Rapid Reaction Valve (RRV)
The RRV-Rapid Reaction Valve was developed originally to control gas jets for orbiting satellites. It is a highly reliable valve and delivers the smallest amounts of pressurized gas to precisely control the satellite’s movements. The special feature of the RRV valve is its operating principle. The plug of the valve, here a valve ball, is pressed into the valve seat only by a pressure difference between the valve input and the valve output. Rolling the valve ball away from the valve seat opens the valve. The gas or liquid streaming through the valve then conveys the valve ball back to the valve seat, closing the valve.
In Figure 1 the principle set up of a RRV is shown in a schematic drawing. The valve ball is lying on the valve seat and is kept fixed to the seat only by the pressure difference between the valve input and the valve output (Figure 1a). A magnetic field is used to exert a lateral force on the valve ball, rolling it away from the valve seat and opening the valve (Figure 1b). The valve ball is the only moving part in the RRV. The rapid reacting magnetic valves can be designed to have one or several valve balls. In this case a valve with one valve ball is described. Using the leverage effect, the valve ball is pulled from the valve seat very efficiently. The lever arm reaches from the middle of the valve ball to a contact point between the valve ball and the valve seat. Only a small force is needed to move the valve ball away from seat, in comparison with the effort necessary to lift the ball upwards from the valve seat. A coil surrounding the valve generates the magnetic field that acts laterally on the valve ball. The flux is guided in a magnetic circuit made of magnetisable materials, which has a gap made of a non-magnetisable material at the same level as the middle of the valve ball. The non-magnetisable material guides the magnetic flux through the magnetisable ball and creates the force acting on the valve ball. To close the valve, the valve ball has to be reliably carried back to the valve seat by the streaming gas/fluid. This is achieved by limiting the free space where the valve ball can be moved, which keeps it close to its respective valve seat, in areas with high streaming velocities. The streaming of gaseous or liquid media transports the valve ball back to the valve seat.
With a high viscous medium, friction forces are the dominant forces acting on the ball. In the case of low viscous media high streaming velocities next to the ball, close to the valve seat, generate pressure differences, which move the ball. The liquid media can be cryogenic liquefied gases like liquid oxygen or liquid hydrogen.
The reaction time decreases proportionally to the decreasing density and the mass of the ball, and the increasing velocity of the medium flow.
The advantage of the RRV is that the response times can be milliseconds. The RRV is capable of delivering the smallest of amounts of medium. A valve with a ceramic cabinet can also be used and has the special advantages of low density, high hardness and a high corrosion resistance of the material. It is actuated by a piezo-electrical pulse, which causes the cabinet to bump the ball off its seat.
Innovations & Advantages
The Rapid Reaction Valve can deliver media of high-viscosity such as glues, oils and adhesives. A further feature of the RRV is that media at high pressure can be controlled with low energy consumption.
Current and Potential Domains of Application
Dosing technology, dosing of adhesives, lubrication technology, deformation technology, automobile industry, filling industry, dye and varnish industry, pharmacy, food industry and biotechnology.