No matter what brand of oil injection air compressor, its compression working principle is the same, and the functions of each valve are roughly the same. If we can thoroughly understand the design function and working principle of each valve, we will give some support and help to solve the common faults of the air compressor!

The five major valves of the oil injection air compressor are: unloading valve, Min pressure valve, oil stop valve, check valve and thermostatic valve. The following explains the functions and troubleshooting of each valve one by one.

1. Unloading valve

Function:

When the gas consumption changes, the inlet valve adjusts the opening degree of the valve body through the control system to match the gas consumption. It is a valve that controls the gas production and non production of the air compressor.

Common corresponding faults:

The air compressor is not loaded. This fault control panel displays (no alarm; the operating state is "loaded"; the injection pressure is very small or "0"; the head outlet temperature is less than 70C °), and it can be concluded that the unit is not loaded. The problem lies in the unloading valve body, control circuit, loading and unloading solenoid valve and other parts, which need to be checked and eliminated one by one.

The air compressor does not unload. This fault control panel displays (no alarm; operation status is "unloading"; injection pressure rise>4; head outlet temperature>80 ℃), and it can be concluded that the unit does not unload. The problem lies in the unloading valve body, control circuit, loading and unloading solenoid valve and other parts, which need to be checked and eliminated one by one.

2. Minimum pressure valve

Function:

The opening pressure of the minimum pressure valve is about 4bar, so as to ensure that the pressure in the oil cylinder is not lower than this minimum pressure when the air is output, so as to avoid the reduction of the separation effect of the oil-gas separator due to the excessive air flow rate.

When the machine starts, a certain pressure is established in the oil cylinder to ensure the circulation of lubricating oil and provide initial control pressure for the control circuit.

It has the function of one-way valve to prevent the compressed air from flowing back into the machine.

Common corresponding faults:

During operation, the oil cylinder safety valve sprays air. This fault is because the minimum pressure valve is not opened, resulting in high pressure in the oil cylinder and pressure relief protection of the safety valve.

The computer appears motor overload protection during operation. The fault is that the minimum pressure valve is not opened, resulting in too high pressure in the oil cylinder, increased load and current of the main motor, and shutdown of the thermal relay protection.

The air compressor failed to start. The fault is that the check valve of the minimum pressure valve is not closed tightly, which causes the return of compressed air in the pipe network, causing a certain pressure in the oil cylinder, causing the unit to fail to start. When the air compressor is started, the unit cannot be started when the control computer detects a certain pressure in the oil cylinder.

The oil pressure is high when the air compressor is unloaded. The fault is that the minimum pressure valve is not tightly closed, and the compressed air in the pipe network returns when the unit is unloaded, which increases the pressure in the oil cylinder, leading to an increase in oil pressure and an increase in energy consumption of the unit.

3. Oil shutoff valve

Function:

After the air compressor is started, the oil shutoff valve is opened to inject lubricating oil through the oil filter into the main engine. After shutdown, the oil shutoff valve is closed to cut off the oil supply.

Common corresponding faults:

After startup, the machine trips rapidly at high temperature. The fault is that the oil shutoff valve is not opened, and the lubricating oil cannot be injected into the machine head. The oil shutoff valve needs to be checked and maintained.

High temperature alarm of air compressor. The fault is that the oil shutoff valve is not fully opened, and the amount of lubricating oil injected into the machine head is not enough, so the oil shutoff valve needs to be cleaned and maintained.

In case of sudden shutdown, the lubricating oil is sprayed back into the air filter. This fault is caused by the delayed closing or untight closing of the oil shutoff valve when the unit stops suddenly. The oil shutoff valve needs to be cleaned and maintained.

4. Check valve

Function:

The compressed oil and gas mixture of the main engine is sent to the oil cylinder in a one-way way to prevent the oil and gas mixture in the cylinder from spraying back into the machine head in case of sudden fault shutdown, causing the rotor to reverse.

Common corresponding faults:

During shutdown, the oil gas mixture is sprayed back into the air filter. This fault is caused by the stuck or damaged check valve when the unit stops suddenly. The check valve needs to be cleaned and maintained.

5. Temperature control valve

Function:

Through the principle of thermal expansion and cold contraction, the temperature control valve core extends and contracts to adjust the changes in the oil passage between the valve body and the housing, control the proportion of lubricating oil entering the oil cooler, and ensure that the rotor temperature is within the control range.

The temperature control valve is the original part that controls the outlet temperature of the machine head not less than 68 ℃. When the oil temperature is low, the temperature control valve is closed, and the lubricating oil is directly injected into the machine head without passing through the cooler for rapid heating, so that the outlet temperature of the machine head rises rapidly, and the condensate in the compressed air is prevented from generating in the oil cylinder.

Note:

1. The opening temperature of thermostatic valve is generally marked at the valve core.

2. The maximum opening temperature of thermostatic valve is the marked temperature +15 ℃.