Improved speed sensor ring

Abstract

The invention relates to a signal inducing device (3) that comprises a magnetic interaction surface (10) that can be sensed by a sensor. Along the magnetic interaction surface (10), a first group of parts (6) comprising a first material and a second group of parts (9) comprising a second material are arranged in an alternating way. The first material and the second material show a different magnetic behaviour. The parts (6) from the first group of parts and the parts (9) from the second group of parts are connected to each other in a force-fit way, wherein the parts (6, 9) from at least the first group of parts and / or from the second group of parts are designed and arranged in a way that only a fraction of the adjacent surfaces (11, 13) of neighbouring parts (6, 9) connect to each other in a force-fit way.

Description

[0001] Improved Speed Sensor Ring

[0002] The invention relates to a signal inducing device, comprising a magnetic interaction surface that can be sensed by a sensor, wherein along the magnetic interaction surface a first group of parts comprising a first material and a second group of parts comprising a second material are arranged in an alternating way, wherein the first material and the second material show a different magnetic behaviour, wherein the parts from the first group of parts and the parts from the second group of parts are connected to each other in a force-fit way.

[0003] The invention also relates to a signal inducing arrangement, comprising a sensor device and a signal inducing device.

[0004] Signal inducing devices, sometimes referred to as speed sensor rings or tone rings are frequently used for a plethora of technical devices. As an example, they are used to determine the speed, and sometimes even the position, of a device that is turning with respect to a (main) part of a machine being at rest.

[0005] An example for this is the shaft of a hydraulic pump or of a hydraulic motor. Other examples are a turning axle of a vehicle (where wheels are attached to) or a crankshaft of a combustion engine.

[0006] Due to the wide and frequent use of such speed sensor rings, a huge variety of speed sensor rings is known in the state of the art which all work reasonably well.

[0007] Just to name some examples of designs that are known in the state-of-the-art: DE 10 2015 117 498 A1 discloses a signal inducing device comprising a first material and a second material. The first material and the second material show a different magnetic behaviour. The first material and the second material are arranged in a way that the resulting magnetic behaviour of the signal inducing device varies over a magnetic interaction surface of the signal inducing device. The signal inducing device is further designed in a way that the magnetic interaction surface shows an essentially smooth surface, in particular with respect to the standard moving direction of the magnetic interaction surface.

[0008] DE 42 30 043 A1 describes a pulse ring with a rotation sensor. The pulse ring has an annular section with magnetic or ferromagnetic teeth which are scanned magnetically. The gaps between the teeth are filled with a magneti- cally-neutral material, in order to obtain a smooth outer surface. The teeth are formed in one piece with the carrier part of the ring which is then coated with the magnetically-neutral material, with a cylindrical outer edge around the carrier part, used to attach the pulse ring to the vehicle wheel. This way, smooth outer surface prevents adherence of dirt which impairs the function the of pulse ring.

[0009] DE 195 13 669 A1 discloses a hydrostatic pump or motor that has a driven or drive shaft mounted in a housing and that is connected to rotate around an axis with a meter ring which rotates within a housing inner chamber filled with a hydraulic medium or lubricating oil. The surface contour of the meter ring is designed so that it has the same radial extent around its circumference when viewed cross-sectionally. The meter ring is made of a metal and enveloped in a polymer which is sprayed onto it, or is made of the polymer with metal inserted into empty spaces situated at regular intervals.

[0010] DE 10 2009 053 916 A1 suggests a device comprising a sensor disk including a disk element, and signalling elements arranged at an outer peripheral surface of the disk element. The disk element is made of plastic in an injection moulding process, and the signalling elements are made of metal or plastic. The signalling elements are partially surrounded by the plastic of the disk element, where the plastic of the disk and signalling elements are selected from a group consisting of polyamide, polypropylene, polyethylene and / or fiber-reinforced plastic.

[0011] Undeniably, those sensor rings do work reasonably well in practice and do show certain advantages. Nevertheless, there is always the problem of finding a good compromise between easy and cheap manufacturing on one hand and a reliable and long-lasting design of the respective sensor ring on the other hand.

[0012] Therefore, the object of the invention is to propose a signal inducing device that comprises a magnetic interaction surface that can be sensed by a sensor and that is improved over signal inducing devices that are known in the state of the art. In particular, its production should be cost effective while not severely deteriorating its reliability and lifetime.

[0013] A signal inducing device according to claim 1 solves this object.

[0014] It is suggested to design a signal inducing device, comprising a magnetic interaction surface that can be sensed by a sensor, wherein along the magnetic interaction surface a first group of parts comprising a first material and a second group of parts comprising a second material are arranged in an alternating way, wherein the first material and the second material show a different magnetic behaviour, wherein the parts from the first group of parts and the parts from the second group of parts are connected to each other in a force-fit way, characterised in that the parts from at least the first group of parts and / or from the second group of parts are designed and arranged in a way that only a fraction of the adjacent surfaces of neighbouring parts connect to each other in a force-fit way.

