Micromotor and micropump

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 09/043,790, filed Sept. 2, 1998, issued on Jan. 30, 2001 as U.S. Pat. No. 6,179,596 which is a 371 of PCT/DE96/01837 filed Sep. 26, 1996.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to pumps and motors of smallest constructional size, in the following referred to as one of micropump and micromotor. The terms designating orders of magnitude, being of a diameter range below 10 mm, particularly less than 3 mm. Such pumps may find manifold uses in the technical and medical sectors, for instance in microsystems engineering in dosing apparatuses, in medical engineering, as a drive means for one of a micro milling cutter and a bloodstream support pump.

2. Prior Art

Prior art is rich of specifications regarding the principle and the function of gear pumps having an inner wheel and an outer wheel, the wheels being in mating/meshing engagement (compare DE-A 17 03 802, claim 1, page 4, last paragraph and page 6, last paragraph, disclosing radially directed inflow and outflow channels). These operational units to be used as one of pumps and motors are characterized by having two axes, one axis of an inner rotor and another axis of an outer rotor, which axes are offset with respect to each other, and which rotors being in meshing engagement to circumferentially form pressure spaces (pressure chambers) cyclically changing their size and position.

SUMMARY OF THE INVENTION

The object of the invention is to provide a micropump of a minimum constructional volume, with which pump a continuous flow of a fluid to be conveyed is achieved and at the same time a high conveying capacity and a high feed (discharge) pressure are obtained.

Said object is achieved with a micropump, wherein an outlet pressure opening of a face end insert part for a sleeve casing of slightly larger diameter is adapted to extend in an axial direction. An inlet opening of a second face end insert part for the sleeve casing of slightly larger diameter may also be adapted to extend in axial direction. Thus, the entire pump is in a position to generate a continuous flow of fluid in axial direction, which flow is oriented to a circumferential direction only in an inner portion of the pump, where the rotors are in meshing engagement to circumferentially displace the pressure chambers. As soon as the flow of fluid to be conveyed enters the face end insert part on the outlet side, it is discharged from there in the axial direction through a pressure opening extending in axial direction. The pressure opening may consist of a number of individual bores arranged at circumferential intervals, it may consist of one single bore and it may be provided by one bore together with a kidney-shaped receiving groove on the inside surface of the outlet insert part.

The advantage of the pumps provided according to the invention is that, despite their almost unimaginable miniaturization, they are of a simple structure. An assembly of the micropump being available by a manufacturing method, wherein substantially cylindrical parts as components being assembled in a uniaxial direction. The two end insert components, being inserted in axial direction, are positioned at both ends of the sleeve casing, while the meshing wheels (inner rotor and outer rotor) which are likewise inserted in (the same) axial direction are interposed axially between them.

The pump is driven for example on an extended end portion of the shaft of the inner rotor or radially via the casing by one of a mere mechanical and electromechanical force. If an electromechanical drive force is used, e. g. one of the outer rotor and the sleeve casing may for a far reaching miniaturization be provided with integrated magnets, to serve as a rotor of a synchronous drive, the radially outer sleeve casing, which has a further outside radial position, permitting a penetration of electromagnetic fields.

Advantageously, slight conveying losses resulting from circumferential inexactnesses are used as a bearing for each respective rotatable component in the casing.

A motor for driving the pump is also characterized by being of smallest constructional size, simultaneously providing a high power density and even presenting a favorable characteristic line (torque in relation to speed). If the number of revolutions is not too high, the motor achieves a torque permitting to drive a pump without gearing. The driving energy of the motor is generated by a fluidic flow, passing the meshing wheels (inner rotor and outer rotor) and being discharged to the environment at the outlet side. A drive fluid enters through an inlet tubing or connection piece which is adapted to be fixedly mounted at the sleeve casing of the insert part or at the insert part itself.

When mounted at the face end insert, said insert may be slightly to markedly extended in relation to the sleeve casing to provide a firm fit for the inlet tubing.

