The correct selection and general principle of hydraulic valve

The correct selection and general principle of hydraulic valve

Correct selection of hydraulic valve

For any hydraulic system, the correct selection of hydraulic valve, will make the hydraulic system design reasonable, excellent performance, easy installation, easy maintenance, and ensure the normal operation of the system is an important condition. The following from several aspects to describe how to choose a reasonable hydraulic valve.

1. General principles of choice

First of all, according to the functional requirements of the system, determine the type of hydraulic valve. The standard series of generic products should be selected as far as possible. Select different connection modes according to the actual installation conditions, such as tubular or plate connection. Then, according to the system design of the highest working pressure to choose the hydraulic valve pressure rating, according to the maximum flow through the hydraulic valve to choose the hydraulic valve flow specification. If the relief valve should be selected according to the maximum flow of the hydraulic pump; The flow valve should be selected according to the flow range controlled by the loop, the minimum stable flow should be less than the minimum stable flow required by the speed control range.

2. Hydraulic valve installation mode selection

The installation of hydraulic valve has a decisive impact on the structure of the hydraulic device, so it is necessary to choose the appropriate installation mode according to the specific situation. Generally speaking, when choosing the installation of hydraulic valve, it should be determined according to the size of the selected hydraulic valve, the complexity of the system and the layout characteristics. The above described several installation methods, each has its own characteristics. Threaded connection type, suitable for the system is simple, the number of components is less, the installation position is more spacious. Plate type connection, suitable for the complex system, the number of components, installation position is relatively compact occasions. The connecting plate can be drilled to communicate the oil circuit, and a number of hydraulic components are installed on the connecting plate, which can reduce the connection pipe between the hydraulic valve, reduce the leakage point, making installation and maintenance more convenient. Flange connection type is generally used for large diameter valves.

3. Selection of hydraulic valve pressure rating

The rated pressure of hydraulic valve is the basic performance parameter of hydraulic valve, which marks the pressure capacity of hydraulic valve, and refers to the nominal pressure of hydraulic valve in rated working state. The rated pressure of hydraulic valve should be selected according to the working pressure of hydraulic system design. Generally speaking, the rated pressure value indicated on the hydraulic valve should be greater than the working pressure of the system.

4. Selection of hydraulic valve flow specifications

The rated flow rate of the hydraulic valve refers to the nominal flow rate through the hydraulic valve under rated working conditions. The actual working flow of the hydraulic valve is related to the connection mode of the oil circuit in the system: the flow of the series circuit is equal to each other, and the flow of the parallel circuit is equal to the sum of the flow of each oil circuit. When choosing the flow specification of the hydraulic valve, it is obviously the most economical if the rated flow of the valve is close to the working flow of the system. If the rated flow rate of the selected valve is smaller than the working flow rate, it is easy to cause hydraulic clamping and hydraulic power, and may have adverse effects on the working quality of the valve. In addition, the valve flow can not be selected simply according to the rated output flow of the hydraulic pump, because for a hydraulic system, the flow through each circuit is not possible to be the same. Therefore, in the selection, should consider the hydraulic valve circuit may pass the maximum flow.

For example, if the differential hydraulic cylinder is used in the primary circuit, when the hydraulic cylinder reversing action, the discharge flow from the rodless cavity is much larger than the discharge flow from the rod cavity, and may even exceed the maximum flow output of the hydraulic pump. When choosing the reversing valve, it should be considered to reach a point, so as to achieve a reasonable match. Another example is that some flow through a relatively large loop, if you choose the reversing valve with the corresponding flow specifications, it may produce a large hydraulic impact when the reversing action. In order to improve the working performance, you can choose a large size of the reversing valve.

5. Hydraulic valve control mode selection

There are many ways to control the hydraulic valve, which is generally selected according to the control needs of the system and the configuration ability of the electrical system. Manual control is optional for hydraulic systems that require low degree of automation, small size or are not often adjusted; For the higher degree of automation or control performance requirements of the hydraulic system can choose electric, hydraulic and other ways.

6. The economic choice

When choosing hydraulic valves, we should choose hydraulic valves with low cost and cost as far as possible under the premise of meeting the working requirements, so as to improve the economic indicators of the main engine. For example, for the speed stability requirements of the system is not high, should choose throttle valve rather than choose speed control valve. In addition, when choosing hydraulic valves, do not blindly choose cheaper valves, to consider the reliability and working life of its work, that is, to consider the comprehensive cost. At the same time, we should also consider the convenience and speed of its maintenance, so as not to affect the production.