The present disclosure relates to a measuring head for detecting a magnetic field which is provided by a magnet block for an energy converter, a corresponding measuring system that uses the measuring head, a method for determining a quality of a magnet block for a power converter as well as a corresponding computer program product.
Energy converters, also referred to as energy harvesters, are used in more and more applications. In order to ensure a proper operation of such power converters, it is necessary to check or monitor their geometric and magnetic properties as well as material properties.
The disclosure document DE 10 2010 003 151 A1 describes an induction generator for a radio switch with a magnetic element and an induction coil with a coil core.
The DE 10 2011 07 8932 A1 discloses an induction generator for a radio switch comprising a magnetic element having a north pole contact segment and a south pole contact segment as well as a coil core which consists of pole contact segments for connecting to the north pole contact segment and the south pole contact segment.
In view of the above, the present disclosure provides an improved measuring head for detecting a magnetic field which is provided by a magnet block for an energy converter, a measuring system for determining a quality of a magnet block for an energy converter, a corresponding method for determining a quality of a magnet block for an energy converter as well as a corresponding computer program product with a program code to execute the method. Advantageous embodiments can be derived from the following description.
By means of a measuring device or procedure it is possible to perform a measurement of magnetic and geometric properties of a magnetic system, or of a magnetic composite with magnet conductor pieces during the production. The magnet system or the magnet composite may hereby be referred to as a magnetic head. By detecting and evaluating the magnetic field that is caused by a magnetic system, it is possible to draw conclusions regarding the geometrical properties. It is therefore possible to define a tolerance for the magnetic field, which is in accordance to the corresponding geometric tolerances. The magnetic field can be tapped at defined positions and supplied to respective sensors via magnet conductors.
A measuring head for detecting a magnetic field which is provided by a magnet block for an energy converter, whereby the magnet block consist of three pole surfaces that are arranged in one plane in order to provide the magnetic field, comprises:
three magnetic conductors to conduct the magnetic field, whereby one arrangement of the three magnetic conductors where the end faces are arranged in one plane corresponds to one reference arrangement of the three pole surfaces; and
two sensors to detect the magnetic field.
The magnet block may be part of one induction generator or of one energy converter for a radio switch. This may be an energy converter as it is described in the disclosure documents DE 102010003151 A1 and DE 102011078932 A1. The magnet block can be a magnet system with a backiron. The magnet block may consist of at least one magnet and two conductor pieces that are formed as pole pieces, whereby the one conductor piece may be designed with two of the pole surfaces and the other conductor piece with the other pole surface. The magnet block can be a magnetic element with at least one north pole contact segment and at least one south pole contact segment, whereby two of the pole surfaces are assigned either to the north pole contact segment or to the south pole contact segment and the remaining pole surface is assigned to the other pole contact segment. It is thus possible that the three pole surfaces have at least two different polarities. The two pole surfaces with the greatest distance can have the same polarity. When the end faces of the three magnet conductors are arranged to the pole surfaces of the magnet block, then the magnetic field, which is provided by the magnet block, can be directed through the magnet conductors.
The three magnet conductors may include a first side magnet conductor, a middle magnet conductor and a second side magnet conductor. The three magnet conductors may hereby be arranged parallel to each other. The three magnet conductors can be arranged at a distance towards each other. The three magnet conductors may feature an essentially rectangular form. The respective end faces may hereby be arranged in the direction of the main extension direction of the magnet conductor. Without the two sensors, a gap may occur between the magnet conductors.
The two sensors can be designed as Hall sensors. A Hall sensor or Hall effect sensor can also be described as a Hall probe or Hall generator. The two sensors can use the Hall effect to measure magnetic fields.
It is also practical, if a first sensor of the two sensors is arranged between the first side magnet conductor and the middle magnet conductor. It is furthermore practical if a second sensor of the two sensors is arranged between the middle magnet conductor and the second side magnet conductor. Thus, two magnet conductors can be positioned directly on one sensor. It is thus impossible that an air gap can form between sensor and magnetic field. The sensors can therefore be arranged at one longitudinal side of the magnet conductor. The middle magnet conductor can be bordered by two sensors. Advantageously, due to the arrangement of the sensors it is possible to precisely detect the magnetic field that is directed through the magnet conductors.
