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Valve System Security Features
Jul 18, 2017

Load-sensitive proportional multi-directional valve for a good energy-saving, proportional control easy to achieve remote control, stepless control and load changes have nothing to do with multiple actuators at different loads under the same characteristics and widely used in construction, mining , Agriculture, and other fields of construction machinery and ship machinery. Based on the analysis of the principle of load-sensitive proportional multi-way valve, this paper analyzes the problems in the use of the valve in detail with the internal structure of the valve. Finally, the technical characteristics of the valve are reviewed in the light of the research status of the multi-way valve.

The load-sensitive proportional multi-way valve is used in the quantitative or variable pump hydraulic system to control the speed and direction of the hydraulic actuator and to ensure that the output flow rate is proportional to the input control signal current (voltage) or mechanical signal (handle operating angle) Or hydraulic signal ratio changes, without being affected by changes in load, while controlling multiple actuators in different load conditions at the same time action. Load-sensitive proportional multi-way valve is generally composed of three functional units, respectively, for the connection block, proportional valve block, and the tail plate composed of three parts.

When all reversing valves are in the neutral position, the three-way pressure compensator unloads the pump at a pressure of about 10 bar and the system is in a low-pressure standby state for energy saving. The two-way pressure compensator (differential pressure relief valve) in the directional control valve is used to ensure that the multiple actuators operate independently at different pressures and speeds and that the control flow is not affected by the load. The secondary relief valve limits the maximum operating pressure of the reversing valve load port A or B by limiting the pressure of the LS. In addition, the optional two-way solenoid valve (normally open or normally closed) is used to unload the system, and the system can be protected by electronic control. Seeing the valve is made up of a more complex hydraulic system.

Analysis of Several Problems in Application

First, the quantitative pump system load sensitive multi-way valve regulator problem

In the quantitative pump + load-sensitive proportional multi-valve system, the system pressure valve safety valve, three pressure compensator, secondary relief valve and other mutual coupling, the user if the working principle of the valve is not thorough or not professional Of the test bed, the pressure adjustment is more difficult.

General suppliers will be based on user requirements to adjust the pressure and flow, but this set value is based on the design phase of the theoretical value, the user in the actual application or field debugging often appear with the design value more or less deviation of the situation,

This requires the user to re-set the pressure or flow rate of the multi-way valve that has access to the whole hydraulic system. System, the safety valve to set the pressure is higher than the secondary relief valve set pressure. Safety valve, in this multi-valve system from the security protection, normally closed. As shown in Figure 3, the pressure oil P and the load pressure lead-out slot is not connected, the load-sensitive oil circuit without pressure, that is, no LS pressure signal into the differential relief valve spring chamber, so as long as the pump outlet Pressure greater than the differential pressure (9bar), can be unloaded by the differential relief valve, so that the pump outlet pressure can not be established.