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To the solenoid valve project for the most, it mainly includes the following items:
1. Reliability of work
Refers to whether the electromagnet can be reliably reversed after power-on and can be reliably reset after power-off. The solenoid valve can only work normally within a certain flow and pressure range. The limit of this operating range is called the commutation limit.
2. Pressure loss
Since the opening of the solenoid valve is very small, a large pressure loss occurs when the fluid flows through the valve port.
3. Internal leakage
In each different working position, under the specified working pressure, the leakage from the high pressure cavity to the low pressure cavity is the internal leakage. Excessive internal leakage will not only reduce the efficiency of the system and cause overheating, but also affect the normal operation of the actuator.
4. Commutation and reset time
The commutation time of AC solenoid valve is generally 0.03~0.05s, and the commutation impact is large; while the commutation time of DC solenoid valve is 0.1~0.3s, and the commutation impact is small. Usually the reset time is slightly longer than the commutation time.
5. Commutation frequency
The commutation frequency is the number of commutations allowed by the valve per unit time. At present, the commutation frequency of the solenoid valve of the single electromagnet is generally 60 times/min.
6. Service life
The service life of the solenoid valve mainly depends on the electromagnet. The life of wet electromagnet is longer than that of dry type, and the life of DC electromagnet is longer than that of AC.
7. Hydraulic clamping phenomenon of slide valve
Slide valve hydraulic clamping phenomenon not only in the valve, other hydraulic valves are also widespread, in the high pressure system is more prominent, especially the spool valve residence time is longer, the greater the hydraulic clamping force, resulting in moving the slide valve thrust (such as electromagnet thrust) can not overcome the clamping resistance, so that the slide valve can not be reset.
The causes of hydraulic clamping are: some are difficult to move the spool due to dirt entering the gap, and some are stuck due to the expansion of the spool when the oil temperature rises due to the gap being too small. However, the main reason is the radial unbalanced hydraulic pressure caused by the geometric shape error and concentricity change of the spool valve pair. In order to reduce the radial imbalance force, should strictly control the spool and valve hole manufacturing accuracy, in the assembly, as far as possible to make it into a conical type, on the other hand in the spool open ring pressure groove, also can greatly reduce the radial imbalance force.