What are the Two Main Types Solenoid Valves?

Solenoid valves in construction machinery are critical control elements used to manage the flow of liquids or gases to ensure proper operation of mechanical equipment. Solenoid valves are usually categorized into two main types, namely, straight-through solenoid valves (Normally Open, NO) and closed solenoid valves (Normally Closed, NC).

 

Straight-through solenoid valves (NO)

The operating principle of a straight-through solenoid valve is based on electromagnetic induction. It consists of a solenoid coil and a removable spool. When there is no current passing through the solenoid coil, the spool is usually pushed by a spring that keeps the valve open. At this point, fluid can pass freely through the solenoid valve.

 

When current is passed through the solenoid coil, the solenoid coil generates a magnetic field that attracts the spool, causing it to move and close the valve. This stops the flow of fluid. Therefore, the state of the solenoid valve depends on whether the current is energized or not, thus controlling the flow of fluid on and off.

 

In-line solenoid valves are usually composed of the following major components:

Solenoid Coil: The solenoid coil is the core component of a solenoid valve and generates a magnetic field to control the position of the spool.

Spool: The spool is a movable element that determines the state of the valve (open or closed). The position of the spool is controlled by the magnetic field of the solenoid coil.

Spring: The spring is normally used to hold the spool in the open position, i.e. the position when no current is energized.

 

When there is no current passing through the solenoid, the spool is usually pushed by a spring that keeps the valve open. This means that fluid can pass through it freely.

Once current is passed through the coil, a magnetic field is created that attracts the spool and closes the valve so that fluid cannot pass through.

In-line solenoid valves are usually very responsive and can control the passage of fluid in an instant.

In the absence of electrical current, they will keep the valves open, which increases the reliability of the system and ensures the safety of other diesel engine parts.

 

In summary, straight-through solenoid valves are a powerful control tool for quickly controlling the flow of fluids in a wide variety of mechanical and industrial systems, ensuring that they operate properly in conjunction with other components such as starter motor and alternators and responding quickly when needed.

 

Closed Circuit Solenoid Valves (NC)

The principle of operation of a close-coupled solenoid valve is very simple. When current passes through a solenoid coil, it generates a magnetic field which attracts the spool and causes it to move, thus opening the valve. When the current stops flowing, a spring closes the spool back together, closing the valve. This process can be accomplished quickly, allowing closed solenoid valves to achieve on/off control of fluids in milliseconds.

 

In construction machinery, closure-type solenoid valves are often used to control the action of hydraulic cylinders, hydraulic motors and other hydraulic actuators. For example, an excavator may use a closure-type solenoid valve to control the action of an arm, a bucket lever, and a bucket, enabling it to perform operations such as digging, loading, and unloading. In addition, closure solenoid valves may be used to control brake systems, suspension systems, and other mechanical components that require hydraulic control.

 

Closed-cell solenoid valves usually consist of the following main parts:

Valve body: usually made of metal or plastic, it is used to house other components and connect to the piping system.

Solenoid Coil: The heart of a closed diesel solenoid valve, it is a coil of wire that is wrapped around an iron core and passes an electric current to create a magnetic field.

Spool: Located inside the core of the solenoid coil, the spool is a movable element used to control the flow of liquid or gas.

Spring: Used to keep the spool closed in the absence of current.

Seal: located between the valve body and the spool, to prevent liquid or gas leakage.

 

In short, closed solenoid valves play a vital role in construction machinery, they improve the performance and maneuverability of construction machinery by accurately controlling the flow of the hydraulic system, so that construction machinery can efficiently and accurately complete a variety of work tasks.