DE102018117230B4 - Resonance compensated stator coupling - Google Patents

Abstract

Natural frequency-optimized coupling (10), in particular a stator coupling (12), for the rotationally fixed connection of a first component, in particular a rotary encoder (14) with encoder shaft, to a second component, in particular a system to be measured with a shaft to be measured, the coupling (10), when the components are connected to one another in a rotationally fixed manner, is arranged in an axial direction (Z) between the components and is aligned coaxially with the components, the coupling (10) being set up, axial and / or radial relative movements between the components within tolerance limits and wherein a body (18) of the coupling (10) has: an annular central section (20) which extends in an unloaded state in a substantially radially oriented first plane and which has a centrally arranged passage opening (26) for coaxially connected, rotating shafts of the components; at least two primary wing sections (22), which are connect radially to the central section (20) and which are arranged equidistantly in a circumferential direction (U); each of the primary wing sections (22) having a mounting section (32) which extends in a second plane, parallel to the first plane, and which has a mounting opening (36), and has a connecting section (34) connecting the mounting section (32) to the central section (20), each of the connecting sections (34) extending in a plane that is at an acute angle (38 ), with the angle of attack (38) being selected so that it does not fall below a predetermined natural frequency, which is based on a common moment of inertia of the clutch and the rotary encoder and on a torsion spring constant of the clutch.

Description

The present invention relates to a (stator) clutch, which also realizes a torque arm. The stator coupling is used to fix a rotary encoder to an object to be measured (e.g. a motor or its rotating shaft).

Encoders are well known in the art. Encoders are set up to record partial or complete revolutions of a shaft to be measured. Encoders can e.g. Find use in drive technology, automation technology, transport technology, energy technology, elevator technology and the like. Encoders are set up to record absolute and / or relative rotational angles or rotational angles and / or rotational speeds or the number of revolutions of rotating components of a measurement object. A relative measurement can also be called an incremental measurement.

An angular position in the range between 0 ° and 360 ° (single turn, ST) and / or a number of complete revolutions (multi turn, MT) of a measurement object can be determined by means of a rotary encoder. Typical objects to be measured can be designed as motors or gears, for example. A rotating component of the object to be measured, the movement of which is to be recorded, can be referred to as a shaft to be measured.

The assembly of the encoder can be especially with e.g. high-speed and / or heavily loaded shafts to be measured place high demands on an alignment between the shaft to be measured and an encoder shaft of the encoder. Usually, the shafts to be measured and the encoder shaft, which are firmly connected to one another, should be aligned concentrically with one another.

However, it can happen that the wave to be measured is shifted statically and / or dynamically (unintentionally). Such shifts should be compensated for as far as possible by the encoder.

In particular, shock-like loads can cause deformations of the shaft to be measured, which can affect the encoder shaft and impair the overall functional reliability of the encoder. Impact loads can occur, for example, on non-rotating machines, e.g. Internal combustion engines, presses or the like occur. However, sudden loads can also occur during load changes and / or abrupt accelerations or decelerations on the shaft to be measured.

Known encoder systems therefore have e.g. elastic shaft couplings for tolerance compensation, which are arranged between the shaft to be measured and the encoder shaft. Elastic shaft couplings can have, in particular, flexible, tolerance-compensating elements, so that positional deviations of the shaft to be measured do not act directly on the encoder shaft. However, such solutions frequently have the disadvantage that flexible shaft couplings increase the measurement inaccuracy. The shaft couplings dampen the measurement signal. There is also the disadvantage that flexible shaft couplings take up a certain amount of installation space, which is greater the more tolerably the coupling is to react to bearing deviations.

An alternative approach to designing encoder systems is to connect the encoder shaft as rigidly and directly as possible to the shaft to be measured. It is consciously accepted that the encoder shaft immediately detects misalignments or positional deviations of the shaft to be measured. This has the advantage that the measurement can be carried out with high precision and unfiltered. With this design, it is advantageous to attach a housing of the rotary encoder to the measurement object in such a way that tolerance compensation is possible.

In this case, however, care must be taken to ensure that the encoder housing does not rotate relative to the measurement object. Torsion leads to an increase in measurement inaccuracy. At the same time, however, the aim is to accommodate the encoder housing softly enough to be able to compensate for positional deviations of the shaft to be measured.

So-called stator couplings are used for this purpose. Stator couplings connect two components to each other in a torsionally rigid manner, the stator coupling, however, permitting tolerance-related radial and axial relative movements of the two components. Such stator couplings are often used on encoders that are attached to motors.

