Inductance sensor

Abstract

An inductive sensor (1) for detecting metal objects, comprising:-a sensor housing (4) having a first housing surface (41) representing an active surface of the sensor (1); -a coil system (2) having a front face (21), where the front face (21) is positioned rearward in front of the first housing surface (41), facing the rear housing surface (44); -a vertical positioning element (5) wherein the vertical positioning element (5) is configured and arranged to exert a force on the coil system (2) in the direction of and preferably perpendicular to the active surface (41) and the rear housing surface (44) such that the front face (21) of the coil system (2) remains in direct contact with the rear housing surface (44) of the sensor (1), wherein the vertical positioning element (5) is formed by and / or attached to the sensor housing (4).

Description

Technical Field

[0001] The invention relates to an inductive sensor for detecting metal objects, a sensor system comprising a plurality of such sensors and a method for assembling such an inductive sensor. Background Art

[0002] Inductive sensors are widely used in a variety of applications, such as automotive, industrial, and consumer electronics. These sensors operate based on the principle of detecting changes in the impedance or pulse response of a coil system, or changes in the inductive coupling between multiple coil systems, when a metal object approaches the sensor. Precise positioning of the coil system within the sensor is crucial for accurate metal object detection. Conventional techniques require precise positioning of the coil system (or coils) in both vertical and lateral directions relative to the rear surface of the sensor housing to ensure that the sensor properly responds to the detected object. During operation, the coil system should not move or shift laterally, and the front face of the coil system should maintain contact with the rear surface of the sensor housing. Standard casting resins and adhesives are commonly used to secure the coil system in place. However, these resins often lack sufficient temperature resistance. Furthermore, the thermal expansion coefficients of the resin and other sensor components often differ significantly, which can lead to thermally induced mechanical strain and displacement, particularly in the coil system, leading to operational and accuracy issues for the sensor. One approach to addressing these issues involves using silicone-based casting materials, which are suitable for higher operating temperatures. However, this approach still requires long waiting times for the casting material to cure and specialized casting machinery, such as a vibrating plate. Furthermore, adhesives and casting materials can be harmful to the environment and can complicate the overall assembly process.

[0003] These and other problems are solved by the subject matter of the appended independent claims. Summary of the Invention

[0004] The present invention aims to provide an improved inductive sensor that overcomes the aforementioned shortcomings. The present invention relates to an inductive sensor designed for detecting metal objects, particularly suitable for applications in automation technology and detecting motion of components, including lateral continuous motion. The present invention offers several advantages over the prior art, including simpler manufacturability, no waiting time for adhesive drying, and no need for silicone or resin-based casting materials. This eliminates curing time and the need for specialized casting machines. Furthermore, the present invention eliminates the need for adhesives, making it more environmentally friendly. Furthermore, the sensor, sensor system, and method according to the present invention can save costs, particularly because the additional components required compared to the prior art, such as springs, nuts, and centering pins, are significantly less expensive than the resin-hardener-based or silicone-based encapsulation currently used in the art. Therefore, the inventors have discovered that it is important to precisely position the coil system or coil systems of the inductive sensor in both the vertical and lateral directions, with the front facing the back of the housing surface, to ensure that the sensor responds correctly to the object to be detected. During operation, the coil system or systems should be stably arranged and, in particular, not experience significant lateral movement or displacement, and the end faces should not lose contact with the rear wall of the housing, even if the material expands due to temperature. Thus, the sensor of the present invention is uniquely configured to withstand high operating temperatures and accurately detect vertical or lateral approaches of target objects.

[0005] The core of the present invention is that in the inductive sensor according to the present invention, the coil system is positioned facing the rear housing surface of the sensor housing, so that a vertical positioning element, such as a spring element, exerts a force on the coil system in the direction of the active surface of the sensor (more specifically the rear housing surface) so that the front face of the coil system remains in direct contact with the rear housing surface of the sensor. In addition, a lateral positioning element, such as a centering pin, is provided to ensure the positioning of the coil system in any direction transverse to the active surface. Therefore, a person skilled in the art will immediately recognize and understand that, depending on the corresponding embodiment, such a lateral positioning element can also provide positioning in another direction (in particular the vertical direction). In this way, the front face of the coil system is maintained in a desired and predetermined position relative to the rear housing surface, so that the sensor reacts accurately to the object to be detected.

[0006] It should be noted that the core of the present invention is the elastic mounting of the entire coil system. This allows for compensation of material expansion caused by mechanical shock and / or temperature, which could otherwise cause the coil system to lose contact with the front and back surfaces. Without wishing to be bound by theory, the inventors believe that mechanical stability at high temperatures is also important. Therefore, the material is selected to expand as little as possible. However, irreversible material expansion may occur, which can be largely compensated by the vertical positioning elements (particularly springs).

[0007] Therefore, the present invention also addresses temperature-induced material expansion by compensating for the expansion using vertical positioning elements (e.g. spring elements). The material used in the sensor housing preferably has a very small coefficient of expansion, thereby minimizing unwanted expansion of the effective surface. In particular, the sensor housing is preferably made of a material such as PEEK with a high glass fiber content, which is selected to minimize material expansion. Unlike standard casting resins that lack temperature resistance and are commonly used in sensor manufacturing, the sensor of the present invention does not require the use of such resins. As a result, there is no need for waiting times for adhesive drying and resin curing, simplifying the manufacturing process. In addition, the present invention provides precise lateral positioning by means of lateral positioning elements (e.g. small diameter centering pins), and thereby prevents lateral displacement of the coil system during operation.

[0008] Furthermore, the inventors surprisingly discovered that the combination of a centering pin (i.e., a lateral positioning element) and a spring ring (i.e., a vertical positioning element) provides an advantageous system, wherein the lateral positioning element, in particular via the vertical positioning element, supports the tensile forces of the entire coil system. This force application is generated by the combination of the lateral positioning element and the vertical positioning element, i.e., in a narrower embodiment, by the interaction of the centering pin and the spring ring. The inventors have found this to be advantageous in preventing the bulging effect.

[0009] Thus, the present invention provides an inductive sensor with improved performance, manufacturability, and resilience to high operating temperatures.

[0010] The above objects of the present invention are achieved by an inductive sensor, a sensor system comprising a plurality of sensors and a method of assembling an inductive sensor according to the appended claims.

[0011] Preferred embodiments can be derived from the dependent claims and, apart from them, from the following description, particularly including the various embodiments covered and described in the appended claims.

[0012] The skilled person will understand that any embodiments described in the following description are covered and encompassed by the subject matter covered by the appended claims.

[0013] The embodiments, features and feature combinations described herein in connection with the invention and the feature combinations given in the appended claims as well as any combination of features mentioned and described in connection with the embodiments are to be considered disclosed herein, however, at least as derivable by a skilled person.

