Pumps – Motor driven – Electric or magnetic motor
Patent
1996-07-29
1998-06-02
Freay, Charles G.
Pumps
Motor driven
Electric or magnetic motor
4174132, F04B 1700
Patent
active
057590141
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a micropump comprising at least one base plate and a second plate secured to the base plate, so as to define a pumping chamber, inlet and outlet control members in direct connection with the pumping chamber, the control members being located on or in at least one of the two plates, at least one of these plates being machined by micromachining techniques by photolithography of a sealing material; an internal volume (Vi) comprising the volume of the pumping chamber and the volumes of the spaces for connection with the control members, the pumping chamber comprising a movable wall machined in one of the plates, actuation means being provided to display the movable wall to effect a periodic decrease and increase of the internal volume.
BACKGROUND OF THE INVENTION
Such pumps can be used particularly for the in situ administration of medications, the miniaturization of the pump permitting the sick person to carry it himself, even if desired to receive a pump directly implanted in the body. Moreover, such pumps permit the administration of small doses of the fluid to be injected.
In an article entitled "A piezoelectric micropump based on micromachining of silicon" which appeared in "Sensors and Actuators", No. 15 (1988), pp 153-157, H. Van Lintel et al. give a description of two embodiments of a micropump, each comprising a stack of three plates, which is to say a machined silicon plate disposed between two glass plates.
The silicon plate is incised to provide a cavity, which with one of the glass plates defines the pumping chamber, an inlet or suction valve and at least one outlet or discharge valve placing the pumping chamber in communication respectively with an inlet channel and an outlet channel. The portion of the wall forming a wall of the pumping chamber can be deformed by the control element constituted for example by a wafer or a piezoelectric crystal. The latter is provided with two electrodes which, when they are connected to a source of electrical voltage, effect the deformation of the wafer and, as a result, the deformation of the plate, which gives rise to a variation of volume of the pumping chamber. This movable or deformable wall of the pumping chamber can thus be displaced between two positions.
The operation of the micropump is as follows. When no electrical voltage is applied to the piezoelectric wafer, the inlet and outlet valves are in closed position. When an electrical voltage is applied, it produces an increase of pressure in the pumping chamber which gives rise to opening of the outlet valve. The fluid contained in the pumping chamber is then discharged through the outlet channel by the displacement of the deformable wall from a first position toward a second position. During this phase, the inlet valve is maintained closed by the pressure prevailing in the pumping chamber.
On the contrary, when the electrical voltage is decreased, the pressure in the pumping chamber decreases. This gives rise to closing of the outlet valve and opening the inlet valve. There is then a suction of the fluid into the pumping chamber through the inlet channel because of the displacement of the flexible wall from the second position toward the first position.
GB-A-2 248 891 showing the closest state of the art discloses a micropump of the same type as that previously described. In this micropump the inlet valve is however replaced by a flow limiter having a restricted flow cross section.
The operation of this type of micropump is greatly influenced by the compressibility of the fluid contained in the internal volume and in fact such a micropump does not operate if it contains too much air; the flow rate pumped is thus greatly decreased, even reduced to zero.
Similarly, the starting of such pumps is complicated and requires considerable apparatus, such as a vacuum pump, starting chamber or injection device. Because of this, starting cannot be effected other than in a specialized establishment or in the factory during manufacture.
Certain micropumps a
REFERENCES:
patent: 5224843 (1993-07-01), Van Lintel
patent: 5271724 (1993-12-01), Van Lintel
"Liquid Control Micro-Device", Nikkei Electronics (no. 480), Aug. 1989.
Smith, L., et al., "A Silicon Self-Aligned Non-Reverse Valve", Transducers '91, Jun., 1991, IEEE, pp. 1049-1051.
Van Lintel et al., "A Piezoelectric Micropump Based on Micromachining of Silicon", Sensors and Actuators, vol. 15, 1988, pp. 153-167.
Freay Charles G.
Westonbridge International Limited
LandOfFree
Micropump does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Micropump, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Micropump will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1452999