Electro hydraulic proportional directional flow valve

Pilot pressure: at least 1.0 MPa (10 kgf/cm ²), which is the pressure difference between the pilot port and the return port (or drain port).

Pilot flow rate:

G03: At least 2 L/min

G04: At least 3 L/min

G06: At least 5 L/min

If the pilot pressure exceeds 9 MPa (92 kgf/cm ²), it is recommended to install a modular pressure reducing valve (such as OG-G01-P1-21) at the P port and set the pilot pressure to around 2 MPa to avoid excessive hydraulic force on the proportional solenoid.

2.3 Weight

ESD-G01：2.2 kg

ESD-G03：7.2 kg

ESD-G04：9.2 kg

ESD-G06：15.0 kg

Model Code and Selection Guide

The basic structure of the model coding rule (taking the illustration in the document as an example) is:

ESD - G 03 - * * * * * * * * * * - 12

Meaning of each field:

ESD: Product Series Code

G: Equipped with modular pilot pressure reducing valve (height increased by 40mm) or specific configuration identification

03: Specification code (01/03/04/06)

Middle section: valve core form, spring configuration, flow regulation range, etc. (refer to the selection table for details)

12: Design Number

The document provides a slide valve type table (Table 1), which lists the hydraulic circuit symbols corresponding to different valve cores, such as C5, C6, etc. Users should choose the appropriate valve core model based on the required slide valve function of the actuator (such as center closing, center floating, etc.).

Attachment and option identification:

Auxiliary symbol "G": indicates that a modular pilot pressure reducing valve has been installed, and the total height of the valve will increase by 40 mm.

The installation surface complies with ISO 4401 standard:

ESD-G01：ISO 4401-03-02-0-94

ESD-G03：ISO 4401-05-0-05

ESD-G04：ISO 4401-07-06-0-05

ESD-G06：ISO 4401-08-07-0-05

This means that the series of valves can be directly installed on any base plate that meets the same ISO standards, with good interchangeability.

Structural composition and sectional diagram

4.1 ESD-G01 Direct Acting Structure

The core components of a direct acting valve include:

Valve Body

Spool valve core

Retainer

Spring (Spring)

Proportional solenoid with coil

Multiple O-rings (used for various sealing parts)

Seal ring

When the proportional electromagnetic iron on one side is energized, the electromagnetic force directly pushes the valve core to move, compressing the spring on the other side. The displacement of the valve core is proportional to the magnitude of the current, thereby controlling the opening of the throttle port. Due to the absence of a pilot stage, the direct acting valve responds faster, but the controllable flow rate is limited by the electromagnetic thrust, resulting in a maximum flow rate of only 25 L/min for the 01 specification.

4.2 ESD-G03/G04/G06 Pilot Structure

The pilot operated valve adds a pilot spool and pilot stage spring outside the main stage. The proportional electromagnet pushes the pilot valve core, controlling the flow of pilot oil into the chambers at both ends of the main valve core, creating a pressure difference to drive the movement of the main valve core. This two-stage amplification structure enables low-power electromagnets to control high flow main valves.

The sectional view shows that the pilot operated valve includes:

Main valve body

Main valve core (Spool)

Pilot spool

Pilot spring and spring seat

Manual adjusting screw

Various seals (O-rings)

The manual adjustment screw is located on one side of the pilot stage, and clockwise rotation can force the valve core to the working position, which is used for initial adjustment or manual operation in emergency situations such as power outage. During normal use, the adjusting screw should be fully retracted counterclockwise.

4.3 Changes in Pilot Oil and Oil Discharge Method

The document provides detailed methods for modifying the pilot/drain system. Users can configure the valve according to their circuit needs as follows:

Internal pilot: The pilot oil comes from the P port and is suitable for systems where there is always pressure at the P port.

External pilot: The pilot oil comes from an independent X port (or Pp port), suitable for systems with large pressure fluctuations at the P port or requiring low-pressure start-up.

Internal drain: The pilot drain oil returns to the T port, which is simple and convenient, but the back pressure at the T port should not be too high.

External drain: The pilot drain oil is directly returned to the tank (DR port), allowing the T port to withstand high back pressure.

The usual way to change the oil circuit connection is by screwing in or out certain Hexagon socket head plugs. For example, for G03, changing the inner pilot to the outer pilot requires removing the plug from position A, while changing the outer pilot to the inner pilot requires inserting the plug. These operations require disassembling the end cover of the valve and replacing the corresponding sealing ring.

Key points for installation and use

5.1 Exhaust

The air dissolved in hydraulic oil will precipitate under high temperature and pressure, affecting control stability. Before starting, the air vent plug on the valve must be loosened and tightened after the air is discharged and pure oil flows out. Special note in the document: There is an M4 fastening screw on the coil cover plate. If you need to change the direction of the exhaust port, you can loosen the screw and rotate the cover plate. After completing the exhaust, tighten it again.