The mounting of the inlet tubing implicates that the inlet tubing has about the same diameter as the micromotor.

If a fluidic drive is used, there is no difficulty with regard to an electric insulation for smallest constructional sizes. The fluidic drive medium may simultaneously serve as coolant, lubricant, rinsing medium and bearing fluid.

The motor consists of the same components as the pump, only different operational elements are one of fixedly and rotatably connected with each other. When uniaxially assembling the mentioned operational elements, a number of embodiments are provided to realize the motor and the pump, depending on which part is fixedly mounted on which, which part is rotatably mounted on which and which part the arrangement uses as a support on a fixed position. Using an inlet tubing as drive, the inlet tubing itself is the support. Driving the pump by an extended shaft portion, an elongated drive shaft is used.

BRIEF DESCRIPTION OF DRAWINGS

In the following, the invention is described in detail on the basis of several embodiments.

FIG. 1

is an embodiment of a pump

1

having a termination part

41

and a drive shaft

50

.

FIG. 1

a

illustrates an embodiment of adapting the components according to

FIG. 1

to be one of fixedly and rotatably mounted in relation to each other, hatches indicating a fixed mounting. Surfaces adjoining each other and not being hatched in the border area are movable in relation to each other.

FIG. 2

illustrates an embodiment of a motor

2

having an extended termination part

41

on which an inlet tubing for a drive fluid may be attached.

FIG. 2

a

illustrates an embodiment in which one of relatively movable and fixed “border areas” for a motor according to

FIG. 2

are provided, hatches indicating a fixed border area.

FIG. 3

a

,

FIG. 3

b

and

FIG. 3

c

show three radial positions of an inner rotor

20

in relation to an outer rotor

30

, both rotors being in meshing engagement.

FIG. 4

shows both, a side view of a casing

60

with two inserted face end parts

41

,

42

, and a sectional view A—A.

FIG. 5

shows an arrangement wherein, in a practical experiment, a pump

1

is provided in a conveying channel leading from a suction end S to a pressure end D. In this embodiment, a circumferentially directed driving force to a casing

60

of the pump

1

is selected.

FIG. 6

a

,

FIG. 6

b

and

FIG. 6

c

are embodiments illustrating connections for a tubing SH through which a fluid for driving the motor

2

is entered. The tubing is mounted not to be rotatable.

FIG. 7

a

,

FIG. 7

b

,

FIG. 7

c

and

FIG. 7

d

are embodiments illustrating connections for a drive A on one of a shaft

50

and an insert part

41

and an outer casing

60

with a circumferential drive

63

a

,

63

b

as illustrated in the arrangement of FIG.

5

.

FIG. 7

b

shows an electromechanical drive according to the principle of a synchronous motor.

FIG. 8

consists of three sketches A, B and C, illustrating three different embodiments of inlet and outlet openings

41

n

,

42

n

located in the face end parts

41

,

42

according to FIG.

1

.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1

shows a diagrammatic sketch of a micropump

1

which has a diameter of the order of below 10 mm, but which, preferably by manufacturing processes of wire spark erosion and cavity sinking, can be reduced to sizes of less than 2.5 mm in diameter. The length of the pump is in the latter diameter of 2.5 mm about 4 mm only, measured in the axial direction

100

.

Other manufacturing methods may also be used, such as LIGA engineering, plastics injection molding, ceramics injection molding, extrusion molding, metal sintering and micromilling or microturning or general microcutting.

The micropump

1

consists of a casing

60

in which five operational elements are integrated, some of them movably, some of them fixed, whereby in the after “fixed integration”, operational elements which do not perform a relative movement with respect to each other or which by their function require a fixed connection may also be manufactured as one part if allowed by the manufacturing process. At each end face of the casing

60

there is a face end insert

41

and

42

, respectively, both having an eccentric bore for receiving a pump shaft

50

. The bores are flush along a first axis

100

which is slightly radially offset to the outside in relation to the center axis

101

of the casing

60

.