The encoder shaft is rigidly connected to the motor shaft to be measured. The scanning mounted on the encoder shaft must be connected to the motor housing as torsionally rigid as possible. The stator coupling is used to accommodate inevitable misalignments between the encoder shaft and the motor shaft and any axial movements (e.g. due to thermal expansion) of the motor shaft.

The DE 89 15 109 U1 discloses a stator coupling which is made as a one-piece stamped and bent part from a spring steel sheet. The stator coupling has an annular disk-shaped flat base surface with a central opening, on which diametrically arranged pairs of tabs are formed, which are perpendicular to the plane the base surface are bent and have mounting points for attachment to the components. The two pairs of tabs each form a spring parallelogram, which allows radial deflection in the plane of the base surface in mutually perpendicular directions.

Stator couplings with vertical tabs have several natural frequencies, so there is a high risk of resonance excitation due to the rotation of the shaft to be measured. If the resonance case occurs, there are measurement errors of the encoder. In the worst case, the encoder no longer measures anything.

The DE 100 22 555 A1 discloses an angle measuring device. In the angle measuring device, a stator is coupled to a stationary motor housing via an axially and radially flexible coupling. The coupling is designed in such a way that when the angle measuring device is brought axially towards the motor housing, it clamps itself against a surface of the motor housing in a torsionally rigid manner and expands.

The DE 102 16 376 A1 discloses a rotation angle measuring system for measuring angle-dependent measurement quantities of an encoder shaft with a stator coupling for the rotationally fixed connection of a stator housing to a stator of a drive system to be measured, the encoder shaft being rotatably connected to a drive shaft of the drive system to be measured and the drive shaft of the drive system being at least largely common Has axis of rotation with the encoder shaft of the angle-of-rotation measuring system, the encoder shaft having a fit that can be inserted into a recess in a mounting plate connected to the stator coupling in a rotationally fixed manner, so that the encoder shaft of the angle-of-rotation measuring system is secured against rotation in the non-assembled state that the shaft end of the Encoder shaft has a thread for connecting to the drive shaft, to connect the shafts by rotating the stator housing and thus rotating the encoder shaft, which is non-rotatably connected via the mounting plate of the stator coupling the drive shaft can be screwed on and that when the mounting plate is fastened to the stator of the drive system, the encoder shaft and the mounting plate disengage and thus the recess releases the shaft fit, so that the encoder shaft can be moved in the assembled state.

US 2014/0037368 A1 discloses a stator coupling for the rotationally fixed connection of two components, which enables radial and axial relative movements within tolerance limits with a base area with first and second tabs. The second tabs are positioned on the straight edges between the mounting points. Bent edges, which are parallel to each edge, are bent away at least twice, so that a flange is formed parallel to the surface of the base. Two second tabs positioned on circumferential edges are arranged and overlap with mutually facing ends of their flanges, and these ends together form a mounting point of a set of second mounting points.

The object of the invention is to provide a clutch whose natural frequency is greater than or equal to a minimum natural frequency limit value specified by the customer. The natural frequency (s) of the coupling should therefore lie in a range outside a range which is predetermined by the shaft to be measured.

This object is achieved by a natural frequency-optimized clutch, in particular a stator clutch, for the rotationally fixed connection of a first component, in particular a rotary encoder with encoder shaft, to a second component, in particular a system to be measured with a shaft to be measured, the clutch if the Components are connected to one another in a rotationally fixed manner, arranged in an axial direction between the components and aligned coaxially with the components, the coupling being set up to allow axial and radial relative movements between the components within tolerance limits and wherein a body of the coupling has: an annular , in particular mirror-symmetrical, central section, which extends in an unloaded state in a substantially radially oriented, first plane and which has a centrally arranged passage opening for rotating shafts of the components to be connected coaxially; at least two primary wing sections which adjoin the central section radially and which are arranged equidistantly in a circumferential direction; wherein each of the primary wing sections has a mounting section that extends in a second plane, parallel to the first plane, and that has a mounting opening to secure the coupling to one of the components, and a connecting section that connects the mounting section to the central section; wherein each of the connecting sections extends in a plane which includes an acute angle of attack with the first plane, the angle of attack being selected such that a predetermined, application-dependent natural frequency, which is based on a common (angle of attack independent) moment of inertia of the clutch and the rotary encoder, and on based on a (torsion angle dependent) torsion spring constant of the clutch, is not undercut.

