EP0945630A1 - Rodless linear actuator - Google Patents

Abstract

The linear drive (1) with a housing (3) and an inner chamber (2). The housing has a longitudinal slot (12) opening out in the chamber. A drive part (13) is arranged with a drive component (14), longitudinally movable in the chamber, and projects with a follower part (15), outwards through the slot. The slot is closed by a sealing strip (43). A position determination unit (58) determines the relative position of the drive part and the housing, which has a housing side detecting element (59) provided at the sealing strip. A drive side detection element (60) is provided at the drive part. In addition an evaluation unit is assigned to one of the detecting elements.

Description

The invention relates to a rodless linear drive, with a housing interior delimiting Housing that opens into the interior of the housing Has longitudinal slot, with a drive part that a in Housing interior longitudinally movable drive section and one through the longitudinal slot to the outside protruding driver section, the longitudinal slot at least on the drive part on both sides in the longitudinal direction adjacent lengths by means of a Sealing tape is closed, and with a position determining device to determine the relative position of drive part and housing, on the housing or on the drive part provided first detection means and with these cooperating, provided on the other component has second detection means and the one the first and / or second detection means assigned evaluation unit contains.

Such a rodless linear drive goes out the DE-GM 29 508 517. The housing-side detection means are there from two on the two slot flanks of the longitudinal slot arranged resistance strips formed. One in contact with the two resistance strips standing sliding contact arranged on the driver section provides the drive part-side detection means The evaluation unit is from one side with the Resistance measuring strips connected so that they are in Changing depending on the position of the contact point Resistance of the two shorted sections of the Measure resistance measuring strips and from them the relative position of the output part and housing can determine.

The production of such a rodless Linear drive is relatively complex because both the Resistance strips as well as the sliding contacts inside of the longitudinal slot must be arranged. Because of the little space for attaching the resistance strips and the sliding contacts are available precise manufacturing is required to ensure mobility of the drive part along the housing not by possibly jamming occurring in the area of the longitudinal slot to hinder. The housing consists of electrical conductive material, this must also compared to the Resistance strips are electrically isolated.

It is therefore the object of the present invention, a rodless linear drive with position determining device to create the easy to assemble is and reduces the manufacturing costs.

This object is achieved in that the Housing-side detection means provided on the sealing tape are.

At least at the point where the driver part of the Drive part protrudes through the longitudinal slot, the sealing tape runs at a distance from the longitudinal slot in the Housing interior. There is the possibility of the drive part side Arrange detection means so that they with the section of the longitudinally spaced Seal tape work together, the assembly of the drive part Detection means due to the sufficient available space is simplified. The housing-side detection means can already the manufacture of the sealing tape provided on this become. For example, it is possible to use the housing Detector during extrusion of the sealing tape in to incorporate this, similar to the manufacturing process of jacketed cables or wires. When attaching of the sealing tape on the housing of the rodless Linear drives become the housing side at the same time Detection means mounted, which makes the working and Reduced time spent producing the linear drive is.

Advantageous embodiments of the object of the invention emerge from the subclaims.

The evaluation unit can only be used with the first or second detection means. In this case the other means of registration do not require a connection point to the evaluation unit, so that it is one have a simple structure and therefore with little effort can be produced.

The first and the second advantageously work Detection means together without contact, which on the one hand the relative movement of the drive part and housing can take place unhindered and on the other hand frictional wear in the relative movement between the first and second detection means is avoided.

In such an embodiment, the first Detection means for the relative movement of the housing and Drive part, for example, in the field of cause second magnetic field changing magnetic field, the second detection means being magnetic field dependent Generate detection signal that of the evaluation unit is fed to determine the relative position. This structure of the position determining device ensures a reliable function at low manufacturing costs.

This may be the first means of registration several electrically conductive and / or magnetizable or permanent magnetic detection elements that act in the direction of the relative movement of the drive part and Housing, for example, regularly spaced apart are arranged. First detection means designed in this way are particularly easy to manufacture.

Furthermore, it is advantageous if the second Detection means contain a coil arrangement. This can be used as a magnetic field dependent sensor. It is possible that in the area of the coil arrangement existing magnetic field from the coil arrangement itself is caused. This way the first Detection means itself no magnetic field in the area Generate coil assembly so that for their manufacture cheaper, non-permanent magnetic and in particular electrically conductive material can be used can.

The configuration in which the evaluation unit especially only with the first means of registration connected, opens up the possibility that the Evaluation unit via the first detection means a measurement signal emits that by interacting with the second Detection means for determining the relative position serves. The relative position is via such a measurement signal can also be determined if the starting position of Housing and drive part unknown before the relative movement are. This means that none known to the evaluation unit Starting position must be defined to the relative position to be able to determine.