The two end inserts

41

,

42

are at an axial distance from each other, and between them there are two rotors which rotate with one another and engage into one another, an outer rotor part

30

and an inner rotor part

20

. The inner rotor

20

has outwardly directed teeth distributed at uniform intervals about its circumference. The teeth engage with the outer rotor part

30

which has longitudinal grooves

30

a

,

30

b

, . . . which open inward and which are distributed circumferentially at uniform intervals and, in their shape, match the teeth of the inner rotor

20

, such that each tooth of the inner rotor—when performing its meshing rotational movement—forms an axially directed sealing line on the inner surface of the corresponding groove

30

a

,

30

b

, . . . of the outer rotor

30

. All the sealing lines move in the drive direction A about the axis

100

, whereby, when performing a rotational movement in a direction towards the end of the outlet opening

42

n

, transport or pump chambers

20

a

,

30

a

;

20

b

,

30

b

(etc.) which are defined between two sealing lines, respectively, are reduced in their volume on one half of the pump, as shown in

FIGS. 3

a

to

3

c

, and continuously increase on the opposite half of the pump to obtain a recurring cycle of minimum and maximum chamber volumes and vice versa.

The inner wheel

20

provides a rotational movement together with the drive shaft

50

, a drive mechanism can couple in a rotary movement A via a longer flexible shaft, an electrical drive mechanism can also be arranged directly on the shaft

50

.

FIG. 1

a

illustrates an embodiment of a definition of fixed border areas (closely adjacent surfaces of two adjoining parts of the pump). Hatches indicate a fixed (non-rotatable) border area, the remaining border areas allow a rotational movement of the adjacent parts.

While the rotation shaft

50

together with the inner wheel

20

arranged fixedly thereon and the outer wheel

30

are rotatable in the sleeve casing, the other parts of this embodiment of a micropump—the face end inserts

41

,

42

and the sleeve casing

60

extending along the length of the pump

1

—are connected circumferentially to one another in a fixed manner. The shaft

50

is rotatably mounted in the bores of the end inserts

41

,

42

, and the outer wheel

30

is likewise rotatably mounted in the fixed casing

60

. Thus, in the embodiment of a rotary drive via the shaft

50

according to

FIG. 1

a

, represented by an angle velocity vector A, both the outer wheel

30

and the inner wheel

20

move with a rotational movement of the sealing lines as shown in FIG.

3

and simultaneously changing chamber volumes

20

a

,

30

a

(etc.) between the outer wheel and the inner wheel during rotation.

The fixed border areas may for example be manufactured by gluing. The chamber volumes decrease in the direction toward the smallest distance between the axis

100

of the rotation shaft

50

and the casing

60

, as a result of which the fluid conveyed in them is subjected to increased pressure, whereas they become larger again on the other side after exceeding the smallest distance between axis

100

and inner surface

61

of the sleeve casing

60

.

Together with kidney-shaped openings

41

n

,

42

n

in the end faces

41

,

42

, which are so arranged that their smallest radial width begins at the position at which the distance between the axis

100

and the inner surface

61

of the casing

60

is at its smallest, whereas their maximum radial width is located at the position which is close to the greatest distance of axis

100

from the inner surface

61

of the casing

60

, a feed pump is obtained. The inflow kidney

41

n

, which is situated on the side for the suction of the fluid V′ to be conveyed, is mounted in the opposite direction to that outflow kidney

42

n

which in

FIG. 1

a

is represented at the outflow position for the delivered (discharged) volume V being conveyed under pressure.

FIG. 1

a

thus shows on the inflow side an inflow kidney

41

n

which, in the shown rotational direction A of the pump, widens in its radial extension from the smallest distance of the axis

100

to the greatest distance of the axis

100

from the inner surface

61

, while the inflow kidney

41

n

is situated in the face end insert

42

and narrows, in its radial extension, with its greatest radial width from the position of the greatest distance of the axis

100

from the inner surface

61

of the sleeve casing to the smallest distance of the axis

100

from the inner surface

61

of the casing

60

.

