Electro hydraulic proportional directional flow valve

A pressure compensation valve (also known as a flow control valve or differential pressure reducing valve) is connected in series before the proportional valve, which can automatically adjust its own throttle port to maintain a constant pressure difference at the valve port of the proportional valve (e.g. 1.0 MPa). In this way, the flow rate is only proportional to the opening area of the proportional valve, thereby achieving load independent flow control.

7.2 JHF series specifications

The document provides four types of pressure compensation valve kit models:

Model Maximum pressure MPa Compensation pressure difference MPa Maximum flow L/min Weight kg

JHF-01027 21 1.0 27 1.5

JHF-03040(E) 25 0.6 40 4.7

JHF-03080(E) 25 1.4 80 4.7

JHF-06170(E) 21 0.8 170 5.0

The "E" in the model indicates an external pilot type, and without an E, it is an internal pilot type. The pilot oil of the internal pilot type comes from the P port; The external pilot type requires the introduction of pilot oil from the external Pp port, which is suitable for situations where the compensating valve and proportional valve need to be supplied separately.

Important note: When using the pressure compensation kit, it is necessary to use an external pilot type ESD valve (i.e. with an external pilot option in the model). This is because the compensating valve will change the pressure characteristics of the P port of the main valve, and the internal pilot may not be able to obtain stable pilot pressure.

7.3 Installation and piping

The pressure compensation valve kit is usually installed in a stacked or tubular manner between the proportional valve and the base plate. The installation bolts need to be purchased separately, please refer to the bolt list on pages D-93 to D-95 in the document. The external dimension diagram shows the installation dimensions of JHF-01027 and JHF-06170 (E), including oil port position, bolt hole spacing, etc. When designing the integrated block, the installation surface must be machined strictly according to the dimensions shown in the diagram.

Selection of compensating pressure difference: For systems that require low pressure loss, JHF-03040 (E) with a compensating pressure difference of 0.6 MPa can be selected; For applications that require higher response speed or more stable control, JHF-03080 (E) with a pressure difference of 1.4 MPa can be selected. A larger compensation pressure difference helps to overcome the frictional force and hydraulic force of the valve core, but it will increase the power loss of the system.

Seals and repair kits

8.1 ESD-G01 Sealing Kit

Model: JDS-G01-1A

Includes parts: O-ring AS568-012 (4 pieces), AS568-019 (2 pieces), NBR-90 P22 (2 pieces), AS568-016 (2 pieces), NBR-90 P7 (2 pieces), S-25 (2 pieces), NBR-70-1 P20 (2 pieces), sealing ring CW1000F02 (1 piece). The material hardness meets the JIS B2401 standard.

8.2 Pilot stage sealing kit (for G03/G04)

Kit models: JHS-G03 and JHS-G04

It includes various O-rings for pilot valve core, screw plug and other parts, such as NBR-90 P12, P9, P28, P10A, etc. When replacing, be sure to refer to the parts list and exploded view to avoid installing in the wrong position, which may cause leakage or valve core jamming.

8.3 Pilot stage sealing kit (for G06)

Kit model: JHS-G06

Includes O-rings NBR-90 P28 (4 pieces), P20 (2 pieces), G45 (2 pieces), P10 (2 pieces), P8 (3 pieces). The sealing structure of G06 is slightly different from other specifications and cannot be mixed.

When disassembling the valve for maintenance or changing the pilot/oil discharge method, all removed O-rings should be replaced to ensure sealing reliability.

Typical application scenarios

Injection molding machine: Control the speed switching and pressure relief of the injection cylinder, and use slope signals to achieve graded control of injection speed.

Press: Control the speed and direction of the slider's rapid descent, pressing, holding, and return, and cooperate with the pressure compensation valve to overcome the influence of unbalanced load.

Test bench: When testing the performance of hydraulic components, it is necessary to accurately adjust the flow rate and frequently change directions. The combination of proportional valves and PLC can achieve automated testing cycles.

Mobile machinery (such as forklifts and excavators): remote electronic proportional control, simplifying the mechanical linkage mechanism of the cab control lever.

Wind power variable pitch system: Real time adjustment of blade angle based on wind speed, requiring fast response and long-term operation in vibration environment.