A particularly simple position determination can take place if the relative position over time between sending out the measurement signal and arrival of one of the Measurement signal and the second detection means triggered Signal response is determined on the evaluation unit.

It is also advantageous if the evaluation unit with the housing-side detection means is connected. Most of time the drive part moves along the stationary Housing, so that connecting cable to the evaluation unit this embodiment do not have to be moved.

Furthermore, the first detection means on Sealing tape may be provided and one in the longitudinal direction of the sealing tape extending conductor arrangement included. This enables simple transmission of the measurement signal or the signal response.

The second detection means on the drive part be provided and a discontinuity in the Induce conductor arrangement, the measurement signal at the Discontinuity is a return to the evaluation unit Triggers signal response. The discontinuity thus defines the relative position of the drive part and Casing. The signal response can in particular be from a Reflection of the measurement signal at the point of discontinuity be educated. A reflection can be of the second Detection means caused in a particularly simple manner become.

For this purpose, the second detection means expediently contain a magnetic device whose magnetic field is on the conductor arrangement acts and the discontinuity evokes. In particular, at least one has the conductor of the conductor arrangement has magnetostrictive properties on so that this is due to the action of the magnetic field deformed, the deformation being the point of discontinuity represents.

Furthermore, it is expedient if the conductor arrangement at least one externally accessible electrical Head has. The second Detection means one in contact with the electrical conductor have standing conductor tap, the contact point between conductor tap and electrical conductor Represents discontinuity. Through the conductor tap can at the contact point in a particularly simple manner a change in resistance of the conductor, from the incoming Seen measurement signal ago, what is a reflection at the point of discontinuity. At a particularly simple embodiment variant connects the Conductor tap several electrical conductors of the conductor arrangement electrically at the point of discontinuity. The conductor tap is designed as a shorting bar, so to speak.

Fig. 1

einen mit einer Positionsbestimmungseinrichtung ausgestatteten fluidbetätigten kolbenstangenlosen Linearantrieb im Längsschnitt,

Fig. 2

den Linearantrieb aus Fig. 1 in einem Querschnitt gemäß der Schnittlinie II-II,

Fig. 3

den prinzipiellen Aufbau eines ersten Ausführungsbeispiels einer Positionsbestimmungseinrichtung, wobei die antriebsteilseitigen Erfassungsmittel eine Spulenanordnung und die gehäuseseitigen Erfassungsmittel mehrere magnetisierbare Erfassungselemente aufweisen, in einer schematischen Darstellung,

Fig. 4

ein zweites Ausführungsbeispiel einer Positionsbestimmungseinrichtung in der Darstellung wie Fig. 3, wobei die antriebsteilseitigen Erfassungsmittel einen magnetfeldabhängigen Sensor und die gehäuseseitigen Erfassungsmittel mehrere permanentmagnetische Erfassungselemente aufweisen,

Fig. 5

ein drittes Ausführungsbeispiel einer Positionsbestimmungseinrichtung in der Darstellung wie Fig. 3, wobei die gehäuseseitigen Erfassungsmittel von außen zugängliche elektrische Leiter und die antriebsteilseitigen Erfassungsmittel einen Leiterabgriff aufweisen, und

Fig. 6

weitere Ausführungsformen der Positionsbestimmungseinrichtung in der Darstellung gemäß Fig. 3, wobei die gehäuseseitigen Erfassungsmittel einen magnetostriktiven Leiter und die antriebsteilseitigen Erfassungsmittel eine Magneteinrichtung aufweisen.

In the following, the rodless linear drive according to the invention is explained in more detail with reference to the accompanying drawing. Show it:

Fig. 1

a longitudinally sectioned fluid operated piston rodless linear drive equipped with a position determining device,

Fig. 2

1 in a cross section along the section line II-II,

Fig. 3

the basic structure of a first embodiment of a position determining device, the drive part-side detection means having a coil arrangement and the housing-side detection means having a plurality of magnetizable detection elements, in a schematic representation,

Fig. 4

3 shows a second exemplary embodiment of a position determining device, the detection part on the drive part side having a magnetic field-dependent sensor and the housing-side detection means having a plurality of permanently magnetic detection elements,

Fig. 5

a third embodiment of a position determining device in the representation as FIG. 3, wherein the housing-side detection means have externally accessible electrical conductors and the drive part-side detection means have a conductor tap, and

Fig. 6

3, wherein the housing-side detection means have a magnetostrictive conductor and the drive part-side detection means have a magnetic device.