The clutch of the invention has an application-dependent optimized natural frequency that is optimized via the angle of attack of the connecting sections of the primary wing sections. The natural frequency of the coupling is optimized in such a way that no resonance occurs in the application, which would lead to intolerable measurement errors by the encoder. In the event of a resonance, a shaft to be measured rotates with the or one of the natural frequencies of the coupling, so that the overall system consisting of the object to be measured with the shaft to be measured, stator coupling and encoder with encoder shaft swings up so strongly that a position of the encoder shaft swings on position-determining element (e.g. a dipole or a code disk is attached can no longer be reliably determined. The encoder shaft performs an eccentric movement (imbalance), for example, so that a signal transmitter (e.g. permanent magnet) attached to the encoder shaft can no longer be reliably detected In the invention, the natural frequency is selected such that there is never a resonance case, but the coupling is nevertheless designed in such a way that axial and in particular radial tolerances are maintained.

In a special embodiment, a respective width of the connecting sections is selected so that the axial and radial tolerance is maintained.

A length of webs which form the annular central section can be influenced via the width of the connecting sections. The length of the webs influences the deformability of the coupling under radial load and / or axial load.

Each of the connecting sections is preferably formed over the entire surface, in particular without an internal recess.

Since the connecting sections have no internal recesses, the full-surface connecting sections give the body of the coupling high torsional rigidity. A linear spring characteristic (cf. 10 ) occurs with increasing torsional forces. The spring characteristic has a direct influence on the natural frequency.

In particular, the clutch has only one (single) natural frequency.

It is further preferred if the body of the coupling has secondary wing sections which extend on a side of the central section which is axially opposite the primary wing sections, the secondary wing sections being arranged equidistantly from one another in the circumferential direction.

The primary wing sections are used to attach the coupling to the component to be measured. The secondary wing sections are used to attach the coupling to the encoder. The primary and secondary wing sections face each other in the axial direction. The wing sections axially enclose the central section between them. The secondary wing sections serve in particular for axial tolerance compensation.

Preferably, each of the secondary wing sections has a mounting section and a connecting section, the mounting section preferably extending in a third plane that is oriented parallel to the first and second planes, the connecting section extending along the axial direction, and the mounting section for mounting is set up on the other component.

In a further embodiment, a number of the secondary wing sections corresponds to a number of the primary wing sections, and the secondary wing sections sit centrally in the circumferential direction between the primary wing sections.

With this type of arrangement, a uniform distribution of the power flow through the clutch can be achieved when the clutch is subjected to radial, axial and / or torsional loading.

It is also advantageous if the coupling is designed in one piece, in particular as a stamped and bent part.

In this case, the coupling can be manufactured easily and cheaply.

The coupling is preferably made of spring steel.

Spring steel has the required elasticity for tolerance compensation.

In particular, the primary wing sections extend radially inwards or outwards.

The coupling can therefore be adapted to any geometry of the component to be measured.

Furthermore, the object is achieved by a method for optimizing a natural frequency of a (stator) coupling, which is used for the rotationally fixed connection of a first component, which is a rotary encoder with an encoder shaft, to a second component, in particular a system to be measured with a shaft to be measured, is set up, wherein the coupling when the components are rotatably connected to each other in is arranged in an axial direction between the components and is aligned coaxially with the components, the coupling being further configured to allow axial and radial relative movements between the components within tolerance limits, and wherein a body of the coupling has: a central section; and at least two primary wing sections, each having a mounting section and a connecting section, the connecting section being oriented at an angle of attack to a radially oriented plane of the central section; and the method comprising the steps of: a) determining a geometry of the coupling and a material of the coupling; b) calculating an moment of inertia, in particular from a CAD model, a turning system which is formed from the coupling and the rotary encoder; c) determining a deflection angle for the rotating system; d) calculating a deflection force which is required to achieve the deflection angle by rotating the rotating system about an axis of the encoder shaft, preferably using the finite element method; e) calculating a torsion spring constant for the clutch based on the deflection force and the deflection angle; f) calculating a natural frequency of the coupling, in particular based on the model of a mathematical pendulum; g) comparing the calculated natural frequency with a predetermined (desired) natural frequency; h) changing the angle of attack of the primary wing sections and repeating steps d) to g) until the calculation of step f) results in a natural frequency which is greater than or equal to the predetermined natural frequency. The angle of attack is not changed if the calculated natural frequency is greater than or equal to the specified natural frequency in the first pass. It is preferable to start with an angle of attack of 45 °.