[0014] In particular, each feature and each combination of features in the embodiments as described herein may, for example, be claimed in different combinations (in particular different claim categories), at least because the skilled person will recognize that each and each combination of features mentioned herein is suitable for helping to solve the underlying problem.

[0015] Furthermore, each feature and each combination of features used in the claims and in the following description may be used and claimed independently of the corresponding claimed subject matter, independently of claim dependencies and back references, and independently of the claim class in which the feature is claimed. For example, it is contemplated that it may be used and claimed in any combination selected from one or more of the claims, from one or more of the embodiments as set forth below, and / or from the accompanying drawings.

[0016] The inductive sensor for detecting metal objects according to the present invention comprises at least:

[0017] a sensor housing having a first housing surface, which represents the active surface of the sensor;

[0018] - a coil system having a front face, wherein the front face is positioned rearwardly in front of the first housing surface, facing the rear housing surface;

[0019] - a vertical positioning element, wherein the vertical positioning element is configured and arranged to exert a force on the coil system in the direction of the active surface and the rear housing surface and preferably perpendicularly thereto, so that the front face of the coil system remains in direct contact with the rear housing surface of the sensor, wherein the vertical positioning element is formed by the sensor housing and / or is attached to the sensor housing.

[0020] The sensor housing is the physical structure or housing that houses the sensor's internal components. It has a first housing surface, which represents the sensor's active surface. This is the surface through which the sensor interacts with its environment to detect metal objects.

[0021] The coil system of the sensor of the present invention preferably represents the sensor's primary sensing component. It has a front face positioned rearwardly in front of the first housing surface and facing the rear housing surface. The coil system is responsible for generating the electromagnetic field used by the sensor to detect the presence of metal objects.

[0022] The vertical positioning element is a component that is configured and arranged to exert a force on the coil system in the direction of the active surface and towards the rear housing surface. This ensures that the front face of the coil system remains in direct contact with the rear housing surface of the sensor, regardless of any potential changes in temperature or other conditions that may cause it to move.

[0023] The vertical positioning element thus holds the coil system in contact with the active surface of the sensor.The vertical positioning element, which can be designed in particular as an elastic element or spring element, can compensate for reversible material expansions.

[0024] The sensor of the invention may also comprise at least one ferrite core, in particular as part of the coil system, which increases the inductance and enhances the sensitivity towards the front.

[0025] In this application, as used herein, terms such as "axial", "radial", "lateral", "vertical" or "laterally", "vertically", "rear", "front", "upper", "lower", "bottom", "relative", "inner", "outer" and the like describing the position of a first object relative to another object preferably refer to the relative position of the corresponding parts or objects relative to the position in which they are fully installed for their intended use.

[0026] In an advantageous embodiment of the sensor according to the invention, the inductive sensor according to the invention further comprises a lateral positioning element. This lateral positioning element is configured and arranged to ensure positioning of the coil system in any direction transverse (in particular radial) to the active surface, such that the front face of the coil system remains in a desired and predetermined position relative to the rear housing surface, wherein the lateral positioning element is preferably formed by the sensor housing and / or is attached to the sensor housing. Preferably, the lateral positioning element is formed by the rear housing surface and / or is attached to the rear housing surface.

[0027] Advantageously, this configuration of the sensor according to the present invention ensures that the front face of the coil system remains in the desired and predetermined position, particularly enabling the sensor to react correctly to the object being detected. In other words, the vertical and / or lateral positioning advantageously reduces the tolerances of the coil system and the corresponding measurement uncertainty of the sensor. Precise positioning of the coil system improves the efficiency of the sensor and ensures its responsiveness even with small lateral deviations.

[0028] It should be understood that "lateral" is preferably understood as a direction in a plane parallel to the active surface of the sensor. Since various sensor configurations and geometries can be implemented within the scope of the present invention, lateral is also preferably understood as a direction in the main plane of the sensor's coils. In particular, lateral can also refer to "radial," preferably if a radial coil system is used.

[0029] In an advantageous embodiment of the sensor of the present invention, the vertical positioning element and / or the lateral positioning element are formed by the sensor housing and / or are attached to the sensor housing. It will therefore be understood that the vertical positioning element can be formed by the sensor housing. Alternatively or additionally, the vertical positioning element can also be attached to the sensor housing. Thus, the integration of the vertical positioning element with the sensor housing can simplify the design, reduce components and enhance structural integrity. This can result in a more compact and robust sensor assembly. Regarding the lateral positioning element, this can also be formed by the sensor housing. Alternatively or additionally, the lateral positioning element can also be attached to the sensor housing. Similar to the vertical positioning element, integrating or attaching the lateral positioning element to the sensor housing can improve the overall stability and accuracy of the sensor. This can contribute to a more reliable and durable sensor construction.

[0030] In a further advantageous embodiment of the inductive sensor according to the invention, the sensor housing is provided in a multi-part form, comprising at least a main housing part and a coil cover part, and wherein the vertical positioning element and / or the lateral positioning element is formed by the coil cover part of the sensor housing and / or is attached to the coil cover part of the sensor housing.

[0031] This advantageously allows for greater flexibility and ease during the assembly process of the inductive sensor. By making the sensor housing multi-part, comprising at least a main housing portion and a coil housing portion, the individual components can be manufactured, handled, and assembled separately. This can simplify the manufacturing process, allow for more effective quality control of the individual components, and potentially reduce production costs.

[0032] Furthermore, having the vertical and / or lateral positioning elements formed by and / or attached to the coil housing portion of the sensor housing ensures secure and precise positioning of the coil system. This arrangement can enhance the reliability and accuracy of the sensor by maintaining proper alignment of the coil system, which is critical to its operation. It also simplifies the assembly process because the positioning elements are integrated into the coil housing portion of the sensor housing, thereby reducing the number of separate components that need to be assembled.

[0033] In a further advantageous embodiment of the inductive sensor according to the invention, the vertical positioning element comprises a spring element in order to exert a force on the coil system in the direction of the rear housing surface.

[0034] This advantageously ensures that the coil system maintains constant contact with the rear housing surface, which is critical to the correct operation of the sensor. A spring element in the vertical positioning component provides a consistent force that holds the coil system in place, even when environmental conditions such as temperature changes cause the material to expand. By using a spring element, the sensor can automatically adjust to these changes, maintaining the correct positioning of the coil system and ensuring accurate detection of metal objects. This design enhances the reliability and performance of the sensor, making it more suitable for varying operating conditions.

[0035] Preferably, the vertical positioning element and / or the lateral positioning element are positioned or attached rearwardly to the active surface in order to exert a force on the coil system in the direction of the active surface and the rear housing surface.

[0036] This advantageously ensures that the coil system is always correctly positioned relative to the sensor's active surface, which is crucial for accurate detection of metal objects. By positioning or attaching the vertical and / or lateral positioning elements rearwardly to the active surface, the elements exert a force on the coil system in the direction of both the active surface and the rear housing surface. This arrangement ensures that the front face of the coil system maintains direct contact with the rear housing surface, even under conditions that could cause material expansion, such as temperature fluctuations. This design enhances the sensor's reliability and accuracy, ensuring consistent performance under varying operating conditions.