In Fig. 1 a rodless linear drive 1 is shown, which delimits a housing interior 2 Housing 3 has. The housing 3 contains one extending in the longitudinal direction 4, tubular Housing body 5, which at its two end regions 6, 7 by means of a housing cover 8, 9 is closed. On the housing body 5 is a wall at a circumferential point radially penetrating longitudinal slot 12 provided, which opens into the housing interior 2 and in the longitudinal direction, for example, over the entire Length of the housing body 5 extends.

A drive part 13 is provided on the housing 3 so as to be longitudinally movable, one in the housing interior 2 longitudinally movable arranged drive section 14 and one through the longitudinal slot 12 driver portion 15 projecting outwards having. The drive section thus provides the force-absorbing, driven part of the drive part 13, on which the driver section 15 is provided. This serves for example, objects not shown such as grippers, tools, workpieces or sensors wear that by means of the linear drive 1 in a desired Position should be brought.

In the preferred embodiment according to FIG. 1 it is a fluid-operated, especially pneumatic Linear drive 1, the drive section 14 of a piston 18 is formed. Alternatively there is also the possibility of the rodless linear drive 1 to be electrically driven, for example, the drive section 14 via a longitudinal spindle, a Toothed or V-belts or the like can be moved.

According to the example, the housing interior 2 has an approximately circular cylindrical cross section. The piston 18 is in the Housing interior 2 arranged longitudinally movable. He has an elongated, tube-like piston body 22, which at its two longitudinal end regions 23, 24 of each have a substantially cylindrical piston end piece 25, 26 is closed. Inside the piston body 22 is thus between the two piston end pieces 25, 26 Piston interior 27 limited.

The piston 18 lies in the region of the piston end pieces 25, 26 sealing on the inner wall facing the housing interior 2 30 of the housing body 5. For this, the Pistons on the two piston end pieces 25, 26 each a circumferential sealing arrangement 31, 32, which according to the example is formed by a sealing ring. For better Guiding the piston 18 in the housing interior 2 of the housing 3 is additionally on each piston end piece 25, 26 Guide ring 33, 34 provided.

In the longitudinal direction 4 are on both sides of the piston 18 in Housing interior 2 fluid chambers 37, 38 formed that on the one hand from the assigned housing cover 8, 9 and on the other hand by the relevant piston end piece 25, 26 are limited. For supplying or removing fluid into the or from the fluid chamber 37, 38 it is also fluid one which penetrates the respectively assigned housing cover 8, 9 central fluid channel 39, 40 connected. On this can in turn be connected to a corresponding fluid line be with a fluid source or fluid sink connected is.

The two fluid chambers 37, 38 are in the region of the longitudinal slot 12 closed by means of a sealing tape 43, the inside of the slot flanks 44, 45 of the longitudinal sections extending along the fluid chambers 37, 38 46, 47 of the longitudinal slot 12 abuts.

The sealing tape 43 is preferably seen in cross section trapezoidal, the two opposite, sloping side surfaces 48, 49 of the sealing tape on also inclined, radially towards each other Slit flanks of the longitudinal slot 12 lie flat.

Enforcement around the driver section 15 of the drive part 13 of the longitudinal slot in the connection area 52 with the To enable the drive section 14 is the sealing tape 43 there lifted inwards from the longitudinal slot 12 and runs in one provided in the connection area 52, the drive part 13 penetrating through opening 53.

The sealing tape 43 is in the area with its two ends the housing cover 8, 9 fixed to the housing 3. Between these two fastening points 54, 55 is the sealing tape 43 stretched in its direction. Since it is usually made of elastic sealing material, are to increase the tensile strength according to FIG. 2 in the embodiment two in the sealing tape 43 continuously in the direction of extension of the sealing tape 43 extending reinforcing strands 56, 57 arranged. These can be made of a solid plastic be made or consist of metal. It understands yourself, that in a modification to the embodiment too only one or more than two reinforcement strands could be provided, which are also on the outside of the sealing tape 43 could be arranged.

In a non-fluidic, not shown actuated linear drive fulfills the sealing tape 43 no sealing function, but it protects it from contamination, that could penetrate into the housing 3.

To determine the relative position between the drive part 13 and housing 3, the linear drive 1 has a Position determining device 58, which is dash-dotted in FIG. 1 is indicated. About the specification and registration the relative position of drive part 13 and housing 3 can the position of the provided on the driver section 15, object to be positioned as required become.

