Rexroth solenoid directional valve, 4WE6J7X/HG24N9K4 Rexroth

Bosch Rexroth Solenoid Directional Valve, 4WE6J7X/HG24N9K4

• Directional Valve

• Function:

• By changing the relative position of the valve core with respect to the valve body, the oil circuit is opened, closed, or the direction of oil flow is changed, thereby enabling the hydraulic actuator to start, stop, or change the direction of movement.

• 1. Performance Requirements for Directional Control Valves

• (1) Pressure loss should be small when the oil is flowing;

• (2) Leakage should be small when the oil is disconnected;

• (3) Operating force should be small when the valve core is repositioned.

• 2. Types

• Classification by valve core shape: slide valve, rotary valve

• Classification by valve installation method: pipe type, plate type, flange type.

• Classification by operating method:

• Manual, motorized, electric, spring-controlled, hydraulic, hydraulic pilot control, electro-hydraulic, etc.

• 3. Main Structure and Working Principle of Directional Control Valves

• Structure of Several Typical Directional Control Valves

• 1. Manual Directional Control Valve

• 2. Mechanically Operated Directional Control Valve, also known as a stroke valve.

• It uses a stop or cam mounted on the workbench to force the valve core to move. It is usually two-position, and comes in two-way, three-way, four-way, and five-way configurations.

  The two-position two-way mechanically operated valve is further divided into normally closed and normally open types.

• ③ Electromagnetic Directional Control Valve

• Working Principle:

• It uses the energization and de-energization of an electromagnet to directly push the valve core to control the direction of fluid flow.

• Type:

• AC (D, 36V or 220V or 380V)
  DC (E, 24V or 100V)

• Dry type, Wet type

• AC electromagnet: Operating voltage is AC 110, 220, 380V. Features include high starting force, no need for a dedicated power supply, fast engagement and release, and an action time of approximately 0.01~0.03s.

  Disadvantages include a significant decrease in electromagnet attraction force when the power supply voltage drops by more than 15%, and if the armature does not operate, the coil of a dry type electromagnet will burn out after 10~15 minutes (1~1.5h for a wet type).

  It also experiences high impact and noise, has a short lifespan, and the permissible switching frequency is 10 times per minute.

• DC Electromagnet: Uses DC 110V and 24V, reliable operation, pull-in and release time is approximately 0.05~0.08s, switching frequency is generally 120 times/min, low impact, small size, long lifespan, but requires a dedicated DC power supply, resulting in high cost.

• AC Rectified Electromagnet: The electromagnet is DC-powered, with a built-in rectifier. AC power is rectified before being supplied to the DC electromagnet.

• Dry-type Electromagnet: The electromagnet coil, iron core, and yoke are in the air and do not come into contact with oil.

  When connecting the electromagnet to the valve, a sealing ring is installed at the push rod to prevent oil from entering the electromagnet, and it is easy to install and disassemble.

  To prevent backflow into the dry-type electromagnet, the backflow pressure of the directional valve must not be too high.

• Wet electromagnet: The push rod and valve core of a wet electromagnet are integrated, eliminating the dynamic seal at the push rod. Therefore, it has low friction, good reset performance, good cooling and lubrication, and long service life.

• Features:

• (1) Quick action, easy operation, convenient for remote control;

• (2) Due to the limitations of electromagnet size and thrust, it can only control small flow rates (less than 63 L (min) of liquid);

• (3) Electromagnet energization requires electrical signal control: such as push-button switches, limit switches, travel switches, etc. in equipment;

• (4) Fast reversal, prone to hydraulic shock.

• REXROTH directional valve 4WE6J7X/HG24N9K4

• WE model directional valves are solenoid coil operated directional spool valves. These valves control the start, stop, and direction of fluid flow.

• These directional valves mainly consist of a housing (1), one or two coils (2), a control valve core (3), and one or two return springs (4). In the absence of power, the control valve core (3) is fixed in the center or initial position by the return springs (4).

  The control valve core (3) is activated by the coil (2) with wet-pin connectors.

• To ensure proper operation, ensure that the pressure chamber of the coil is filled with hydraulic oil!

• The force of the coil (2) acts on the control valve core (3) through the push rod (5) and pushes the latter from its rest position to the desired end position. This allows the desired flow direction to be released according to the symbol.

  In the coil (2) After demagnetization, the return spring (4) pushes the control valve core (3) back to its rest position.

• Manual emergency operation (6) allows the control valve core (3) to be moved even when the coil is not energized