Fluid handling – Systems – Multi-way valve unit
Patent
1983-12-22
1986-02-25
Michalsky, Gerald A.
Fluid handling
Systems
Multi-way valve unit
91455, 13759617, 13762537, 13762514, 13762548, F15B 1304
Patent
active
045722382
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a valve means, which adjustably controls the flow direction and the volume flow so that this is substantially constant for each setting and independent of load variations, and where the adjusting can be carried out mechanically by positioning, electrically by a force or positioning, or hydraulically or pneumatically by a pressure, but where the control work can be held so low that one person, for example by a lever, or alternatively a relatively small electromagnet, can control the valve means directly and without auxiliary force. The volume flow passes alternatively, depending on two possible cases, in one case from a pressure source to two alternative sides of, for example, a hydraulic cylinder, and in the other case from one of the two sides of the cylinder to a return conduit, in such a manner that the requirements of low valve leakage and safety in the event of conduit rupture cn be satisfied simultaneously.
2. Description of the Prior Art
Hydraulic directional valves have the object to control the direction of movement and the speed of hydraulic cylinders and rotary motors. The directional valves most commonly used control adjustably the speed, i.e. in this case the volume flow, via adjustable throttlings in the valve. With these valves, the volume flow depends on the size of the load and on the load variations. In order to decrease or eliminate the changes in speed caused by variations in the load, in recent years valves have come into use which are load-independent. These valves maintain at every setting a volume flow independent of the pressure drop through the valve.
Basically, there exist to-day two known principles meeting the requirement of controlling the volume so as to be substantially constant and independent of the pressure drop through the valve.
The oldest principle, most known and applied, is based on two co-operating valves connected in series. One of these co-operating valves controls adjustably the volume flow by adjusting the throttling area through the valve. Thereby, the pressure drop through the throttling area always is maintained constant, and thereby the volume flow passing through the valve for each setting of the throttling area is substantially constant and independent of the pressure drop prevailing through both valves together. The second co-operating valve has the object to automatically throttle the volume flow so that the pressure drop through the adjustable throttling place of the first-mentioned valve is relatively low and most important for a constant pressure drop.
The newest principle, which so far has not been used to a great extent, is based on the capability by one and the same valve function to control a volume flow, which is adjustable, and to maintain for each setting a substantially constant volume flow, which is independent of the pressure drop through the valve. At varying pressure drops through the valve, thus, the prevailing throttling area must vary in such a manner, that the volume flow remains constant for every valve setting. This is effected by so designing the valve means that flow forces are obtained which close the throttling area, and that simultaneously an opening constant adjusting force acts on the valve means, which force determines the volume flow to pass through the valve, and also a non-adjustable spring force from a centering spring acts in the closing direction on the valve means. The throttling area must increase linearly with the movement of the valve means in the respective opening direction. The constant adjustable opening force to-day is brought about hydraulically by causing an adjustable pressure to act on an area, for example the end area of the valve slide.
As regards adjusting the flow direction and the size of the volume flow, two types of application fields can be distinguished. Especially in mobile working machines such as an excavator, loader, hoisting crane etc., the different movements of the machine are controlled by a driver. Especially
REFERENCES:
patent: 3282168 (1966-11-01), Hayner et al.
patent: 3757820 (1973-09-01), Aylesworth
patent: 4266572 (1981-05-01), Schuttenberg et al.
patent: 4504069 (1985-03-01), Stenlund
Hep Products AB
Michalsky Gerald A.
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