For this purpose, the position determination device 58 first provided according to the example on the sealing tape 43 Acquisition means 59 and cooperating with them, second detection means provided here on the drive part 13 60 on. For better differentiability, the first detection means 59 therefore in the following as the housing side and the second detection means 60 as the drive part side Means of detection.

Both the housing side and the drive part side Detection means 59, 60 are only in FIG. 1 shown schematically in dash-dotted lines. The drive part side Detection means 60 are preferably on the Drive section 14 or in the connection area 52 between Drive section 14 and driver section 15 arranged. The housing-side detection means 59 extend along the sealing tape 43 substantially above it whole length. The drive part-side detection means 60 work with them depending on the current relative position between drive part 13 and Housing 3 assigned point of the housing side Detection means 59 together, which as detection point 61 be designated. This detection point 61 is located in the embodiment on the section of the housing side Detection means 59 or the sealing tape 43, the runs inside the feed-through opening 53.

The passage opening 53 can face the piston interior 27 be open as shown in FIG. 1. This gives there is a lot of space for arranging the drive part side Detection means 60 in the area of the assignment office 61. Also the assembly of the drive part Detection means 60 can thus be carried out without problems become.

An evaluation unit is provided with the housing-side detection means 59 64 of the position determining device 58 connected, the signals from the assigned housing-side Detection means 59 receive or signals to them Can send means of registration. By evaluating this The evaluation unit 61 can signal the current relative position between the drive part 13 and the housing 3 determine.

In a modification of this, it is also possible to use the evaluation unit 64 additionally or alternatively with the drive part To connect detection means 60. This depends in particular from the embodiment of the position determining device 58 from, with different versions in Figures 3 to 6 in the form of schematic diagrams are shown schematically. Based on these figures the operation of the various versions is explained play the position determining device 58 below explained in detail.

In the two embodiments according to FIGS. 3 and 4 is the evaluation unit only with the drive part Detection means 60 connected. This connection is, for example, by means of electrical connecting conductors 66 realized. The housing-side detection means 59 and the drive part-side detection means 60 work contactlessly together so that during the relative movement the drive part 13 and the housing 3 no additional Friction or no additional wear occurs.

The basic principle of the operation of the position determining device 58 is based on the fact that the housing-side detection means 59 during the relative movement of housing 3 and drive part 13 or Sealing tape 43 and drive part 13 are in the area of on the drive part-side detection means 60 changing magnetic field cause, the drive part side detection means 60 a magnetic field dependent detection signal generate that the evaluation unit 64 for determining the Relative position is supplied.

To detect the changing magnetic field, the drive part-side detection means 60 at least one magnetic field-dependent sensor 67, which in the embodiment 3 is formed by a coil 68. This coil is connected to a voltage via the evaluation unit 64 applied so that it produces the magnetic field itself.

The housing-side detection means 59 are in the sealing tape spaced apart along its direction arranged, magnetizable and / or electrically conductive detection elements 69 formed. The detection elements can, for example, of spaced individual metal balls can be formed. However, it is also possible, the individual detection elements connect with each other, thereby introducing the Detection elements 69 in the sealing tape 43 during manufacture is much easier. For example the detection elements 69 to a chain or band-like Structure. The external form of the In principle, detection elements 69 can be freely selected.

The coil 68 surrounds the sealing tape 43 in the area of the detection point 61. With a relative movement of the drive part 13 and housing 3, the coil 68 moves along the Sealing tape 43, the magnetic flux in the Coil through the sensing elements moved through the coil 68 69 changes, which also becomes one changing voltage on the coil 68 leads from the evaluation unit 64 can be measured. The voltage signal on the coil 68 serves as a measure of the path that during the Relative movement between drive part 13 and housing 3 covered has been. Starting from a known, defined one The starting point can be the distance covered current relative position of drive part 13 and housing 3 can be determined in the evaluation unit 64.

About the arrangement of the detection elements 69 on the sealing tape 43 can simultaneously determine the distance traveled Distance also the direction of movement of the relative movement be determined. For this purpose, the detection elements 69 have irregular distances, so that during the Relative movement recorded by the evaluation unit 64 detection signal formed by the voltage on the coil 68 certain, periodically recurring voltage profiles has, the voltage curves depending on the direction of movement are different. The periodically recurring, voltage curves containing the direction code, so to speak can also by in a section of the Sealing tape 43 different detection elements 69 caused be, the different detection elements 69 different voltage changes of the Cause coil voltage.