[0015] When talking about the parts being arranged in an alternating way, this is typically to be understood that, when seen in the direction of the lengthwise extent of the magnetic interaction surface, a part from the first group of parts is followed by a part from the second group of parts, which is again followed by a part from the first group of parts and so on. The alternating arrangement can also be considered to be some kind of a toothed rack arrangement. Usually, it is preferred that (only) two groups of parts are used for the magnetic interaction surface (i.e. “first material - second material - first material - second material

[0016] - first material - etc”). Nevertheless, it is possible to arrange sections of a different (third) material at essentially any arbitrary position, including in between a part from the first group of parts and a part from the second group of parts. Thus, possible arrangements would include (without limitation): “first material - second material - third material - first material - second material - third material - first material - etc”; “first material - third material - second material

[0017] - third material - first material - etc”; or the like. The third (or further) group of parts may be parts that are basically similar to the parts of the first and / or second group of parts. However, the third group of parts / the third material (or more) may serve a different purpose well. As an example, a third material may be a glue or an adhesive for supporting / enhancing the force-fit connection between at least some of the parts from the first and / or the second group of parts. In this context it should be noted that those parts of the third group of parts / a third material might also be considered as not constituting a separate group of parts (meaning that such an embodiment with glue / adhesive may fall under the aforementioned preferred possibility that (only) two groups of parts are used for the magnetic interaction surface, just to name an example). Further, it is to be noted that additional / different materials may be used for sections of the signal inducing device that are different from the magnetic interaction surface. As an example, in case the signal inducing device shows a wheel-like shape, the support structure between an axle bearing and the magnetic interaction surface may be made from a material being different from both the first and / or the second material (of course it is possible that even those parts do comprise the first and / or the second material).

[0018] The adjacent surfaces, where the neighbouring parts connect to each other in a force-fit way using only a part / parts of that adjacent surfaces, are usually the surfaces which follow to each other in the direction of the alternating arrangement of the respective part of the first and second group of parts / in the direction of the magnetic interaction surface / in the movement direction of the magnetic interaction surface. Typically, those surfaces will be more or less normal (perpendicular) to the the direction of the alternating arrangement of the respective parts of the first and second group of parts / in the direction of the magnetic interaction surface / in the movement direction of the magnetic interaction surface. To use example of a tone wheel / signal inducing device, where the magnetic interaction surface is ring-like, the respective adjacent surfaces are typically aligned in an essentially radial direction. Preferably, at least some of the surface parts that are effectuating a force-fit connection are essentially only provided for performing a force-fit connection (and, as an example, not a positive form-fit connection). However, (at least) some of the / a few of the surface parts that are effectuating a force-fit connection may also serve for providing an additional fixation technique, like a positive form fit connection.

[0019] For the magnetic interaction surface to be functional, it is usually necessary that the first material and the second material are different with respect to a magnetic behaviour. In particular, the first material and / or the second material should induce a different signal in the sensor (where it is sufficient that a sensor signal is generated when there is a changeover from the first material to the second material and vice versa). The magnetic behaviour of the parts from the first group of parts and of the parts from the second group of parts (and even more groups) can vary in various ways. As an example, a different magnetic behaviour with respect to the underlying physical effect of the respective material can be envisaged. To elucidate this, the first material can be a non-mag- netic substance, a paramagnetic substance or a diamagnetic substance, while the second material can be a ferromagnetic substance. However, different combinations are possible as well. In particular, when it comes to ferromagnetic substances, a differentiation between hard magnetic substances (presumably showing a permanent magnetism and / or not showing a permanent magnetism per se) and soft magnetic substances can be made. Due to the limited magnetic effect of paramagnetic and diamagnetic substances, both can be considered to be (essentially) non-magnetic substances (in particular within the context of the present application and / or invention). Another differentiation between different magnetic behaviour can be made based on the strength of the respective effect. As an example, both first and second material can be a magnetic substance, while the first material is a soft magnetic material and the second material is a hard-magnetic material (or the like). It is even possible that the first and the second material are taken from the group, showing the same “underlying physical effect”, while they differ in “strength of the respective effect”. As an example, both the first and the second material can be a soft magnetic material. However, it is possible that the first material shows a lower (relative) magnetic susceptibility with respect to the second material (or vice versa). Furthermore, it should be noted that the “first material” and the “second material” cannot only be understood in the sense that different “pure” substance are used. Of course, it is possible that one or both of the materials involved are composite materials comprising a mixture of different materials (for example an alloy, a ceramic substance, or a plastic material containing small particles of a ferromagnetic material). In effect, it is even possible that the first material and the second material are to be understood to be a mixture of the same components, but the ratio of the different components is different. The “resulting magnetic behaviour” can be particularly understood as the “combined magnetic effect” at a certain location with respect to the signal inducing device, in particular with respect to the magnetic interaction surface. Typically, said certain location is a position, where the sensor (in particular the magnetic sensor) will be typically arranged when employing the signal inducing device in its intended place in a more complex machine (including the respective sensor). It is to be noted that said certain position (i.e. where typically the sensor is placed) will usually move with respect to the signal inducing device (or to be more exact: typically the signal inducing device will move with respect to the certain position; in particular the position where the sensor is placed). The certain position, where the measurement is taken (in particular location of the sensor) is typically considered with respect to a reference frame of a more complex machinery, the signal inducing device is used in. In this reference frame, the certain position (of the sensor) is at rest. As an example: if the signal inducing device (and presumably the sensor) is used in a vehicle, the reference frame of the vehicle is typically moving with respect to a factory building, of course. Therefore, both the signal inducing device and the sensor of the vehicle are typically moving with respect to the factory building, while the sensor is at rest with respect to the vehicle's body. Furthermore, the resulting magnetic behaviour of the signal inducing device can change in essentially every thinkable way. Not only an (absolute) value like the magnetic susceptibility and / or the (absolute) strength of a permanent magnetic field might vary, but also additionally and / or alternatively a direction of susceptibility, a direction of a permanent magnetic field and so on. In particular, it should be noted that the parts from the first group of parts and the parts from the second group of parts may be differing within the group to a certain extent, but may also be preferably (highly) similar and / or (essentially) identical. This may relate to the respective size, the outer shape, the magnetic behaviour and / or the material composition. Hence, certain, typically small, variations in composition are allowed, even within the same group of parts. The decisive differentiation between the first and second group of parts lies usually in that they can be clearly distinguished from each other, in particular by a sensor placed in the vicinity of the magnetic interaction surface, once the signal inducing device is employed in its intended way. Furthermore, it should be noted that the notion “comprising a material” may (preferably) mean that the respective part (essentially) consists of the respective material. However, it is perfectly allowable that some filler material or the like is used in combination with at least one of the first material and / or the second material, where the ratio of filler material versus the first and / or the second material may change in the respective group, at least to a certain extent. Only for completeness, it should be noted that, while it is possible that even more group of parts are employed, it is usually preferred if exactly two groups of parts are employed with the presently proposed signal inducing device.

