Excavator solenoid valve 457-9878 hydraulic pump proportional solenoid valve

1, proportional valve structure.

Proportional valve is a new type of hydraulic control device. The pressure, flow, or direction of the oil stream can be controlled remotely according to the input electrical signal continuously and proportionally. The proportional valve is composed of two parts: the electro-mechanical proportional conversion device and the hydraulic control valve body.

There are many kinds of proportional electromagnets, but the working principle is basically the same, and they are all developed according to the control needs of the proportional valve. Its function is to continuously and proportionally convert the input electrical signal into the mechanical force and displacement output, and the latter outputs the pressure and flow proportionally and continuously after accepting the mechanical force and displacement.

2. Working principle of proportional valve.

The command signal is amplified by the proportional amplifier, and the proportional output current to the proportional solenoid of the proportional valve, the proportional solenoid output force and the proportional movement of the valve core position, you can proportional control the flow of the liquid flow and change the direction of the liquid flow, so as to achieve the position or speed control of the actuator. In some applications requiring high position or speed accuracy, the closed-loop control system can also be formed by detecting the displacement or speed of the actuator.

Principle of proportional solenoid valve

It is based on the principle of the solenoid switch valve: when the power is cut off, the spring presses the iron core directly against the seat, closing the valve. When the coil is energized, the resulting electromagnetic force overcomes the spring force and lifts the core, thus opening the valve. The proportional solenoid valve makes some changes to the structure of the solenoid on-off valve: the spring force and the electromagnetic force are balanced under any coil current. The size of the coil current or the size of the electromagnetic force will affect the stroke of the plunger and the opening of the valve, and the opening of the valve (flow rate) and the coil current (control signal) have an ideal linear relationship. Direct acting proportional solenoid valves flow under the seat. The medium flows under the valve seat, and its direction of force is the same as the electromagnetic force, but the opposite of the spring force. Therefore, it is necessary to set the sum of the small flow values corresponding to the operating range (coil current) in the operating state. When the power is off, the Drake liquid proportional solenoid valve is closed (normally closed).

Proportional solenoid valve function

Throttle control of the flow rate is achieved by electrical control (of course, pressure control can also be achieved by structural changes, etc.). Since it's throttle control, there must be a loss of power.