Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B43/00—Machines, pumps, or pumping installations having flexible working members
  • F04B43/02—Machines, pumps, or pumping installations having flexible working members having plate-like flexible members, e.g. diaphragms
  • F04B43/04—Pumps having electric drive
  • F04B43/043—Micropumps
  • F04B43/046—Micropumps with piezoelectric drive

Definitions

• the invention relates to a micropump and its manufacturing method, this micropump comprising at least one base plate, at least one upper plate and an intermediate plate interposed between the two other plates and made of a material capable of be machined so as to define a pumping chamber, at least one fluid inlet control member for connecting the pumping chamber with at least one inlet of the micropump, and at least one outlet control member for said fluid to connect the pumping chamber with at least one outlet of the micropump, the pumping chamber comprising a movable wall machined in the intermediate plate, said movable wall being capable of moving in two opposite directions during aspiration or expulsion of said fluid in the pumping chamber, the upper plate being provided with at least one orifice connecting a cavity with at at least part of the movable wall, actuation means fixed on the free face of the upper plate being provided for moving said movable wall in order to cause a periodic variation in the volume of the pumping chamber.
• one of the elements of the actuation means is constituted by an intermediate part which is intended to bring the piezoelectric device into contact with the movable wall of the chamber pumping.
• the fabrication by micro-machining of this intermediate part and its mounting in the micropump device require great precision in order to obtain a micropump operating in a safe and regular manner.
• FIG. 1 represents one of the embodiments of the micropump described in the aforementioned document.
• This micropump comprises a base plate 82, an intermediate plate 86, an upper plate 88, actuating elements 87 intended to cooperate with the piezoelectric device 80 and an intermediate piece 84 in the form of a push pin connected by its flat head to the elements d actuation 87.
• the objective of the present invention is to provide a micropump having an intermediate part whose manufacture is simplified while making it possible to obtain a micropump operating in a reliable and constant manner.
• the actuation means are formed by an actuation plate made of a material capable of being machined so as to define a mobile zone and said cavity, a part. intermediate obtained from the upper plate being fixed on the actuating plate so as to establish contact with the movable wall.
• the manufacture of the intermediate piece from the upper plate avoids manufacturing the intermediate piece independently of all the other elements of the micropump so that this intermediate piece integrates perfectly into the micropump as will be explained later .
• FIG. 2 shows schematically and partially, in section, a first embodiment of the micropump according to the invention
• FIG. 3 is a figure similar to Figure 2 showing a second embodiment of the micropump according to the invention
• FIG. 4A to 4D show certain stages of manufacturing a micropump according to a preferred manufacturing process
• FIG. 5A to 5F show the different stages of the manufacturing process of a micropump according to the invention.
• FIGS. 1 and 2 represent only the central part of a micropump as it is delimited by zone A of FIG. 1.
• the central part of this micropump comprises a base plate 1 and an upper plate 2 which are preferably made of glass such as Pyrex. Between these two plates 1 and 2 is interposed the intermediate plate 3 which defines, with the base plate 1, the pumping chamber 4.
• the central part of the intermediate plate 3 constitutes a movable wall 5 intended to allow the variation of the volume of the pumping chamber 4 under the action of a piezoelectric device 6 surmounting the micropump.
• An actuating plate 7 is interposed and fixed between the piezoelectric device 6 and the upper plate 2 by creating a cavity 8 between the actuating plate 7 and the upper plate 2.
• a free face 9 of the upper plate 2 is fixed, preferably, by anodic welding to a portion of the actuating plate 7, on either side of the cavity 8.
• the free face 10 of the actuating plate 7 is connected to the piezoelectric device, in the extension of the central part of the cavity 8.
• the central part of the actuating plate 7 constitutes a mobile zone 11.