The dimensioning and the change in width of the two kidneys

41

n

,

42

n

are adapted to the following criteria:

A short circuit of the delivery, i.e. a direct connection between the inlet kidney and the outlet kidney, is prevented in all positions of rotation;. thereby, the circumferential extension of the reniform openings

41

,

42

n

is defined.

The inlet and outlet cross section of the kidneys—the change in radial dimensioning—is oriented to the root diameter of the outer wheel

30

and the root diameter of the inner wheel

20

. The cross-sectional surface should be chosen as large as possible, in order to obtain minor pressure losses, at any rate maintaining the stated dimensional specifications.

The two kidneys can alternatively be incorporated also as curved grooves

41

k

,

42

k

into the inner flat wall of the end faces, in which case a cylindrical bore

41

b

,

42

b

is then provided in the axial direction of the pump as outlet and inlet, respectively. This increases the stability, which, with the small component sizes, is not unimportant. Different embodiments of inlet and outlet kidneys are illustrated in FIG.

8

.

A single production of the pump consisting of only six components or less is advantageously possible with the stated wire spark erosion and cavity sinking, in which case all the pump parts can be adequately described with cylinder coordinates, which, for the production, means that one dimension requires no additional working. The end inserts

41

and

42

can be manufactured by wire spark erosion. The shaft

50

is cylindrical anyway, the inner rotor

20

can likewise be manufactured by wire spark erosion, as can the outer rotor

30

. The casing

60

, finally, is also a pump component, which can be manufactured by wire spark erosion.

If the aforementioned kidney-shaped inlet and outlet grooves

41

k

,

42

k

are made in the inner sides of the end inserts

41

,

42

, then cavity sinking can be used for this.

A material which is recommended for the manufacture of the micropump is hard-sintered metal which has a low stress and is fine-grained, can easily be worked by wire spark erosion and cavity sinking, and is medically acceptable. More favorable from the medical point of view is a ceramic material which, however, can only be processed in larger batch numbers and is not quite suited for the manufacture of individual functional samples. If the erosion methods are used, attention must be paid to the electrical conductivity of the material, if a ceramic injection molding process is used—with molds which can be made, for example, by wire spark erosion and cavity sinking—then the electrical conductivity of the material of the micropump is no longer necessary. In large batch numbers, plastic or metal injection molding processes can be used.

The pump

1

described with reference to the

FIGS. 1 and 1

a

and to the manufacturing process, may readily be used for medical purposes, such as catheters. Said drive A may be provided by a thin, flexible shaft. The drive of the micropump may also be effected by a motor

2

which is driven by a fluid, and which is made in the same way and has the same appearance as the described pump

1

, only with said motor

2

a fluidic drive via the inflow kidney

41

n

with a tubing SH is chosen, which tubing is arranged fixedly on the insert

41

(FIGS.

2

,

2

a

). Since the casing

60

in the fluidic micromotor

2

is arranged fixedly on the outer wheel

30

—for example by adhesive bonding or by a matching fit or by a weld or solder connection—the casing

60

is rotated and can transmit its output drive force A′ to the drive A of the pump

1

.

Said drive A′ according to

FIG. 2

a

has a mechanically rigid coupling to the drive shaft

50

of the pump

1

according to

FIG. 1

a.

The pump can be driven—instead of via the shaft

50

with direction of rotation A—also via the casing

60

which is illustrated by embodiments in

FIGS. 7

c

and

7

d

. It is likewise possible to reverse the drive direction in order then to obtain the conveying action of the micropump in a conveying direction from V to V′.

If all aforementioned pump components are adapted to be sufficiently describable with cylinder coordinates, they may as well be assembled in one axial direction, the assembly of the six basic components of one of the pump

1

and the motor

2

being effected by putting them together (uniaxially) only in said axial direction and by one of connecting them in a mechanically rigid manner and leaving them movable at certain predetermined sections (in the aforementioned border areas). This embodiment of a uniaxial assembly is advantageous for an automatized series production which is desirable for such small constructional sizes.