The three magnet conductors can be held in a non-magnetic mounting fixture. The non-magnetic mounting fixture can be made of e.g. non-ferrous metal, plastic or ceramic. It is thus possible to create a form-stable unit.
One side surface of the measuring head can be designed as an even reference measuring plane. An even reference measuring plane may particularly be created by means of a sanding and additionally or alternatively by means of a polishing of the side surface. The reference measuring plane can stretch within a tolerance range of a plane. The side surface of the arrangement of the end faces of the three magnet conductors that are arranged in one plane may hereby correspond to a reference arrangement of the three pole surfaces. If a magnet block is manufactured within the tolerance range, it is thus possible to pick up the magnetic field from the magnet conductors and to detect it by means of the sensors.
A measuring system to determine a quality of a magnet block of an energy converter includes:
a measuring head according to one of the previously described embodiments; and
a data evaluation system, which is connected to the two sensors of the measuring head, whereby the data evaluation system is designed to record a first sensor signal of the first sensor that is representing the magnetic field of the magnet block and a second sensor signal of the second sensor that is representing the magnetic field of the magnet block and to additionally or alternatively evaluate it, in order to determine a quality of the magnet block.
The quality can be determined by monitoring a magnetic field emanating from the magnet block. The magnet block may consist of at least one magnet and two conductor pieces that are formed as pole pieces, whereby three pole surfaces are formed on one side of the magnet block. The magnet block can preferably be designed as it was described before.
A data evaluation system can be an electrical device, which processes sensor signals and issues control signals in dependence on these. The data evaluation system can consist of one or more suitable interface/s, which can be designed as hardware and/or software. When designed as hardware, the interfaces can be e.g. part of an integrated circuit in which functions of the data evaluation system are implemented. But, the interfaces can also be separate, integrated circuits, or at least partially be composed of discrete components. When designed as software, the interfaces may be software modules which are available e.g. on a micro-controller in addition to other software modules.
The measuring head can be arranged in a positioning device. The positioning device can hereby feature at least one guide rail, in particular two guide rails. A base plane of the positioning device can feature three recesses, in which the magnet conductors are arranged in such a way that the end faces of the magnet conductors are situated in an even way within this base plane.
The measuring system can include a means for transporting. The means for transporting can be designed to transport the magnet block to the measuring system. The magnet block can hereby be moved over the end faces of the magnet conductors. The means for transporting can be designed to align the pole surfaces of the magnet block to the end faces of the magnet conductors or to move the pole surfaces over these. Advantageously, the means for transporting and the positioning device can work together.
A method for determining a quality of a magnet block for an energy converter is presented. A magnetic field can hereby emanate from the magnet block. The magnet block can consist of three pole surfaces that are arranged in one plane on one side of the arrangement in order to provide the magnetic field. The method involves the following steps:
conducting of the magnetic field through three magnet conductors;
detecting of the magnetic field by using two sensors and providing of a first sensor signal and a second sensor signal, whereby the first sensor signal represents a force of the magnetic field at a sensor position of a first sensor of the two sensors and the second sensor signal represents a force of the magnetic field at a sensor position of a second sensor of the two sensors; and
evaluating of the first sensor signal and of the second sensor signal to determine a quality of the magnet block.
The underlying idea of the disclosure can also be implemented efficiently and economically by means of the method to determine a quality of a magnet block of an energy converter.
In the step of evaluating, the first sensor signal and the second sensor signal can be combined in order to generate a result signal representing the quality of magnet block. The first sensor signal and the second sensor signal can hereby be combined by means of addition in order to generate the result signal. A difference between the amount of the first sensor signal and the amount of the second sensor signal can be calculated in order to generate the results signal. Alternatively, the second sensor signal can be subtracted from the first sensor signal in order to generate the result signal.
The step of evaluating can include a step of comparing. In the step of comparing the results signal can be compared at least to a predetermined threshold in order to determine the quality of the magnet block. Alternatively, the result signal can be compared to two thresholds in order to verify whether the result signal is within a tolerance range, to determine the quality of the magnet block.
Such an approach can be used, for example, as a replacement or complement to other methods and procedures for the dimension measurement of an object or component, which use e.g. measuring microscopes, cameras, or tactile measuring equipment. It is hereby possible to fall back to methods and procedures for the measurement of a magnetic field, such as e.g. measurements on the basis of Hall sensors, or corresponding scan procedures. The described approach can also be used, for example in the context of methods for the determination of the material or of material properties.