In the embodiment shown in Fig. 3 Position determining device 58 have the drive part side Detection means 60 via only one Coil 68. As a modification to this, these could also contain a coil arrangement, one with the evaluation unit 64 connected measuring coil is provided, the causes the detection signal. At least one more The coil of the coil arrangement could then be used as an excitation coil be formed, which is present in the area of the measuring coil Magnetic field. In the preferred embodiment 3 are the excitation coil, so to speak and the measuring coil simultaneously from the single coil 68 educated.

The coil 68 can also be part of an oscillating circuit 73 be, wherein, for example, a series resonant circuit is realized where the capacitor 74 and the ohmic Resistor 75 is provided in the evaluation unit 64, so that the connection to the coil 68 via the connecting conductor 66 takes place. It is understood that the capacitor 74 and the resistor 75 together with the coil 68 also on Drive part 13 could be arranged. If the ohmic Resistance of the coil 68 together with that of the connecting conductor 66 is already large enough, the separate Ohmic resistance 75 is also eliminated.

Is now due to the detection elements moved relative to the coil 68 69 the magnetic flux inside the Coil 68 changes, the resonance frequency also changes and thus the detuning of the resonant circuit 73. The changing mood serves here of the resonant circuit 73 as a detection signal via which the Evaluation unit 64 the distance traveled and thus also the current relative position of drive part 13 and Housing 3 can determine.

In contrast to the embodiment of FIG. 3 is the Magnetic field-dependent sensor 67 of the drive part-side detection means 60 in the exemplary embodiment according to FIG. 4 for example from a magnetoresistive sensor or a Hall sensor, with another any magnetic field-dependent sensor can be used can. The existing in the area of the sensor 67 itself changing magnetic field is, for example, from the housing side Detection means 59 generated. With these on Sealing tape 43 provided detection means 59 is as in the previous embodiment spaced apart in the direction of extension of the Sealing tape 43 arranged detection elements 69, wherein this in the present case in the form of permanent magnets are executed. The sensing elements 69 are preferred connected together so that a kind of magnetic tape 78th arises. The magnetic tape 78 can already at Production of the sealing tape 43 introduced into this are or can be arranged on the outside of the sealing tape 43.

The connecting the individual detection elements 69 Longitudinal strands 79, 80 can simultaneously function as Reinforcement strands 56, 57 in the sealing tape 43 take over sufficient stability of the sealing tape 43 in its Ensure direction of extension seen.

Each of the permanent magnetic detection elements 69 is generated a local magnetic field 81, which is schematic in FIG. 4 is indicated. During the relative movement of the drive part 13 and housing 3, sensor 67 moves along of the sealing tape 43, whereby it is replaced by the successive local magnetic fields 81 applied to the detection elements 69 becomes. That caused in sensor 67 Detection signal is forwarded to the evaluation unit 64 and evaluated there to determine the relative position. As in the previous embodiment described, a coding by the The detection elements 69 are arranged or configured, so that the distance covered from the detection signal Distance and the direction of movement of the relative movement let determine what the determination of momentous relative position is possible.

As an alternative to the two design variants explained above 3 and 4, the first Detection means 59 can also be provided on the drive part 13, so that they are the drive part-side detection means form. The housing-side detection means are here formed by the second detection means 60.

There is the possibility here of sealing tape 43 to provide a plurality of spaced-apart magnetic field-dependent sensors 67, for example, several coils 68 that the represent second, housing-side detection means 60. The first detection means 59 on the drive part side could then be from a permanent magnetic or magnetizable and in the case of one formed by a coil 68 magnetic field dependent sensor 67 from an electrical conductive detection element 69 may be formed. Dependent on from the relative position of housing 3 and drive part 13 acts that arranged on the drive part 13 Detection element 69 mainly on the magnetic field or dependent Sensors 67 a at the assignment point 61 are present on the sealing tape 43. Because of the the assignment point 61 acting magnetic field Evaluation unit determine which of the magnetic field-dependent Sensors 67 is applied to the sealing tape 43, and thus the relative position of housing 3 and drive part 13 determine.

The arrangement of the first and second detection means 59, 60 is therefore compared to the exemplary embodiments according to FIG 3 and 4, so to speak, vice versa, now the Magnetic field-dependent sensors on the sealing tape 43 and one or Several detection elements 59 are provided on the drive part 13 are. The advantage of this modification is that the current relative position of drive part 13 and Housing 3 does not have the last determined relative position and the relative movement that followed is determined, but results directly from it, which of the magnetic field-dependent sensors 67 on the sealing tape 43 is acted upon by the detection element 59 on the drive part side becomes. The more sensors 67 are provided on the sealing tape 43 are and the smaller their distance from each other is selected, the more precise the relative position can be be determined between drive part 13 and housing 3.