[0037] According to the invention, the spring element can have various forms, in particular selected from the group consisting of a spring ring, a compression spring, a coil spring, a leaf spring, a spring washer, a diaphragm spring, a claw, a snap hook, a substantially elastic solid joint or a rubber spring.

[0038] Therefore, a skilled person will understand how to design or select the corresponding vertical positioning elements according to the intended purpose of the present invention. This advantageously provides flexibility in the design and function of the inductive sensor. Different types of spring elements can be selected based on specific application requirements, environmental conditions or desired sensor characteristics. For example, rubber springs can be used in environments where corrosion resistance is important, while disc springs can be selected for applications that require high load capacity in a small space. This versatility in spring element selection enhances the sensor's adaptability to a wide range of applications and operating conditions, thereby improving its overall performance and practicality. This also advantageously allows the sensor to be customized to a wide range of applications and operating conditions, thereby enhancing its versatility and performance. The ability to modify the geometry and material composition of the coil housing and spring element provides flexibility in the design and manufacture of the sensor, potentially leading to improved sensor characteristics and cost-efficiency.

[0039] In a further advantageous embodiment of the inductive sensor according to the invention, the lateral positioning element comprises a centering pin.

[0040] This advantageously ensures an exact positioning of the coil system within the sensor housing, which is crucial for accurate detection of metal objects. The lateral positioning element comprises a centering pin which can in particular work together with the coil cover or a corresponding housing part to position the coil system laterally, or even laterally and vertically.

[0041] The centering pin helps maintain the coil system in the correct lateral position, i.e., perpendicular to the sensor's axis, while the vertical positioning element provides support to maintain the correct vertical position, i.e., along the sensor's axis. This dual positioning mechanism ensures that the coil system is always perfectly aligned within the sensor housing, regardless of any external factors or conditions that might otherwise cause misalignment. Furthermore, the use of the centering pin simplifies the assembly process by providing a direct means of aligning and securing the coil system within the sensor housing. This can lead to efficiencies in the manufacturing process, potentially reducing production time and costs. Overall, using the centering pin as part of the lateral positioning element significantly enhances the reliability, accuracy, and manufacturability of the inductive sensor. In particular, in this configuration, the coil system can be advantageously designed to adjust to the centering pin. For example, the coil system can include a through-hole, particularly a central recess, through which the centering pin can be received. This is particularly preferred in embodiments where the centering pin has a threaded portion at its distal end to receive a nut configured to secure the coil system.

[0042] In an embodiment of the sensor according to the invention, the lateral positioning element can be configured in particular to fix the vertical positioning element. For example, in a particular embodiment, the centering pin serving as the lateral positioning element is also configured to hold and / or fix the spring element and thus simultaneously position the spring element vertically and prevent any lateral displacement.

[0043] In one advantageous embodiment, the centering pin is preferably a rigid element, but alternatively, it can also be elastic and / or designed to be flexible. In particular, the centering pin can be provided with a spring force, so that the centering pin itself also serves as a spring element. In particular, in one embodiment, the centering pin can be constructed and configured as a spring element to exert a force on the coil system in the direction of the rear housing surface. For this purpose, the centering pin can include an additional spring element, such as a spring latch or the like.

[0044] In another advantageous embodiment of the inductive sensor of the present invention, a vertical positioning element, particularly a spring element, is attached and / or fixed to a lateral positioning element, particularly a centering pin. This advantageously simplifies the assembly process and enhances the stability and reliability of the sensor. By attaching and / or fixing the vertical positioning element, particularly the spring element, to the lateral positioning element, particularly the centering pin, the two elements work together to maintain the precise positioning of the coil system. This combined positioning mechanism ensures that the coil system remains correctly aligned in both the lateral and vertical directions, which is crucial for accurate detection of metal objects. It also ensures that the coil system maintains constant contact with the rear housing surface, even under conditions that may cause material expansion, such as temperature fluctuations. Furthermore, this design reduces the number of separate components that need to be assembled, which can simplify the manufacturing process and potentially reduce production costs. It also enhances the structural integrity of the sensor, as the spring element and centering pin provide mutual support, thereby increasing the overall durability and lifespan of the sensor. Overall, attaching and / or fixing the spring element to the centering pin offers significant advantages in terms of sensor performance, reliability, and manufacturability.

[0045] In a further advantageous embodiment of the inductive sensor according to the invention, the sensor housing and / or the lateral positioning element, in particular the centering pin, comprise a threaded portion, and wherein the sensor housing and / or the vertical positioning element comprise a nut, wherein the nut serves to secure the coil system to the rear housing surface.

[0046] This advantageously allows for secure and adjustable attachment of the coil system within the sensor housing. A threaded portion on the sensor housing or lateral positioning element, particularly a centering pin, combined with a nut threaded onto the threads of the vertical positioning element, provides a means for precisely adjusting and securing the position of the coil system. This ensures that the coil system maintains constant contact with the rear housing surface, which is crucial for accurate detection of metal objects. Furthermore, this design simplifies the assembly process and enhances the overall reliability and durability of the sensor.

[0047] In a particularly preferred embodiment, the vertical positioning element is provided in the form of a spring ring, and the lateral positioning element is provided in the form of a centering pin. Thus, the centering pin can be attached to the rear housing surface, particularly the rear housing surface of the coil cover, allowing the coil to slide over the centering pin, followed by the spring ring and nut. Consequently, when the vertical positioning element applies a force on the coil system in the direction of the active surface and the rear housing surface, the nut secures the coil system, with the front face positioned rearwardly in front of the first housing surface, facing the rear housing surface and the spring ring, ensuring that the front face of the coil system remains in direct contact with the rear housing surface of the sensor. The centering pin serves as a lateral positioning element and ensures the correct positioning of the coil system in any direction transverse to the active surface, maintaining the front face of the coil system in the desired and predetermined position relative to the rear housing surface, allowing the sensor to react correctly to objects to be detected. This allows the initial spring force of the spring ring to be precisely adjusted by applying torque to the securing nut. In other words, the coil system is vertically guided on the centering pin and secured to the rear housing surface by the spring assembly comprising the spring ring and nut. This prevents lateral displacement of the coil system during operation. Despite any possible irreversible material expansion, the spring arrangement ensures that the end face of the coil system remains in contact with the housing rear wall.