In a quick manner, during series production and without any damage to the parts, it can be checked whether the right materials were used or a quality state of pole pieces or of a magnet can be assessed, a correct polarity or orientation of the magnet (North-South) can be checked. Magnetic properties of the magnet and the pole pieces (process fluctuations) can advantageously be tested. Thermal damage during an injection molding process can be discovered. Thus, a dimensional accuracy of the metal components and/or plastic component particularly in the area of the pole surfaces can be assessed, as well as flatness, symmetrical deviation, surface defects, ridges and overmolding. The advantage hereby is that such an examination can be performed quickly and in an economically feasible way and an integration in the production line is guaranteed.
Another advantage is a computer program product with a program code that can be stored on a machine-readable carrier such as a semiconductor memory, a hard drive or an optical storage and which can be used to execute the method according to one of the embodiments that were described earlier when the program is run on a computer, a device or a data evaluation system.
Advantageously it is possible to check and/or to monitor the quality, the dimensional accuracy and the compliance with the magnetic properties by means of an embodiment of the presented in the manufacturing process of a magnet block or of a magnetic system with backiron, such as are used e.g. for a self-sustaining energy converter.
The current embodiments are explained in more detail by means of the examples in the enclosed drawings. It is shown:
In the following description of preferred embodiments of the present disclosure, same or similar reference signs are used for the elements that are depicted and that function in a similar way in the various figures, whereby a repeated description of these elements is omitted.
The measuring system 100 features a measuring head 104 with three magnet conductors 105, 106, 107 and two sensors 108, 109 and a data evaluation system 110. In the shown embodiment, measuring system 100 further includes an optional positioning device 112 as well as an optional means for transporting 114. The two sensors 108, 109 are connected to the data evaluation system 110. The first sensor 108 provides a first sensor signal 116 of the data evaluation system 110. The second sensor 109 provides a second sensor signal 118 of the data evaluation system 110.
The magnet block 102 consists of three pole surfaces 120. A more detailed description of an embodiment of the magnet block 102 will follow in
The measuring system 100 furthermore consists of an optional control unit 124. The control unit 124 is connected via control lines to the data evaluation system 110 and to the means for transporting 114. The control unit 124 is designed to provide appropriate control signals for the means for transporting 114 in order to move the magnet block 102 into a measuring position. The means for transporting 114 is designed to transport the magnet block 102 to the measuring system 100. By means of appropriate control signals and a corresponding action of the means for transporting 114 after a measurement, it is furthermore possible to perform a sorting operation or also a dividing or separating of good and bad magnet blocks 102, i.e. according to the quality that was determined by the measuring system 100. In addition to that, the control unit 124 is connected to the data evaluation system 110 in order to provide appropriate control signals to start a measurement or a data analysis or to receive a corresponding signal from the data evaluation system 110 that is representing a quality. Thus the quality can be depicted as binary information for good and bad, or alternatively in a deviation from a standard size or the like.
The magnet block 102 of an energy converter 230 consists of a magnet 232 and of two conductor pieces 234, 236 (pole pieces 234, 236) molded with a plastic fitting 238. The conductor pieces 234, 236 are designed in such a way that three pole surfaces 120 are arranged on the moveable side of the magnet block 102.
In each case, two of three pole surfaces 120 of the magnet block 102 are magnetically coupled with the pole surfaces of magnetic core 240 by means of a mechanical support plate in an alternating way. When the energy converter 230 is activated, the pole surfaces of magnetic core 240 are commutated with the other two pole surfaces 120 of the magnet block 102 (with support plate). The result within the magnetic core 240 is a sudden change of the magnetic flux and induction of electrical energy in the coil 242 of the energy converter 230. When switching backwards, the reverse process is created. The polarity of the voltage pulse changes hereby and is used for a detection of a direction in the radio switch.
It is enormously important that the pole surfaces 120 of the magnet block 102 and the pole surface of the magnetic core 240 are formed without any geometric error, that the contact surfaces of both positions must fully rest on the complete area, that the materials must have defined magnetic properties and that the magnets 232 feature a defined magnetic orientation.
It is possible to detect geometric errors with an inspection by a camera, but this would be accomplished with a high measuring inaccuracy. The flatness errors, damages on the surface and a possible ridge can only be detected by means of very complex measuring procedures.