[0020] The parts from the first group of parts and the parts from the second group of parts are connected to each other in a force-fit way. It is to be noted that this does not rule out the presence of some “intermediary” material, which would mean that the parts from the first group of parts and / or the parts from the second group of parts may connect to the respective “intermediate material”, in particular in a force-fit way. The generalisation along these lines is obvious to a person skilled in the art. Furthermore, it should be noted that the connection in the force-fit way does not rule out any additional connection techniques, like a positive substance connection and / or a positive form locking connection “on top of” the present force-fit connection (where the glue / adhesive of the positive substance connection may or may not be considered as a third material, as previously described). However, typically a force-fit connection may be sufficient. Furthermore, the force-fit connection may be some kind of a “base connection”, so that - as an example - a positive form locking connection may be foreseen with a certain play, so that the positive form locking connection will mainly play a role as a fall-back position and / or in case that very high rounds- per-minute are encountered or the like, while the presently suggested force-fit connection will at least hinder that the respective parts are loose at a standstill or the like. Furthermore, particularly a positive form locking connection will typically be designed in a way that the positive form locking will only hold the parts together in a certain direction, while it does not hinder a movement of the respective parts in another direction. Different from this, the force-fit connection will usually work in all directions (which does not rule out the possibility that the strength of the force-fit connection will differ in different directions; nevertheless, there is typically a substantial force-fit holding force present in any direction). Again, while it is possible that (at least) some of the force-fit connection providing / friction providing surfaces might serve additional purposes as well (for example to provide a positive form lock connection), at least some of the force-fit connection providing / friction providing surfaces do preferably (essentially) only provide a force-fit connection / a friction-based fixation. This may particularly be true for protrusions like web-like protrusions, dimples and the like.

[0021] Presently, it is proposed to establish the force-fit connection in a way that only a fraction of the adjacent surfaces of the neighbouring parts connect to each other in a force-fit way. So far, usually (essentially) all of the overall size of the adjacent surfaces was used for a force-fit connection. The underlying idea was obviously to effectuated a particularly tight connection. However, it has been found that for most areas of application it is sufficient that only a fraction of the respective surfaces establishes the force-fit connection. This fraction may be chosen from an interval between 0.5%, 1 %, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30% (lower limit) to 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80% (upper limit) of the overall size of the respective surface. It is acknowledged that certain combinations of upper and lower limit do not make any sense and are to be omitted, which is obvious to person skilled in the art.

[0022] Using only a fraction of the size (area) of the respective surfaces, however, may simplify the manufacturing process, even considerably. In particular, using the present proposal, the respective contacting areas may be dimensioned in a way that the respective parts / areas / sections that are used to effectuate the force-fit connection have to be deformed when connecting the parts together. This deformation may be used to effectuate a particularly advantageous force-fit connection.

[0023] Furthermore, it is possible that only one part of the neighbouring two parts shows a certain deformation to establish such a force fit connection. However, it is also possible that both parts of the two neighbouring parts show an appropriate surface deformation to establish a force-fit connection.