In the embodiments of the Position determination device 58 is the evaluation unit 64 now only with the first detection means 59 connected, which in turn is the housing-side detection means represent. This eliminates the need to move the Connection conductor 66 with the drive part 13. Die Connection between the housing-side detection means 59 and the evaluation unit 64 is, for example, in Area of one of the attachment points 54, 55 between Sealing tape 43 and housing 3 are provided.

The connection is made as in the previous ones Embodiments via one or more electrical connecting conductors 66, alternatively also a connection can be realized with galvanic isolation could. For example, the evaluation unit 64 and the housing-side detection means 59 inductively with one another be coupled.

The basic principle of the design variants of the position determining device 58 is based on FIGS. 5 and 6 that the evaluation unit 64 a measurement signal on the transmits housing-side detection means 59 through Interaction between the housing side and the second, drive part side detection means 59, 60 for Determination of the relative position is used.

The signal form of the measurement signal can in principle be arbitrary be, for example pulses, pulse trains or Waves, especially high-frequency waves, come into question.

In the preferred embodiments, the relative position determined in the evaluation unit 64 in that the time between sending the measurement signal and arrival one of the measurement signal and the drive part Detection means 60 via the housing-side detection means 59 signal response returning to the evaluation unit 64 is determined. Over the period and the known transmission speed of measurement signal and Signal response can be the relative position of Drive part 13 and housing 3 are determined.

When determining the position by sending a measurement signal it is possible to find the relative position directly in the To determine evaluation unit 64. A specific one, the evaluation unit 64 known, defined starting positions between drive part 13 and housing 3 does not have to be fixed because the current relative position does not exceed the distance traveled, but directly through the Evaluation of the measurement signal or the signal response takes place.

Both the measurement signal and the signal response are transmitted via a conductor arrangement 84, which the housing-side Detection means 59 forms. The drive part side Detection means 60 cooperate in this way the conductor arrangement 84 together that they in this at the Detection point 61 cause a discontinuity 85, at which the emitted by the evaluation unit 64 Measurement signal the signal response returning to the evaluation unit triggers.

At least one of the conductors of conductor arrangement 84 can doing so to increase the tensile strength of the sealing tape 43 serving reinforcement strand 56, 57 form.

The conductor arrangement 84 has in the exemplary embodiment 5 over at least one and preferably over two externally accessible electrical conductors 88, 89, see above that measurement signal and signal response in the form of electrical Signals are present. The electrical conductors 88, 89 are expediently on one of the outer surfaces of the sealing tape 43 provided that has no sealing function. According to the example, the electrical conductors 88, 89 are on the rear surface 90 facing housing interior 2 of the sealing tape 43 arranged.

The discontinuity 85 is thereby in this embodiment caused that a conductor tap 91 of the drive part Detection means with the or electrical conductors 88, 89 is in contact, the Contact point of discontinuity 85 corresponds.

5 could be modified there is only one electrical conductor 88 or 89 be connected to the evaluation unit 64. Of the Conductor tap 91 of the drive part-side detection means 60 would then be designed such that he the resistance of the electrical conductor 88, 89 at the point of discontinuity 85 changed so that the incoming measurement signal reflects and may be broken. The reflection poses the signal response returning to the evaluation unit 64 As already described, you can then use the Time between sending the measurement signal and arrival the signal response the relative position between Drive part 13 and housing 3 are determined.

If at discontinuity 85 next to the reflection If the refraction should also take place, the evaluation unit can 64 opposite end of the associated electrical Conductor 88, 89 by means of a corresponding Resistance adjusted to reflect the reflection of the Discontinuity from in the direction of propagation of the measurement signal continuous refractive signal at the end of the conductor avoid.

With such a configuration, it is useful if the measurement signal is formed by an electrical pulse.

As already described, are in the embodiment according to 5 two externally accessible electrical conductors 88, 89 available, which together form a two-wire line. The conductor tap 91 of the drive part-side detection means 60 is designed here as a shorting bar, the the two electrical conductors 88, 89 of the two-wire line electrically short-circuits at the point of discontinuity 85.

In the present case, the two-wire line forms a so-called "Lecher line", the measurement signal in particular is formed by a high frequency wave. Here it is Measurement signal completely reflected at discontinuity 85, where the reflection forms the signal response, which is 180 ° out of phase with respect to the measurement signal. A standing wire is thus formed in the second wire line Wave out. As with the previous cases, the Runtime measurement the relative position between the drive part 13 and housing 3 determined in the evaluation unit 64.

