Proposal of a Component to Restrict Dust from Entering an Oil Hydraulic System through an Oil Hydraulic Cylinder

This research proposes a component to restrict dust from entering an oil hydraulic system through the rod-seal clearance of an oil hydraulic cylinder.The oil hydraulic cylinder as one of main parts of the hydraulic system,controls position of load by reciprocation.For example,on construction machines such as excavators and graders,the cylinder controls position of folk lift,crane and bucket.However,during operation,dust enters the cylinder,wears seals,causes fluid degradation and affects lubrication of valves,pumps and other parts of hydraulic system.This increases breakdown rate of cylinder and entire system.Thus,it seems necessary to reduce on intrusion of dust into the system via the hydraulic cylinder.In this research,we made an experimental apparatus to simulate intrusion of the dust into system.Results proved that the apparatus is a suitable simulator to realize the intrusion.The proposed component to restrict dust from entering cylinder was fabricated and its performance tested when inserted with various elastic rings.The component gave tremendous results when inserted with O-ring seal and a plastic nylon washer,and can be retrofitted on new and old hydraulic cylinders.It is an appropriate technology especially in developing countries where dust is still a major concern.

Expansion of Application Range of Component Restricting Pressure Change Caused by Oil Temperature Change

One of the advantages of an oil-hydraulic system is that the system keeps the value of oil pressure when the pressurized oil is enclosed in a container.However,when the pressurized oil is enclosed in a head or a rod end chamber of an actuator by a check valve or a shut-off valve,the value of the oil pressure deceases gradually by the leakage from the check valve or the shut-off valve.Then,it is necessary to employ non-leakage valve which is expensive or to control the pressure by using a valve or a pump control.In pressure control,energy to compensate pressure is required.From the view point of cost reducing or especially energy saving,it seems to be desirable to develop a component which prevents this pressure drop without energy consumption.Authors had developed a component restricting pressure change caused by oil temperature change.This component has simple mechanism and hardly needs energy.In this study,the possibility of the component to prevent pressure drop due to leakage is investigated experimentally.Consequently,it makes clear that the component is effective to prevent pressure drop by leakage and the enclosed pressure decreases only about 3%in 3 min and about 7%in 60 min when the target enclosed pressure is 3.5 MPa.