The product history of the control valve can be traced back to the earliest self-operated control valve. Its most original structure is a ball valve with a weight, which uses the weight of the weight to balance the fluid action on the spool for adjustment.This kind of regulating valve later evolved into a self-operated type that uses the pressure behind the valve to regulateControl valve.
In the 30s, there were many types of products, and the spherical valve with a spherical valve body became a representative product. After the 40s, angle valves, butterfly valves, diaphragm valves and ball valves all appeared one after another, occupying a leading position in the market successively. The products are relatively complete. The sleeve valve that appeared after the 60s quickly gained attention and became the mainstream product of the spherical valve. The new product that appeared in the 70s was the cam deflection valve. It has a large capacity, simple flow path, and small unbalanced force. These advantages make it a leader in quarter-turn valves.During this period, various valves have become more perfect and formed series.At the same time, the side-mounted force-increasing control valve (also called ΣF type valve) was successfully developed. Because of its unique structure, small installation height, and ability to increase force, it is welcomed by many factories and users.Since the 80s, people have successively manufactured various light-duty (or so-called fine and small) regulating valves. Its main feature is that in the pneumatic actuator, multiple springs are used to replace the original large spring. In this way, the pneumatic actuator The mechanism can appear in a new look. It makes the regulating valve small and high-capacity. This kind of actuator may replace the old and bulky actuator.In the 90s, due to the emergence of intelligent valves, a new page was opened for the development of regulating valves.
my country’s pneumatic control valve production industry started late, and the relevant factories and departments independently designed and produced straight-through single-seatControl valve, Double-seat control valves, three-way control valves, high-pressure control valves, butterfly valves, long-stroke actuators and valve positioners and other traditional main products are still in use today.my country’s pneumatic control valve has made a leap since the 80s. Many factories have successively introduced foreign advanced technology. On the basis of improving the performance of the original products, further standardization and serialization, they have successively developed side-mounted pneumatic control valves and light-duty regulators. Valves and other new products.
The electric control valve of our country also started relatively late. In the mid-50s, it mainly imitated the products of the Soviet Union and manufactured electric actuators with contacts. The development of non-contact electric actuators began in the 60s. After more than 20 years of development, there are already many manufacturers specializing in the production of electric control valves, producing various non-contact DKZ-type linear electric actuators and DKJ-type rotary electric actuators. Executive agency.In the last 20 years, we have mainly developed some new products, such as DDZ-Ⅱ and DDZ-Ⅲ electric actuators.But these products have reached the time of upgrading, they have obvious shortcomings, such as large dead zone, narrow operating temperature range (-10 ~ +55 ℃), torque protection and performance protection are poor, and the insulation level is not high.Therefore, at present, domestic manufacturers are committed to product innovation and develop new types of electric actuators, such as:
① High-power (greater than 6000N.m) and low-power (less than 100N.m) electric actuators. High-power actuators can be used in large power stations, power plants, and metallurgical plants. It uses three-phase power as power and three-phase servo amplifiers. , Three-phase controller and three-phase manipulator are used together to realize disturbance-free switching, accident alarm and continuous protection.Low-power electric actuators are used in small control systems.
② Multi-turn electric actuator The maximum number of turns of the output shaft of this actuator is 5 to 120 turns. It is mainly used to control high temperature and high pressure regulating valves. It is suitable for frequent starting and control, and is suitable for automatic control and remote control, and adjusts the speed. It can be fast or slow, and can be quickly closed or opened in an emergency.
③ High-resolution stepper motor actuator The stepper motor controller is controlled by a microprocessor and equipped with a display unit. It has the characteristics of easy operation, convenient operation, high temperature control, good stability, and low power consumption. It can be used for conventional The open-loop loop is controlled by the host computer, and can be used in the closed loop. It accepts conventional analog control signals and can adapt to the requirements of various control systems.
④ The electric actuator with microcomputer replaces the traditional analog amplifier with an intelligent servo amplifier, which has the functions of self-diagnosis, self-processing, and characteristic correction. This new type of terminal control element is very promising and will be introduced in detail in Chapter 2. .
Currently,Control valveThe new theories and calculation formulas have been accepted by everyone, but there is still no uniformity, and various formulas left over from history are still retained.Although the error is large with the old formula, the calculation is relatively simple; the new formula is accurate, but it is more troublesome, because there are many calculation coefficients and many charts to be consulted.