[0048] The nut according to the invention can be provided in various forms and can in particular be selected from a flat hexagonal nut, a high hexagonal nut, a quick release nut, a square nut, a clamping strap, a flange nut, a crown nut, a cap nut, a butterfly nut, a ring nut, a slotted nut, a knurled nut, a slotted nut. The fixing method can be adapted or varied in terms of form, material and function. In principle, an alternative form of fixing can be used, for example, it can involve a screw or bolt with a thread, or a groove or notch, for example, provided at the distal end of the centering pin. Additionally or alternatively, the centering pin can be fixed using a spring washer, a retaining ring, a locking ring or a circlip, preferably instead of a conventional nut. Another possible embodiment comprises a centering pin equipped with a snap hook, wherein a washer-like component can be used instead of a nut to achieve the fixing. Furthermore, a centering pin featuring a bayonet closure is also conceivable.

[0049] In a further embodiment of the inductive sensor, precise lateral positioning is achieved by a centering pin having an inner diameter of the coil system that is smaller than the outer coil diameter or the housing diameter and has smaller tolerances.

[0050] In another advantageous embodiment of the inductive sensor of the present invention, a vertical positioning element, in particular a spring element, is positioned on and / or attached to the coil system, in particular to the rear of the coil system. This advantageously ensures that force is applied directly to the coil system, thereby enhancing the performance and reliability of the sensor. By positioning or attaching the vertical positioning element, in particular the spring element, to the coil system, the spring element can exert a direct force on the coil system, maintaining its correct positioning. This design ensures that the coil system maintains constant contact with the rear housing surface, which is crucial for accurate detection of metal objects. In addition, this arrangement simplifies the assembly process and reduces the number of separate components, potentially improving cost and time efficiency during the manufacturing process.

[0051] In another advantageous embodiment of the inductive sensor of the present invention, the coil system includes a through-hole, particularly a central recess, and the through-hole, particularly the central recess, includes a thread, preferably an internal thread. This advantageously provides a means for securely attaching and adjusting the coil system within the sensor housing. The through-hole, particularly the central recess, includes a thread, preferably an internal thread, allowing for precise adjustment of the coil system's positioning. This design ensures that the coil system maintains proper alignment within the sensor housing, which is crucial for accurate detection of metal objects. Furthermore, this arrangement simplifies the assembly process and enhances the overall reliability and durability of the sensor. This further allows the coil system to be screwed directly onto a corresponding component, particularly a centering pin, which has a corresponding mating counter-thread, such as an external thread. For example, a centering pin attached to or forming part of the coil housing can provide such a thread, and the coil system can be screwed directly onto the thread of the centering pin. Those skilled in the art will appreciate that, in such an embodiment, such a thread can provide a vertical positioning element. However, in such an embodiment, an additional spring element can also be advantageously used to compensate for, for example, reversible material expansion.

[0052] In another advantageous embodiment of the inductive sensor according to the invention, the sensor housing, in particular the main housing part and / or the coil cover part, is made of a material having a material expansion coefficient α of less than 125 ppm / K, preferably less than 100 ppm / K, more preferably less than 75 ppm / K, still more preferably less than 50 ppm / K, and most preferably less than 25 ppm / K.

[0053] In another advantageous embodiment of the inductive sensor according to the invention, the sensor housing, in particular the main housing part and / or the coil housing part, is produced from a material with a low material expansion coefficient α, in particular polyetheretherketone (PEEK) with a high proportion of glass fibers.

[0054] Those skilled in the art are aware of various methods for determining the material coefficient α. For PEEK with a 30% glass fiber content, a representative value for this material coefficient α is preferably approximately 18 ppm / K, which is particularly preferred and significantly lower than other materials. However, PEEK without glass fibers can also be used, which has a material coefficient α of approximately 60 ppm / K. In comparison, PTFE can exhibit a material expansion coefficient α of approximately 130 ppm / K. This advantageously enhances the performance and reliability of inductive sensors by minimizing the effects of temperature-induced material expansion. Using a material such as polyetheretherketone (PEEK) with a high proportion of glass fibers for the sensor housing, particularly the main housing portion and / or the coil housing, ensures that its structural integrity and dimensional stability are maintained even under varying temperature conditions. This material choice reduces the risk of misalignment of the coil system, which is crucial for accurate detection of metal objects. Furthermore, the use of this material can enhance the overall durability and lifespan of the sensor, making it more cost-effective in the long term. It should be understood that PEEK is particularly useful at the very high temperatures in which the sensor is used. Furthermore, PEEK is advantageous as a material that does not affect electromagnetic fields.

[0055] In another advantageous embodiment of the inductive sensor according to the invention, the sensor housing, in particular the main housing part and / or the coil housing part, is made of a material selected from plastics including etherketones and fluoroplastics, in particular PFA, PTFE and PEEK, preferably PEEK.

[0056] In another advantageous embodiment of the inductive sensor according to the present invention, the sensor housing, in particular the main housing portion and / or the coil housing portion, is made of a metallic material with low electrical conductivity and permeability, such as stainless steel or metallic glass. Such materials generally only slightly affect the sensor's electromagnetic field, especially at low operating frequencies. Coil housings made of ceramic can also be used within the scope of the present invention. Ceramic coil housings are hard and extremely temperature-resistant, but can also be brittle and are generally more difficult to process.

[0057] As referred to herein, "a high proportion of glass fibers" preferably means at least 15%, preferably at least 20%, more preferably at least 25%, most preferably at least 30%.

[0058] Those skilled in the art will immediately recognize that PEEK without glass fibers will have an expansion that is approximately 3 times higher. Ideally, the expansion should be zero, while other factors such as processability, chemical resistance, etc. may have to be considered in addition.

[0059] The material of the sensor housing, in particular the coil housing as part of the active surface, can be deliberately selected to minimize material expansion. In this respect, PEEK with a high proportion of glass fibers is preferred.

[0060] Compared to coil covers made of Teflon, the elastic-plastic material expansion caused by the backward force on the coil system can lead to significant bulging of the active surface, up to 1-2 mm in extreme cases, such as at high temperatures. In contrast, the inventors found that the bulging of the active surface made of PEEK was less than 0.1 mm. The bulging effect, as mentioned herein, can preferably be detected and determined as a flatness deviation, which can be determined tactilely and optically.

[0061] In a further advantageous embodiment of the inductive sensor of the invention, the sensor housing is provided in a multi-part form and at least one first housing part of the sensor housing comprises a fastening mechanism, preferably a bayonet locking mechanism, which is configured to attach the first housing part of the sensor housing to at least one second housing part of the sensor housing.

[0062] In another advantageous embodiment of the inductive sensor according to the present invention, the sensor housing is provided in a multi-part form, and at least one first housing part of the sensor housing comprises a fastening mechanism, preferably a thread, a snap hook, a bayonet locking mechanism, or the like, configured to attach the first housing part of the sensor housing to at least one second housing part of the sensor housing, wherein the second housing part of the sensor housing is preferably a coil cover part. Advantageously, the coil cover part may comprise threads provided on an outer inner diameter of the coil cover part.

