CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is the national stage of International Pat. App. No. PCT/EP2018/061673 filed May 7, 2018, and claims priority under 35 U.S.C. § 119 to DE 10 2017 211 190.9, filed in the Federal Republic of Germany on Jun. 30, 2017, the content of each of which are incorporated herein by reference in their entireties.

BACKGROUND

Numerous sensors are known from the related art that detect at least one rotation characteristic of rotating elements. Examples of such sensors are described in Konrad Reif (Ed.): Sensoren im Kraftfahrzeug [Sensors in the Motor Vehicle], 2ndedition, 2012, pp. 63-74 and 120-129. For example, a position of a camshaft of an internal combustion engine relative to a crankshaft having a so-called phase sensor can be determined using a Hall sensor.

A sensor wheel is typically mounted on the rotating axle. Teeth can be situated on the sensor wheel that are scanned by the Hall sensor when the camshaft rotates. Thus, a method is described in DE 10 2012 213 539 A1 for determining a phase position of an adjustable camshaft of an internal combustion engine that includes a sensor wheel and a camshaft adjuster. The phase position of the camshaft is determined based on phase flank interrupts triggered by the sensor wheel and by a model that is dependent on at least one operating parameter of the camshaft adjuster.

A system for position detection is described in US 2013/0057263 that includes an incremental track having a plurality of sectors and an ancillary measuring system. The measuring system includes at least two separate reading heads, each of which includes at least one primary coil and at least two separate secondary coils. The secondary coils generate output signals, the amplitude of which is modulated by the sectors of the incremental track.

SUMMARY

Despite the improvements effectuated by such sensor devices, there is still a potential for improvement. One challenge in the case of many known methods continues to be the enablement of a continuous position detection or of an absolute position determination. An absolute position determination is often possible only in a dynamic case, when the sensor wheel rotates. However, an instantaneous ascertainment of an angular position when switching on the power supply, i.e., a true power-on function, would be desirable. A position is often not exactly known, in particular, during a start of a motor of the internal combustion engine. A rotation speed measurement is often possible only after the passing of at least two tooth flanks. Moreover, such methods exhibit in many cases a high sensitivity to magnetic interference fields. In the case of methods, in which an angular position is determined and in the case of corresponding sensor devices, however, a complex computing algorithm is required in many cases in order to determine the rotation characteristic, for example, the angular position, based on the detected signals.

Within the scope of the present invention, therefore, a sensor system is provided for determining at least one rotation characteristic of a rotating element. A “sensor system” is understood within the scope of the present invention to mean, in principle, an arbitrary device that is suitable for detecting at least one measured variable. Accordingly, a sensor system for determining at least one rotation characteristic is understood to mean a sensor system that is configured to detect, for example, to measure, the at least one rotation characteristic, and which is able, for example, to produce at least one electrical signal corresponding to the detected characteristic such as, for example, a voltage or a current. Combinations of characteristics can also be detectable. A “rotation characteristic” is understood within the scope of the present invention to mean, in principle, a characteristic that at least partially describes the rotation of the rotating element. This can be, for example, an angular velocity, a rotational speed, an angular acceleration, an angular position, or another characteristic that is able to at least partially characterize a continuous, discontinuous, uniform, or non-uniform rotation or revolution of the rotating element. The rotation characteristic can, for example, be a position, in particular, an angular position, a rotational speed, an angular acceleration, or a combination of at least two of these variables. Other characteristics and/or other combinations of characteristics can also be detectable. An “angular position” is understood within the scope of the present invention to mean, in principle, a rotation angle of a device capable of rotating, for example, of the rotating element or of the sensor wheel, with respect to an axis located perpendicularly on the rotation axis.

The sensor system can be configured, in particular, for use in a motor vehicle. A “rotating element” is understood within the scope of the present invention to mean, in particular, an arbitrary element that rotates about at least one axis. The rotating element can, for example, be a shaft, for example, a shaft in a drive machine, for example, a camshaft or a crankshaft. An angular position of a camshaft or a rotational speed of a camshaft or an angular acceleration of a camshaft or a combination of at least two of these variables can be determined, for example. Other characteristics and/or other combinations of characteristics can also be detectable.

The sensor system for determining at least one rotation characteristic of an element rotating about at least one rotation axis includes at least one sensor wheel connectable to the rotating element. The sensor wheel can, for example, be permanently or reversibly connected or connectable to the rotating element or can also be designed together with the rotating element as one piece or can be integrated into the rotating element.