In the exemplary embodiment explained below according to 6 of the position determining device 58 act on the drive part side detection means 60 contactless the housing-side detection means 59. These are formed by the conductor assembly 84 which, in contrast to the previous embodiments play at least one contains magnetostrictive, electrically conductive conductor 96.

The drive part-side detection means 60 comprise one Magnet device 94, which in the present case by a Permanent magnet is formed, the magnetic field on the magnetostrictive conductor 96 of the conductor arrangement 84 acts and causes the discontinuity 85.

The magnetostrictive conductor 96 is, for example an amorphous or nanocrystalline, ferromagnetic conductor. By the influence of a Magnetic field, this is ferromagnetically saturated, causing a deformation (magnetostriction) of the magnetostrictive Conductor 96 is caused. This Deformation point forms the discontinuity 85 the measurement signal emitted by the evaluation unit 64 is reflected and broken.

A first possibility is that the reflection forms the signal response. That is based on the Discontinuity 85 in the direction of propagation of the Measurement signal along the magnetostrictive conductor 96 on Spreading refractive signal would be at the evaluation unit 64 reflected the opposite end one more time become. This could lead to errors in the calculation of the Lead relative position. That is why the magnetostrictive Conductor 96 on its opposite the evaluation unit 64 Terminated by means of a resistor 97 in such a way that the reflection factor is zero and therefore Adaptation exists.

The second possibility for the formation of the signal response results itself through the amorphous or nanocrystalline formation of the magnetostrictive conductor 96. At the point of discontinuity 85 one emerges simultaneously in both Mechanical wave propagating directions, in particular Torsion shaft. The one returning in the direction of the evaluation unit 64 mechanical wave provides the signal response represents and can therefore due to their known propagation speed about the runtime measurement for Determination of the relative position of housing 3 and drive part 13 serve. The distance from the discontinuity 85 together with the refractive signal to that of the evaluation unit opposite end of the conductor 96 spreading further mechanical shaft is preferably on this The end of the conductor is so attenuated that there is no significant reflection takes place to errors in determining the relative position to be avoided in the evaluation unit 64.

The evaluation unit also leads with these design options 64 a transit time measurement of the measurement signal and Signal response through, from which they get the relative position determined between drive part 13 and housing 3.

6 is a further variant for the execution of the Position determining device 58 shown. Here is the magnetostrictive conductor in the form of a tube-like one Sound wave guide 100 is formed, which in FIG. 6 is shown in broken lines. Coaxial within the Sound waveguide 100 is an electrical measuring conductor 101 arranged, via which the measurement signal starting from the evaluation unit 64 is transmitted. At the discontinuity 85 triggers the incoming measurement signal via the Sound waveguide 100 returning to the evaluation unit 64 first and one opposed to this further propagating second mechanical wave, where it is in the present case a torsion shaft acts. The first mechanical wave is the Signal response represents, and the second mechanical wave Damped at the end of the conductor to avoid reflections. in the The difference to the previously explained variant is spreading the signal response is not on the one transmitting the measurement signal Head 101, but on a separate additional one Head 100 out. The position is also determined here in the evaluation unit 64 via the measurement of the transit time of the measurement signal or the signal response. That with this Principle exploited variant is called Inscribed "Wiedemann effect".

Claims (26)