With the method described here, the natural frequency-optimized clutch described above can be dimensioned.

Furthermore, it is advantageous if the method additionally has the following steps: verifying by calculation whether the axial and radial tolerances can be maintained with the geometry determined in this way and the selected angle of attack; and, if the tolerances in step i) cannot be met, changing a geometry of the central section, in particular by changing the width of connecting sections of the primary wing sections, until the tolerances can be met.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own without departing from the scope of the present invention.

Further features and advantages of the invention result from the following description of preferred exemplary embodiments with reference to the drawings.

• 1 zeigt eine perspektive Ansicht einer Kupplung gemäß der Erfindung;
• 2 zeigt eine perspektivische Ansicht einer herkömmlichen Kupplung;
• 3 zeigt eine Tabelle, die zur Optimierung einer Eigenfrequenz in Abhängigkeit von einem Anstellwinkel benutzt wird.
• 4 zeigt die Kupplung der 1 unter Torsionsbelastung.
• 5 zeigt die Kupplung der 1 unter Axialbelastung.
• 6 zeigt die Kupplung der 1 unter Radialbelastung.
• 7 zeigt ein Flussdiagramm zum Optimieren einer Eigenfrequenz einer Kupplung.
• 8 zeigt eine Unteransicht der Kupplung der 1.
• 9 zeigt Messkurven für die Kupplung der 1.
• 10 zeigt Messkurven für die Kupplung der 2.

Show it:

• 1 shows a perspective view of a coupling according to the invention;
• 2nd shows a perspective view of a conventional clutch;
• 3rd shows a table that is used to optimize a natural frequency depending on an angle of attack.
• 4th shows the coupling of the 1 under torsion.
• 5 shows the coupling of the 1 under axial load.
• 6 shows the coupling of the 1 under radial load.
• 7 shows a flowchart for optimizing a natural frequency of a clutch.
• 8th shows a bottom view of the coupling of the 1 .
• 9 shows measurement curves for the coupling of the 1 .
• 10 shows measurement curves for the coupling of the 2nd .

1 shows a perspective illustration of a coupling 10 that as a stator coupling 12th for the rotationally fixed connection of an encoder (not shown) 14 (see. 4th ), especially its stator (not shown) 16 , on a component (not shown) which has a rotating shaft (not shown) to be measured.

The coupling 10 exhibits a body 18th on, which extends in several (especially radial) planes.

The body 18th has an annular central portion 20 in a (middle) radial plane, primary wing sections 22 that are axially below the central section 20 extend, and optional secondary wing sections 24th on, which is axially above the central section 20 extend.

The central section 20 has a central passage opening 26 on, which is set up to receive from the (not shown) shafts of the (coaxial) components to be rotatably connected to one another (for example, rotary encoder and motor). The central section 20 extends essentially in a radial plane (XY plane) that is perpendicular to the connection axis 28 is oriented. The connection axis 28 thus extends parallel to an axial direction which is oriented parallel to the Z direction of the Cartesian coordinate system XYZ shown. The axial direction corresponds to a longitudinal extension of the shafts, not shown, of the components to be connected to one another. These waves extend coaxially to the connection axis 28 . The connection axis 28 is centrally located in the passage opening 26 .

The central section 20 is in a circumferential direction (circle in the XY plane with connecting axis 28 as the center) is ring-shaped. This means that the central section 20 the passage opening 26 completely encloses. The central section does not have to be circular. In the 1 is the central section 20 diamond-shaped. The central section 20 is plate-shaped. This means the central section 20 extends essentially in a (single) plane, namely the radial XY plane.

The central section 20 is in the 1 through four bridges 30-1 to 30-4 formed the passage opening 26 enclose. It is understood that, particularly depending on a number of the primary and secondary wing sections 22 and 24th , more or less bars 30th can be provided.

The central section 20 is axially centered between the primary wing sections 22 and the secondary wing sections 24th arranged. The primary wing sections 22 are axially below the radial plane of the central section 20 arranged. The secondary wing sections 24th are axially above the radial plane of the central section 20 arranged.

The primary and secondary wing sections 22 and 24th are each made up of a (planar) assembly section 32 and a (planar) connection section 34 educated. The sections 32 and 34 represent flat surfaces without curvatures. The assembly sections 32 also extend in a radial plane that is parallel to the radial plane of the central portion 20 is oriented. The assembly sections 32 of the primary wing sections 22 extend in a radial plane lying below the plane of the central section.