The sensor wheel has a sensor wheel profile. The sensor wheel profile can include, in particular, at least one profile element. The sensor system further includes an inductive position sensor. The inductive position sensor includes at least one coil arrangement. The coil arrangement includes at least one excitation coil, also referred to as a transmitter coil, and at least two receiver coils, also referred to as receiving coils. The at least two receiver coils can, for example, form at least one receiver coil system. One or multiple receiver coil systems can be provided, for example, each of which is assigned one or multiple receiver coil(s). One or two or also more receiver coil system(s) can be provided, each of which is assigned two or more receiver coils.

The sensor system can, for example, be configured to apply at least one alternating voltage and/or at least one alternating current to the at least one excitation coil, for example, via at least one corresponding controller. The alternating voltage and/or the alternating current can, for example, have a frequency in the range of several MHz, for example, a frequency in the range of 1 MHz to 50 MHz, for example, 2 MHz to 20 MHz, in particular, 3 MHz to 10 MHz, for example, 5 MHz. In this way, an electromagnetic alternating field can form that couples into the receiver coils where, for example, it induces corresponding alternating voltages and/or alternating currents.

A “sensor wheel” can be understood within the scope of the present invention to mean an arbitrary component connectable to the rotating element that, when connected to the rotating element, is configured to trigger at least one measurable signal, in particular, a magnetic field change, per revolution of the rotating element. A “sensor wheel profile” can be understood within the scope of the present invention to mean, in principle, an entirety of profile elements and of gaps situated between the profile elements. A “profile element” of the sensor wheel can be understood within the scope of the present invention to mean an arbitrary implementation of the contour of the sensor wheel, in particular, a convexity, for example, a pin-shaped, a tooth-shaped, or a serrated convexity, or a notch or a recess, for example, a hole.

The sensor wheel can, for example, be designed to “shadow” areas of the receiving coil structure, depending on its position. In this way, a coupling between the transmitter coil structure and the receiving coils can be influenced as a function of the rotation angle. A typical value range of a coupling factor can, for example, be −0.3 to +0.3. Thus, a coupling factor in this case can be understood to mean, in particular, an amplitude ratio between a receive signal and a transmitter signal or excitation signal. The coupling factor can extend, in particular, sinusoidally with the rotation angle.

The sensor system, for example, of an evaluation circuit, can be configured, in particular, in order to deduce an absolute value and a phase of the coupling by demodulating a signal induced in the receiving coils with a carrier signal, i.e., with a signal of the transmitter coil. The absolute value can vary, in particular, continuously with the rotation angle. A phase position can be 0° or 180°, for example. A preferably offset-free sine/cosine-system can be formed by multiplying the absolute value with the cosine, in particular when using two receiving coils having a 90° phase shift relative to the measuring range. When using three receiving coils typically having a 120° phase shift relative to the measuring range, a, in particular, three-phase sinus signal can be formed that can be transferred into a sine/cosine system, for example, by applying the Clarke transformation. The rotation angle can then be deduced using the ArcTan function.

An “inductive position sensor” can be understood within the scope of the present invention to mean an arbitrary sensor that is able to produce a signal corresponding to a detected characteristic, in particular, a measuring signal, in particular, an electrical measuring signal, for example, a voltage or a current, a production of the measuring signal being based on a change of the magnetic flux. The detected characteristic can include, in particular, a position, for example, an angular position. The inductive position sensor can, in particular, be an inductive magnetic sensor. However, other designs are, in principle, also possible.

A “coil arrangement” can be understood within the scope of the present invention to mean an arbitrary device that includes at least one coil. A “coil” is understood within the scope of the present invention to mean an arbitrary component that exhibits an inductivity and is suitable for generating a magnetic field when current is flowing and/or vice versa. A coil can, for example, include at least a complete or partially closed conductor loop or winding. An “excitation coil” can be understood within the scope of the present invention to mean a coil that generates a magnetic flux when an electrical voltage and/or an electrical current is applied. The excitation coil can include at least one excitation winding. An “excitation coil” is understood within the scope of the present invention to mean a coil that is designed due to an inductive coupling between the excitation coil and the receiver coil to generate a signal that is a function of the inductive coupling. A “receiver coil system” can be understood within the scope of the present invention to mean an arbitrary device that includes at least two, preferably at least three, receiver coils.