The conceptions of a pump

1

and a motor

2

shown in

FIGS. 1 and 2

are specified for an embodiment in

FIG. 1

a

and

FIG. 2

a

, respectively, in which border areas presenting a fixed connection (for example glued or having positive fit) are indicated by hatched lines, whereas those border areas between two components which are not provided with hatched lines are adapted to be rotatable in relation to each other. In

FIG. 1

a

, the two end inserts

41

,

42

are non-rotatably (fixedly) connected to the inner surface

61

of the sleeve casing

60

. The border areas of the pump according to

FIG. 2

a

are adapted to be rotatable. The pump according to

FIG. 1

a

is provided with a further fixed connection between the shaft

50

and the inner rotor

20

, whereas said connection is adapted to be rotatably movable in the motor according to

FIG. 2

a

, instead the motor of

FIG. 2

a

has a border area between the casing

60

and the outer wheel

30

which is nonrotatably connected, said border area being rotatably movable in the pump

1

according to

FIG. 1

a.

Further embodiments of the motor

2

are illustrated in

FIGS. 6

a

,

6

b

and

6

c

; further embodiments of pumps are shown in

FIGS. 7

a

,

7

b

,

7

c

and

7

d.

In

FIG. 6

a

, a fluidic motor is shown, which is provided with a drive fluid V through a tubing SH. Said tubing is fixedly plugged on the end insert

41

(basic support or basic component) extending in direction of an axis

101

. Thus, the basic support

1

does not rotate, instead the inner rotor

20

and the outer rotor

30

rotate, which latter drives the casing

60

. The tubing SH is exemplarily adapted to have a mechanically immobile support at position

44

.

FIG. 6

a

corresponds to

FIG. 2

a

as far as the arrangement is concerned,

FIG. 2

a

not yet showing said tubing SH. The basic component

41

is extended in axial direction for the mounting of the tubing SH to obtain an easy plug-on means. Accordingly, the tubing and the basic component have the same diameter, therefore, the tubing for entering a fluid V has a diameter corresponding to that of the motor

2

. The output and thus the drive force is performed via the casing

60

, accordingly the axis

101

of the casing is the axis of rotation.

In

FIG. 6

b

, a tubing SH is firmly supported in relation to the environment, as schematically represented by reference numeral

51

. The firm support may also be provided by the inherent stiffness of the tubing SH without requiring a firm support directly at the motor

2

. In this embodiment, the tubing SH is put on the casing

60

, a drive being effected via the shaft

50

, an axis

100

being the axis of rotation. In the present embodiment, the shaft

50

is extended in axial direction to mechanically couple the drive output. As far as the hatched border areas and the corresponding non-rotatable connection are concerned, reference is made to the aforementioned specification.

In

FIG. 6

c

, a tubing SH is also coupled to the casing

60

, alternatively to an end insert

41

prolonged in backward direction. In the present embodiment, the drive output is realized over an axially extended cover

42

, which is the second end insert on the front face end of the pump

2

. An axis

101

(casing axis) is the axis of rotation, the shaft

50

has a slight radial runout, i.e. the axis of rotation

100

moves along an orbital path.

FIG. 7

a

illustrates an embodiment of a pump corresponding to that of

FIG. 1

a

, a shaft

58

being provided which applies a rotary force “d” on a shaft

50

extended in axial direction. Reference numeral

100

designates the axis of rotation (the axis of the shaft

50

), the casing

60

does not move and is coupled in a mechanically rigid manner at position

51

. In

FIG. 7

a

, the inner rotor

20

and the outer rotor

30

rotate inside the casing

60

. The two end inserts

41

and

42

, which do not have to be axially prolonged, are adapted to be rigidly mounted inside the casing

60

.