The assembly sections 32 of the secondary wing sections 24th extend in a radial plane that is above the plane of the central section 20 is arranged. The assembly sections 32 of the secondary wing sections 24th but could also lie in a plane that is oriented perpendicular to the radial plane.

The assembly sections 32 generally have an assembly opening each 36 to, for example, take up screws that hold the coupling 10 Connect non-rotatably to the components. The assembly openings 36 can be circular or an elongated hole. Elongated holes allow the coupling to be adjusted 10 relative to the components.

The connecting sections 34 of the primary wing sections 22 close with the axial direction Z or with the radial XY plane (not shown) an angle of attack 38 a. In the 1 is the angle of attack 38 at the primary wing section 22-1 with an auxiliary line 40 illustrated that extends along the direction Z extends.

An entire area of the connecting sections 34 of the primary wing section 22-1 closes in the example of 1 the angle of attack with the XZ plane 38 a. It is understood that the primary wing section 22-2 also with the (same) angle of attack 38 is inclined or inclined with respect to the Z direction.

The angle of attack is general 38 an acute angle. The angle of attack 38 is in particular in a range of approximately 20 ° to 70 ° (opposite to the direction Z ).

Furthermore, it is understood that the angle of attack 38 also opposite the radial plane XY can be defined.

The connecting sections 34 of the secondary wing sections 24-1 and 24-2 are, for example, perpendicular to the radial plane XY of the central section 20 oriented. The assembly sections 32 of the secondary wing sections 24th are, for example, radially inwards, ie to the connection axis 28 there, oriented. The primary wing sections 22 are oriented radially outwards, for example. The primary wing sections 22-1 and 22-2 are aligned along the (radial) direction Y, whereas the secondary wing sections 24-1 and 24-2 perpendicular to it, ie along the (radial) direction X, are oriented. This means that the primary wing sections 22-1 and 22-2 enclose an angle of 180 ° in the radial XY plane. Also the secondary wing sections 24-1 and 24-2 form an angle of 180 ° in the radial XY plane.

The primary wing sections 22 are preferably perpendicular to the secondary wing sections in the radial XY plane 24th oriented.

The body 18th the clutch 10 of the 1 is particularly mirror-symmetrical. The body 18th of the 1 has two axes of symmetry, namely the Y axis and the X axis.

It goes without saying that more than two primary and / or secondary wing sections 22 or. 24th can be provided, the number two being preferred. The wing sections 22 are arranged equidistantly in the circumferential direction. The same applies to the secondary wing sections 24th . This means if there are three primary wing sections 22-1 to 22-3 are provided, so close wing sections 22 an angle of 120 °. If four wing sections 22 or. 24th are provided, so close wing sections 22 or. 24th an angle of 90 °.

The secondary wing sections 24th are preferably centered in the circumferential direction between the primary wing sections 22 arranged. In the 1 does that mean the secondary wing sections 24th (in plan view) an angle of 90 ° with the primary wing sections 22 lock in.

In 2nd Figure 3 is a perspective illustration of a stator coupling 12 ' shown, which comes from the house of the applicant. The stator coupling 12 ' is largely similar to the stator coupling 12th of the 1 built up. Some significant differences between the new stator coupling are shown below 12th of the 1 and the known stator coupling 12 ' of the 2nd be shown.

In addition to the angle of attack 38 the connecting sections 34 of the primary wing sections 22 these connecting sections differ 34 further in that the connecting sections 34 ' in 2nd additional internal cutouts 42 exhibit. These inner recesses 42 ' the stator coupling 12 ' of the 2nd essentially allow a radial tolerance (spring parallelogram). The bending stiffness of the connecting section 34 ' in the event of a radial deflection of the stator coupling 12 ' (eg in the Y direction) leads to these connecting sections 34 ' in the 2nd be tilted to the left and thus implement a spring parallelogram. A corresponding radial deflection can be caused, for example, by an unrest of the waves. This means that at least one of the two coaxially connected shafts of the two components rotates eccentrically, that is to say also executes movements in the radial direction.

These recesses 42 ' however affect a natural frequency of the stator coupling 12 ' negative, in that natural frequencies increasingly occur, in particular in a low frequency range which lies in a range in which the excitation frequency or rotational frequency of the shaft to be measured also lies. In other words, this means that a (negative) resonance effect occurs when the or one of the natural frequencies of the stator coupling 12 ' is in the range of the excitation frequency (ie the frequency at which the exemplary motor rotates). In the event of a resonance, the deflection of the stator coupling 12 ' amplified so that the encoder is no longer able to measure a frequency and / or rotational position.