[0024] In particular, it is proposed that the signal inducing device is designed and arranged in a way that the parts from the first group of parts and / or the parts from the second group of parts comprise at least one protruding surface section, preferably at least a web-like protruding surface section, in particular to effectuate the aforementioned force-fit connection. Consequently, it is possible that the opposing, corresponding neighbouring surface (section) is designed to be (essentially) flat. This may particularly relate to the vicinity of the area, where the contact between the neighbouring parts is realised in order to establish the force-fit connection. However, it is also possible that both neighbouring surfaces show a protrusion (web-like protrusion) to establish the force- fit connection. While it is preferred to use a web-like protrusion, other types of protrusions are possible as well, like dimple-like protrusions and so on. The web-like protrusion may be preferably arranged in a direction that lies (essentially) perpendicular (normal) to the direction of the force (movement-induced force) that acts on the respective parts when the signal inducing device is used in its intended machinery / place and way of use. Therefore, in case of a wheel- like / circular signal inducing device, the respective web is typically aligned in an essentially axial direction. The number of protruding surface sections (per overall single surface, so to say) is typically comparatively small and may vary between 1 , 2, 3, 4, 5 (lower limit) and 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 (upper limit). Again, certain combinations are invalid. Furthermore, an exact number may be chosen from the lower and the upper limit as well. This design has proven to be particularly versatile and yet comparatively easy and cheaply to realise in first experiments.

[0025] It is further suggested to design the signal inducing device in a way that the parts from the first group of parts have a higher deformability as compared to the parts from the second group of parts. Additionally or alternatively, the signal inducing device may be designed and arranged in a way that a surface section of a part that shows a deformation for contacting another part, more preferred a protrusion of a part, has a higher deformability as compared to the corresponding adjacent surface section of the neighbouring part. This way a joining process of the respective parts is particularly easy to realise. Also, the force-fit connection may be particularly durable and may show a comparatively high strength. While the deformed part / protrusion may be made of a different material (in particular a material that is particularly well suited for this purpose), as compared to the “base body” of the respective part from the first and / or second group of parts, it is usually preferred, if it is made from (essentially) the same material, as the “base body” of the respective part from the first and / or second group of parts, respectively.

[0026] Even further, it is suggested to design the signal inducing device in a way that for at least some parts, protruding surface sections are arranged on both surface sides in the direction of the lengthwise extent of the magnetic interaction surface. This way, the respective part is sort of clamped in position from both directions. However, it is also possible to provide such protruding surface sections only on one surface side of the respective part. This way, the manufacture of the signal inducing device (more particular of the respective part; or of the preassembled unit, comprising the respective part) may be realised in a simpler way.

[0027] Even further, it is suggested to design the signal inducing device in a way that the first material (and / or possibly the second material and / or possibly an additional material) comprises a non-magnetic material and / or a soft magnetic material and / or a material that is taken from the group comprising raisin, plastics, elastomers, plastomers, copper and copper alloys. Additionally or alternatively, it is suggested to design the signal inducing device in a way that the second material (and / or possibly the first material and / or possibly an additional material) comprises a magnetic material and / or a hard magnetic material and / or a material that is taken from the group comprising iron, iron alloys, steel and ferrites. First experiments have shown that such a design is particularly advantageous. In particular, if a material is used that shows no (or little) permanent magnetism, an agglomeration of metallic particles around the signal inducing device can be avoided, which is particularly advantageous. Furthermore, if a (soft and / or hard) magnetic material is used in combination with a non-magnetic material, a particularly profound change of the resulting magnetic behaviour (particularly at the sensor's position) can be realised along the magnetic interaction surface of the signal inducing device. Therefore, a simpler and less sensitive sensor can be employed. Furthermore, if iron, steel or the like is used as (one of the) “basic substances” of the signal inducing device, a particularly stiff and stable signal inducing device can be realised, since metals or the like typically show a high strength and are comparatively cheap and / or are easily available. Furthermore, they are a standard material for a lot of technical applications.

[0028] It is further suggested to design the signal inducing device in a way that the magnetic interaction surface is designed as a closed surface, in particular as a rounded surface, preferably as a circular surface. Additionally or alternatively, it is suggested to design the signal inducing device in a way that the signal inducing device is designed as a ring-like object and / or as a wheel-like object. Using such a design, the signal inducing device will typically show low counteracting viscous forces. Furthermore, such a shape will comply with the typical requirements of machinery the signal inducing device is typically used in connection with. Since the suggested shapes are somewhat according to the usual design for signal inducing devices, the proposed signal inducing device can be used as a “snap-in”-solution, which can increase the acceptance of the device. Furthermore, the proposed design will usually result in a particularly stable configuration of the resulting signal inducing device. Even further, the proposed design, particularly a circular design, will facilitate the assembly of the resulting signal inducing device.

[0029] Further, it is suggested to design the signal inducing device in a way that at least some of the parts from the first group of parts and / or at least some of the parts from the second group of parts show a bar-like configuration along the magnetic interaction surface. This way, the alternating arrangement / toothed rack design of the magnetic interaction surface can be realised particularly easy. Furthermore, the output signal, the sensor can create, can be particularly advantageous as well. The expression “bar-like configuration” may be interpreted in a broad sense. In particular, cubicle-shaped or ashlar-formed shapes are possible as well. However, different forms are also possible. Nevertheless, a strictly rectangular or quadratic cross-section is usually preferred. Certainly, according to the present suggestion, the design with a force-fit connection using only a fraction of the adjacent surfaces, in particular the design with protruding surface sections, does of course result in a certain deviation from the aforementioned shapes, when considering those shapes in a strict mathematical sense. Therefore, those cross sections may be considered as a “basic shape”, that is modified in the sense of the present disclosure.

