Parker EHC Electrohydraulic Controls

Customer Value

Advantage:

Most vehicles equipped with hydraulic valves benefit from smooth proportional control.

Electro-hydraulic controllers provide precise, repeatable and adjustable functions for any machine.

This helps ensure operator productivity and equipment profitability.

Parker electronic controllers have extensive product and system expertise to

provide solutions that scale machine functions, provide ergonomic fingertip control for the operator, and help extend the life of the machine.

Products and Features:

- Input Devices

- Joysticks

- Displays

- Motion Controller

- CAN bus and analogue signals

- Real-time calculations

- Fine control capability

Electrohydraulic operation

Hydraulic pilot spool with coil Proportional electrohydraulic control is usually generated by a controller or electronic actuator.

The controller or electronic actuator regulates the current supplied to the valve's solenoid coil based on a reference signal from an input device.

The current produces a magnetic field that moves the armature, which in turn moves the hydraulic spool or spool of the pilot section, or in some cases acts directly on the spool.

The coils all have resistance, which usually varies with temperature. For good electro-hydraulic control, it is necessary to be able to regulate the current to accommodate temperature/resistance variations.

In addition, manufacturing and design differences in coils and hydraulic valves can cause performance to vary from valve to valve, even if they are of the same type.

Optimal electro-hydraulic control requires the ability to manage and adjust all parameters that may affect coil current and valve flow or pressure.

Parker ECD offers a wide range of controllers and displays to build state-of-the-art electrohydraulic control systems.

Electrohydraulic (EH) control is the effective proportional control of hydraulics through the use of solenoid coils.

EH control is the effective proportional control of hydraulics through the use of electromagnetic coils.

Good EH control should be

- Accurate and smooth

- Repeatable

- Adjustable

An electric current is passed through the coil to create hydraulic pressure. The current generates a magnetic force that moves the spool or armature.

- Coil has resistance

- Voltage is used to push current through resistance

- Resistance varies with temperature

PWM

The proportional control of a valve depends on the use of a PWM signal. The frequency used is constant and usually depends on the design of the valve.

The percentage of time that the output is high or "on" during each frequency cycle is called the modulation ratio (MR).

If the output is "on" 50% of the time during each cycle, the modulation ratio is 50%.

The apparent voltage is approximately half of the system voltage, which drives a certain amount of current through the coil, resulting in hydraulic pressure and flow.

The system voltage and coil resistance affect the current through the coil. The higher the apparent voltage, the higher the current through the fixed resistance.

As the temperature of the coil increases, so does its resistance.

Since coil resistance varies with temperature, the current through the coil varies with temperature even if the voltage remains constant.

The EH valve has three key parameters:

Minimum Current - The current that passes through the coil when hydraulic fluid begins to flow. When the current is less than the minimum current, no oil will flow through the valve.

Valve.

Maximum Current - The current through the coil at which maximum flow of oil through the valve is achieved.

Deadband - The amount of change in the corresponding input before a flow command is sent to the output of the valve.