Pilot Ratio Calculation and Selection Experience of Balance Valve

 

The balance valve is a valve with special functions. In some industries, the medium has a large pressure difference or flow difference in each part of the pipeline or container in hydrostatic drive systems. In order to reduce or balance the difference, between the corresponding pipeline or container, a valve is installed to adjust the relative balance of the pressure on both sides, or to achieve the balance of the flow through the method of diversion, the valve is called the balance valve.

 

 

Pilot Ratio of Balance Valve

The pilot ratio of the balance valve in hydraulic power transmission system is the ratio of the pilot area to the overflow area, which means that this value is also equal to ratio of the pressure that needs to be opened when there is no pilot oil and the pressure that the pilot oil opens it alone, when the balance valve spring is set to a certain fixed value.

 

When there is no pressure oil in the pilot port, the balanced opening pressure is the spring setting value. If there is no pilot oil supply, the balance valve in hydraulic transmission system is opened by the load, and the pressure drop will increase sharply as the flow increases. This is also used to balance the load. If the outlet pressure is not considered, the opening pressure can be set by adjusting the relief valve bolt. The specific formula is opening pressure equals to the ratio of the difference between the set pressure and the maximum load pressure to the pilot ratio of the valve.

 

For the balance valve in hydrostatic drive transmission system, if the pilot pressure ratio is 3:1, because the pilot oil and the oil inlet opening spool correspond to different force areas, there is a ratio of 3:1, so the control pressure required to open the spool should be low. The ratio of control pressure to the pressure of the inlet opening spool is approximately 1:3.

 

3:1 is suitable for the condition of large load changes and the stability of construction machinery load in hydraulic power transmission system. 8:1 is suitable for the state where the load requirement remains constant.

 

Under different working occasions and environments, the selection of pressure ratio is different. In the case of simple load and small external interference, a large hydraulic control ratio is generally selected, which can reduce the pilot pressure value and save energy. In occasions with large load interference and easy vibration, a smaller pressure ratio is generally selected to ensure that pilot pressure fluctuations will not cause frequent vibration of the balance valve core.

 

 

Precautions for Selection of Balance Valve

1. The flow of the balance valve in hydraulic mechanical transmission system can be slightly higher than the rated flow.

 

2. Use balance valve with low pilot ratio as much as possible, because it is more stable.

 

3. The balance valve is used to control pressure rather than speed.

 

4. All set pressures of the balance valve are opening pressures.

 

5. The balance valve cannot be used as a relief valve.

 

6. The balance valve should be as close as possible to the actuator to prevent the hose from bursting.

 

 

When the balance valve is used in automatic transmission hydraulic system, its quality is very important. Jazzy Industrial is a professional manufacturer with professional machines, such as brass fitting machine and hose clamp making machine. And we can provide you with high-quality parts such as hydraulic ball valve.