Abstract
A piezoelectric drive unit for a syringe pump includes a drive frame, a control unit, a push rod movable on the drive frame in an oscillating manner via a longitudinal stroke device with a first piezo actuator, a linear guide, and a carriage traversable along the linear guide. A first clamping device is coordinated by the control unit for alternating coupling and decoupling of the carriage to or from the push rod. During coupling, an advance of the carriage is generated according to the longitudinal stroke of the push rod movable from an axial starting position. In the first decoupling state, the push rod is released for a motion separate from the carriage. The first clamping device includes a second piezo actuator connected to the control unit. The second piezo actuator is configured to cause at least the first coupling state by expansion or contraction thereof.
Claims
1.-15. (canceled)
16. A piezoelectric drive unit for dispensing and/or dosing of medical liquids from a medical container, the piezoelectric drive unit comprising: a drive frame; a control unit; a push rod configured at the drive frame to be movable in an oscillating manner about a longitudinal stroke in a longitudinal direction by a longitudinal stroke device to be moved back and forth with acting of at least one first piezo actuator of the longitudinal stroke device connected to the control unit by expansion and contraction of thereof; a linear guide arranged at the drive frame parallel to the push rod; a carriage traversable along the linear guide for conveying in the longitudinal direction; and a first clamping device of the carriage, coordinated by the control unit, which is configured to switch between a first coupling state for coupling of the carriage to the push rod and a first decoupling state for decoupling of the carriage from the push rod, the first coupling state being provided to generate a carriage advance of the carriage, according to the longitudinal stroke of the push rod movable from an axial starting position, to an advance position of the carriage incremental in longitudinal direction, the first decoupling state being provided to release the push rod for a motion separate from the carriage for its retracting motion back to the axial starting position while remaining of the carriage at the advance position, and the first clamping device comprising at least one second piezo actuator connected, for its actuating, to the control unit, whereby the at least one second piezo actuator is configured to cause, by expansion or contraction thereof, at least the first coupling state.
17. The piezoelectric drive unit according to claim 16, wherein the at least one second piezo actuator is configured to release, by expansion of the second piezo actuator, the first clamping device into the first decoupling state and/or to cause, by contraction of the second piezo actuator, the first coupling state.
18. The piezoelectric drive unit according to claim 16, wherein the at least one second piezo actuator is configured to act, by expansion of the second piezo actuator, by the first clamping device in a cross direction in a releasing and/or clamping manner on the push rod.
19. The piezoelectric drive unit according to claim 16, wherein the piezoelectric drive unit further comprises: a guide rail provided parallel to the push rod at the drive frame; and a second clamping device of the carriage, which is actuatable by the at least one second piezo actuator and/or of at least one third piezo actuator connected to the control unit, whereby the second clamping device is configured to switch between a second coupling state for run-inhibiting securing of the carriage to the guide rail against unintended axial movements and a second decoupling state for run-free de-securing of the carriage from the guide rail.
20. The piezoelectric drive unit according to claim 19, wherein the control unit is configured to: provide the second decoupling state, respectively, temporally precedingly or simultaneously to the first coupling state in order to perform a carriage advance of the carriage according to the longitudinal stroke of the push rod movable from the axial starting position; and/or provide the second coupling state, respectively, temporally directly subsequently or simultaneously to the performed carriage advance.
21. The piezoelectric drive unit according to claim 16, wherein the longitudinal stroke device and/or the first clamping device and/or the second clamping device is or, respectively, are formed as a respective solid body joint-supported mechanism, especially is or, respectively, are formed durable with respect to an oscillation of at least one piezo actuator from the at least one first, second and/or third piezo actuator.
22. The piezoelectric drive unit according to claim 21, wherein, where the first clamping device is formed as a solid body joint-supported mechanism, the first clamping device comprises a bending spring arranged in a push rod clamping section between the push rod and the carriage, whereby the bending spring is rotatably supported on the drive frame in a bending spring pivot point to form a bending spring lever arm extending toward the push rod clamping section.
23. The piezoelectric drive unit according to claim 21, wherein, where the second clamping device is formed as a solid body joint-supported mechanism, the second clamping device comprises a pivot arm-like clamping lever, whereby the clamping lever is rotatably supported about the longitudinal axis of the linear guide to cause the second coupling state with piezoelectrically actuated expansion of the at least one second piezo actuator and/or third piezo actuator by a deflection force.
