The role of the accumulator is to provide sufficient oil pressure to the brake when the engine suddenly stops, the brake pump fails or the output oil pressure is insufficient, so that the forklift driver can achieve braking stop in an emergency. This article takes a certain type of internal combustion forklift as an example to explain the working principle and troubleshooting method of the energy storage alarm device.
1. Working principle
The structure of the energy storage alarm device is shown in the drawing, which is mainly composed of a check valve 1, an oil chamber 2, an energy storage spring 3, a low pressure alarm switch 4 and a safety valve 5.
The principle of energy storage alarm device
The pressure oil output by the brake pump enters the oil chamber 2 through the check valve 1 and compresses the storage spring 3, thereby converting the pressure energy of the oil into the potential energy of the storage spring 3 being compressed. The function of the check valve 1 is to prevent the oil from flowing back from the inlet of the pressure oil.
Low pressure alarm switch 4 is a diaphragm type normally closed switch. When the oil pressure in oil chamber 2 is higher than 3.9MPa, the low pressure alarm switch is turned off, and the alarm circuit is cut off to stop the alarm.
In order to limit the pressure value of the accumulator to a safe range, the system is provided with a safety valve 5. When the oil pressure in the oil chamber 2 exceeds the set value (13 MPa) of the safety valve 5, the safety valve 5 is unloaded, and the discharged oil flows back to the oil tank 6.
When the forklift driver steps on the brake pedal, if the brake supply oil pressure is too low, the energy storage spring 3 releases the compression potential energy, and the oil in the oil chamber 2 is hydraulically pressed into the brake valve to provide the required oil pressure for braking .
When the forklift with energy storage is started, the alarm is usually in the alarm state. The reason is that when the forklift starts, the oil pressure in the oil chamber 2 is too low. At this time, the forklift driver should press the brake pedal to the end 3 to 5 times with the foot when the engine is started and the forklift is stopped to close the brake valve. After the brake valve is closed, the oil pressure in the oil chamber 2 rises, and the alarm can automatically release the alarm.
2. Troubleshooting methods
There are usually two kinds of faults in the energy storage alarm device: one is that the alarm signal of the alarm is not lifted, and the other is that there is no alarm at all times.
(1) The alarm signal is not released
The fault manifests as after the forklift is started, the brake pedal is depressed 3 to 5 times with the foot in the parking state, and the alarm is never released. The reason may be blocked check valve, system oil leakage, low safety valve pressure or alarm failure, etc. The method of troubleshooting is as follows:
First, connect an oil pressure gauge with a range of 20MPa to the pressure oil outlet to observe the change of the accumulator oil pressure.
Next, check whether the check valve is blocked. After pressing the brake pedal to the end 3 to 5 times with your feet, if the pointer of the oil pressure gauge does not change, it means that the check valve is blocked by dirt and the oil cannot enter the oil chamber. You need to clean the check valve. If it is still clogged after cleaning, it should be replaced.
Again, check the system for leaks. After the brake pedal is pressed for 3 to 5 times, if the pointer of the hydraulic pressure gauge changes, but the change is slow, and it does not reach 3.9MPa, it may be caused by oil leakage in the accumulator housing or the safety valve. Oil points, and replace damaged parts.
Then, check the safety valve set pressure. After 3 to 5 times of the foot brake pedal, if the oil pressure increases quickly, but the pointer suddenly stops before reaching the specified pressure value (13MPa), this means that the relief pressure of the safety valve is low, that is, the accumulator has not reached this Before the value, the safety valve has started to drain. At this time, it needs to be cleaned, and then the unloading pressure is reset.
Finally, check the low voltage alarm switch. If the pressure reaches 13MPa and no alarm is given, the low-pressure alarm switch is damaged and needs to be replaced.
(2) The alarm has no alarm
The fault manifests as the alarm does not alarm when the engine is started for many times after the forklift is parked for a long time. The reason may be the failure of the low-voltage alarm switch, alarm or related circuit.
First, connect an oil pressure gauge with a range of 20MPa to the outlet of the pressure oil, and then connect an oil drain switch. Turn on the oil drain switch to gradually release the oil in the accumulator, so that the pressure value displayed by the pressure gauge is slightly lower than 3.9MPa.
Secondly, check whether the low-pressure alarm switch is damaged. If the alarm sounds after starting the engine, it means that the low-pressure and low-pressure alarm switch and the alarm are good, and the pressure storage performance of the accumulator and brake valve is good. If the alarm does not alarm, you need to replace the new low-voltage alarm switch and repeat the inspection. If the low-pressure alarm switch can be used to replace the low-pressure alarm switch, the low-pressure alarm switch is damaged. If the replaced low-voltage alarm switch still has no alarm, it means that the alarm circuit or the alarm is faulty.
Finally, check the alarm circuit and alarm failure. You can use a test lamp or a multimeter to check whether the alarm has power. If it is powered, it can be determined as an alarm failure and should be repaired or replaced. If it cannot be powered, the alarm circuit is broken, and the broken part should be found section by section
