Patent ID: 12203749

DETAILED DESCRIPTION

FIG.1shows the chain elongation monitoring device200according to the invention for determining the elongation of segments of a chain100. The chain100to be monitored is designed as a roller chain in this and the following exemplary embodiments and has alternating inner110and outer side parts120, which are connected to one another by chain link pins140guided in chain sleeves130. In the new condition of the chain100, the chain pins140have a distance p0to one another.

To determine the elongation of the chain100during operation, the chain elongation monitoring device200is positioned perpendicular to the joint axis of the chain100to be monitored such that in the new condition of the chain100, the distance d of the differential transformers210,220to one another corresponds exactly to an integer multiple of the distances p0between two adjacent chain pins140of the chain100to be monitored. The first differential transformer210and the second differential transformer220of the chain elongation monitoring device200itself are arranged on a base plate250. The differential transformers210,220together with the electrical connections are arranged in a housing (not shown) for protection against soiling. The differential transformers210,220are made up of a primary coil and two secondary coils and therefore have three sensor elements. Each of the differential transformers210,220is thus suitable for simultaneously recording measured values over a length range of the chain100to be monitored. The length of the length range in the direction of the chain movement is based on the length p, p0of a chain link of the chain100to be monitored and is p0in this exemplary embodiment. The detection of the measured values by the two differential transformers210,220also takes place simultaneously.

The length L0of the chain100in new condition between the sensors210,220is an integer multiple of the distance p0between two adjacent chain pins140(L0=n*p0), in this exemplary embodiment seven times the distance p0. A chain pin140located above the differential transformer210,220is at a distance a, b from the edge (in this and the following exemplary embodiments, the respective left edge) of the differential transformer210,220. The chain length L0is therefore L0=d−(a0+b0)=d−2a0=d−2b0because the distances a, b are the same in the new condition of the chain100(a0=b0). Due to a length change ΔL of the chain100, the distances a, b are different. The elongation ΔL of the chain100to be monitored is first determined by determining the lengths a and b. Then the following applies to the elongation ΔL of the chain100: ΔL/L0=L−L0/L0=L/L0−1 and DL/Lo=(d−a+b)/(d−ao+bo)−1=(b−bo+a−ao)/(d+bo−ao)

Differential transformer A210generates the phase shifts A sin and A cos, differential transformer B220generates the phase shifts B sin and B cos. The following then applies to the distances a, b of the chain100in the actual condition: a=arctan (A sin/A cos), b=arctan (B sin/B cos). The elongation ΔL of the chain100then results from the phase shifts that the two differential transformers A, B210,220detect: ΔL/Lo=(arctan (B sin/B cos)−arctan (A sin/A cos))/d.

To determine1the elongation of the chain100and its segments, a first signal is detected2by means of the first differential transformer A210. Simultaneously, a second signal is detected4by means of the second differential transformer B220. The position of a first chain component is then determined3from the first signal, and the position of a second chain component is also determined5simultaneously from the second signal. In this exemplary embodiment, the two chain components are chain pins140. Then the distance between the two chain pins140is determined according to ΔL/Lo=(arctan (B sin/B cos)−arctan (A sin/A cos))/d.

Advantageously, the first and second signals are continuously detected2,4, and the positions of the first and second chain components are also continuously determined3,5. The detections2,4and determinations3,5in particular also take place with a stationary chain100, a minimum speed of the chain100is thus not necessary to operate the chain elongation monitoring device200.