24. The piezoelectric drive unit according to claim 21, wherein, where the longitudinal stroke device is formed as a solid body joint-supported mechanism, the longitudinal stroke device comprises a double-sided lever rocker element, whereby the lever rocker element is pivotally supported about a lever rocker rotation axis orthogonal to the longitudinal direction in its central lever rocker midsection at a rear end of the drive frame with respect to a direction of the carriage advance, and for this purpose forms on both sides at the opposite ends a short lever rocker arm and a long lever rocker arm, respectively, in order to cause the longitudinal stroke of the push rod with piezoelectrically actuated expansion of the at least one first piezo actuator by a first piezo stroke.
25. A method of dispensing and/or dosing of medical liquids from a medical container, the method comprising the steps of: providing a piezoelectric drive unit according to claim 16; coupling of the carriage to the push rod by the first clamping device of the carriage into a piezoelectrically actuated first coupling state; generating of a carriage advance of the carriage to an advance position incremental in longitudinal direction, coupled with a longitudinal stroke of the push rod from an axial starting position with acting of the longitudinal stroke device piezoelectrically actuated by means of the at least one first piezo actuator; decoupling of the carriage from the push rod by means of the first clamping device of the carriage into a piezoelectrically actuated first decoupling state; and separate motion of the push rod as a retracting motion of the push rod from the advance position incremental in the longitudinal direction back to the starting position, with acting of the longitudinal stroke device piezoelectrically actuated by the at least one first piezo actuator.
26. The method according to claim 25, further comprising the step of controlling oscillation of at least one piezo actuator from the at least one, second and/or third piezo actuator.
27. A medical-technical syringe pump comprising a piezoelectric drive unit according to claim 16.
28. A computer program on a data medium configured for performing the method according to claim 25.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0068] The disclosure is described in more detail below based on preferred embodiments with reference to the accompanying drawings.
[0069] FIG. 1 is a perspective view of a piezoelectric drive unit for a medical-technical syringe pump (itself not shown) according to a first preferred embodiment according to the present disclosure;
[0070] FIG. 2 is a further perspective view (rotated in space to the view of FIG. 1) of the piezoelectric drive unit according to the first embodiment;
[0071] FIG. 3a or, respectively, 3b are two respective plan views of the piezoelectric drive unit according to the first embodiment, illustrating a piston plunger travel path of the drive unit, relevant in use in the corresponding medical-technical syringe pump;
[0072] FIGS. 4b to 4d (with reference to the view section line B-B indicated in the plan view of FIG. 4a) are different illustrations of a longitudinal stroke device of the piezoelectric drive unit according to the first embodiment, as exemplarily formed here as a preferred solid body joint-supported mechanism:
[0073] FIG. 4b is a cross-section view in sectional plane B-B;
[0074] FIG. 4c is a corresponding rear view; and
[0075] FIG. 4d is a perspective plan view on another sectional plane for illustration of the kinematic operation of the longitudinal stroke device, piezoelectrically actuated by means of a first piezo actuator;
[0076] FIG. 5 is an enlarged detail of the perspective view of FIG. 2 (rotated in space for this purpose) of the piezoelectric drive unit according to the first embodiment, focusing on the region of the longitudinal stroke device for a push rod;
[0077] FIG. 6 is an enlarged detail of the perspective view of FIG. 1 (rotated in space for this purpose) of the piezoelectric drive unit according to the first embodiment, focusing on the region of a second clamping device for a carriage traversable on the push rod, configured for its run-inhibiting securing to a guide rail;
[0078] FIG. 7 is a perspective view of a drive frame of the piezoelectric drive unit according to the first embodiment (shown isolated in manner of an exploded view and in a profile-like cross-section), especially showing the guide rail;
[0079] FIGS. 8a to 8c (with reference to the view section line A-A indicated in the plan view of FIG. 4a) are different illustrations of a first clamping device as well as of a second clamping device of the carriage of the piezoelectric drive unit according to the first embodiment, as exemplarily formed here as further two preferred solid body joint-supported mechanisms:
[0080] FIG. 8a is a cross-section view in sectional plane A-A (see FIG. 4a), showing the first clamping device as well as the second clamping device;
[0081] FIG. 8b is a corresponding detail section C from FIG. 8a regarding the second clamping device; and
[0082] FIG. 8c is a corresponding detail section D from FIG. 8a regarding the third clamping device;
[0083] FIG. 8d is another (essentially corresponding to FIG. 8a) cross-section view for illustration of the kinematic operations of the first clamping device, piezoelectrically actuated by means of a second piezo actuator, or, respectively, of the second clamping device, piezoelectrically actuated by means of a third piezo actuator, of the piezoelectric drive unit according to the first embodiment;
[0084] FIG. 9 is a second embodiment of the piezoelectric drive unit according to the disclosure, for schematic illustration of the temporal sequence or, respectively, coordination of (working) steps executable by means of a control unit in the basic principle, i.e. when considering only one first clamping device; or, respectively, for schematic illustration of a corresponding method (with respect to essential steps of a cycle) for dispensing and/or dosing of medical liquids; and
[0085] FIG. 10 is a third embodiment of the piezoelectric drive unit according to the disclosure, for schematic illustration of the temporal sequence or, respectively, coordination of (working) steps executable by means of a control unit, illustrating the case of a drive unit identical or comparable to the first embodiment (cf. FIGS. 1 to 8d) with a preferred second clamping device; or, respectively, for schematic illustration of the corresponding method (including optional, i.e. preferably executable, steps of a cycle); whereby otherwise comparable conditions exist in relation to the second embodiment in FIG. 9.