[0030] Even further, it is suggested to design the signal inducing device in a way that a plurality of parts from the first group of parts and / or a plurality of parts from the second group of parts are interconnected using a ring-like connection structure, respectively, wherein the ring-like connection structure preferably comprises the same material as the parts of the respective group of parts. In particular the majority and / or essentially all of the parts from the first group of parts and / or from the second group of parts are interconnected using a respective ring-like connection structure. This way, it may be possible to premanufacture two separately handable subassembly parts that are simply joined together to complete the signal inducing device. This joining can be made as some kind of a comb-like connection process. In particular, a part in form of a block (bar-like) that is protruding from the ring-like connection structure can be arranged with such an angular offset that the block is arranged adjacent to a gap in the adjacent preassembled part. Then, a simple linear movement may result in joining the two parts together. Even more particular, it may be even possible to produce one or both preassembled subassemblies by a moulding, casting, sintering or other type of manufacturing process separately from each other. Afterwards the two preassembled subassemblies are fitted together.

[0031] The ring-like connection structure is typically designed and arranged in a way (preferably using an appropriate material) that the ring-like connection structure is stiff / self-supporting. Therefore, it can, at least in principle, be used in machinery it is intended to be used, without a supporting mandrel or the like. The parts from the first group of parts and / or the part from the second group of parts may be arranged on a radial outside surface of the respective ring-like connection structure, and / or may be arranged at an axial outside surface of the respective ring-like connection structure. It is expressly noted that it is noted that the parts may actually be arranged in a way that they contact both an axial outside surface and a radial outside surface of the respective ring-like connection structure. For completeness: for the respective contact, the whole extent of the surface of the respective ring-like connection structure, or only a part thereof might be used (typically, for radial outside surface, this extent relates to an axial direction, while for an axial outside surface, this extent relates to a radial direction). In particular in case the parts are arranged on a radial outside surface of the respective ring-like connection structure, they nevertheless may (and even should, at least for one group of parts) protrude in an axial direction, sticking out from the respective ring-like connection structure / structure clearance of the ring-like connection structure. This design may be seen as some kind of a toothed wheel / cog-like design, where the teeth are protruding in an axial direction (at least in one axial direction, but also possibly in both) additionally (arrangement of the parts from the group of parts on the radial outside surface of the ring-like connection structure). However, a comb-like design is also possible (only protruding in (at least one) axial direction; arrangement of the parts from the group of parts on an axial outside surface of the ring-like connection structure). Usually, the respective dents, parts, protrusions (or the like) are open on a side that is different from (or even opposed to) the respective surface, where they are connected to the ring-like connection structure. While this is typically the preferred design, other designs may be used as well, in particular any embodiments that are designed and arranged in a way that the respective subparts may be connected together by a simple (linear) pushing movement.

[0032] Further, it is suggested to design the signal inducing device in a way that the parts and the corresponding ring-like connection structure are provided as a preassembled subunit, more preferably as a single-piece subunit. This way, the manufacture of the signal inducing device can become even simpler and more cost-effective. As an example: the preassembled subunit comprising a ring-like shaped structure and corresponding bar-like parts can simply be manufactured using an injection die casting process.

[0033] Yet further, it is suggested to design the signal inducing device in a way that at least one of the ring-like connection structures is arranged at a side of the magnetic interaction surface. This way, a highly symmetric signal inducing device can be realised. Furthermore, viscous forces, when the signal inducing device is moved in its usual direction of movement (when employed in its final machinery) can be particularly small as well. Furthermore, the provision of two separate subassemblies that are simply joined together afterwards in the afore described sense may be realised particularly simple. In particular, the respective ring-like connection structure is arranged on one axial end side / ax- ially limiting side of the overall structure). In particular, the arrangement may be designed in a way that both ring-like connection structures touch each other, at least partially, when the signal inducing device is fully assembled.

[0034] Even further, it is suggested to design and arrange the signal inducing device in a way that the magnetic interaction surface shows an essentially smooth surface, in particular with respect to the standard moving direction of the magnetic interaction surface, wherein the signal inducing device is preferably designed and arranged in a way that essentially all exposed surfaces of the signal inducing device show an essentially smooth surface, in particular with respect to the standard moving direction of the signal inducing device. This way, viscous forces that are occurring when turning the signal inducing device can be minimised. This is particularly advantageous, if the signal inducing device is used in the context of hydraulics and is possibly even partially or fully immersed in hydraulic oil (something that is everything but unusual in hydraulic applications). Using this design, mechanical / hydrodynamical losses can be reduced, which may result in a higher efficiency of the final arrangement. Furthermore, a heating up of the hydraulic oil and possibly the generation of noise can be also reduced.