In

FIG. 7

b

, a coil arrangement

63

is shown coupling an electromagnetic field into the pump

1

. The rotor of this embodiment, which is adapted to be a synchronous motor, is the outer wheel

30

, which may for example be provided as a permanent magnet. In this embodiment, the casing

60

has to be arranged fixedly and simultaneously permit the passage of electromagnetic fields, thus it has to be made e.g. from plastics or ceramics. In

FIG. 7

b

, the rotatable components are the outer rotor

30

and the inner rotor

20

inside the casing

60

. The two rotors

20

are supported in said end inserts

41

,

42

by a fixed coupling between inner rotor

20

and shaft

50

, said inserts being fixedly mounted at the casing

60

. The axis of rotation of the outer rotor

30

is the axis

101

of the casing, the axis of rotation is the axis

100

of the rotating shaft

50

. An inlet

41

n

and an outlet

42

n

are immobile in circumferential direction and thus arranged at a radially defined position.

FIG. 7

c

illustrates a mechanical drive over a pinion or a driving gear

63

a

engaging at the casing

60

in circumferential direction and essentially without slip. The axis of rotation of this arrangement is the casing axis

101

. The end insert

41

does not move and is extended in axial direction to provide a mechanical fixing

44

. The outer rotor

30

is fixedly mounted at an inner jacket surface

61

of the casing

60

. The inner rotor is provided on the shaft

50

to be rotatably movable, whereas the shaft

50

itself is arranged not to be rotatable on the two end inserts

41

,

42

, which in turn are supported at the inner jacket surface

61

of the casing

60

. With the present arrangement of the pump

2

according to

FIG. 7

c

, a practical test was effected according to

FIG. 5

, in which a cylindrical ring

63

a

arranged in circumferential direction was used as a driving gear or pinion.

FIG. 7

d

illustrates another embodiment of a driving gear or pinion

63

b

provided as drive at the axially prolonged end insert

41

, a casing

51

being fastened in a mechanically fixed manner. The axis of rotation is constituted by the axis

101

of the casing, the shaft

50

slightly wobbles, i. e. an axis of rotation

100

of the shaft

50

moves on an orbital path.

In the same way as

FIG. 7

b

shows a pump electromagnetically driven according to the synchronous principle,

FIG. 7

d

may be transformed into such a synchronous embodiment by the mechanical engagement pinion

63

b

, the basic support

41

being provided with a corresponding permanent magnet. In this case, one of a metallic and non-metallic design may freely be selected for the casing

60

.

The operational principle according to

FIG. 3

, wherein a number of circumferentially moving sealing lines are provided delimiting individual conveyance chambers between them, which on one half side of the pump increase (suction side) and on the opposite half side (pressure side) decrease from a maximum size, is shown again in

FIG. 4

in a side view. In the sleeve casing

60

, the two face end inserts

41

,

42

are arranged concentrically and between the end inserts

41

,

42

, rotors

20

and

30

are shown, which are represented in

FIG. 3

in a top plan view for a definition of the sealing lines. An inlet kidney

41

k

and an outlet kidney

42

k

, which are schematically illustrated in

FIG. 3

, are turned to the sectional plane in

FIG. 4

to make visible that they lead directly to the outward directed face ends of the rotors

20

,

30

. A non-rotatable attachment between the shaft

50

and the inner rotor

20

is realized by providing a flat section

50

f

, said section allowing a positive force transmission in addition to an attachment by gluing.

The structure of the pump was already explained in

FIG. 7

c

. In

FIG. 5

, said pump was tested in a practical experimental arrangement with regard to its performance values and characteristic data. The pump is visible in the middle of

FIG. 5

, an inflow and an outflow lead the supplied fluid V′ to be pumped from the suction side S through the pump

1

in the direction of a pressure side D where the fluid V is under an increased pressure. Pressures that could be obtained with a pump arrangement of this kind were of a difference pressure of about 50 bar, at a pump performance of 200 ml/min, whereby it should be added that the pump

1

had a casing

60

of an outer diameter of the order of 10 mm.