Therefore, the connecting sections 34 of the primary wing sections 22 the stator coupling 12th of the 1 preferably formed over the entire surface (ie without an internal recess). The full-surface formation of the connecting sections 34 is responsible, among other things, for a natural frequency of the stator coupling 12th of the 1 is not adversely affected. This means that the natural frequency is in particular not reduced to a range that is in the range of the excitation frequency. In other words, this means that the natural frequency is increased so that it is far from the lower, application-related excitation frequency.

In order to nevertheless provide a sufficient radial tolerance, the webs are 30th of the central section 20 dimensioned in a suitable manner, as will be described in more detail below.

The angle of attack 38 influences the natural frequency of the clutch 10 also, as is apparent from Table 44 of the 3rd can be derived.

In Table 44, four exemplary angles of attack 40 °, 45 °, 50 ° and 60 ° are plotted against each other. Except the angle of attack 38 the clutch 10 became the geometry of the clutch 10 not changed to generate the values shown. You can see in the 3rd that the highest natural frequency (1150 Hz) at an angle of attack 38 of 50 ° is achieved. This will be explained in more detail below.

4th shows a schematic illustration of a deformation of the clutch 10 of the 1 under torsion. In the 4th is the clutch 10 in a connected state with the encoder 14 or its stator 16 shown. The encoder 14 is only partially shown.

In the 4th is shown how the clutch 10 deformed under torsion. The load manifests itself in particular in a deformation of the webs 30th and a twist of the connection sections 34 of the primary wing sections 22 . The twist of the connecting sections 34 of the primary wing sections 22 but is of a much smaller extent than the deformation of the webs 30th .

5 shows a perspective illustration of the coupling 10 of the 1 under axial load. Essentially only the webs deform under axial load 30th . The connecting sections 34 of the primary wing sections 22 deform almost not at all.

In 5 an axial force acts on the clutch in the negative Z direction 10 which here again without the encoder 14 is shown. That is why the bridges are inclined 30th in the 5 down, ie in the negative Z direction, the closer you are to the secondary wing sections 24th located. The primary wing sections 22 deform almost not at all.

6 shows the clutch 10 of the 1 under radial load. The bridges 30th and the primary wing sections 22 deform only slightly. In particular the connecting sections 34 of the primary wing sections 22 deform only slightly. The connecting section 34-2 is set slightly steeper than the connecting section 34-1 of the primary wing section 22-1 .

The following will refer to 7 a flowchart describing a method for optimizing the natural frequency of the clutch 10 represents.

In one step S10 becomes a geometry of the clutch 10 , in particular the dimensions of the sections 20 , 22 and 24th , as well as a material of the coupling 10 certainly. The geometry of the coupling 10 is determined in advance by a developer, for example, by the developer of the clutch 10 eg constructed or modeled in a CAD program. The modeling particularly includes the geometries of the central section 20 , the passage opening 26 , the jetties 30th , the primary and secondary wing sections 22 and 24th and in particular a material thickness (eg sheet thickness) of the body 18th .

Once these parameters are set, and thus can be determined, can be done in one step S12 a moment of inertia of an overall system consisting of the clutch 10 and the encoder 14 be calculated. The calculation is based in particular on the corresponding CAD data.

Next is one step S14 a deflection angle under torsion loading is determined or selected (cf. second column in Table 44 of the 3rd , where is deflected by 0.001 rad). This means that the overall system consists of the clutch 10 and the encoder 14 around the connection axis 28 (same 1 ) is rotated by the corresponding angle.

In a next step S16 based on these parameters, a deflection force is calculated to reach the selected deflection angle of the step S14 by turning the rotating system around the connecting axis 28 is needed. The finite element method (FEM) can be used for this purpose. The finite element method is a well-known numerical method, for example for strength and deformation studies of solid bodies with a geometrically complex shape. Such deflection forces are calculated in the third column of table 44 3rd shown as an example.

In a further step S18 becomes a torsion spring constant (TFK) for the clutch 10 calculated based on the deflection force and the deflection angle. The TFK is calculated in particular from the product of the deflection force and a lever arm length, which is then divided by the deflection angle. Exemplary TFK are in the fourth column of Table 44 3rd shown. The TFK corresponds to a torsion spring stiffness.