[0035] Yet further, it is suggested to design the signal inducing device in a way that the parts from the first group of parts and / or the parts from the second group of parts are spaced evenly and / or in that the parts from the first group of parts and / or the parts from the second group of parts are spaced in a special encoding arrangement and / or in that the signal inducing device, in particular the parts from the first group of parts and / or the parts from the second group of parts is / are designed and / or arranged in a way that the magnetic interaction surface produces an essentially binary signal. Choosing an embodiment according to the present disclosure, the signal inducing device can be used for typical requirements. For example, the signal inducing device can be used for a simple measurement of speed (for example rotational speed of an axle). However, using a special encoding, it is also possible to determine the position of the signal inducing device (which can be an axle of a wheel or a crankshaft of an engine or the like). Typically, it is preferred if the resulting signal is of a binary type. This is not only because the resulting logic is usually easier to implement. In addition, if the signal is of a binary type, aggregation of dirt, alterations of the devices or the like usually play a less relevant role (where in case the value of an analog signal (size / reading of the respective signal) is used, where the value contains some information, this will usually result in “bad readings”). Parts from a third group of parts / a third material may or may not be employed for realising a special encoding arrangement.

[0036] Even further, it is suggested to design the signal inducing device in a way that the magnetic interaction surface and / or a circular surface of the signal inducing device shows a surface comprising at least two surface parts that are arranged at an angle. This design may be advantageous for weight saving purposes and / or for mounting space considerations. Using a tapered surface part, the arrangement of a sensor might become easier and / or the signal induced in the sensor might become more profound. The angle between the two surface parts, i.e. the flat surface part and the tapered surface part may preferably be between 5°, 10°, 15°, 20°, 25°, 30° (lower limit) and 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 60° or 70° (upper limit). It is to be noted that an angle of 0° would be equivalent to a flat surface without any observable bent.

[0037] Even further, a signal inducing arrangement, comprising a sensor device and a signal inducing device according to the previous disclosure is proposed. In particular, the signal inducing device and the sensor device are combined in a “sensible way”. In particular, this usually means that in the presently proposed arrangement, the sensor will read the (varying) magnetic behaviour of the signal inducing device along a magnetic interaction surface thereof. Furthermore, the arrangement and the positions of both devices will be chosen in a way that a good signal will be produced by the sensor and / or in a way that no adverse mechanical effects (for example an impact or the like) will occur, at least under standard operating conditions. In particular, the signal inducing device and / or the signal inducing arrangement according to the previous disclosure can be used for any kind of rotating device. In particular, the rotating device can be an axle, crankshaft, wheel, wheel support, spindle device and / or a shaft of essentially any type of machinery. The machinery can be (just to name some examples) a motor, a combustion engine, a machine tool, an electric motor, an electric generator, a fluid working machine, a fluid pump, a fluid motor (where the fluid can be hydraulic oil and / or water in those cases), a turbine, a carriage device, an undercarriage device, a generator device, a wind generator device or the like. The signal inducing device and / or the signal inducing arrangement can be used for stationary machinery, landcraft (including on-road use, offroad use and / or rail bound use), watercraft, aircraft and / or spacecraft. In particular vehicles like cars, trucks, buses, vehicles comprising hydraulic installations, forklift trucks, tractors, farm machinery, construction vehicles, construction machinery and the like are possible.

[0038] Further advantages, features, and objects of the invention will be apparent from the following detailed description of the invention in conjunction with the associated drawings, wherein the drawings show:

[0039] Fig. 1 : two corresponding subassembly rings, one comprising block-shaped parts from a first group comprising a first material that are connected to each other by means of an interconnecting ring, the other one comprising block-shaped parts from a second group comprising a second material that are connected to each other by means of an interconnecting ring, in a schematic top view;

[0040] Fig. 2: an enlarged view of a section of the first subassembly ring in a schematic top view and in a schematic perspective view;

[0041] Fig. 3: a schematic perspective view of the assembled signal inducing device; Fig. 4: an enlarged view showing details of the block-shaped parts of the subassembly rings, both in preassembled situation and in an assembled situation;

[0042] Fig. 5: an enlarged view of different sides of a section of an assembled signal inducing device in a top view and a perspective view, respectively.

[0043] Fig. 1 shows an arrangement of two subassembly rings 1 , 2 in a schematic top view. The two subassembly rings 1 , 2 are still separated from each other. However, the alignment of the two subassembly rings 1 , 2 is such that they can be connected to each other easily to form the finished signal inducing device 3 (tone ring; see Fig. 3). For this, the two subassembly rings 1 , 2 have to be moved sideward with respect to each other (linear movement in the plane of the drawing of Fig. 1 ). When the two subassembly rings 1 , 2 are correctly aligned (where a certain angular alignment by turning the two subassembly rings 1 , 2 in a rotational direction with respect to each other might be necessary), the two subassembly rings 1 , 2 are pushed towards each other in a comb-like connection way (movement normal to the plane of the drawing of Fig. 1 ). When the two subassembly rings 1 , 2 are fully connected, the signal inducing device 3 according to Fig. 3 is completed.

[0044] In Fig. 2 an enlarged section of one of the subassembly rings 1 , 2, presently of the first subassembly ring 1 , is shown in a schematic view from the top (Fig. 2a), and in a schematic perspective view (Fig. 2b).