As far as

FIG. 5

is concerned, which is self explanatory, it should be mentioned that the drive casing

63

a

was fixedly coupled to the casing

60

of the pump and the driving power was transmitted to the pump over a drive tube

77

arranged centrically. Adaption casings are arranged at the end inserts

41

,

42

which were extended in the axial direction, said adaption casings serving for non-rotatably supporting the end inserts

41

,

42

as illustrated in

FIG. 7

c

. For measurement purposes, a wire resistance strain gauge DMS

74

is disposed around an inlet tubing

71

. Bores

73

provided in the measurement arrangement serve for the detection of leakages during conveyance and, as illustrated schematically, a drive

76

is adapted to be in engagement with a drive tubing

77

.

The arrangement according to

FIG. 5

allowed to test the basic data and performance limits of the pump

1

.

In the fluidic micropump

1

, a fluid is pumped through a rotating displacement piston 30/20 changing its chamber volumes by rotation in a way to permit a fluid to be continuously sucked in through the inlet

41

n

and to be continuously discharged on the outlet side

42

n

. In contrast to most of the other prior art pump systems, the invention also permits a reverse operation mode as a fluidic motor.

Due to a fluidic transmission of energy, the systems proposed by the invention are characterized by a high power to weight ratio, high pressures to be generated, high driving torques and high flow rates.

As manufacturing processes for a prototype realization of such motor/pump systems, the processes of wire spark erosion and cavity sinking may be used. Actual wire spark erosion machines operate with resolutions of 0.5 &mgr;m and achieve contour tolerances of 3 &mgr;m at surface roughnesses of a minimum of Ra=0.1 &mgr;m. Machines operating with more exactness and fineness are actually being developed. On the one hand, the erosion methods may be used directly for the manufacturing of prototypes of micropumps/micromotors, on the other hand, these methods permit an industrial scale manufacture of molds and tools for the production of components according to alternative manufacturing methods in large series (ceramic, metal, plastics). The mentioned alternative methods for the manufacturing of motor and pump components may be one of extrusion molding, fine sintering, injection molding and diecasting. Other manufacturing methods, such as the LIGA-method, seem to be suited as well.

The following results are obtained with the erosion manufacturing method:

Inexpensive and simple manufacture of individual components and small series

Large width/height ratios (aspect ratios up to a maximum of 12 mm; compared to the LIGA method: 1 mm)

Wall inclinations up to 30.degree. permitted

Processing of very different and hard materials permitted if they are electrically conductive, such as hard metal, silicium and electrically conductive ceramic materials.

Technology with low technological risk.

The advantages of hydraulic micromotors and micropumps:

Simple structure

Resistant, insensitive against pollutions

No valves required

Pump direction and rotating direction of the motor directly reversible

High driving torques

High weight coefficient

Characteristic line of torque/speed relatively inflexible.

Drive medium (fluid) of the motor may be used for cooling or rinsing

No electrical connections required (e.g. in explosion-proof environment or for operations on the brain or on the heart).

Fields of application of the micropump and the fluidic micromotor:

microhydraulic aggregate: coupling the micropump with a motor for the generation of hydraulic energy

analysis/dosing pump: for a removal and output of exactly defined fluid volumes in chemistry, medicine, food industry, mechanical engineering.

volume counter/flowmeter: application in measurement techniques

heating burner pump.

drive for a micro milling cutter for medical and technical applications

endoscopic drive

dilatation catheter with an integrated micropump for maintaining the bloodstream during a balloon dilatation

medication catheter with an integrated micropump for maintaining the bloodstream during a medication (e.g. lysis treatment)

bloodstream support pump

control aggregate for ultrasonic mirrors (transducers) in catheters

drive for a rotating cutting tool provided on endoscopes, catheters

miniature generator: coupling the fluidic micropump with an electrical miniature generator for the generation of electric energy

pumps for fluidic and hydraulic microsystems

compressor for a miniature cooling aggregate: e.g. for the cooling of processors)

driving elements for large controlling torques

sun antiglare device: in multiplex panes, a light-absorbent liquid is pumped between the panes.

