Classification and working principle of reversing directional control valve
The reversing type directional control valve (referred to as reversing valve) is to change the direction of gas flow by changing the air flow channel, so as to achieve the purpose of changing the movement direction of the pneumatic actuator. It includes air pressure control directional valve, electromagnetic control directional valve, mechanical control directional valve, manual control directional valve and time control directional valve.
1. Air pressure control directional valve The air pressure control directional valve uses the gas pressure to move the main spool to change the flow of gas. According to different control methods, it is divided into three types: pressure control, pressure relief control and differential pressure control. Pressure control means that the pressure of the applied control signal is gradually increased. When the air pressure increases to the operating pressure of the spool, the main valve changes direction; the pressure relief control means that the pressure of the added air control signal is reduced. When the pressure decreases to a certain pressure value, the main valve changes direction; poor Pressure control is to change the main spool under the effect of the pressure difference between the two ends.
According to the structure of the main valve, the gas-controlled reversing valve can be divided into two main types: cut-off type and slide valve type. The structure and working principle of the spool valve type air control directional valve are basically the same as the hydraulic directional valve. Here mainly introduces the cut-off directional valve.
2. Pilot operated solenoid directional valve
The pilot-type electromagnetic directional valve is controlled by the electromagnet to generate the pilot pressure first, and then the pilot pressure is used to push the main valve spool to change the direction. Suitable for occasions with large diameter.
Pilot-operated dual-electric control two-position four-way electromagnetic directional valve. It consists of pilot valve (Dl, D2) and main valve. The main valve includes the valve body 1 and the piston assembly 2 in two parts. The figure shows that both D1 and D2 are in a power-off state. The moving iron cores 5 and 6 of the solenoid valve are closed. When D1 is energized and D2 is de-energized, the moving iron core 5 is sucked up, and the compressed air from the P port enters the valve f cavity through the hole a (dashed line). And enter the hole from the lip around the sealing plug 4 (one-way valve), and enter. Wide cavity, push the piston assembly 2 down to make P and A pass, B passes through the center hole of the spool and T pass (exhaust). At the same time as there is compressed air output from port A, a part of compressed air flows into the hole g, one of which enters the cavity c through the orifice d, so that the sealing plug 4 moves downward to seal the exhaust hole b, and the other compressed air enters the cavity f, acting The upper end of the piston assembly 2. At this time, even if D1 is powered off, the piston assembly 2 will not be in position, that is, the valve has a memory function.
Pilot-operated dual-electrically controlled two-position four-way electromagnetic directional valve When the pilot valve D2 is energized and Dl is de-energized, the moving iron core 6 is sucked up, and the compressed air in the c cavity is discharged through the T1 port. At this time, the compressed air from P to A acts on the large and small pistons. Due to the difference in area between the large and small pistons, an upward force is generated to move the piston assembly 2 upward. At the same time, the sealing plug 4 also moves up, and opens the valve port 3, so that the compressed air at the upper end of the piston assembly 2 is discharged through the hole 6. After the piston assembly 2 moves up, P and B pass, and A and T pass (exhaust). At this time, even if D2 is powered off, the upward force due to the difference in the area of ​​the pistons still exists, so the output state will not change, that is, it has a memory function. Pneumatic electromagnetic directional valve is the same as hydraulic electromagnetic directional valve, there are many types, and its working principle is similar, no longer go into details.
Incremental encoders provide speed, direction and relative position feedback by generating a stream of binary pulses proportional to the rotation of a motor or driven shaft. Lander offers both optical and magnetic incremental encoders in 4 mounting options: shafted with coupling, hollow-shaft, hub-shaft or bearingless. Single channel incremental encoders can measure speed which dual channel or quadrature encoders (AB) can interpret direction based on the phase relationship between the 2 channels. Indexed quadrature encoders (ABZ) are also available for homing location are startup.
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