• the cavity 8 is extended at the level of the upper plate 2 by a connecting orifice 12 of annular shape surrounding an intermediate part 13 produced from the same original part as the upper plate 2.
• the cavity 8 also has an annular shape and surrounds a portion of the movable zone 11 fixed to the intermediate piece 13.
• the upper plate 2 is in simple contact, without fixing, with the wall mobile 5 (zone 16 forming a stopper) so as to block any movement of the mobile wall 5 beyond this contact zone.
• This fixing is preferably avoided by virtue of an insulating layer covering the zone 16 forming a stopper of the upper plate 2, this layer being for example made of silicon oxide.
• the zone 16 forming a stopper limits the upward movement of the movable wall 5, stops 17, fixed on the face of the movable wall 5 located opposite the pumping chamber 4, limit the downward movement of the movable wall 5.
• the upper plate 2 and the intermediate plate 3 are fixed, preferably by anodic welding, to one another in the contact zones located outside with respect to the intermediate cavity 14.
• the intermediate 3 and actuating wafers 7 are preferably made of a semiconductor such as silicon.
• the actuation means, consisting in particular of the piezoelectric device 6, the intermediate piece 13 and the movable wall 5 are centered around the same axis.
• the intermediate part 13 and the upper plate 2 come from the same initial plate, it is understood that the manufacture of the micropump device is considerably simplified, that the problems of tolerance and compatibility between the various constituent elements of this micropump are strongly minimized or even eliminated. Indeed, the thickness of the intermediate part 13 being necessarily identical to the thickness of the upper plate 2, during assembly, the adjustment between the parts of the micropump device is then possible with a high degree of precision.
• the first preferred embodiment illustrated in FIG. 2 provides that the intermediate plate 3 and the actuation plate 7 delimit a sealed space, composed of the cavity 8, the connection orifice 12 and the intermediate cavity 14, a partial vacuum that can be set up within this sealed space.
• the sealing of the aforementioned space is made possible by the very high precision adjustment between the parts making up the micropump (mobile zone 11 of the actuating plate 7, upper plate 2, intermediate part 13, and mobile wall 5) .
• the strict identity between the thickness of the intermediate piece 13 and the upper plate 2 is a very important characteristic for obtaining a good fit between the pieces, which allows the aforementioned space to be sealed.
• the presence of a partial vacuum in the sealed space 8, 12, 14 makes it possible to pull the movable wall 5 of the pumping chamber 4 in the direction of the upper plate 2. If a partial vacuum is established in the sealed space 8, 12, 14, it is preferable not to fix the intermediate piece 13 to the movable wall 5 so as not to create residual stresses at this fixing.
• the sealed space 8, 12, 14 cannot be placed under partial vacuum but a conduit 15 connects this sealed space outside the micropump.
• this duct 15 is produced in the upper part of the actuating plate 7 and communicates with the cavity 8 by connecting the latter with the outside of the part of the micropump shown in FIG. 3 so that the 'space defined above has a pressure equal to that of the outer space into which the conduit 15 opens, this pressure may be atmospheric pressure.
• EDM Electro Discharge Machining
• UD Ultrasonic Drilling
• a second method of manufacturing a micropump it is possible, by machining the connecting orifice 12 and the intermediate piece 13 in two stages, to obtain better precision on the ribs of the various elements of the micropump. so that it presents a more reliable operation.
• the following steps are carried out: a) machining of the actuating plate 7 so as to create the cavity 8, b) machining of the upper plate 2 so as to partially create the connection orifice 12 and the intermediate piece 13, c) fixing of the actuation plate 7 to the upper plate 2, d) machining of the upper plate 2 so as to complete the creation of the connection orifice 12 and the intermediate part 13, e ) fixing of the upper plate assembly 2 - actuation plate 7 to the intermediate plate assembly 3 - base plate 1, and f) fixing of an actuation device, such as piezoelectric 6, to the plate of actuation 7.
• an actuation device such as piezoelectric 6
• the partial machining of the upper plate 2 is carried out by an electro-erosive machining process (EDM) or by an ultrasonic machining process (UD).