The contour of the rotors

20

,

30

is an equidistant of one of an epicycloid and an hypocycloid and is calculated according to a generally known formulation.

The basic components of the micropump are:

basic support (first end insert)

41

shaft

50

cover (second end insert)

42

inner rotor

20

outer rotor

30

casing

60

.

According to

FIG. 2

a

, the inner rotor

20

and the shaft

50

of the micropump

1

are fixedly connected. A cover

42

and a basic support

41

are also fixedly connected with each other over the casing

60

. The connections may be provided as an adhesive connection, a press fit, one of a weld and a solder connection, etc. The pump

1

is driven by rotating the shaft

50

, e. g. by one of an electrical micromotor, a micromotor

2

driven by a fluid according to

FIG. 2

a

and a flexible shaft

58

according to

FIG. 7

a

. Consequently, a fluid is pumped from the basic part

42

in the direction of the cover

42

or vice versa, depending on the direction of rotation.

A micromotor

2

according to FIGS.

2

,

2

a

is provided with a basic part

41

and a cover

42

which are fixedly connected with the shaft

50

. Further, the outer rotor

30

is connected with the casing

60

. A fluid under pressure is supplied at the inflow side of the basic part

41

to operate the motor. Consequently, the casing

60

(drive output A′) rotates around its axis

101

. The fluid leaves the micromotor at the outlet side with less pressure than at the inlet side. After deduction of the losses, the pressure difference is transformed into mechanical energy. Changing the pressure side and the outlet side results in a reversal of the direction of rotation A′ of the motor.

The micropump

1

and the micromotor

2

operate on the basis of the displacement principle. The operating chambers

20

a

,

20

b

cyclically enlarge and reduce in volume, as described according to FIG.

3

.

A fluid under high pressure flows into the enlarging operating chamber of the micromotor

2

and effects a torque on the rotors

20

,

30

due to the pressure difference between inlet and outlet. The rotors

20

,

30

of the micropump

1

are driven. The fluid is sucked in by the enlarging chamber and is brought to a higher pressure when the chamber reduces in volume. The micropump

1

is driven by a small electric motor or by the fluidic micromotor

2

. Further embodiments of drives are provided by corresponding shafts.

FIG. 3

show that the fluid, when being pumped, is supplied into the pump chamber

20

a

,

30

a

via the suction side, it is ejected via the pressure side. For a clear understanding, a tooth of the inner rotor is marked by a black point in FIG.

3

. For the micromotor, the pump principle is simply reversed. When operated as a motor, a high pressure is provided in the chamber

20

a

,

30

a

via the inflow on the inflow side, the pressure having an effect on the tooth flanks and generating a force which is larger than the counterforce on the outlet side, since there, the pressure is reduced. The resulting torque drives the motor.

Modifications

Instead of by shaft

50

, the pump

1

may also be driven over the casing

60

(

FIGS. 7

c

,

7

d

). The advantage of such a drive is that the casing

60

may be driven via an inflexible drive, whereas, in case of driving the shaft

50

, which wobbles, a flexible connection piece is used.

The drive output A′ of the motor

2

may also be effected at the shaft

50

instead of the casing

60

. In this embodiment, the output is connected over a flexible connection piece or a jointed shaft. The advantage of such a drive is that the outflowing drive fluid does not have to pass through a possibly connected tool, but is permitted to flow out therebehind or to be returned.

In compensation of an axial gap between the combination of the inner/outer rotor

20

,

30

and the joining basic part

41

and cover

42

, additional compensation pockets

41

k

,

42

may be provided at the basic part

41

and the cover

42

(axial gap compensation).

Bores

41

d

,

41

e

,

41

f