The functional principle of the differential transformers A, B210,220is shown inFIG.2upon the detection of a ferromagnetic body280and inFIG.3upon the detection of an electrically conductive body290. In this exemplary embodiment, the principle is illustrated on the basis of the sensor A210; this applies similarly to the second sensor B220. The sensor210has a primary coil230and two symmetrically arranged secondary coils240,241. An AC voltage having a constant frequency and amplitude is applied to the primary coil230. An electromagnetic alternating field is generated via the primary coil230, which induces a respective opposite voltage U cos and U sin in each of the secondary coils240located therein. With the same position, the amplitudes of the voltages also change over the distance of the object from the secondary coils240,241. The secondary coils240,241are connected in series in phase opposition, as a result of which the voltages at their connections subtract from each other. The resulting voltage is exactly zero when the two coils of the sensor210are each constructed symmetrically. If the symmetry is disturbed, an output voltage results, the phase of which in relation to the primary voltage indicates the direction and the value of which indicates the size of the asymmetry. This is achieved by forming the arctan=K*U sin/K*U cos. However, since the object disturbing the symmetry is always at the same distance from the two secondary coils in a first approximation, the factor K is canceled out of the equation and what remains is the ratio of the induced voltages U sin/U cos, which represents the position of the object disturbing the symmetry. The symmetry of the sensor210is disturbed here by the passage of a chain component280,290. A ferromagnetic chain component280(FIG.2) disturbs the magnetic field lines such that they are closer together, so that the magnetic field at and around the chain component280is amplified. The asymmetry generated by the chain component280is greatest when the chain component280is arranged in the region of the sensor210at the edges of the sensor210(FIGS.2a,2c), i.e., is moved out of or into the sensor region. The sensor210then generates a maximum output voltage U=+1 (FIG.2a), shown schematically on the display245, when the chain component280is positioned at the left edge of the sensor210, and an output voltage U=−1 when the chain component280is positioned at the right edge of the sensor210(FIG.2c). The asymmetry and the resulting output voltage generated by the sensor210is U=0 when the chain component280is positioned in the middle of the sensor210(FIG.2b). An electrically conductive chain component290(FIG.3) disturbs the magnetic field lines in such a way that they are further apart, so that the magnetic field at and around the chain component280is reduced. The asymmetry generated by the chain component290is greatest when the chain component280is arranged in the region of the sensor210at the edges of the sensor210(FIGS.3a,3c), i.e., is moved out of or into the sensor region. The sensor210then generates a maximum output voltage U=−1 (FIG.3a), shown schematically on the display245, when the chain component290is positioned at the left edge of the sensor210, and an output voltage U=+1 when the chain component290is positioned at the right edge of the sensor210(FIG.3c). The asymmetry and the resulting output voltage generated by the sensor210is U=0 when the chain component290is positioned in the middle of the sensor210(FIG.3b).

FIG.4shows a top view of a sensor A210for detecting the position of a chain link. The chain100to be monitored has alternating inner and outer side parts, which are connected to one another by chain link pins140guided in chain sleeves. The chain pins140have the distance p to one another. The sensor210has a primary coil230and two symmetrically arranged secondary coils240,241. An AC voltage having constant frequency and amplitude is applied to the primary coil230. An electromagnetic field is generated via the primary coil230, which induces a voltage U cos and U sin oriented opposite in each of the secondary coils240,241located therein. The resulting voltage when the object is not present is zero since the induced voltages are in the form of an 8 and the current-carrying areas cancel each other out.

FIG.5shows a top view of a further exemplary embodiment of the sensor device200according to the invention having an evaluation circuit310,320. The sensors A, B210,220are also positioned in such a way that in the new condition of the chain100, the distance d between the sensors210,220corresponds exactly to an integer multiple of the distances p0 between two adjacent chain pins140of the chain100to be monitored. As in the previous exemplary embodiments, the sensors210,220can be designed as inductively operating differential transformers, using which the position of chain components is determined. However, the sensors210,220can also be optical or magnetic sensors or a combination of the types of sensors mentioned. The sensors210,220are each connected to an evaluation circuit310,320. The evaluation circuits310,320supply the detected measured values to an A/D converter330, in which the analog measured values are converted into digital values in order to be stored on the microcontroller340.

In this exemplary embodiment, a permanent magnet260is arranged on chain100, the position of which is detected by means of a Hall sensor270. This embodiment is particularly useful when the chain100is made of diamagnetic materials, such as stainless steel. The microcontroller connected to the Hall sensor270registers the number of passes through the permanent magnet260and thus allows conclusions to be drawn about the wear rate of the chain100. Alternatively, a single component of the chain100can be made of a magnetic material. The geometry of the chain100is then not changed. An exemplary embodiment of the method1according to the invention for determining the elongation of chains100is shown inFIG.6.

The method1begins with the detection of a first signal2of the first differential transformer210and the determination3of the position of a first chain component by means of the first signal. Simultaneously, a second signal is detected4by the second differential transformer B220and the position of a second chain component, which is structurally identical to the first chain component, is determined by means of the second signal5. A first210and second sensor220have a defined distance d to one another, which corresponds to an integer multiple of the pitch p0of the chain100. In the next step6, the distance between the chain components is determined5from the detected measured values and the length of the chain100. The wear-related elongation of the chain100is determined by relating the determined length of the chain100to the length of the chain100in the new condition.