[0086] The Figures are of a schematic nature only and serve solely for the purpose of the understanding the disclosure. The same elements are designated with the same reference signs.
DETAILED DESCRIPTION
[0087] The following embodiments of the present disclosure are described on the basis of the corresponding figures.
[0088] FIGS. 1 to 8d relate to a piezoelectric drive unit 100 for a medical-technical syringe pump (not shown; for example, an infusion pump marketed under the brand name Space Plus Perfusor of the present applicant B. Braun) according to a first preferred embodiment according to the present disclosure. Then again, FIGS. 9 and 10 schematically illustrate (in the basic principle, i.e. with the patent legal character of a general disclosure) the temporal sequence or, respectively, coordination of (working) steps executable by means of a control unit 110. Especially, the extended scheme of FIG. 10 illustrates a method corresponding to the first preferred embodiment.
[0089] As can be seen from the overall views of a piezoelectric drive unit 100 in the FIGS. 1 to 4d, this is formed with a piston plunger 90 for the axial (longitudinal) drive of a (not illustrated) medical-technical syringe pump or comparable pump for dispensing and/or dosing of medical liquids. Thereby, the piston plunger 90 is traversable in the (axial) longitudinal direction x about a (total or, respectively, cumulative) piston plunger travel path X (see especially FIGS. 3a and 3b). For this purpose, the piston plunger 90 is moved stepwise (or, respectively, clockwise, cyclewise) in a plurality of incremental advances (cf. with reference to the FIGS. 9 and 10: of carriage advances s).
[0090] The piezoelectric drive unit 100 (FIGS. 1 to 8d) further has a drive frame 70 with a (rear) frame plate 75 at an end opposite the piston plunger 90. The drive frame 70 functions in the sense of a fixed profile or of a stable outer base housing. The piezoelectric drive unit 100 further comprises a linear guide 60. Thereby, the linear guide 60, designed in the form of a guide shaft, is chucked in the drive frame 70 in the longitudinal direction x.
[0091] Thus, along the linear guide 60, a carriage 20 movably arranged (on it) can be traversed in order to realize the actual advance function for conveying. Together with the carriage 20, a first clamping device 21 of the carriage is also traversed.
[0092] The piezoelectric drive unit 100 further comprises a push rod 10. The push rod 10 is arranged at the end at the drive frame 70 or, respectively, at the frame plate 75 via a longitudinal stroke device 11. Thereby, the linear guide 60 and the push rod 10 are parallel to each other (essentially, within the usual positional tolerances).
[0093] The piezoelectric drive unit 100 further comprises (at least) a first piezo actuator 1 of the longitudinal stroke device 11, a second piezo actuator 2 of the first clamping device 21 and a third piezo actuator 3 of a second (optional) clamping device 32. That is, the first piezo actuator 1 (esp. FIG. 4c), the second piezo actuator 2 and the third piezo actuator 3 (esp. FIG. 6) each consist of two such ones side by side, i.e. in the manner of a first/second/third double piezo actuator.
[0094] The respective first/second/third piezo actuators 1, 2, 3 are connected to a control unit 110 (indicated or, respectively, drawn in as a dashed outlined symbol box) for piezoelectrically actuated expansion and contraction by a first/second/third piezo stroke. For this purpose, the controlling from the control unit 110 takes place in the respective Figures via the control connections shown as dashed lines or, respectively, arrows (cf. FIGS. 1, 1, 3a/b, 4a/d, 8a/d; 9 and 10). Thereby, the first/second/third piezo stroke is preferably steplessly adjustable (in dependence of a respective control voltage applied).
