Csbf type manual proportional flow directional compound valve
The manual proportional flow direction compound valve is a kind of three position four-way directional valve with pressure compensation, flow proportional regulation and safety protection. The operation handle of the valve and the flow adjustment mechanism act synchronously. It can carry out stepless speed change and has good reversing speed regulation performance. Therefore, it can be widely used in the hydraulic system of marine machinery and other machinery. With rotary device, it can realize remote control Remote control. This product has obtained the national patent, the patent numbers are zl02318735.2 and 2z102220987.5.
1) Principle of pressure compensation mechanism
When the fluid flowing from the oil inlet (P port) leads to the load (a port or B port) through the throttle port of the main valve core, a force is also obtained under the valve core of the diverter valve to push the valve core upward. The force is pa (a is the cross-sectional area of the valve core), and the pressure P is reduced to P2 due to passing through the throttle port, P2 acts on the top of the valve core and pushes the valve core downward. In addition, the spring forces the valve core downward, so the downward pushing force is P2a + F (F is the spring force). If P2a + F > PA is established, the valve core will be pushed down to make the throttle face of the diverter valve in a closed state, and the flow of flow will all lead to the load through the throttle port of the main valve core.
When the flow into port P increases, PA + F < PA, then the valve core moves upward and the throttle surface opens, so that the excess flow flows out from port 0 and the flow through the throttle port decreases. Until up = P, - P2a, the valve core is in a stable state.
As soon as the load pressure increases, the valve core will be pushed down when the load pressure is higher than P-P, and the opening a of small flow surface will be reduced, and P will also increase until = P, - P, and the valve core will be in a stable state again. A if the load pressure decreases, then the valve core will be pushed upward and the throttle face opening will be increased, P1 will also decrease, until "a = p-p2" and the valve core is in a stable state. Therefore, no matter how the inlet and outlet oil pressure changes, the pressure difference pr-p2 always remains constant, that is constant, and the flow through the throttle is also constant, so the flow is determined by its flow area, and has no relationship with the change of load pressure.
2) Direction switching and throttling principle of main valve (taking M-type as an example)
When the handle is in the middle position, the oil ports (ports a and b) are closed, the oil discharged from the oil pump returns to port o from port P, and the oil motor stops. When the handle is on the right side, the main valve core moves upward. The oil flowing from port P flows to port a through the throttle port, and then flows out from port a to drive the oil motor to rotate. The return oil of the oil motor returns from port B to port 0. At this time, the handle pulls different tilt angles to make the main valve core in different positions to adjust the opening of the throttle port, so as to achieve the speed regulation of the oil motor. On the contrary, when the handle is on the left side, the oil flows from P-B and A-0, and the result is completely similar, but the oil motor turns to the opposite direction.
3) Overflow principle (safety valve part)
The principle of the oil motor is the same as that of the general relief valve. When the load pressure is low, because the poppet valve is closed by the spring force, the oil motor runs normally. When the load pressure increases, it will exceed the spring force on the poppet valve, which will open the poppet valve, and the high pressure oil will flow from port p to port 0 to protect the oil motor.