The receiver coils have a sinusoidal shape, at least in sections. “Sinusoidal” is understood within the scope of the present invention to mean an arbitrary shape that has a profile of a sine curve. A profile of a complete sine curve, for example, or merely a part of a sine curve, can be included. “Sinusoidal, at least in sections” in this case can be understood to mean, in particular, that the receiver coil has at least one section that has a sinusoidal shape. In addition, one or multiple sections can also be included that have no sinusoidal profile, for example, straight sections. The receiver coils can, for example, include at least one complete sine curve. A “complete sine curve” in this case can be understood to mean, in particular, a profile of a sine curve that includes at least one period. In this case, the sine curve can begin at point zero or at an arbitrary other point of the sine curve. In general, slight deviations from the sinusoid are also possible in a sinusoidal profile. For example, deviations can be tolerated that in each point amount to not more than 20%, in particular, not more than 10% or even not more than 5% of the absolute value of the sinusoid. Thus, for example, the sinusoid can also be composed in sections of other functions, so that on the whole an approximate sinusoid results. For example, sections of the sinusoid can be composed of circular strip conductor sections. The sinusoid can thus be composed, for example, of circular arc sections, for example, of semicircles placed against one another and opened opposite one another.

At least one of the receiver coils can include, in particular, at least two partial windings. One partial winding in this case can have a shape that includes at least one complete sine curve, in particular, also exactly one sine curve. The successive partial windings of a receiver coil can directly succeed one another. Successive partial windings can, in particular, also be connected, for example, by a straight or non-curved section. Successive partial windings can have, in particular, the same period. Successive partial windings can have, in particular, the same amplitude, for example. Successive partial windings of a receiver coil can, in particular, be inversely oriented. Successive partial windings of a receiver coil can, in particular, be inversely oriented in such a way that the partial windings intersect at least at one point. The intersecting partial windings can, in particular, pass over one another so that the two intersecting partial windings do not touch at the point of intersection.

In addition to the receiver coils, signals can also be sinusoidal. The receiver coils can, in particular, be situated in such a way that the receiver coils generate sinusoidal signals when the rotating element rotates at a constant angular velocity about the rotation axis. In terms of the definition “sinusoidal,” reference can also be made to the definition above with respect to the signals, in this case, for example, a spatial dimension being replaced by a time dimension.

The sensor system can include a number ‘n’ of receiver coils, n being a positive integer. The generated sinusoidal signals of the n receiver coils can be phase-shifted against one another. For example, adjacent sinusoidal signals can have a phase spacing of 2π/(2π) and/or 360°/(2π) for n=2. Adjacent sinusoidal signals can, for example, also have a phase spacing of 2π/(n) and/or 360°/(n) for n≥3. Adjacent sinusoidal signals of exactly two receiver coils can, in particular, have a phase spacing of 90°. Adjacent sinusoidal signals of exactly three receiver coils can, in particular, have a phase spacing of 120°.

The at least one coil arrangement can be situated on at least one circuit carrier. A multitude of coil arrangements can, in particular, also be situated on a shared circuit carrier. The circuit carrier can be situated essentially coaxially relative to the rotation axis. The circuit carrier can surround the sensor wheel or a circular segment of the sensor wheel essentially circularly or circularly segmented. The term “essentially circularly” is understood within the scope of the present invention to mean that the described component has a radius of curvature. The radius of curvature can vary within the component by a value from 0% to 80%, preferably from 0% to 50%, more preferably from 0% to 20% and particularly preferably from 0% to 5%. The radius of curvature can, in particular, also be constant. Alternatively or in addition, the circuit carrier can be composed of two or more segments, each of which can be designed flat or also curved, for example, and which can be connected to one another, for example. The segments can then also all be situated coaxially relative to the rotation axis, even if the individual segments are then situated tangentially, for example.

The coil arrangement, in particular, the coil arrangement situated on the circuit carrier, can surround the sensor wheel or at least a circular segment of the sensor wheel essentially circularly segmented or circularly. The coil arrangement, in particular, the coil arrangement situated on the circuit carrier can, in particular, cover at least one profile element and at least one gap between two profile elements of the sensor wheel in at least one angular position of the sensor wheel.

The circuit carrier can be flexibly designed. The circuit carrier can, in particular, include a flexible material. The circuit carrier can, in particular, be selected from the group made up of: a circuit board, in particular, a Starrflex circuit board, for example, a curved Starrflex circuit board; a rigid circuit board, in particular, a rigid circuit board with notches; a circuit card; and a board and a printed circuit, in particular a “printed circuit board” (PCB). The circuit carrier can, in particular, include at least two flat surfaces. The flat surfaces can be situated at an angle to one another. The circuit carrier can, in particular, include at least one connecting element, the connecting element connecting the flat surfaces to one another. The flat surfaces can, in particular, encompass an angle, the angle being able to have a value of 10° to 180°, preferably of 30° to 150° and particularly preferably of 60° to 120°. The circuit carrier can also be situated in a housing, in particular, in an injection molded housing.