[0095] The push rod 10 is configured by means of the longitudinal stroke device 11 to be movable in an oscillating manner by a longitudinal stroke h in the longitudinal direction x or, respectively, is (longitudinally) oscillated or, respectively, moved back and forth. Thereby, at least one first piezo actuator 1 of the longitudinal stroke device 11 acts on the push rod 10. Thus, the carriage 20 is moved along the linear guide 60 due to the first piezo force converted by means of the longitudinal stroke device 11 by the carriage 20 being pushed (or, respectively, pulled back) from the push rod 10.
[0096] As can be seen from FIGS. 4b to 4d (with reference to the view section line B-B indicated in the plan view of FIG. 4a), the longitudinal stroke device 11 is formed with a double-sided lever rocker element 15 (as a preferred solid body joint-supported mechanism). The lever rocker element 15 is, in its central lever rocker midsection 16 on the frame plate 75, pivotally supported about a lever rocker rotation axis Y orthogonal to the longitudinal direction x. At the opposite ends of the (double-sided) lever rocker element 15, a short lever rocker arm f and a long lever rocker arm e are formed, respectively.
[0097] With piezoelectrically actuated expansion of the at least one first piezo actuator 1 by a first piezo stroke, the longitudinal stroke h of the push rod 10 is to cause (cf. FIGS. 9 and 10). FIG. 4d ought thereby to illustrate the kinematic functionality or, respectively, the lever translation by means of arrows. For example, the maximum conveying force required for a syringe pump or, respectively, common infusion syringes may be ca. 100 Newton. The push rod 10 is designed to apply this conveying force. For example, piezo actuators selected for the (at least one) first piezo actuator are specified by the manufacturer at maximum 850 Newton piezo force of and a maximum piezo stroke of 0.009 mm. By means of the lever rocker element 15, the force (piezo force converted to push rod force) is now reduced and at the same time the stroke (piezo stroke converted to longitudinal stroke as push rod working stroke) increased. Here, according to the lever law, the two lengths of lever of the long lever rocker arm e and of the short lever rocker arm f engage. In the FIGS. 4a to 4d, an exemplary force lever reduction of 1:2 is illustrated.
[0098] The first clamping device 21 of the carriage 20 is controlled by the control unit 110 via the second piezo actuator 2. After completed clamping, the carriage 20 can be moved together with the (travelling) push rod 10 in a (temporary) first coupling state. Consequently (cf. FIGS. 9 and 10), a carriage advance of the carriage takes place according to the longitudinal stroke of the push rod. In order to enable the push rod 10 to perform a separate retracting motion, independent of the carriage 20, back to its starting position, without retracting the carriage 20 again or, respectively, undesirably reversing the desired carriage advance, the first clamping device 21 is set back into a first decoupling state.
[0099] As can be seen especially from FIGS. 8a (with reference to the view section line A-A indicated in the plan view of FIG. 4a), 8c, 8d, the first clamping device 21 is formed with a bending spring 25 (as a preferred solid body joint-supported mechanism). The bending spring 25 is arranged in a push rod clamping section 26 between the push rod 10 and the carriage 20. Further, the bending spring 25 is thereby rotatably supported on the drive frame 70 in a bending spring pivot point Q in order to form a bending spring lever arm d extending toward the push rod clamping section 26. The bending spring 25 is further restoringly counter-supported at the carriage 20 in an abutment point R in extension of the bending spring lever arm d. With or, respectively, by expansion of the second piezo actuator 2 in the cross direction (see FIG. 1: y, z), the bending spring is deformed such that the push rod 10 is decoupled or, respectively, released from the carriage 20. Thereby, the deformation also causes a preload with a bending spring restoring force resulting in the cross direction (reaction to F2, as indicated by the arrows), so that with contraction of the second piezo actuator 2 the carriage 20 is coupled or, respectively, clamped back to the push rod 10 into the first coupling state.
[0100] The piezoelectric drive unit 100 according to the preferred first embodiment further comprises a guide rail 30 and a second clamping device 32 of the carriage 20. The guide rail 30 is provided in the longitudinal direction x or, respectively, parallel to the push rod 10 at the drive frame 70 (especially FIG. 7). The second clamping device 32 of the carriage 20, as especially shown in FIGS. 6, 8a, 8b and 8d, is actuated by means of the third piezo (double) actuator 3 in order to switch between a second coupling state and a second decoupling state. For the temporary time period of the second coupling state (but especially also occurring without current), the carriage 20 is run-inhibitingly secured or, respectively, blocked at the guide rail 30 against unintended axial movements. For the temporary time period of the second decoupling state, the carriage 20 is released or, respectively, unblocked from the guide rail or, respectively, the previously existing blockade for free running in the longitudinal direction is removed again.
