information by opening the valve D / A converted into analog signal output is used to access indicator shows valve opening or connection to other control equipment. In the design of the system, all the serial digital data input and output are used, and in order to save chip resources and space, enter the 4 ~ 20mA for analog to digital quantities in the transformed, using the existing 4-way chip DA SCM system resources and combines an 8-bit AD use.
2, the digital circuit parts include: microcontroller, power-down protection, two-way monitor pulse input signal, two-way normally open normally closed contact output conversion.
Currently used in the design of commonly used 51 series AT89C4051. AT89C4051 is a low voltage, high-performance CMOS8 bit microcontrollers, it has a 4K-byte erasable, reprogrammable read-only memory. Combined in a single chip by a multi-purpose 8-bit CPU memory, performance, instruction set and pin compatible with 80C51 and 80C52.
Taking into account the power-down or restart the system, the need to maintain the previously set number of valve instrument parameters, the data in the microcontroller memory storage do not have the power-down, so expands the chip features a power-down save chip X5045. X5045 is a set of watchdog, power control and serial EEPROM3 kinds of functions in a programmable circuit, this combination can reduce the circuit design of circuit board space requirements, X5045's watchdog for the system provides protection When the system is set to send failure over time, the watchdog circuit will RESET signal to the CPU to respond. X5045 provides three times the value for the user to choose. It has a voltage monitoring function can protect the system from the impact of low-voltage, when the power supply voltage drop below allowable range, the system will be reset until the supply voltage returns to a stable value so far. X5045 memory and CPU interfaces through a serial communication. A total of 4069, can be 512 × 8 bytes to place the data.
X5045 pin arrangement, which a total of eight pins, each pin function as follows:
CS: Circuit choice side, active-low;
SO: serial data output;
SI: Serial data input;
SCK: serial clock output;
WP: Write Protect input, active low;
RESET: Reset output;
Vcc: Supply-side;
Vss: ground.
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valve switching state. Two-way valve input module receives test pulse input, the pulse A and pulse B. Running state, the input pulse A light A bright light pulse input B B light. Enter the order of AB, said the open valve. Expressed concern for the BA input sequence valve. A and B pulsed valve test signal must be part of the stack, or can not properly detect the valve opening.
Through the PLC output module OC225 control two relays, relays with two normally open normally closed output contacts, one group for the open valve output contact, a group providing valve output contacts. Open valve, when the valve opening is greater than or equal to the limit values established by the valve opens when the valve output contact action, the valve opening is less than the limit value set to open valve valve output contact action, invention valve opening is less than the limit value is set to open valve when the output contacts reset. Off valve, when
the valve to zero and no pulse input within 21s off valve output contact action; if there 21s pulse input, the output contact delay 21s off valve action. Pull-through relay to control the switching of two solenoid valves, solenoid valve opens, it can control the pneumatic valve actuator allows the valve to do the appropriate action to open valves on or off valves. At the same time close to the sensor to switch the valve in the case are then transmitted to PLC, and with the requirements of the valve opening for comparison, until the compliance requirement.
Auto zero and auto-Man: With automatic control system with auto-zero full function, when the valve opening is less than zero value or the valve opening range from full scale value of less than full-scale adjustment range, and the big time than or equal to the value established by the stability of the time value, PLC automatic control valves for zero or auto-filled.
In the experiment, the calculated valve position sensor on the valve opening.
A sensor when the valve first left, then left the B sensor, said valve in the valve off. When the valve is first to leave B sensors, and left A sensor that valve in the open valve. Sensor receives a pulse signal, the signal through the position sensor to record the collection valve switches state.
PC programming software used in the CX-programmer write ladder, and then downloaded to the PLC ladder run in the PC configuration software to control and monitor how much the amount of valve switch configuration software interface can be entered Numerical Determination of circle. After doing the configuration interface, open valve, closing valve, stop, total switch control and movement control can be directly in the configuration interface is very intuitive and visual way to operate.
Working principle of pneumatic valve actuators
Promote the use of air actuators in multiple combination pneumatic piston, transfer to the beams and the inner curve of the track characteristics, driven hollow shaft rotates, and compressed air to the cylinder input tray, change the location and out of gas in order to change spindle direction, depending on the load (valve) of torque required to rotate the request, the number of adjustable cylinder combination to drive the load (valve) work.
2 5 solenoid valve is usually double acting pneumatic actuator and supporting the use of two two position control: - off, five have five channels through ventilation, including a connection with the gas source, two with double the role of the external air cylinder air inlet connection and out of rooms, two with the internal air chamber and out of air intake series of specific works can be double acting pneumatic actuator reference works.