[0045] As can be seen, the subassembly ring 1 comprises an interconnecting ring 4 with an overall circular shape. Along the outer circumferential edge 5 of the interconnecting ring 4, a plurality of generally bar-shaped interaction parts 6 are provided. Since the outer circumferential surface of the signal inducing device 3 / the magnetic interaction surface 10 of the signal inducing device 3 shows presently a bent surface (see also Fig. 3 and 5), the bars of the barshaped interaction parts 6 do not show a strict cuboidal design; instead, a corner section of the cuboid is so-to-say cut off from the bar-shaped interaction part 6. The interaction parts 6 and the interconnecting ring 4 form a single piece device. It is to be noted that the arrangement is made in a way that only a side section of the interaction parts 6 connect to the interconnecting ring 4. Namely, in the view of Fig. 2, the interconnecting ring 4 lies flat on the table plane, while the plurality of bar-shaped interaction parts 6 point towards the viewer of Fig. 2.

[0046] Presently, the first subassembly ring 1 is made of a thermoplastic material. Consequently, the subassembly ring 1 can be easily produced using injection die casting techniques for its production. Hence, the respective subassembly ring 1 can be produced easily and very cost-effective.

[0047] The second subassembly ring 2 has a generally similar design. Namely, the second subassembly ring 2 shows an interconnecting ring 7. Similar to first subassembly ring 1 , on the radially outer edge 8 of interconnecting ring 7, again a plurality of bar-shaped interaction parts 9 are attached in a single piece way of design. It is to be noted that in the view of Fig. 1 , the bar-shaped interaction parts 9 do point away from the viewer of Fig. 1 , i.e. they are pointing towards the table plane. Nevertheless, the bar-shaped interaction parts 9 (presently also designed as some kind of a cuboid with a cut off corner section) do protrude from the interconnecting ring 7, although this is not clearly visible from the drawing.

[0048] In the assembled state of the signal inducing device 3, the bar-shaped interaction parts 6 of first subassembly ring 2 and the bar-shaped interaction parts 9 of second subassembly ring 2 are arranged in an alternating way, so that consequently a magnetic interaction surface 10 is formed on the radially outer side of signal inducing device 3. Due to the different magnetic behaviour of the materials chosen (i.e. of first subassembly ring 1 - and therefore of bar-shaped interaction parts 6 - on one hand, and of second subassembly ring 2 - and therefore of bar-shaped interaction parts 9 - on the other hand), a magnetic sensor that is placed in the vicinity of the magnetic interaction surface 10 of signal inducing device 3 can sense a varying magnetic signal when the signal inducing device 3 is rotated. It is to be noted that in the presently shown embodiment the magnetic interaction surface 10 is of a bent design. Namely, the magnetic interaction surface 10 comprises a first, flat section 14 that is arranged parallel to the axial direction. Neighbouring the flat section 14, a tapered section 15 is arranged at an angle of presently 45° with respect to the flat section 14 of the magnetic interaction surface 10.

[0049] The second subassembly ring 2 is presently made from steel and hence shows ferromagnetic properties. The subassembly ring 2 may be produced by standard abrasive manufacturing techniques as they are well known in the state-of- the-art.

[0050] A significant detail of the design of signal inducing device 3 can be seen in Figs. 2 and 4. In detail, Fig. 4 shows an enlarged view showing details of the block-shaped parts 6, 9 of the subassembly rings 1 , 2, both in a preassembled situation (Fig. 4a) and in an assembled situation (Fig. 4b).

[0051] As can be seen in Fig. 4, the bar-shaped interaction parts 6 of the first subassembly ring 1 (which is presently made from thermoplastic material) do show protruding webs 12 on their side surfaces 11 . Namely, each side surface 11 of each interaction part 6 shows two protruding webs 12. A side surface 11 of an interaction part 6 is a side surface 11 that is normal to a rotating direction / tan- gential direction of the subassembly ring 1 / the signal inducing device 3. These side surfaces 11 will contact corresponding side surfaces 13 of the bar-shaped interaction parts 9 of second subassembly ring 2 when the two subassembly rings 1 , 2 are fitted together to form the signal inducing device 3 (see particularly Fig. 4b). As can further be seen in Fig. 4, the side surfaces 13 of the barshaped interaction parts 9 of subassembly ring 2 are essentially flat (see particularly Fig. 4a), i.e. they do not show protruding webs or other types of protrusions that are somewhat similar to the protruding webs 12 of the interaction part 6 of first subassembly ring 1 . This difference is mainly based on the two different materials used, their material properties and their ability to be machined. For a person skilled in the art, it is obvious that web-like protrusions 12 can easily be provided when using an injection die casting technique, like it is done for producing the first subassembly ring 1. However, they are more problematic to be machined using abrasive machining techniques.

[0052] When bringing the two subassembly rings 1 , 2 together to form the signal inducing device 3, the protruding webs 12 of the interaction part 6 of first subassembly ring 1 will be deformed by the contact with the neighbouring side surfaces 13 of the interaction parts 9 of the second subassembly ring 2. Due to the material properties of thermoplastic material, in particular due to their elastic deformability (at least to a certain extent), the deformation and the tendency to return to the original (undeformed) shape will result in a force-fit connection between the two subassembly rings 1 , 2, thus holding the two subassembly rings 1 , 2 tightly together to form the signal inducing device 3. This assembled situation becomes particularly clear from Figs. 3 and 5. Fig. 5 shows an enlarged view of different sides of a section of an assembled signal inducing device 3, as shown in Fig. 3. Namely, Fig. 5a shows the situation in a top view onto a first side surface 16 (the side bearing the tapered part 15 of the magnetic interaction surface 10), where for clarity a slight perspective view aspect is drawn as well. Fig. 5b shows a top view onto a second side surface 17 opposite of the first side surface 16 of the signal inducing device 3.