Based on the mathematical model of a rotary pendulum is then in one step S20 the natural frequency of the clutch 10 calculated. The formula for a mathematical pendulum is ${\text{f}}_{\text{E}}=\frac{1}{\mathrm{2nd}Pi}\sqrt{\mathrm{C.}:\mathrm{I.}}.$

In this formula, f _{E represents} the natural frequency of the coupling in [Hertz]. C represents the torsion spring constant of the coupling 10 in [Nm / Rad]. I represents the moment of inertia of the entire system in [kgm ² ].

The natural frequency is calculated according to the formula given above and is exemplarily in the last column of Table 44 3rd shown.

After that, in one step S22 asked whether a desired natural frequency (eg 800 Hz) has been reached. The desired natural frequency depends on the application and is usually specified by the user of the component to be measured (eg the motor). The permissible natural frequency depends on the frequency range in which the shaft of the other component is predominantly operated. The desired natural frequency is higher than the application-typical frequency.

If the query in step S22 shows that the desired natural frequency has not yet been reached, the angle of attack 38 in one step S24 changed what the geometry of the clutch 10 and thus the moment of inertia changes, and the calculation of the natural frequency starts with the step S16 repeated.

This loop is run through until the desired natural frequency is reached. When the desired natural frequency is reached, the process ends 46 .

Optionally, you can query the step S22 Connect further steps when the desired natural frequency has already been reached. These further steps will be described below.

As soon as the desired natural frequency has been reached, a further, subsequent step can be used to verify whether the required axial and radial tolerances are met, if the corresponding angle of attack 38 is selected, which results in the desired natural frequency. Should the axial and / or radial tolerance match that in step S10 certain geometry of the coupling 10 The geometry of the central section can in particular not yet be ensured to a sufficient degree 20 (subsequently) changed. In particular, a length L (cf. 8th ) the bridges 30th can be varied. 8th shows a bottom view of the clutch 10 of the 1 . This means that you are in the positive Z direction on the clutch 10 of the 1 looks.

8th shows that the geometry of the webs 30th essentially from the geometry of the passage opening 26 and a width B of the primary and secondary wing sections 22 and 24th depends. The width B of the wing sections 22 and 24th , and in particular their connecting sections 34 is determined parallel to the directions X and Y or in the circumferential direction U. The wider the wing sections 22 and 24th are, the shorter is a length L of the webs 30th as is exemplary for the footbridge 30-4 in the 8th is made clear. The length L is in a longitudinal direction of the webs 30th certainly.

A (unspecified) width (perpendicular to the length L) of the webs 30th is determined by the geometry of the passage opening 26 influenced.

Furthermore, a thickness (parallel to the direction Z ) the bridges 30th can be varied. A variation in the thickness of the webs 30th but results in a usual way in a variation in the thickness of the coupling 10 overall since the clutch 10 is preferably produced as a one-piece stamped and bent part, for example from spring steel.

The length L of the webs 30th is further characterized by a bolt circle of the assembly openings 36 of the primary wing sections 22 (see diameter D1 in 8th ) and a bolt circle of the assembly openings 36 of the secondary wing sections 24th (see diameter D2 in 8th ) influenced. These bolt circles are usually fixed.

In other words, this means that in order to optimize an axial and / or radial tolerance, essentially the central section 20 , and in particular its webs 30th , be changed in terms of shape and location.

Then, in a further step, it can be verified again whether the desired natural frequency can still be achieved even after the change just described, by recalculating the natural frequency based on the corresponding (changed) geometries (cf. 7 ).

It is understood that the connecting sections 34 of the secondary wing sections 24th with an angle of attack 38 can be provided, even if in the figures always vertically oriented connecting sections 34 for the secondary wing sections 24th are shown.

The 9 and 10 show measurement curves with a clutch 10 according to the invention (cf. 9 ) and with the conventional clutch 10 ' of the 2nd (see. 10 ) were won. It can be seen that the natural frequency in the 9 is almost constant at approx. 3 kHz and the TFK is also constant, whereas the natural frequency is in the 10 changes with increasing angle of rotation.

