Manifold block

How to deal with excessive oil temperature of Manifold block hydraulic system?


Hydraulic oil is the working medium of the hydraulic transmission system, and it is generally suitable to work within the range of 35-60℃. When working in the hydraulic system, pressure loss, solvent loss and mechanical loss will be converted into heat energy and make the oil temperature rise. The change of oil temperature will cause the viscosity change of the oil, thus leading to the instability of the mechanical system.


The system oil temperature is too high, and the equipment will strike:


1, affect the life of hydraulic oil and hydraulic components, accelerate the oxidation of oil, resulting in oil deterioration;


2. Excessively high oil temperature will seriously affect the stability of hydraulic oil, thus affecting the sealing, life and transmission efficiency of the entire hydraulic system.


Therefore, when monitoring the normal temperature rise of the hydraulic system, the abnormal temperature rise of the hydraulic system should be found in time, and the cause should be found in time to troubleshoot.


Causes and elimination methods of abnormal oil temperature in hydraulic system


1. Design of hydraulic system


Excessive power of hydraulic system causes a large amount of energy loss during the working process and the oil temperature is too high. The hydraulic components specification is not reasonable, the capacity of the components is too small, the flow rate is too high; The system circuit design is not good, the efficiency is too low, there are redundant components and circuits; Improper throttling mode; In the non-working process of the system, there is no effective relief measures, so that a lot of pressure oil loss into oil heating; The pressure of the hydraulic system is too high, so that it has a lot of pressure loss in the non-working cycle, resulting in excessive oil temperature. The above unreasonable design can be improved and perfected.


Cause of abnormal oil temperature 2. Loss of ambassador pressure can be converted to heat


The most common is the pipeline design, installation is unreasonable, and pipeline maintenance and cleaning is not timely resulting in increased pressure loss, which should be improved in debugging and maintenance. If the viscosity of the oil is too high, replace the oil with the appropriate viscosity;


If the pipeline is too thin and too long resulting in oil resistance is too large, energy loss is too large, the appropriate size of the pipeline and valve should be selected, as far as possible to shorten the length of the pipeline, appropriately increase the diameter of the pipe, reduce the bending radius of the pipe.


3. Oil heating caused by large volume loss


After entering the air in the circuit, it will be mixed, dissolved into the oil or free from the oil as the oil circulates in the high pressure and low pressure area, resulting in pressure shock and a sharp rise in the oil temperature, resulting in the oxidation deterioration of the oil and the erosion of parts. Therefore, at the joints and clearance of the hydraulic pump, measures should be taken to prevent internal and external leakage, reduce volume loss, and completely remove the air in the loop.


(1) In order to prevent the return pipe from bringing air into the oil return, the return pipe must be inserted under the oil surface.


(2) After the inlet filter is blocked, the suction resistance is greatly increased, and the air dissolved in the oil is separated, resulting in the so-called cavitation phenomenon.


(3) Suction pipe fittings and pump shaft sealing parts below atmospheric pressure should pay attention not to leak into the air.


(4) The liquid level of the oil tank should be as large as possible, the suction side and the oil return side should be separated by a partition, and the oil return filter with liquid flow diffuser should be selected to achieve the purpose of eliminating bubbles.


(5) The highest part of the pipeline and hydraulic cylinder should have pores, and the air should be released when starting.


4. Oil heating caused by large mechanical loss


Mechanical loss is often caused by the poor machining accuracy and assembly quality of oil hydraulic components, poor installation accuracy and excessive friction heating between relative moving parts. Improper installation of seals, especially improper compression of seals, will increase frictional resistance.


5. If the pressure is adjusted too high, the oil becomes hot


Under bad working conditions, the system pressure can not be raised to ensure normal operation, which will increase energy loss and make the oil heat. Under the condition of meeting the working requirements, the system pressure should be adjusted to the minimum as far as possible.

Pressure gauge

From the pressure gauge to see the system working pressure ▲


System failure caused by oil heating


1) Relief valve damage: cause unable to discharge, if the discharge pressure is raised, the pressure loss is too large, at this time need to replace the relief valve, adjust to the normal working pressure.


2) The performance of the valve deteriorates: for example, the valve is prone to vibration and may cause abnormal heating.


3) Wear of pump, motor, valve, cylinder and other components: wear components should be replaced at this time.


4) Hydraulic pump overload: check the support and seal condition, check whether there is a load beyond the design requirements.


5) Dirty oil or insufficient oil supply: if oil deterioration is found, the filter should be cleaned or replaced; Replace the hydraulic oil and fill it to the specified spot.

Cooler performance deteriorates


6) The performance of the cooler deteriorates, and the oil through the cooler cannot be cooled to the specified temperature. If the cooling water supply fails or the fan cannot work, check the cooling water system, replace and clean the solenoid valve and fan. If there is precipitation or scale in the cooling water line, clean, repair or replace the cooler.


Daily maintenance


In the daily use and maintenance of the hydraulic system, pay special attention to the following points:


1) Always keep the oil level in the tank, so that the oil in the system has enough circulation cooling conditions;


2) Check that the water in the cooler is sufficient and the pipeline is smooth;


3) When the system does not work, the hydraulic pump must be unloaded.

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