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From the application range of hydraulic valves, you can find out that, there are so many different industries that have something to do with hydraulic valves. It is a basic control component of every hydraulic system or hydraulic equipment. In order to operate the machines smoothly and safely, the performance of hydraulic valves and hydraulic pumps must stay in good condition. That’s why it is so important for us to choose the right hydraulic solenoid for the hydraulic valves. To choose hydraulic solenoid successfully, the first thing we have to do is to get some information about hydraulic solenoids, such as the types of hydraulic solenoid, the difference between different hydraulic solenoid types, etc.
Hydraulic Solenoid Types
Hydraulic Solenoid is a special type of electromagnetic actuator for hydraulic valves and hydraulic pumps. There are many different ways to classify hydraulic solenoid types. Normally, based on the different working principles, hydraulic solenoid can be divided into three types, on off solenoid, proportional solenoid, servo solenoid. Based on different solenoid shapes, there are square hydraulic solenoid and round hydraulic solenoid. Based on different power systems, there are AC hydraulic solenoid and DC hydraulic solenoid. Among all the hydraulic solenoid types, on off solenoid and proportional solenoid are the mostly used hydraulic solenoid. Therefore, in the following article, we will compare on off solenoid and proportional solenoid, and discuss the main difference between them.
On Off Solenoid for Hydraulic Valve
On off solenoid is designed for hydraulic directional valves. From the name of on-off solenoid, we can easily find out that this type of solenoid is used to realize the on/off functionality of hydraulic valves. Therefore, on-off solenoid armature normally has two positions, the two endpoints. It can not hold any position between both ends of the rated stroke.
Different hydraulic valve manufacturers may have some unique requirements of the on off solenoid for their hydraulic directional valves. Right now, there are some big hydraulic valve brands on the market, such as Rexroth, Yuken, Vickers, Parker, etc. The most common on off solenoid type is used for their wet type hydraulic directional valve NG6 & NG10. The rated force of on off solenoid is no more than 90N, and the rated stroke is no more than 5mm.
Proportional Solenoid for Hydraulic Valve
Proportional solenoid is designed for hydraulic proportional valves. Hydraulic proportional valve includes many different types, such as proportional flow valve, proportional directional valve, proportional pressure relief valve, etc. All these hydraulic valves are actuated by proportional solenoid. Unlike on off solenoid, proportional solenoid has different positioning. The proportional solenoid armature can hold any position along the proportional solenoid rated stroke. Therefore, proportional solenoid maintain a more sophisticated solenoid tube design than on off solenoid. Moreover, it also need a more complicated electronic control so that the proportional solenoid can operate precisely.
Typically, proportional solenoids are used in hydraulic closed-loop control system to control the hydraulic valves that have high control precision. There are many different proportional solenoid types. Due to different connection method, there are screw type proportional solenoid, bolt type proportional solenoid, and 3-pin type proportional solenoid. Due to different shapes, there are square proportional solenoid and round proportional solenoid. The main function of proportional solenoid valve is to control the flow, pressure, and direction of hydraulic fluid media. To achieve that, high quality proportional solenoid is the necessity.
Main Difference Between On Off Solenoid & Proportional Solenoid
There is some big difference between the working performances of on off solenoid and proportional solenoid.
Different Positioning
As we have mentioned before, on off solenoid is used to control the on off functionality of hydraulic directional valves, therefore, it only needs two positions to turn on and turn off the valve. But proportional solenoid is used to control the function of hydraulic valve based on a certain proportionality. Therefore, any point along the rated stroke of proportional solenoids is an available position for proportional solenoids.
Different Force Exerted Methods
On-off solenoid is used to realize the on-off functionality of hydraulic directional valves. For on-off solenoid, the force chart shows a curve shape. As you can see, the shortest stroke length has the highest force, and then the force drops as the rated stroke length increases.
Proportional solenoid is used to realize the proportionality functions of hydraulic proportional valves. Although proportional solenoid has many different positions along the rated stroke, Its force chart shows a flat line, which means the force of proportional solenoid will not change as the working stroke length increases.