• EDM electro-erosive machining process
• UD ultrasonic machining process
• connection orifice 12 and of the intermediate part 13 are practiced by chemical attack on the upper plate 2.
• step b in the context of the second method of manufacturing the micropump, it is possible to deposit one or more metal layers on one face of the upper plate 2 before starting the creation of the connecting orifice 12 and the intermediate part 13 (step b) by machining this face.
• the metal layer or layers can be located on one or the other of the two faces of the upper plate 2: on the face undergoing the partial creation of the orifice 12 and of the part 13 or on the machined face upon completion of the creation of this orifice but in all cases this or these metallic layers are on the side opposite to the actuation plate 7.
• FIG. 4A a layer of chromium 2a, followed by a layer of copper 2b, is deposited on the upper plate 2.
• FIG. 4B the upper plate 2 is machined so as to partially create the connection orifice 12 of the intermediate part 13, this partial machining not relating to the entire thickness of the upper plate 2.
• FIG. 4C which corresponds to step c) of the second manufacturing process, the actuating plate 7, already machined and having the cavity 8, is fixed to the upper plate 2, for example by anodic welding on the side opposite to that carrying the metal layers.
• FIG. 4C which corresponds to step c) of the second manufacturing process
• 4D illustrates step d) of the second manufacturing process and shows that additional machining of the upper plate 2 makes it possible to complete the creation of the annular connection orifice 12 surrounding the intermediate piece 13 so that the connection orifice 12 communicates with the cavity 8 and that the intermediate piece 13 is integral with the actuating plate 7 at the level of the central zone of the mobile zone 11.
• a third method of manufacturing a micropump making it possible to minimize the thickness tolerances, in particular at the level of the upper plate 2 and of the intermediate piece 13, will now be presented in relation to FIGS. 5A to 5F.
• the following steps are carried out: a) deposition of a retaining layer 18 on one face of the upper plate 2 (FIG. 5B), b) machining of the upper plate 2 on the face opposite to the face in contact with the retaining layer 18 so as to create the connection orifice 12 and the intermediate piece 13, the retaining layer 18 which can also be machined (FIG. 5C), but only partially, c) fixing of the actuating plate 7 on the face of the upper plate 2 which is opposite to the face in contact with the retaining layer 18 ( FIG.
• the retaining layer is a polymer or a metal and the plates constituting the micropump device are fixed to each other, if necessary, by anodic welding.
• the three manufacturing methods which have just been described are suitable for producing the first or the second embodiment of the micropump as shown in FIGS. 2 and 3.
• a partial vacuum is established within the sealed space formed by the cavity 8, of the connection orifice 12 and of the intermediate cavity 14.
• a pipe 15 is connected connecting the sealed space formed by the cavity 8, the connection orifice 12 and the intermediate cavity 14 , this space being delimited by the intermediate plate 3 and the actuation plate 7, outside the micropump.
• the intermediate part 13 is fixed to the movable wall 5, for example by welding anodic.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Reciprocating Pumps (AREA)

Applications Claiming Priority (3)

Publications (2)

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ID=9499354

Family Applications (1)

Country Status (10)

Families Citing this family (20)

Family Cites Families (9)

• 1996
  • 1996-12-31 FR FR9616278A patent/FR2757906A1/fr not_active Withdrawn
• 1997
  • 1997-12-19 CN CN97181688A patent/CN1245547A/zh active Pending
  • 1997-12-19 CA CA002276401A patent/CA2276401A1/en not_active Abandoned
  • 1997-12-19 EP EP97954671A patent/EP0951617B1/de not_active Expired - Lifetime
  • 1997-12-19 DE DE69718820T patent/DE69718820T2/de not_active Expired - Lifetime
  • 1997-12-19 ES ES97954671T patent/ES2189994T3/es not_active Expired - Lifetime
  • 1997-12-19 WO PCT/EP1997/007278 patent/WO1998029661A1/fr not_active Ceased
  • 1997-12-19 US US09/331,952 patent/US6309189B1/en not_active Expired - Lifetime
  • 1997-12-19 AU AU59557/98A patent/AU5955798A/en not_active Abandoned
  • 1997-12-19 JP JP52960498A patent/JP2001507425A/ja not_active Ceased

Non-Patent Citations (1)

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