At present, the modern hydraulic servo valve and proportional valve, as important control components in the hydraulic system, respectively represent the development status of the hydraulic servo technology and the proportional technology. Their appearance makes the hydraulic system and the modern electronic technology combine organically and makes a great contribution to the sustainable development of the economy. So next, we will talk about them and introduce their differences and applications in details.

The Difference between Modern Hydraulic Servo Valves and Proportional Valves

The modern hydraulic servo valve and the proportional valve both apply the electric control mode to realize the throttling control of flow. Since it is throttling control, the energy loss is inevitable. Different from other valves, the servo valve has a larger energy loss because it needs a certain flow rate to maintain the control of the pre-stage oil circuit.

The difference between the hydraulic servo valve and the proportional valve is not obvious, because the performance of the proportional valve is getting better and better, and gradually close to the servo valve, so that a new kind of valve, the proportional servo valve, has appeared in recent years. If we must say the differences, they are mainly reflected in:

  • The hydraulic servo valve has no dead zone, but the proportional valve has dead zones.
  • The frequency response of the hydraulic servo valve is high, which can be up to about 200Hz. While the frequency response of the proportional valve is usually only a few dozen hertz.
  • The hydraulic servo valve has higher requirements for hydraulic oil. The hydraulic oil needs to be filtered carefully, otherwise, it will be easy to be blocked. But the proportional valve has lower requirements.

The Application of the Hydraulic Servo Valve

The hydraulic servo valve mainly refers to the electro-hydraulic servo valve, which will corresponding output flow and pressure after receiving the electrical analog signal. The hydraulic servo valve is both an electro-hydraulic converter and a power amplifier. It can convert the weak electrical input signal of low power into the hydraulic energy of high power. In normal conditions, it is mainly used as the actuator in the electrical hydraulic servo system. In the servo system, the hydraulic actuator, compared with the electrical and pneumatic actuator, has the characteristics of large output power per unit weight, stable transmission and strong anti-interference ability. In addition, signals are mostly transmitted by electrical components in the servo system. Therefore, the modern high-performance servo system usually adopts the electro-hydraulic mode, and the servo valve is a necessary component of this system.

Hydraulic servo valves are also widely used in large trucks. In order to reduce the manual labor of the driver and improve the steering flexibility of the truck, we often adopt the steering hydraulic booster. The hydraulic booster is also a hydraulic servo mechanism. It is mainly composed of hydraulic cylinder and control slide valve. When turning, if the steering wheel is turned counterclockwise, the valve core will move to the right, the oil will enter the right cavity of the hydraulic cylinder and return in the left cavity, making the hydraulic cylinder move to the right and driving the wheels to turn to the left.

The Application of the Hydraulic Proportional Valve

As the hydraulic proportional valve has various forms, it is an important part of electro-hydraulic systems controlled by electrical and computer. It has many advantages, such as high control accuracy, flexible installation and strong anti-pollution ability, so its application field is expanding day by day. In recent years, the cartridge proportional valve and proportional multi-way valve developed and produced fully take into account the use characteristics of engineering machinery, with pilot control, load sensing and pressure compensation functions. Its appearance is of great significance to the improvement of the overall technical level of mobile hydraulic machinery, especially in the aspects of the electronic pilot operation, wireless remote control and wired remote control operation, which have shown a good application prospect.

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