Reference list

10th

coupling

12th

Start clutch

14

Encoder

16

Stator of 14

18th

Body of 10

20

Central section

22

primary wing section

24th

secondary wing section

26

Passage opening

28

Connecting axis

30th

Footbridge from 20

32

Assembly section

34

Connecting section

36

Assembly opening

38

Angle of attack

40

Auxiliary line

42

inner recess

44

table

46

Optimization process

Claims (11)

Natural frequency-optimized coupling (10), in particular a stator coupling (12), for the rotationally fixed connection of a first component, in particular a rotary encoder (14) to the encoder shaft, on one second component, in particular a system to be measured with a shaft to be measured, the coupling (10), when the components are rotatably connected to one another, arranged in an axial direction (Z) between the components and aligned coaxially with the components, wherein the coupling (10) is set up to allow axial and / or radial relative movements between the components within tolerance limits, and wherein a body (18) of the coupling (10) has: an annular central section (20) which is in an unloaded state in a extends essentially radially oriented, first plane and which has a centrally arranged passage opening (26) for rotating shafts of the components to be connected coaxially; at least two primary wing sections (22) which adjoin the central section (20) radially and which are arranged equidistantly in a circumferential direction (U); wherein each of the primary wing sections (22) has a mounting section (32) which extends in a second plane, parallel to the first plane and which has a mounting opening (36), and a connecting section (34) which connects the mounting section (32) connects the central section (20); wherein each of the connecting sections (34) extends in a plane which includes an acute angle of attack (38) with the first plane, the angle of attack (38) being selected such that a predetermined natural frequency, which is based on a common moment of inertia of the clutch and Encoder and based on a torsion spring constant of the clutch, is not undercut. Clutch after Claim 1 , Furthermore, a respective width (B) of the connecting sections (34) is selected such that the axial and / or radial tolerance is maintained. Clutch after Claim 1 or 2nd , wherein each of the connecting sections (34) is formed over the entire surface. Coupling according to one of the Claims 1 to 3rd wherein the body (18) of the clutch (10) further includes secondary wing portions (24) extending on a side of the central portion (20) axially opposite the primary wing portions (22), the secondary wing portions (24) in Circumferential direction (U) are arranged equidistant to each other. Clutch after Claim 4 , wherein each of the secondary wing portions (24) has a mounting portion (32) and a connecting portion (34), the connecting portion (34) extending along the axial direction (Z) and wherein the mounting portion (32) for mounting on the other component is set up. Clutch after Claim 4 or 5 , wherein a number of the secondary wing sections (24) corresponds to a number of the primary wing sections (22) and wherein the secondary wing sections (24) are centered in the circumferential direction (U) between the primary wing sections (22). Coupling according to one of the Claims 1 to 6 , The coupling (10) being formed in one piece, in particular as a stamped and bent part. Clutch after Claim 7 , wherein the clutch (10) is made of spring steel. Coupling according to one of the Claims 1 to 8th , the primary wing portions (22) extending radially inward or outward. Method (46) for optimizing a natural frequency of a clutch (10) which is set up for the rotationally fixed connection of a first component, which is a rotary encoder (14) with an encoder shaft, to a second component, in particular a system to be measured with a shaft to be measured , wherein the coupling (10), when the components are connected to one another in a rotationally fixed manner, is arranged in an axial direction (Z) between the components and is aligned coaxially with the components, the coupling (10) being further configured to be axial and / or allow radial relative movements between the components within tolerance limits and wherein a body (18) of the coupling (10) comprises: a central section (20); and at least two primary wing sections (22) each having a mounting section (32) and a connecting section (34), the connecting section (34) being oriented at an angle of attack (38) to a radially oriented plane of the central section or perpendicularly thereto; and wherein the method (46) comprises the steps of: a) determining (S10) a geometry of the coupling (10) and a material of the coupling (10); b) calculating (S12) an moment of inertia of a rotary system which is formed from the clutch (10) and the rotary encoder (14); c) determining (S14) a deflection angle for the rotating system; d) calculating (S16) a deflection force which is required to reach the deflection angle by rotating the rotating system about an axis (28) of the encoder shaft; e) calculating (S18) a torsion spring constant for the clutch (10) based on the deflection force and the deflection angle; f) calculating (S20) a natural frequency of the clutch, in particular based on the model of a mathematical pendulum; g) comparing (S22) the calculated natural frequency with a predetermined natural frequency; h) changing the angle of attack (38) of the primary wing sections (22) and repeating steps d) to g) until the calculation of step f) results in a natural frequency that is greater than or equal to an application-dependent, predetermined natural frequency. Procedure according to Claim 10 , further comprising: i) verifying by calculation whether the axial and / or radial tolerances with the defined geometry and the defined angle of attack (38) can be met; and j) if the tolerances in step i) cannot be met, changing a geometry of the central section (20), in particular by changing a width (B) of connecting sections (34) of the primary wing sections (22) until the tolerances can be met.

Images