Even more problematic for the prior art would be the measuring of the flux density at the pole surfaces 120, i.e. of an interface layer to the magnetic core 240. It is crucial for the function of the energy converter 230, which flux density is induced into the magnetic core 240, since the smallest gap of e.g. 0.05 mm will significantly weaken the flux density in the magnetic core 240.
So-called scanning procedures along a surface would be possible here. However these procedures are very expensive and cannot be integrated in a production process. Both magnetic circuits have to be tested (according to the two switching states, as they are depicted in
The sensors 108, 109 completely fill the space between two adjacent magnet conductors 105, 106, 107. The two sensors 108,109 in the depicted embodiment can be designed as Hall sensors. The connection cables of the sensors 108, 109 can be connected to a data evaluation system.
The measuring system 100 essentially consists of a measuring head 104 and of the electronic data evaluation system as it is described in
Measuring head 104 comprises three magnet conductors 105, 106, 107, which are mounted in a non-magnetic mounting fixture. The non-magnetic mounting fixture can be made of e.g. non-ferrous metal, plastic or ceramic. The surface to the test object is finely sanded or polished, and thus forms a plane reference measuring surface. Two Hall sensors are situated between the three magnet conductors 105, 106, 107, which can detect the magnetic field strength between the conductor pieces or the magnet conductors.
During the examination, magnet block 102 is brought into a measuring position by means of transporting and centering. Magnetic pull ensures that magnet block 102 is pressed onto measuring head 104 with a defined force.
In the measuring position, the magnetic field lines are no longer shorted through the air, but they now run through the magnet conductors of the measuring head 104. To a large extent, the magnetic field is hereby evenly distributed between the middle magnet conductor and the two magnet conductors on the sides. The two Hall sensors are located in two gaps and are designed to detect the magnetic fields.
In one embodiment, the sensors (Hall sensors) are supplied with a constant voltage. A respective voltmeter is connected to the output terminals of the two sensors. Appropriate logic modules of the data evaluation system, for example designed as a PC measuring station, are designed to record the measured voltages, to set these in relation to each other and to compare them with permissible limits and to trigger an appropriate partial manipulation. A partial manipulation can be, e.g. a sorting out of an unsuitable component, an output of a log file or a releasing of a suitable component. The underlying waveforms of the signals are depicted and described in
The magnetic field strength is advantageously adapted to the sensitivity of the programmable Hall sensors. The adaption can be adjusted by the size of the gap (sensor area), or by the surface area of the magnet conductor.
For example, the magnetic fields 851, 852 in the embodiment that is depicted in
The programmable Hall sensors are balanced out or programmed by means of reference components before startup, so that the same output voltage is brought forth from both Hall sensors by means of the idealized components.
In the chart shown in
The magnetic remanence of signal waveforms 956, 958, 960 as it is shown in
As long as the magnet block is symmetrical and the materials properties are as planned, the magnetic fields (reference sign 850 in
If the change of the magnetic field in the area of the sensor is even stronger, it will produce an air gap between the magnet block and the measuring head. Caused by e.g. an irregular contact surface of the magnet block, surface errors, impurities, ridges, excess molding and deformations of the pole surfaces, an air gap can appear. The air gap can also occur asymmetrically, such as when one of the three pole surfaces is shorter than the other two pole surfaces. In practice, this will lead to different energetic pulse generations when a generator is activated or switched back. This is highly undesirable. In such a case, the magnetic field is no longer distributed symmetrically in the measuring head and the Hall sensors will generate different output signals.
The examination is performed in one embodiment as a static examination, which means that the component or the magnet block remains in the measuring position. After the measurement, the component is transported further into a packaging. Since the measuring cycle is relatively short, an integration into the production cycle does not cause any problems. But if the measurement is to be integrated in a production facility with several cavities, one embodiment offers the possibility to realize the examination dynamically. It is hereby not necessary to stop the component in the measuring position. In such a case, the two voltmeters of the data evaluation system will be replaced by a two-channel multi-function device such as e.g. an oscilloscope with a signal resolution on the voltage and timeline.
Two pulses occur during the examination. The highest points of the curves or waveforms correspond to the measured values. If there is a variation of the grid dimension on the magnet block, e.g. by a deformation or deviation of the pole pieces, the two impulses will experience a time offset. In such a case it is possible to set a maximum permissible limit value in the timeline and to select the components where the measured value exceeded the limit as unsuitable parts.