[0101] For a design of the second clamping device 32, preferably not the conveying force, but the possible acting force in the case of a drop may be assumed. In this respect, in such a scenario, breaking loose of the carriage 20 must not occur. For example, with the following assumptions of such a scenario: a drop height of ca. 1 m, a weight of a syringe pump of ca. 2 kg and an impact duration of 10 ms, using the force impact equation, a force acting during an impact can be estimated at ca. 886 Newton. At least this clamping force, especially greater than or equal to 1,000 Newton, must be applied by first and/or second clamping device(s) 21, 32 (alone or together).
[0102] Since, in addition, a minimum value for a (second and/or third) piezo stroke (due to elasticities in the respective clamping mechanism) must also be realized in order to ensure reliable opening and closing, two (second or, respectively, third) piezo actuators are used in each case and their piezo force is connected in parallel as (second or, respectively, third) double piezo actuator (not visible in FIGS. 8a, 8c, 8d due to the views in a cross section).
[0103] As can be seen from FIGS. 6, 8a (with reference to the view section line A-A indicated in the plan view of FIG. 4a), 8b, 8d, the second clamping device 32 is formed with a pivot arm-type clamping lever 35 (as a preferred solid body joint-supported mechanism). The clamping lever 35 is rotatably supported about the longitudinal axis M (especially FIG. 8d) of the linear guide 60. The piezoelectrically actuated expansion of the third piezo actuator 3 causes the second coupling state by its deflection force or, respectively, third piezo force acting on the clamping lever 35 (cf. the deflection in the direction of rotation indicated by means of the arrow at the top left in FIG. 8d). The third piezo force is converted into a guide rail clamping force, thereto amplified according to the lever law, applied to the guide rail 30.
[0104] As can be derived from FIG. 6, the carriage 20 is arranged in an outer sheet metal body. A carriage pressing element 29 is arranged as a bow-shaped wire spring (top in FIG. 6) secured by means of the Torx screws. The carriage pressing element 29 effects that the sheet metal body is always connected without clearance to the transversely oscillating third piezos 3 (expansion to the top right in FIG. 6). When the pair of third piezos 3 expands, the carriage pressing element 29 is pretensioned in order to exert downward counterforces. In this respect, the (bow-shaped) carriage pressing element 29, in its effort to align itself in a straight line, causes a restoring pressing force against the carriage 20 or, respectively, a counterforce to the third piezo force resulting from the expansion of the third piezos 3. In other words, the spring force of the (bow-shaped) carriage pressing element 29 acts downwards or, respectively, against the sheet metal body, by which the guide rail clamping force serving for securing of the carriage 20 is generated.
[0105] FIG. 9 or, respectively, FIG. 10 show a second or, respectively, third embodiment of the piezoelectric drive unit according to the disclosure as well as of the corresponding method. Herein, the temporal sequence or, respectively, coordination of (working method) steps executable by means of a control unit 110 (filled in or, respectively, illustrated with a dotted line) in a (repeatable) basic cycle S1 to S4 or, respectively, in an extended cycle S101 to S106 is schematically (or, respectively, in principle) illustrated. Thereby, the control unit 110 is configured to actuate (or, respectively, to operate, to activate) the at least one first/second/if applicable, third piezo actuator, respectively (via the control connections indicated by dashed-lined lines) (for piezoelectric oscillation).
[0106] In short, the basic cycle S1 to S4 relates to an alternating coordination in which, on the one hand, either the carriage moves or does not move and, on the other hand, the push rod 10 is clamped or not clamped by the carriage.