The sensor system can be configured to detect an inductive coupling and/or a change of an inductive coupling between the excitation coil and the at least one receiver coil. The sensor system can be configured, in particular, to detect an inductive coupling caused by a movement and/or a position of the sensor wheel and/or by the change of the inductive coupling between the excitation coil and the receiver coils caused by a movement and/or a position of the sensor wheel. For this purpose, the sensor system can, for example, include a corresponding evaluation unit. The evaluation unit can, in particular, include at least one evaluation circuit. The evaluation circuit can, in particular, be configured to evaluate the signals of the position sensor. The evaluation circuit can, for example, be a processor. The evaluation unit can be situated together with the at least one coil arrangement on a shared circuit carrier. The evaluation unit can also be situated separately from the at least one coil arrangement.

The sensor system can be configured, in particular, to determine an absolute or relative angular position of the rotating element based on the change of the inductive coupling between the excitation coil and the receiver coils caused by the movement and/or by a position of the sensor wheel. A “relative angular position” in this case can be understood to mean, in principle, a position with respect to a period defined by the receiver coils.

The sensor system can be configured, in particular, to enable a detection of the absolute or relative angular position of the rotating element when switching on a power supply. The sensor system can enable, in particular, a detection of the angular position of the momentarily idle rotating element. This characteristic of the detection when switching on the power supply can also be referred to, in particular, as a “true-power-on” function. Thus, the sensory system can include, in particular, a “true-power-on” function.

The sensor system can include a single sensor wheel or also a multitude of sensor wheels. The sensor system can include, in particular, two sensor wheels. The at least two sensor wheels can, in particular, be situated offset to one another with respect to the rotation axis, i.e., for example, with an axial offset. The at least two sensor wheels can have identical or, in particular, also different sensor wheel profiles.

The sensor system can include at least two, preferably at least three receiver coils. In addition, each of the at least two receiver coils can cover at least one profile element and at least one gap between two elements of the sensor wheel in at least one angular position of the sensor wheel.

The at least two sinusoidal-shaped receiver coils of the sensor system can be situated phase-shifted relative to one another.

The at least two sinusoidal receiver coils can have, in particular, identical periods.

The periodicities of the sinusoidal receiver coils can, in particular, correspond to an integer multiple of an angular distance ß between two adjacent profile elements of the sensor wheel. An “integer multiple” in this case can be understood in general to mean a multiplication with a positive whole number ‘m’ that can also be one, for example.

Exactly two receiver coils can, in particular, also exhibit a phase shift relative to one another. The phase shift of exactly two receiver coils can, in particular, correspond to an integer multiple ‘m’ of the angular distance ß/4. The phase shift of a first receiver coil relative to a second receiver coil can, in particular, correspond exactly to an angular distance of ß/4.

Exactly three receiver coils can, in particular, also exhibit a phase shift relative to one another. The phase shift of exactly three receiver coils can, in particular, correspond to an integer multiple ‘m’ of the angular distance ß/3, for example, to the aforementioned integer multiple m. The phase shift of a first receiver coil relative to a second receiver coil, as well as the phase shift of a second receiver coil relative to a third receiver coil can, in particular, correspond in each case to exactly one angular distance of ß/3.

The sensor system can include a number of ‘n’ receiver coils. Adjacent receiver coils can, in particular, also exhibit a phase shift. The phase shift of n receiver coils of a sensor system can, in particular, correspond to an integer multiple m of the angular distance ß/(2π) for n=2 and/or ß/(n) for n≥3, for example, to the aforementioned integer multiple m.

The sensor system can include an evaluation circuit. The evaluation circuit can be configured, in particular, in such a way that an angular position Φ of the sensor wheel can be deduced from the signals of the receiver coils. The evaluation circuit can be configured, in particular, in such a way that it generates at least one quotient of at least two signals of at least two receiver coils. For example, the law tan Φ=sin Φ/cos Φ can be used for calculating the angular position Φ based on two signals generated by two receiver coils. For example, the Clarke transformation can be used for calculating the angular position Φ based on three signals generated by three receiver coils.

The coil arrangement of the sensor system can include a multitude of receiver coil systems. The coil arrangement can, in particular, include at least two receiver coil systems. The at least two receiver coil systems can, for example, be assigned a shared excitation coil. Alternatively or in addition, exactly one receiver coil system can also be assigned exactly one excitation coil.

