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Method for vacuum control in, for example, breast pump Disclosure Number: IPCOM000175292D
Publication Date: 2008-Oct-08
Document File: 4 page(s) / 137K

Publishing Venue

The Prior Art Database



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Page 1 of 4

This invention is about a magnetic pressure sensor, which does not need a transparent body and constant user attention.

Preferred embodiment 1.

Fig. 2. Pressure sensor

The main working principle of the proposed pressure sensor is the dependency of the tractive force of the magnet from the distance between its pole and attractable ferromagnetic element. Sensor (fig. 2) consists of cylindrical body 1, made of non-magnetic material (for example, bronse or plastic), with openings 2 and 3 on its ends. Between openings we place a magnetized in axial direction magnetic piston 4. At one end of the body we have a rest 5 and a threaded hole, in which a ferromagnetic element 6 can be screwed in or out. Position of the ferromagnetic element is controlled by a knob with a rotation angle indicator 7 and determined from the scale 8. At another end of the body we have a cushion 9, and outside - a reed switch 10. At the starting position piston 4 has been pulled to the ferromagnetic element 6 and fixed at the rest 5, contacts of the switch 10 are open.

Pressure sensor works as follows. By rotating the knob 7 in the threaded hole of the body 1 user sets the distance between the ferromagnetic element 6 and magnetic piston 4, at which magnetic tractive force is equal to the force with which air will push the piston 4 at the required response pressure Pr, namely

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                         Ft=Pr * Sc ,
where Ft is required tractive force, Pr - required response pressure and Sc - effective sectional area of the piston. Adjusted in that way pressure sensor should be connected to the pressure source (i.e. breast pump) through the opening 2, if we intend to measure vacuum pressure, while opening 3 remains open, thus providing atmospheric pressure reference. To control positive pressure (overpressure), pressure source should be connected to the opening 3. If pulsing pressure PH in the breast pump reaches response pressure value Pr , piston 4 comes off the rest 5 and shifts to another end of body 1, where its movement stops on the cushion 9. The purpose of the cushion 9 is to absorb the kinetic energy of the magnetic piston 4 and so to avoid its demagnetization. During this displacement magnetic piston 6 moves close to the reed switch 10, and magnetic field closes the contacts of this switch. It triggers connected to the reed switch 10 light, sound or any other signal device.

To open the contacts of the reed switch 10 pressure sensor should be returned to the starting position. It can be done by shortly switching pressure source to another opening, or by switching off the vacuum source and placing the indicator in the ferromagnetic element 6 down position. Either way, magnetic piston 4 will return to the rest 5.

Proposed pressure sensor can also be used as pressure meter. For that, knob 6 should be s...