[0063] In this configuration, it is particularly advantageous that the thread provided on the outer inner diameter of the coil housing portion can be formed as an integral part of the coil housing portion. This thread can advantageously engage with a corresponding counter-thread, for example, provided on the outer diameter of the coil system or a portion thereof. The thread and / or the coil housing portion of the sensor can be made of a suitable metal or plastic material, in particular glass fiber reinforced plastic. In one embodiment, the coil housing portion of the sensor housing can have a variety of shapes and forms, in particular selected from the group consisting of coil housing portions having a rectangular parallelepiped or cylindrical shape or a combination of both shapes.

[0064] A fastening mechanism (preferably a threaded or bayonet locking mechanism) that is arranged and configured to attach the first housing portion of the sensor housing to at least one second housing portion of the sensor housing advantageously simplifies the assembly and disassembly process of the inductive sensor, making it more user-friendly and maintenance-friendly. By providing the sensor housing with a fastening mechanism (preferably a threaded or bayonet locking mechanism) in a multi-part form, the different components of the sensor housing can be easily attached to or removed from each other. This can be particularly beneficial during maintenance or repair operations because it allows easy access to the internal components of the sensor. In addition, the use of a fastening mechanism (preferably a bayonet locking mechanism) ensures a strong and reliable connection between the different parts of the sensor housing, thereby enhancing the overall structural integrity and durability of the sensor. Therefore, the housing portion containing the coil system can be assembled by a simple rotational motion, and the coil system can be anchored in the second housing portion by a bayonet lock. In addition, a spring element can also be attached behind the coil system, i.e., away from the active surface of the sensor, to press the coil system onto the active surface of the sensor.

[0065] Additionally, centering pins with or without threads can be incorporated into the design.

[0066] This embodiment advantageously provides flexibility in the design and assembly of the inductive sensor. Including threads on the outer and inner diameters of the coil housing allows for precise adjustment and secure attachment of the coil system within the sensor housing. Using a suitable material for the threads, such as metal or certain types of plastic, can enhance sensor performance by minimizing potential issues associated with material expansion or swelling. However, those skilled in the art will appreciate that the material of such threads may have a smaller impact on swelling than the material of the coil housing and / or housing itself. Here, materials with favorable material expansion properties are selected, particularly for active surfaces. In particular, swelling is known in the prior art to primarily occur on the front and side surfaces of the coil housing in prior art sensors. Therefore, the inventors contemplated selecting a material for the coil housing that provides greater stability. For example, in one embodiment of the present invention, the housing, particularly the coil housing, is made of a material with a material expansion coefficient α of less than 125 ppm / K, preferably less than 100 ppm / K, more preferably less than 75 ppm / K, even more preferably less than 50 ppm / K, and most preferably less than 25 ppm / K. The most preferred material is PEEK.

[0067] The ability to shape the active surface represented by the coil housing into a cuboid, a cylinder, or a combination of the two, as well as the option of incorporating centering pins, provides versatility in the sensor design, allowing it to be tailored to specific application requirements. In a further advantageous embodiment of the inductive sensor according to the invention, the vertical positioning element, in particular in the form of a spring element, is formed as part of the rear housing surface or is attached to the rear housing surface.

[0068] This advantageously ensures that force is applied directly to the coil system, thereby enhancing the sensor's performance and reliability. By forming the vertical positioning element, particularly the spring element, as part of or attached to the rear housing surface, the spring element can exert direct force on the coil system, maintaining its correct positioning. This design ensures that the coil system maintains constant contact with the rear housing surface, which is crucial for accurate detection of metal objects. Furthermore, this arrangement simplifies the assembly process and reduces the number of separate components, potentially leading to cost and time efficiencies in the manufacturing process.

[0069] In such an embodiment, a spring element may be provided, in particular in the form of one or more snap hooks, clips or clamps, which has a sufficient spring action over the entire temperature range.

[0070] In another advantageous embodiment of the inductive sensor according to the invention, the vertical positioning element and / or the lateral positioning element, in particular the spring element, is made of metal. This advantageously ensures that a sufficient spring action is provided over the entire temperature range.

[0071] In another advantageous embodiment of the inductive sensor according to the present invention, the vertical and / or lateral positioning elements are formed as part of the sensor housing, preferably as an integral part, preferably as a component of the main housing portion and / or the coil housing portion. This integration is preferably achieved by injection molding, wherein the spring element or any attachment and alignment features for the spring element are seamlessly incorporated into the injection molding process. It is worth noting that the sensor housing, and in particular the coil housing, can be manufactured using injection molding technology, and the vertical positioning element, in particular the spring element or any attachment and alignment features for such a spring element, and / or the lateral positioning element, such as a threaded centering pin, can be formed as an integral component during the injection molding process.

[0072] The aforementioned problems are also advantageously solved by a sensor system comprising multiple sensors according to the present invention. This sensor system comprising multiple sensors is particularly provided for linear positioning. The sensors of this sensor system are inductive sensors according to the present invention. Thus, the sensor system can include the sensors according to the present invention as separate units or parts, or can include multiple sensors arranged on a joint printed circuit board (PCB). Thus, the coil system of this sensor system can include multiple sensors and / or multiple coils according to the present invention, each coil or coils having a front face positioned rearwardly in front of a first housing surface, facing the rear housing surface. Furthermore, in this system, at least one vertical positioning element is provided, configured and arranged to exert a force on at least one of the multiple coils of the coil system, or relative to a coil of a sensor included in the system. Regardless of whether the system comprises multiple coils or multiple sensors, the force exerted is applied in the direction of, and preferably perpendicular to, the active surface and the rear housing surface, such that the front face of the coil and / or coil system remains in direct contact with the rear housing surface of the sensor, wherein each vertical positioning element of the system is formed by and / or attached to the sensor housing.

[0073] This challenge is advantageously addressed by presenting a sensor system comprised of multiple sensors that seamlessly aligns with the principles of the present invention. This system is specifically designed for linear positioning, leveraging the innovative features previously described. The sensors within this system adhere to an innovative inductive sensor design, ensuring enhanced accuracy and reliability in linear positioning applications. Through this advantageous embodiment, the sensor system effectively addresses the challenges posed by integrating multiple sensors for linear positioning tasks as a comprehensive solution.

[0074] In a particularly preferred embodiment of the inductive sensor of the present invention, the sensor comprises a sensor housing, a coil system and a vertical positioning element, the sensor housing having a first housing surface, the first housing surface representing an effective surface of the sensor, the coil system having a front face, wherein the front face is positioned rearwardly in front of the first housing surface, facing the rear housing surface, the vertical positioning element being configured and arranged to exert a force on the coil system in the direction of the effective surface and the rear housing surface and preferably perpendicular to the effective surface and the rear housing surface, so that the front face of the coil system remains in direct contact with the rear housing surface of the sensor, wherein the vertical positioning element is formed by the sensor housing and / or is attached to the sensor housing, and wherein the sensor housing is provided in a multi-component form, comprising at least a main housing part and a coil cover part, and wherein the vertical positioning element and / or the lateral positioning element are formed by and / or attached to the coil cover part of the sensor housing, and wherein the vertical positioning element and / or the lateral positioning element are formed as part of the sensor housing, preferably as part of the main housing part and / or as part of the coil cover part.

