Characteristics and selection of various valve driving devices

Characteristics and selection of various valve drive devices

Valve device driving mode

According to the movement mode of the driving mechanism, the valve driving device is divided into two types: straight stroke and angle stroke.

According to the driving structure, the valve drive device is divided into:

1. Diaphragm type

2. Cylinder type

① Piston cylinder type

② Piston rack type

③ Piston rod type

④ Piston fork

⑤ Piston screw type

3. Blade type

4. Air engine type

5. Combination of film and ratchet

Hydraulic drive hydraulic cylinder type hydraulic motor type linkage drive electro hydraulic linkage

Valve transmission mode: manual driving handle hand wheel type (including deceleration through intermediate gear), spring lever type, electric drive, electromagnetic type, motor type and pneumatic drive.

Characteristics of various valve drive devices

Advantages of electric device

1. Strong applicability, not affected by ambient temperature

2. Wide range of output torque

3. It is convenient to control and can freely use various signals such as DC, AC, shortwave and pulse, which is suitable for amplification, memory, logic judgment and calculation

4. Can be miniaturized

5. It has mechanical self-locking

6. Easy to install

7. Convenient maintenance

Disadvantages of electric device

1. Complex structure

2. Low mechanical efficiency, generally only 25-60%

3. Output speed cannot be too low or too high

4. Easily affected by the change of power supply voltage and frequency

Advantages of hydraulic device

1. Simple structure, compact and small volume

2. High output

3. Easy to obtain low speed or high speed, can stepless speed change

4. Can control automatically from a long distance

5. Due to the high efficiency of the hydraulic oil viscosity, it has self lubrication and rust resistance

shortcoming

1. Oil viscosity change caused by oil temperature change

2. Hydraulic components and pipelines are easy to leak

3. Accompany with the management, inconvenient maintenance

4. Not suitable for various operations on signals

Advantages of pneumatic device

1. Simple structure

2. Easy to obtain gas source

3. High switching speed can be obtained

4. Governor can be installed to adjust the switch speed as required

5. High compressibility of gas, elasticity when closed

shortcoming

1. Compared with hydraulic device, the valve has a larger structure and is not suitable for large caliber and high pressure valve

2. Because of the compressibility of the gas, the velocity is not easy to be uniform

Selection of valve driving mode

The selection of valve driving mode is based on the form, specification and structure of the valve.

Opening and closing moment of valve (pipeline pressure, large pressure difference of valve), thrust.

Environmental temperature and fluid problems.

Usage and usage times.

Opening and closing speed and time.

Diameter, pitch, rotation direction of stem.

Connection mode.

Power source parameters: electric power supply voltage, phase number, frequency; pneumatic air source pressure; hydraulic pressure.

Special consideration: low temperature, anti-corrosion, explosion-proof, waterproof, fire prevention, radiation prevention, etc.