[0053] Of course, it is also possible to enhance the strength of the connection by applying some adhesive and / or to form the respective parts in a way that an additional form-fit connection is realised as well. It is to be noted that a single one or a plurality of the features of one, several or all of the presently disclosed detailed embodiments may be used in combination with the generic description of the present disclosure.

Claims

C l a i m s1. Signal inducing device (3), comprising a magnetic interaction surface (10) that can be sensed by a sensor, wherein along the magnetic interaction surface (10) a first group of parts (6) comprising a first material and a second group of parts (9) comprising a second material are arranged in an alternating way, wherein the first material and the second material show a different magnetic behaviour, wherein the parts (6) from the first group of parts and the parts (9) from the second group of parts are connected to each other in a force-fit way, characterised in that the parts (6, 9) from at least the first group of parts and / or from the second group of parts are designed and arranged in a way that only a fraction of the adjacent surfaces (11 , 13) of neighbouring parts (6, 9) connect to each other in a force-fit way.

2. Signal inducing device (3) according to claim 1 , characterised in that the parts (6) from the first group of parts and / or the parts (9) from the second group of parts comprise at least one protruding surface section (12), preferably at least a web-like (12) protruding surface section.

3. Signal inducing device (3) according to claim 1 or 2, preferably according to claim 2, characterised in that the parts (6) from the first group of parts have a higher deformability as compared to the parts (9) from the second group of parts, and / or wherein a surface section (11 ) of a part (6) that shows a deformation (12) for contacting another part (9), more preferred a protrusion (12) of a part (6), has a higher deformability as compared to the corresponding adjacent surface section (13) of the neighbouring part (9).

4. Signal inducing device (3) according to any of the preceding claims, preferably according to claim 2 or 3, characterised in that for at least some parts (6), protruding (12) surface sections are arranged on both surface sides (11 ) in the direction of the lengthwise extent of the magnetic interaction surface (10).

5. Signal inducing device (3) according to any of the preceding claims, characterised in that the first material comprises a non-magnetic material and / or a soft magnetic material and / or a material that is taken from the group comprising resin, plastics, elastomers, plastomers, copper and copper alloys and / or characterized in that the second material comprises a magnetic material and / or a hard magnetic material and / or a material that is taken from the group comprising iron, iron alloys, steel and ferrites.

6. Signal inducing device (3) according to any of the preceding claims, characterised in that the magnetic interaction surface (10) is designed as a closed surface, in particular as a rounded surface, preferably as a circular surface (10) and / or in that the signal inducing device (3) is designed as a ring-like object and / or a wheel-like object.

7. Signal inducing device (3) according to any of the preceding claims, characterised in that at least some of the parts (6) from the first group of parts and / or at least some of the parts (9) from the second group of parts show a bar-like configuration along the magnetic interaction surface (10).

8. Signal inducing device (3) according to any of the preceding claims, in particular according to claim 7, characterised in that a plurality of parts (6) from the first group of parts and / or a plurality of parts (9) from the second group of parts are interconnected using a ring-like connection structure (4, 8), respectively, wherein the ring-like connection structure(4, 8) preferably comprises the same material as the parts (6, 9) of the respective group of parts.

9. Signal inducing device (3) according to claim 8, characterised in that the parts (6, 9) and the corresponding ring-like connection structure (4, 8) are provided as a preassembled subunit (1 , 2), more preferably as a single-piece subunit (1 , 2).

10. Signal inducing device (3) according to claim 8 or 9, characterised in that at least one of the ring-like connection structures (4, 8) is arranged at a side (16, 17) of the magnetic interaction surface (10).11 . Signal inducing device (3) according to any of the preceding claims, characterised in that the signal inducing device is designed and arranged in a way that the magnetic interaction surface (10) shows an essentially smooth surface, in particular with respect to the standard moving direction of the magnetic interaction surface (10), wherein the signal inducing device (3) is preferably designed and arranged in a way that essentially all exposed surfaces of the signal inducing device (3) show an essentially smooth surface, in particular with respect to the standard moving direction of the signal inducing device (3).

12. Signal inducing device (3) according to any of the preceding claims, characterized in that the parts (6) from the first group of parts and / or the parts (9) from the second group of parts are spaced evenly and / or in that the parts from the first group of parts and / or the parts from the second group of parts are spaced in a special encoding arrangement and / or in that the signal inducing device (3), in particular the parts (6) from the first group of parts and / or the parts (9) from the second group of parts is / are designed and / or arranged in a way that the magnetic interaction surface (10) produces an essentially binary signal.

13. Signal inducing device (3) according to any of the preceding claims, characterized in that the magnetic interaction surface (10) and / or a circular surface (10) of the signal inducing device (3) shows a surface comprising at least two surface parts (14, 15) that are arranged at an angle.

14. Signal inducing arrangement, comprising a sensor device and a signal inducing device (3) according to any of claims 1 to 12.

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