By means of this measure, the measuring cycle can be shortened significantly, since it is no longer necessary to stop the components in the measuring position.
Measuring head 104 is connected to the data evaluation system 110. This means that the first sensor signal 116 will be directed to a first A/D converter 1168 and the second sensor signal 118 will be directed to a second A/D converter 1169. The A/D converters 1168, 1169 form an input interface for the data evaluation system 110. The digitized sensor signals are directed to a device 1170, 1171 for a limit value comparison, i.e. the recorded voltage is checked if it is within the range of a lower and an upper threshold. Thus, the digitized sensor signal from the first A/D converter 1168 is directed to a first device 1170 for a limit value comparison. The digitized sensor signal from the second A/D converter 1169 is directed to a second device 1171 for a limit value comparison. The first device 1170 for a limit value comparison and the second device 1171 for a limit value comparison are connected to a device 1172 for a difference value comparison, where the difference from the two digitized sensor signals is formed and where the result is checked whether it is within a tolerance range. An optional device 1174 for a dynamic examination is depicted, a comparison of a reference value based on a measurement time or Δt. A/D converter 1168, device 1170 for a limit value comparison, device 1172 for a difference value comparison as well as the optional device 1174 for a dynamic examination are altogether referred to as logic module 1176.
In one embodiment, A/D converters 1168, 1169 are designed as a voltmeter or oscilloscope to record a voltage or to detect a voltage change within a time change.
The data evaluation system 110 is designed to record and evaluate the first sensor signal 116 of the first sensor 108 which represents the magnetic field 850 of the magnet block and the second sensor signal 118 of the second sensor 109 which represents the magnetic field 850 of the magnet block, in order to determine a quality of the magnet block.
The logic module is connected to a control unit 124 or to a signal amplifier 124. The control unit 124 is designed to provide a protocol output, i.e. a protocol that can be saved and that can additionally or alternatively be printed. Furthermore, the control unit 124 is connected to control elements of an examination unit such as light barriers, a conveyor system for components, a box for unsuitable components or a marking for suitable components, or it is designed to provide corresponding control signals.
In the step of evaluating in one embodiment, the first sensor signal and the second sensor signal are combined in order to generate a result signal representing the quality of magnet block.
In an optional step 1288 of comparing, the result signal is compared at least to a predetermined threshold in order to determine the quality of the magnet block.
The embodiments described and shown in the figures are chosen only by way of example. Different embodiments may be combined in whole or with reference to individual characteristics. It is also possible that one embodiment can be supplemented by characteristics of another embodiment. Furthermore it is possible that process steps according to the disclosure can be repeated and executed in a sequence other than the one described.
If one embodiment includes an “and/or” linkage between a first characteristic and a second characteristic, this can be understood in such a way that the embodiment according to one design example features both the first characteristic and the second characteristic and according to a further embodiment that it either only features the first characteristic or only the second characteristic.
100 Measuring system
102 Magnet block
104 Measuring head
105 First magnet conductor
106 Second magnet conductor
107 Third magnet conductor
108 First sensor
109 Second sensor
110 Data evaluation system
112 Positioning device
114 Means for transporting
116 First sensor signal
118 Second sensor signal
120 Pole surface
122 End face
124 Control unit
230 Energy converter
232 Magnet
234 Conductor piece
236 Conductor piece
238 Housing
240 Magnetic core
242 Coil
850 Magnetic field
851 First magnetic field
852 Second magnetic field
952 Minimum limit value
954 Maximum limit value
956 Pair of signal waveforms with nominal remanence
958 Pair of signal waveforms with minimum remanence
960 Pair of signal waveforms with maximum remanence
962 Difference signal
1064 Signal waveform for an unsuitable component
1166 Power supply
1168 A/D converter, analog-digital converter
1169 A/D converter, analog-digital converter
1170 Device for limit value comparison
1171 Device for limit value comparison
1172 Device for difference value comparison
1174 Optional device for a dynamic examination
1176 Logic module
1280 Method
1282 Step of conducting
1284 Step of detecting
1286 Step of evaluation
1288 Step of comparing
Number | Date | Country | Kind |
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102013225580.2 | Dec 2013 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2014/074217 | 11/11/2014 | WO | 00 |