Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
1999-10-08
2001-11-06
Kaufman, Joseph A. (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C251S129210
Reexamination Certificate
active
06311951
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a solenoid valve for the opening and shutting of a channel for a medium, the valve features an electromagnet with a soft iron magnetic core and a coil and an armature that can be activated through them. In particular, the invention concerns a valve for a gaseous medium, such as pressurized air, for the actuation of a pressure cuff of a haemo-dynamometer. Therefore, reference is predominantly made to pressurized air without this meaning constituting a limitation. Among other materials, a ferrite core is suited as a soft magnetic core. When reference below is made to a ferrite core, this meaning does not constitute a limitation.
BACKGROUND OF THE INVENTION
For automated haemo-dynamometry, it is required to first pressurize an arm or wrist cuff with air, and to subsequently release the pressure-usually step-by-step. During the individual steps, the pressure within the cuff and heart beat are measured to determine the blood pressure according to the oscillometric method.
For the stepwise release of the pressurized air, usually solenoid valves are used that are connected to the cuff. In particular, in mobile haemo-dynamometric apparatuses that are operated off-line, it is necessary to keep power consumption to a minimum. It is also desirable to minimize the weight of the valve; thus the total weight of the apparatus can be reduced.
Solenoid valves are known that, via an armature and against the force of a spring, actuate a piston contained in a valve body, the free end of which features a seal for sealing the channel. Such valves feature a relatively large moving mass that results in a proportionately large power consumption. Furthermore, these valves are relatively inert. Since the pressurized air in haemo-dynamometers is reduced only in small steps, a quick-responding valve is desirable. The moving armature is often located in the flow channel of the medium to be controlled, which makes the valve susceptive to fouling.
OBJECT OF THE INVENTION
The invention is based on the problem of improving a solenoid valve of the aforementioned type to have reduced weight and to consume little electric power.
SUMMARY OF THE INVENTION
According to the invention, the problem is solved in that the channel passes through the magnetic core with its feed opening ending on the front side of the magnetic core; that the armature is configured as a sheet metal armature that, on the side of the feed opening of the channel, is elastically held against the force of the magnet, and bears, on the side that faces the channel, a seal that shuts the channel in the pulled-down condition of the sheet metal armature. This configuration has the advantage that the armature shuts off the channel without any intermediate elements. The mass of the moving parts is very small, allowing minimum weight and power consumption. Furthermore, the armature is no longer located in the flow of the medium to be controlled, eliminating the risk of functional flaws as a consequence of fouling.
It is particularly useful to configure the mount and the seal to be one piece. The armature sheet metal can be at least partially surrounded by molded plastic to further simplify production.
It is particularly practical if the elastic mount and the seal are constructed in one piece. It can also be provided for the armature sheet metal to be at least partially embedded in plastic by injection molding.
In principle, the type of elastomer to be used is optional, as long as it has the desired and required elastic properties. For example, it could be useful to make the mount and the seal out of silicone. Silicone has the required elasticity for mobile haemo-dynamometers within the desired temperature range of 0° to 50° C.
According to a further embodiment, it is provided that the channel is configured as a nozzle, onto which the soft iron magnetic core can be stacked and held in place. This has the advantage that there is no need for a separate mount for the soft iron magnetic core. In addition, the required power consumption of the valve can be further reduced by possibly providing for a tapered cross-section of the nozzle in the seal area.
Additionally, it could be useful if the nozzle were configured as a projected part of the housing, retaining the valve or the housing of the apparatus into which the valve is installed. In addition, the armature sheet metal could be retained in the housing. Lastly, it is proposed, according to the invention, that the soft iron magnetic core, the coil, and the sheet metal armature be retained in the cover of the housing that retains the valve or in the cover of the apparatus into which the valve is installed. These measures facilitate a particularly simple assembly of the valve, the number of required components being significantly reduced.
It is obvious that the solenoid valve, according to the invention, makes it possible to provide a compact and lightweight valve. Due to its small amount of moving mass, the power consumption is reduced as well. Further, the valve responds quickly due to the low inertia of the sealing element and the armature sheet metal with seal.
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Bastianelli John
I.E.M. Industrielle Entwicklung Medizintechnik und Vertriebsgese
Kaufman Joseph A.
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