Rodless linear actuator, with one Housing interior (2) delimiting housing (3), the one longitudinal slot (12) opening into the interior of the housing (2) has, with a drive part (13), the one in Housing interior (2) drive part arranged to be longitudinally movable (14) and one through the longitudinal slot (12) has outwardly projecting driver part (15), wherein the longitudinal slot (12) at least on the drive part (13) on both sides in the longitudinal direction (4) adjacent lengths (46, 47) by means of a sealing tape (43) is closed, and with a position determining device (58) to determine the relative position of Drive part (13) and housing (3) on the housing (3) or first detection means provided on the drive part (13) (59) and collaborating with them on each other component (13 or 3) provided second detection means (60) and one of the first and / or evaluation unit assigned to second detection means (59, 60) (64), characterized in that the housing-side detection means (59) on the sealing tape (43) are provided. Rodless linear drive according to claim 1, characterized in that the sealing tape (43) at least one in its direction of extension on or in the sealing tape (43) extending reinforcing strand (56, 57), one electrical conductor of the housing-side detection means (59) forms. Rodless linear drive according to claim 1 or 2, characterized in that the first and the cooperate second contact means (59, 60) without contact. Rodless linear drive according to claim 3, characterized in that the first detection means (59) in the relative movement of the housing (3) and Drive part (13) in the area of the second Detection means (60) cause changing magnetic field, wherein the second detection means (60) is magnetic field dependent Generate detection signal that of the evaluation unit (64) to determine the relative position becomes. Rodless linear drive according to claim 4, characterized in that it is the first Detection means (60) around several electrically conductive and / or magnetizable or permanent magnetic Detection elements (69) acts in the direction of Relative movement of drive part (13) and housing (3) in succession are arranged. Rodless linear drive according to one of the Claims 3 to 5, characterized in that the second Detection means (60) at least one magnetic field dependent Have sensor (67). Rodless linear drive according to one of the Claims 3 to 6, characterized in that the second Detection means (60) contain a coil arrangement (68). Rodless linear drive according to claim 7, characterized in that in the area of the coil arrangement (68) existing magnetic field from the coil assembly (68) itself is caused. Rodless linear drive according to claim 7 or 8, characterized in that the coil arrangement (68) at least one that produces the detection signal Contains measuring coil (68), which with the evaluation unit (64) connected is. Rodless linear drive according to claim 9, characterized in that the measuring coil (68) is part of a Resonant circuit (73), the evaluation unit (64) the relative position in particular by means of the detuning the resonant circuit (73) determined. Rodless linear drive according to one of the Claims 1 to 10, characterized in that the evaluation unit (64) via the first detection means (59) sends out a measurement signal, which by interaction with the second detection means (60) for determining the relative position serves. Rodless linear drive according to claim 11, characterized in that the relative position over the Time between sending the measurement signal and arrival one of the measurement signal and the second detection means (60) triggered signal response in the evaluation unit (64) is determined. Rodless linear drive according to claim 11 or 12, characterized in that the first detection means (59) are provided on the sealing tape (43) and one extending in the longitudinal direction of the sealing tape (43) Have conductor arrangement (84). Rodless linear drive according to claim 13, characterized in that the second detection means (60) are provided on the drive part (13) and in the Conductor arrangement (84) cause a discontinuity (85), the measurement signal at the point of discontinuity (85) a signal response returning to the evaluation unit (64) triggers. Rodless linear drive according to claim 14, characterized in that the signal response from a Reflection of the measurement signal at the point of discontinuity (85) is formed. Rodless linear drive according to claim 14 or 15, characterized in that the second detection means (60) contain a magnetic device (94), whose magnetic field acts on the conductor arrangement (84) and causes the discontinuity (85). Rodless linear drive according to claim 16, characterized in that at least one of the conductors (96 or 100) of the conductor arrangement (84) magnetostrictive Has properties. Rodless linear drive according to claim 17 characterized in that the magnetostrictive, especially nanocrystalline or amorphous conductors (96) is electrically conductive, the measurement signal via this Head (96) is transferred and at the discontinuity (85) one on this conductor (96) to the evaluation unit (64) returning mechanical wave that causes the Represents signal response. Rodless linear drive according to claim 17, characterized in that the magnetostrictive conductor formed by a tube-like sound waveguide (100) is the coaxial to one for measuring signal transmission serving electrical measuring conductor (101) is arranged, whereby at the point of discontinuity (85) by the incoming Measuring signal returning to the evaluation unit (64) mechanical wave is caused. Rodless linear drive according to one of the Claims 11 to 19 characterized in that the Sealing tape (43) provided conductor arrangement (84) at least an externally accessible electrical conductor (88, 89) and the second detection means (60) one with this electrical conductor (88, 89) in contact Conductor tap (91) included, the contact point between conductor tap (91) and electrical conductor (88, 89) represents the discontinuity (85). Rodless linear drive according to claim 20, characterized in that the conductor tap (91) several electrical conductors (88, 89) of the conductor arrangement (84) the discontinuity (85) electrically connects. Rodless linear drive according to one of the Claims 1 to 21, characterized in that the evaluation unit (64) only with the first means of registration (59) or the second detection means (60) is. Rodless linear drive according to one of the Claims 1 to 22, characterized in that the first Detection means (59) on the sealing tape (43) and the second Detection means (60) are provided on the drive part (13). Rodless linear drive according to one of the Claims 1 to 23, characterized in that the Evaluation unit (64) only with the housing side Detection means (59 or 60) is connected. Rodless linear drive according to claim 24, characterized in that the connection between the housing-side detection means (59) and the evaluation unit (64) in the area of a fastening point (54, 55) is provided on which the sealing tape (43) on the housing (3) is attached. Rodless linear drive according to one of the Claims 1 to 25, characterized in that it is a fluid-operated linear drive (1), the Drive part (14) is formed by a piston (18).

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