[0075] The above-mentioned problem is also advantageously solved by the method for assembling an inductive sensor according to the present invention. The method for assembling an inductive sensor comprises at least the following steps:

[0076] - a step of providing a sensor housing having a first housing surface, said first housing surface representing an active surface of said sensor;

[0077] - providing the step of having the preceding coil system;

[0078] - positioning the coil system with its front face rearwardly in front of the first housing surface, facing the rear housing surface, so that the front face of the coil system is in direct contact with the rear housing surface of the sensor;

[0079] - a step of providing a vertical positioning element such that the vertical positioning element exerts a force on the coil system in the direction of the active surface and the rear housing surface;

[0080] - and the step of providing lateral positioning elements to ensure positioning of the coil system in any direction transverse to the active surface so that the front face of the coil system remains in an interesting and predetermined position relative to the rear housing surface.

[0081] The front face of the coil system remains in a focused and predetermined position relative to the rear housing surface, which in particular ensures that the sensor reacts correctly to the object to be detected.

[0082] It should be noted that the steps given above do not necessarily have to be performed in the order given. The steps provided may be performed in any other suitable order.

[0083] However, the sequence outlined above can be adapted to specific variations of the method. For example, in one embodiment, the step of providing the vertical positioning element, wherein the vertical positioning element is a spring element, can be performed after the step of positioning the coil system on the centering pin. However, in other embodiments, the steps of providing the vertical positioning element and providing the lateral positioning element can be performed during the injection molding process for manufacturing the housing part, and thus before the step of positioning the coil system.

[0084] Those skilled in the art will immediately recognize that features, embodiments, effects or advantages described herein in conjunction with the inventive inductive sensor and sensor system may also be features, embodiments, effects or advantages of the inventive method, respectively, and vice versa.

[0085] All described embodiments of the present invention offer the following advantages: The sensors of the present invention have improved applicability, particularly in the fields of automation technology and component motion detection, including lateral continuous motion. The sensors are capable of operating at temperatures up to 250°C and ensure accurate detection. A key advantage of this sensor is its ease of manufacturability. No adhesive drying or casting compound curing is required, eliminating waiting times. This is a significant improvement over standard casting resins that are not temperature-resistant. It also allows for precise positioning of the coil system in both vertical and lateral directions, ensuring that the sensor responds correctly to the object being detected. Even during operation and potential material expansion due to temperature, the coil system remains stably positioned, notably experiencing minimal lateral movement or positional shifts, and maintains contact with the rear wall of the housing. The sensor design thus advantageously ensures that the ferrite core is not pressed through the coil cap. The sensor does not require silicone or resin-based casting, making it more environmentally friendly by eliminating the use of such chemicals. This also simplifies the assembly process, as the coil system can be manufactured as a module together with the housing.

[0086] In general, the sensor design of the present invention ensures that the front face of the coil maintains constant contact with the active surface of the sensor. Temperature-induced material expansion is compensated by vertically positioned elements, particularly spring elements (if present). Preferred and recommended materials for the sensor have a very low coefficient of expansion, thereby minimizing undesirable expansion of the active surface.

[0087] The sensor design also prevents lateral displacement of the coil system during operation and allows precise lateral positioning via lateral positioning elements, particularly small-diameter centering pins. The combination of a spring element, for example in the form of a spring ring, and a centering pin with a thread for a fixing nut allows the initial spring force to be precisely adjusted via the torque applied to the fixing nut, thus providing additional flexibility and control in the operation of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] The invention will be described in more detail with reference to the accompanying drawings, from which further features, embodiments and advantages can be gathered, and in which:

[0089] Figure 1 A schematic overview of a prior art sensor is shown;

[0090] Figure 2A 、 2B , 2C and 2D show different views and representations of a sensor according to a first embodiment of the present invention;

[0091] Figure 3 A schematic diagram is shown of a second alternative embodiment of the present invention.

[0092] The features of the invention disclosed in the description, the claims, the examples and / or the drawings may, both individually and in any combination thereof, serve as material for realizing the invention in its various forms.

[0093] In the embodiments shown in the figures, functionally similar or identical elements are denoted by the same reference numerals. It should be noted that the figures may not be drawn to scale relative to each other. DETAILED DESCRIPTION

[0094] Figure 1 A schematic diagram of a prior art inductive sensor (1) for detecting metal objects is shown. The inductive sensor (1) comprises a sensor housing (4) having a first housing surface (41), the first housing surface (41) representing the active surface of the sensor (1). The sensor housing (4) is further divided into a main housing portion (42) and a coil cover portion (43). The sensor housing (4) is designed to protect the internal components of the sensor (1) from external factors. The coil system (2) is positioned within the sensor housing (4). The coil system (2) has a front face (21) ( Figure 1 Not shown, but similar to Figure 2D ), the front face (21) being positioned rearwardly in front of the first housing surface (41) and facing the rear housing surface (44). The positioning of the coil system (2) is crucial for the correct operation of the sensor (1).

[0095] The coil system (2) as used herein preferably refers to an arrangement comprising the coil itself and may in particular comprise other parts attached to and / or functionally associated with the coil, in particular a bobbin, i.e. a winding body, in Figure 2D As can be seen in , and the ferrite core (8). Figure 1 , a bodyless coil wound with self-bonding wire is shown, which uses a special winding technique to operate without a winding body.

[0096] from Figure 1As can be seen in the figure, the coil system (2) includes at least one ferrite core (8) and is attached to a PCB holder (9). The ferrite core (8) is designed to enhance the inductive properties of the coil system (2), while the PCB holder (9) provides structural support to the PCB relative to the coil system (2). A printed circuit board (PCB) (10) is also included in the sensor (1). The electronic circuitry on the PCB (10) is responsible for processing the signals received from the coil system (2) and converting them into useful data. The PCB (10) is housed within the sensor housing (4) for protection. The sensor (1) also includes an LED (12) for indicating the operating status of the sensor (1). The LED (12) provides a visual indication of the operating status of the sensor (1), thereby allowing easy troubleshooting. A seal (13) is provided to prevent dust or moisture from entering the sensor housing (4). The sensor (1) is also connected to a cable (17) for transmitting the processed data to an external device. The sensor (1) is designed to detect the presence of metal objects. When a metal object comes into the vicinity of the sensor (1), specifically the active surface (41), it changes the inductive characteristics of the coil system (2). This change is detected by the coil system (2) and the information is sent to the PCB (10) for processing. The processed data is then transmitted via the cable (17) to an external device for further analysis.