[0107] Insofar as the sequence shown in FIG. 10 relates to the cycle extended by the optional steps S102 and S104, FIG. 10 corresponds especially with the first embodiment (cf. FIGS. 1 to 8d) of the piezoelectric drive unit according to the disclosure, which additionally has the preferably provided second clamping device (securing to the guide rail 30). For reasons of a clear illustration, in FIGS. 9 and 10 the longitudinal stroke device 11, the first clamping device 21 and, if applicable, the second clamping device 32 (reference signs with reference to FIGS. 1 to 8d emphasizing the structural device aspects) are not shown as such, but only one of the corresponding first piezo actuator 1, one of the corresponding second piezo actuator 2 and, if applicable, one of the corresponding third piezo actuator 3 illustrated. In this respect, the (relative or, respectively, incremental) position (on the horizontally drawn travel axis) of the (likewise not shown) carriage (20) can be derived from the (relative or, respectively, incremental) position of the second piezo actuator 2 (if applicable, together with that of the third piezo actuator 3):
[0108] Initially (or, respectively, at each new cycle start of the repeatable cycle S1 to S4; S101 to S106), a step S1, S101 of coupling/clamping of the carriage to the push rod 30 takes place. Thereby, the carriage is clamped to the push rod 30 by means of piezoelectrically actuated expansion of the second piezo actuator 2 (see vertical arrows in FIG. 9). This corresponds to the (temporary) first coupling state of the first clamping device of the carriage.
[0109] In short, in step S1, S101 the push rod 10 is gripped by the carriage (clamped by means of second piezo actuator 2).
[0110] Thereafter, optionally (only FIG. 10) a step S102 of a switching from a second coupling state (run-inhibiting securing of the carriage to the guide rail 30) into a (temporary) second decoupling state (run-free de-securing of the carriage from the guide rail 30) takes place. For this purpose, the third piezo actuator 3 (the second clamping device of the carriage) is piezoelectrically actuated for expansion, so that the previously existing clamping is released in a run-free manner.
[0111] In short, in (optional) step S102, the clamping or, respectively, running restraint of the carriage on the guide rail 30 is removed or, respectively, released.
[0112] Thereafter, a further step S2, S103 (of a generating) of a carriage advance s of the carriage takes place, which is activated or, respectively, caused by a longitudinal stroke h of the push rod (see in FIG. 9/10 the horizontal arrow as well as the fine-dashed vertical line located on the left of the diagram). For this purpose, the first piezo actuator 1 of the longitudinal stroke device expands from an axial starting position. It should be noted that in the schematic illustration of FIGS. 9, 10, the first piezo stroke coincides with the longitudinal stroke h. This means that a preferably vertical line on the left-hand side of the figure is not possible. I.e. any preferably provided lever conversion (cf. FIGS. 4a to 4d) is neglected herein; analogous applies to the piezo actuators 2, 3.
[0113] In short, in step S2, S103 the push rod 10 performs longitudinal stroke h by being advanced by a first piezo stroke of the first piezo 1, and thereby takes the pre-clamped carriage with it.
[0114] Thereafter, optionally, a step S104 (FIG. 10 only) of (back-)switching from the second decoupling state (run-free de-securing of the carriage from the guide rail 30) into the (temporary) second coupling state (run-inhibiting securing of the carriage to the guide rail 30) takes place. For this purpose, the third piezo actuator 3 (of the second clamping device of the carriage) is piezoelectrically actuated for contraction. Due to the coupling/clamping of the carriage to the guide rail 30, the carriage is secured against slipping.
[0115] In short, in (optional) step S104, the carriage is clamped on the guide rail 30 or, respectively, secured or, respectively, inhibited from running.
[0116] In a subsequent step S3, S105, a decoupling of the carriage from the push rod 30 takes place. For this purpose, the carriage is released from the push rod 30 by means of piezoelectrically actuated contraction of the second piezo actuator 2 (see vertical arrows in FIG. 9). This corresponds to the first (temporary) decoupling state of the first clamping device of the carriage.
[0117] In short, in step S3, S105 the carriage releases its clamping to the push rod 30.
[0118] Subsequently, in a step S4, S106 of a motion of the push rod 10 separate from the carriage 10, the push rod 10 is moved or, respectively, pulled back to its starting position (see in FIG. 9/10 the horizontal arrow as well as the fine-dashed vertical line located on the left of the diagram). For this purpose, the first piezo actuator 1 of the longitudinal stroke device contracts back to the axial starting position.
[0119] In short, in step S4, S106 the push rod 10 is again retracted to its starting position, while the carriage remains at a new (incremental) advance position. Compare the offset of the carriage according to that of the second piezo actuator 2 at the beginning of the new cycle at the repeated step S1 or, respectively, S101 (bottom of diagram) compared to its position at the beginning of the first cycle (top of diagram).
[0120] By (multiple) repetition of the cycle, the incremental carriage advances s add up or, respectively, accumulate. Thus, in sum, the piston plunger travel path X results (with reference to FIGS. 3a/3b).