FIG.7shows a side view of an exemplary embodiment of the chain elongation monitoring device200according to the invention, mounted ready for use for monitoring the elongation ΔL of the chain100to be monitored. The chain100to be monitored is designed as a roller chain and has alternating inner110and outer side parts120, which are connected to one another by chain link pins140guided in chain sleeves130. To protect against contamination, the chain elongation monitoring device200has a housing201in which the components first differential transformer210, second differential transformer220, additional position detection sensor270, control unit340, circuit board having first evaluation circuit310and second evaluation circuit320, and base plate250are arranged. The housing201itself has the upper housing part202and the lower housing part203, both of which are firmly connected to one another, for example by means of a clip fastener. The housing201also has a power connection207and a connection for a data line208. The guide surface204is the region of the chain length monitoring device200which has the smallest distance to the chain100. At the opposite ends, the guide surface204has the phase surfaces205,206which are inclined in relation to the guide surface204.

A view of the ready-to-use installed chain elongation monitoring device200along the chain running direction is shown inFIG.8. The chain100to be monitored is designed as a roller chain and has alternating inner110and outer side parts120, which are connected to one another by chain link pins140guided in chain sleeves130. The chain elongation monitoring device200has the housing201in which the components are arranged. A first evaluation circuit310and a second evaluation circuit320are arranged on the circuit board209(FIG.8a). The chain elongation monitoring device is divided into an upper housing part202, which accommodates the connections and the circuit board209, and a lower housing part203, which accommodates the sensor elements210,220and has the guide surface204. The sensor elements210,220are arranged far enough into the lower region203bof the lower housing part203that their upper edge is still below half the height of the lower housing part203. The lower housing part203in turn is also divided. The upper region203aof the lower housing part203comprises the fastening elements for fastening the lower housing part203to the upper housing part202and has the same width as the upper housing part202, while the lower region203bof the lower housing part203having the guide surface204is formed narrower than the upper housing part202or the upper region203aof the lower housing part203.

The chain elongation monitoring device200is fastened in such a way that the guide surface204is at a distance of 0.2 mm from a chain sleeve130of the chain100. In the region that is arranged between the side parts120of the chain100, the guide surface204has a width bFthat is less than the width bKof the chain100between the side parts120. The differential transformers210,220are arranged close to the guide surface204in such a way that they are at the smallest possible distance from the chain100(FIG.8b).

FIG.9shows a sectional view of an exemplary embodiment of the chain elongation monitoring device200according to the invention. The chain elongation monitoring device200has the housing201in which the components are arranged. The first evaluation circuit310and the second evaluation circuit320are arranged on the circuit board209, the position detection sensor270is also arranged directly on the circuit board209between the differential transformers210,220. The differential transformers210,220are arranged close to the guide surface204in such a way that they have the least possible distance to the chain100and are connected to the circuit board209by means of lines211,221. The guide surface204delimits the chain elongation monitoring device200relative to the chain100and has phase surfaces205,208on the end faces. The circuit board209is connected via lines251,252to connections for the power supply206and the data line207. The chain elongation monitoring device200is fastenable by means of the fastening openings255,256.

LIST OF REFERENCE NUMERALS

1method for determining the elongation of chains2detecting a first signal from the first differential transformer3determining the position of a first chain component4detecting a second signal from the second differential transformer5determining the position of a second chain component6determining the distance between the first chain component and the second chain component100chain110chain inner link120chain outer link130chain sleeve140chain pin200chain elongation monitoring device201housing202upper housing part203lower housing part203alower housing part upper region203blower housing part lower region204guide surface205first phase surface206power connection207connection for data line208second phase surface209circuit board210differential transformer A211mount220differential transformer B221mount230primary coil240secondary coil250base plate251power line252data line255,256fastening260permanent magnet270Hall sensor/position detection sensor275evaluation circuit magnetic sensor280ferromagnetic body290non-magnetic body310first evaluation circuit320second evaluation circuit330A/D converter340microcontroller/control unitbKwide chain between the inner platesbFwide guide surfaceΔL elongation of the chainL length of chain between differential transformer A, differential transformer B, actual conditionL0length of chain between differential transformer A, differential transformer B, in new conditionp0 pitch (distance between two adjacent chain pins) in new conditionp pitch (distance between two adjacent chain pins), actual conditiond distance of the differential transformersa distance from chain pin to edge of differential transformer A, actual conditionb distance from chain pin to edge of differential transformer B, actual conditiona0distance from chain pin to edge of differential transformer A, new conditionb0distance from chain pin to edge of differential transformer B, new condition