[0097] As can be clearly seen from the figure, the entire internal components, in particular the coil system (2), ferrite (8), PCB (10) and other components are embedded in the casting resin (18). Part of the coil system can also be glued to the rear housing surface (44) of the coil cover part (43) of the housing (4) with an adhesive (e.g., super glue) before potting. The coil is also usually glued into the core before assembly. In the following, such components are not shown in detail, and the focus will be on the features relevant to the explanation of the embodiments of the present invention.

[0098] Figure 2A 、 2B 2C and 2D show different views and representations of a sensor according to a first embodiment of the present invention. Figure 2A, shows in the form of a perspective schematic diagram an inductive sensor (1) for detecting metal objects according to the present invention in an assembled state. Thereby, the sensor (1) is mounted and fixed to a mounting structure (19). The mounting structure (19) can have various geometric shapes and can be customized according to the needs of the specific use of the sensor. In particular, the mounting structure (19) can have guiding and retaining structures to install the sensor for its intended use, and / or guide or install other components, such as cables (17) for the sensor (1) to communicate with corresponding electronic devices. In particular, when the sensor (1) of the present invention is used in a high temperature environment of about 250°C, it can be considered to place the corresponding electronic devices outside the high heat area and connect the sensor (1) with a longer cable (17). Figure 2B The sensor (1) is shown in a perspective rear view disassembled from the mounting structure (19), and Figure 2C The sensor (1) is shown in an exploded schematic diagram. Figure 2D is a schematic cross-section of the sensor (1) in the exploded view on the left and in the assembled view on the right. The inductive sensor (1) for detecting metal objects of the present invention comprises a sensor housing (4) having a first housing surface (41), the first housing surface (41) representing the effective surface of the sensor (1). The sensor housing (4) is further divided into a main housing part (42) and a coil cover part (43). In other words, the inductive sensor (1) comprises a sensor housing (4) provided in a multi-part form, which comprises at least a main housing part (42) and a coil cover part (43). A coil system (2) is accommodated in the housing (4), the coil system comprising a coil (2) and having a front face (21). From Figure 2D As best seen in FIG, the front face (21) is positioned rearwardly in front of the first housing surface (41) and faces the rear housing surface (44). Figure 2DAs can also be best seen in the figure, the sensor (1) comprises a vertical positioning element (5) in the form of a spring ring (5) which, when mounted, exerts a force F on the coil system (2) in the direction of the active surface (41) and the rear housing surface (44) so that the front face (21) of the coil system (2) remains in direct contact with the rear housing surface (44) of the sensor (1). In addition, a transverse positioning element (6) in the form of a centering pin (6, 61) is provided to ensure the positioning of the coil system (2) in any direction transverse to the active surface (41) so that the front face (21) of the coil system (2) remains in a desired and predetermined position relative to the rear housing surface (44) so that the sensor (1) reacts correctly to the object to be detected. The vertical positioning element (5) and / or the transverse positioning element (6) can both be formed by and / or attached to the coil housing portion (43) of the sensor housing (4). Here, the vertical positioning element (5) is attached to the coil housing portion (43) of the sensor housing (4), while the lateral positioning element (6) is formed as an integral part of the housing (4) by injection molding. In the illustrated embodiment of the invention, the lateral and vertical positioning of the coil system (2) is achieved by means of the coil housing (4, 43), wherein the centering pins (6, 61) are provided with threads (62). Accurate lateral positioning is achieved by the centering pins (6) having the inner diameter of the coil system (2), wherein the inner diameter is smaller than the outer coil diameter or the housing diameter and therefore exhibits smaller tolerances. The coil system (2) is guided vertically on the centering pins (6) and fixed to the rear housing surface (44) by means of a spring assembly (5), a spring ring (51) and a nut (52). This prevents lateral displacement of the coil system (2) during operation. The spring assembly (5) with the nut (52) ensures that, despite material expansion, which may also be irreversible, the front face (21) of the coil system (2) remains in contact with the housing rear wall (44). In the embodiment shown, the vertical positioning element (5) comprises the spring element (5), the spring ring (51) to exert a force F on the coil system (2) in the direction of the rear housing surface (44). It can also be seen that the vertical positioning element (5), in particular the spring element (51), is attached to and fixed to the transverse positioning element (6), in particular the centering pin (61). As already pointed out above, Figure 2CAs can be seen most clearly in the figure 2D, the sensor housing (4), in particular the lateral positioning element (6) in the form of a centering pin (61), comprises a threaded portion (62) onto which a nut (52) can be screwed to tighten the spring ring (5, 51), and whereby the nut (5, 52) also secures the coil system (2) to the rear housing surface (44). Alternative possibilities of securing are of course possible, as described herein in the general part of the description. Thus, as can be best seen from the right figure in 2D, in the assembled state of the sensor (1), the vertical positioning element (5), in particular the spring element (51), is positioned and attached to the coil system (2), in particular the rear part (22) of the coil system (2). In order to arrange the coil system (2) in the illustrated configuration with the central centering pin (6, 61), the coil system (2) comprises a through hole (23) in the form of a central recess (23). Still alternatively, the coil cover portion (43) may include threads disposed on an outer inner diameter of the coil cover portion (43), and thus, the coil cover portion may be screwed onto a correspondingly threaded mating portion of the housing.

[0099] The inventors have found that the sensor housing (4), in particular the main housing portion (42) and / or the coil housing portion (43), can be made more resistant to swelling caused by high temperatures. Therefore, it is advantageous to use materials that can reduce material expansion, in particular PEEK, especially materials with a relatively high proportion of glass fibers.

[0100] Figure 3 A schematic diagram of a second alternative embodiment of the invention is shown. Here, the housing (4) comprises the coil system (2). The sensor housing (4) can be provided in a multi-part form, and at least one first housing part (43) of the sensor housing (4) can comprise a fastening mechanism (7) in the form of a bayonet locking mechanism (7), which is configured to attach the first housing part (42) of the sensor housing (4) to at least one second housing part (43) of the sensor housing (4). The second housing part (43) can comprise corresponding engagement elements (71), here in the form of a pair of pins (71), wherein each engagement element (71) is arranged to engage with a corresponding part of the bayonet mechanism (7). Also in this configuration, the vertical positioning element (5) can be arranged as a spring element (5, 51), so that the coil system (2) is urged towards the first housing surface and the active sensor surface (41) of the sensor (1).

[0101] As an alternative to the bayonet locking mechanism, other fastening mechanisms may be provided, such as threads, snap hooks, etc., which are configured to attach the first housing part (42) of the sensor housing (4) to the at least one second housing part (43) of the sensor housing (4), wherein the second housing part (43) of the sensor housing (4) is preferably a coil cover part (43). Advantageously, the coil cover part (43) may include a thread provided on the outer inner diameter (31) of the coil cover part (43). In this configuration, it is particularly advantageous that such a thread provided on the outer inner diameter (31) of the coil cover part (43) can be formed as an integral part of the coil cover part and engage with a corresponding counter-thread, which is provided, for example, at the outer diameter of the coil system or a part thereof, or at the outer diameter of the first housing part (42) (here in addition to or instead of the bayonet locking mechanism (7)).

