What is the cause of the failure of the flow control valve of the hydraulic press?

In the hydraulic system with a large amount of external load change, the speed control valve is generally used as the speed control valve, because the speed control valve can make the actuator stable under the condition of external load change. If there is a speed instability, it is generally caused by the failure of the speed control valve. There are two aspects to the speed instability.

Clause. 1. Adjustment, when the throttling of the speed control valve is in the wheel, the outlet flow rate does not change, that is, the so-called flow regulation failure. This phenomenon occurs mainly due to jamming of the spool or failure of the throttling section.

If the pressure reducing valve spool or throttle valve spool is stuck in the closed position, there is no flow at the oil outlet, and if the throttle handwheel is adjusted when the full open position or the throttle setting position is stuck, the flow rate at the outlet will not change.

Clause. 2. When the throttle port of the speed control valve is adjusted and locked, the flow rate of the oil outlet is unstable. This is more likely to occur at the minimum stable flow rate due to loose locking devices, partially clogged throttles, increased oil temperatures, and low hydraulic differential between the burst oil outlets.

When the oil flow of QF type speed regulating valve is reversed, the pressure reducing valve does not have the effect of pressure compensation to the throttle valve, so that the speed regulating valve only plays the role of throttle valve, when the oil hydraulic difference through the valve changes, the flow rate through the valve also changes, so the reverse connection should be avoided when using this valve. Hydraulic press.

The reasons for the failure of the hydraulic control valve are as follows:

1. Ignition system failure. The ignition system is what we must use when we start, if there is a problem with the ignition system, the fuel pressure regulator will not start, resulting in a failure and affecting normal driving;

2. Fuel supply system failure. Fuel is the biggest driving force that drives our cars, and there are several systems that regulate fuel use, the most important of which is the fuel supply system, which ensures that our fuel is used normally, so if there is a problem, it is likely to cause the fuel pressure regulator to fail;

3. The fuel injector, throttle body and idle motor are not clean. Fuel injectors, throttle bodies and idle motors are all inextricably linked to the fuel pressure regulator, and the long use of the car, coupled with the driver's dislike of cleaning it, can easily lead to the failure of the fuel pressure regulator.

Relief valves sometimes fail to regulate pressure during operation. There are two situations in which the pressure regulation failure of the pilot-operated relief valve fails:

One is that the pressure of the conditioning handwheel cannot be established, or the pressure cannot reach the set value, and the other is that the pressure of the conditioning handwheel is not reduced, or even continuously increased. In addition to the radial clamping of the valve core, there are several reasons for the failure of pressure regulation:

1) The damping hole on the main valve core is blocked, and the hydraulic pressure cannot be transmitted to the upper cavity of the main valve and the front cavity of the poppet valve, and the pilot valve loses the conditioning effect of the pressure of the main valve. Because there is no oil pressure in the upper cavity of the main valve, and the tension spring force is very small, so the main valve becomes a direct-acting relief valve with very little tension spring force, and under the condition that the pressure of the oil inlet cavity is very low, the main valve core will open the overflow, and the system will not be able to establish pressure. The deformation of the tension spring of the pressure regulator or the fault of selection, the leakage in the valve is too large or the pilot valve is overworn, etc., which is the fundamental reason why the pressure cannot reach the set value.

2) The damping hole on the cone seat of the pilot valve is blocked, and the oil pressure cannot be transmitted to the cone valve, and the same pilot valve loses the conditioning effect of the pressure of the main valve. After the damping hole is blocked, under any pressure, the poppet valve can not be turned over to drain the oil, there is no oil activity in the valve, the oil pressure in the upper and lower cavities of the main valve core is flat, the main valve core is in a closed state under the effect of tension spring force, and can not overflow, and the pressure in front of the valve of the relief valve rises with the addition of load. When the actuator moves to the end and the external load is added indefinitely, the pressure of the system will increase indefinitely.

3) If the long-distance control port of the relief valve is connected to the pressure regulating valve, if the control port is blocked, the pipeline between the control port and the pressure regulating valve is long, and there is air intake, the pressure regulation will be abnormal.

4) The sealing ring in the relief valve is damaged, and the main valve core and the cone valve core are worn too much, resulting in severe leakage from the surface and inside, making the conditioning pressure unstable and even unable to operate normally.