[0102] Furthermore, a centering pin (6) according to the embodiment shown in FIG. 2 is provided.

[0103] A major advantage of the present invention is that the coil system (2) can be mounted in the sensor without the need for casting resin or other bonding materials.

[0104] However, of course, outside the practice of the present invention, such resins or any other glueing materials may still be used in some embodiments.

[0105] The embodiments in the drawings may relate to preferred embodiments, whereas all elements and features described in connection with an embodiment may, where appropriate, be used in combination with any other embodiments and features discussed herein, in particular in connection with any other embodiments discussed further above.

[0106] Reference Signs List

[0107] 1 Inductive sensor

[0108] 2 Coil system

[0109] 21 front

[0110] 22 rear

[0111] 23 Central fovea

[0112] 31 Outer and inner diameter of coil cover

[0113] 4Sensor housing

[0114] 41 first housing surface, active sensor surface

[0115] 42 Main housing

[0116] 43 Coil cover

[0117] 431 coil cover surface

[0118] 44 rear housing surface

[0119] 5 vertical positioning elements

[0120] 51 Spring element

[0121] 52 Nut

[0122] 6 lateral positioning elements

[0123] 61 Centering pin

[0124] 62 threaded part

[0125] 7 Fastening mechanism, bayonet locking mechanism

[0126] 71 Joint elements

[0127] 8 ferrite cores

[0128] 9 PCB retainer

[0129] 10PCB

[0130] 11 Shell

[0131] 12LED

[0132] 13 seals

[0133] 17 Cables and electrical devices

[0134] 18 Casting resin

[0135] 19 Installation structure

Claims

1. An inductive sensor (1) for detecting a metal object, comprising: a sensor housing (4) having a first housing surface (41), said first housing surface (41) representing the active surface of said sensor (1); a coil system (2) having a front face (21), wherein the front face (21) is positioned rearwardly in front of the first housing surface (41) and faces the rear housing surface (44); A vertical positioning element (5), wherein the vertical positioning element (5) is configured and arranged to exert a force on the coil system (2) in the direction of the active surface (41) and the rear housing surface (44) and preferably perpendicular to the active surface (41) and the rear housing surface (44), so that the front face (21) of the coil system (2) remains in direct contact with the rear housing surface (44) of the sensor (1), wherein the vertical positioning element (5) is formed by the sensor housing (4) and / or is attached to the sensor housing (4).

2. The inductive sensor (1) according to claim 1 further comprises a lateral positioning element (6), which is configured and arranged to ensure the positioning of the coil system (2) in any direction transverse to, in particular radially to, the active surface (41), so that the front face (21) of the coil system (2) remains in a position of interest and predetermined relative to the rear housing surface (44), and wherein preferably, the lateral positioning element (6) is formed by and / or attached to the sensor housing (4), preferably by the rear housing surface (44).

3. The inductive sensor (1) according to any one of claims 1 or 2, wherein: The sensor housing (4) is provided in a multi-part form, comprising at least a main housing part (42) and a coil cover part (43), and wherein the vertical positioning element (5) and / or the lateral positioning element (6) are formed by and / or attached to the coil cover part (43) of the sensor housing (4).

4. The inductive sensor (1) according to any one of the preceding claims, wherein The vertical positioning element (5) comprises a spring element (51) for exerting a force on the coil system (2) in the direction of the rear housing surface (44).

5. The inductive sensor (1) according to any one of the preceding claims, wherein The transverse positioning element (6) comprises a centering pin (61).

6. The inductive sensor (1) according to any one of the preceding claims, wherein The vertical positioning element (5), in particular the spring element (51), is attached and / or fixed to the transverse positioning element (6), in particular the centering pin (6).

7. The inductive sensor (1) according to any one of the preceding claims, wherein The sensor housing (4) and / or the lateral positioning element (6), in particular the centering pin (61), comprise a threaded portion (62), and wherein the sensor housing (4) and / or the vertical positioning element (5) comprise a nut (52), wherein the nut (52) is used to fix the coil system (2) to the rear housing surface (44).

8. The inductive sensor (1) according to any one of the preceding claims, wherein The vertical positioning element (5), in particular the spring element (51), is positioned at and / or attached to the coil system (2), in particular to the rear portion (22) of the coil system (2).

9. The inductive sensor (1) according to any one of the preceding claims, wherein The coil system (2) comprises a through hole, in particular a central recess, and wherein the through hole, in particular the central recess, comprises a thread, preferably an internal thread.

10. The inductive sensor (1) according to any one of the preceding claims, wherein The sensor housing (4), in particular the main housing part (42) and / or the coil cover part (43), is made of a material having a material expansion coefficient α of less than 125 ppm / K, preferably less than 100 ppm / K, more preferably less than 75 ppm / K, even more preferably less than 50 ppm / K, and most preferably less than 25 ppm / K.

11. The inductive sensor (1) according to any one of the preceding claims, wherein The sensor housing (4) is provided in a multi-part form, and at least one first housing part of the sensor housing (4) comprises a fastening mechanism (7), preferably a threaded or bayonet locking mechanism, which is configured to attach the first housing part of the sensor housing (4) to at least one second housing part of the sensor housing (4), wherein the second housing part of the sensor housing (4) is preferably the coil cover part (43).

12. Inductive sensor (1) according to any of the preceding claims, preferably according to claim 11, wherein The coil cover portion (43) includes threads disposed on the outer and inner diameters of the coil cover portion (43).

13. The inductive sensor (1) according to any one of the preceding claims, wherein The vertical positioning element (5) and / or the lateral positioning element (6) are formed as part of the sensor housing (4), preferably as part of the main housing part (42) and / or part of the coil cover part (43), preferably as part of the rear housing surface (44).

14. A sensor system comprising a plurality of sensors, in particular sensors for linear positioning, wherein: The sensor is an inductive sensor (1) according to any one of the preceding claims.

15. A method for assembling an inductive sensor (1), the method comprising at least the following steps: - providing a sensor housing (4) having a first housing surface (41), said first housing surface (41) representing an active surface of said sensor (1); - providing a coil system (2) having a front face (21), - positioning the coil system (2) with the front face (21) located rearwardly in front of the first housing surface (41), facing the rear housing surface (44), so that the front face (21) of the coil system (2) is in direct contact with the rear housing surface (44) of the sensor (1); - providing a vertical positioning element (5) such that the vertical positioning element (5) exerts a force on the coil system (2) in the direction of the active surface (41) and the rear housing surface (44); and - Transverse positioning elements (6) are provided to ensure the positioning of the coil (5) in any direction transverse to the active surface (41) so that the front face (21) of the coil system (2) remains in a noted and predetermined position relative to the rear housing surface (44).

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