The excitation coil can, in particular, enclose the receiver coil systems assigned to it. For example, an excitation coil can enclose exactly one receiver coil system assigned to it. For example, an excitation coil can also enclose at least two receiver coil systems assigned to it.

The receiver coil systems can be situated in parallel to one another in the circumferential direction and can be axially offset relative to one another with respect to the rotation axis. The receiver coils within a receiver coil system can each have the same periodicity. However, the periodicities of receiver coils of different receiver coil systems can, in particular, differ. Each of the receiver coil systems can be assigned a separate sensor wheel. A first receiver coil system can, in particular, be assigned a first sensor wheel. The first sensor wheel can, for example, have an angular distance ß1between two adjacent profile elements of the first sensor wheel. The first receiver coil system assigned the first sensor wheel can have a periodicity in this case. The periodicity of the first receiver coil system can, in particular, correspond to an integer multiple of ß1. A second receiver coil system can, in particular, be assigned a second sensor wheel. The second sensor wheel can, for example, have an angular distance ß2between two adjacent profile elements of the second sensor wheel. The second receiver coil system assigned the second sensor wheel can have a periodicity in this case. The periodicity of the second receiver coil system can, in particular, correspond to an integer multiple of β2. The angular distance ß2between adjacent profile elements of the second sensor wheel can differ from the angular distance ß1between two adjacent profile elements of the first sensor wheel.

The sensor system can be configured to offset the signals of the receiver coil systems against one another according to the Nonius principle, each of which can be assigned a separate sensor wheel. The offsetting of the signals of the receiver coil systems according to the Nonius principle can in this case enable a conclusion to be drawn about an absolute angular position of the rotating element. For example, a first single angle calculated from the signals of the first receiver coil systems can have a size 2π/k, with a natural number k. For example, a second single angle calculated from the signals of the second receiver coil system can have a size 2π/j with a natural number j≠k. For example, an absolute angular position in the range of up to 2π can be deduced from the first single angle and from the second single angle. It can, in particular, be possible that an angle in the range of up to 360° can be deduced from two single angles, each of which are a maximum of 360°/k (with a natural number k) and 360°/j (with a natural number j, where j≠k) in size.

In another aspect of the present invention, a method is provided for determining at least one rotation characteristic of an element rotating about at least one rotation axis. The method includes the use of at least one sensor system. The method includes the following steps, preferably in the order indicated. In addition to the cited method steps, the method can also include additional method steps.

The method steps are: receiving at least two inductive signals using at least two receiver coils; and evaluating the inductive signals and ascertainment of the rotation characteristic using the inductive signals.

The method takes place using a sensor system according to the present invention, i.e., according to one of the aforementioned example embodiments or according to one of the example embodiments described in greater detail below. Accordingly, reference can largely be made to the description of the sensor element for definitions and for optional designs. However, other designs are, in principle, also possible.

The inductive signals of the inductive position sensor can include, in particular, at least one signal selected from the group made up of the inductive coupling in the coil arrangement and of the change of the inductive coupling in the first coil arrangement. The inductive signals can, in particular, be voltage signals, in particular, voltages generated in the receiver coils. The voltages can, in particular, be generated in the receiver coils due to the inductive coupling of the receiver coils with the at least one excitation coil. The inductive coupling and/or the change of the inductive coupling in the coil arrangement can, in particular, be a function of a movement and/or of a position of the sensor wheel. The method can further include a determination of the angular position of the rotating element using the detected inductive coupling and/or change of the inductive coupling in the first coil arrangement as a function of the position and/or movement of the sensor wheel.

The method can further include the processing of the inductive signals by an evaluation circuit. The method can further include the forwarding of the inductive signals to a control unit, for example, to a processor. The method can further include an ascertainment of the rotation characteristic, for example, of the angular position, using an evaluation of the inductive signals.

The provided device and the provided method have numerous advantages over known devices and methods. It is possible, in particular, that the sinusoidal signals generated according to the present invention using the receiver coils reduce the complexity of ascertaining at least one rotation characteristic, in particular, the angular position Φ, as compared to the related art. It can be possible, in particular, that the calculation, in particular, the back transformation, can be simplified as compared to the related art by using a calculation rule, for example, the Clarke transformation and/or for example, the law tan Φ=sin Φ/cos Φ.

The generation according to the present invention of the sinusoidal signals using the sinusoidal-shaped receiver coils can, in particular, reduce the complexity of the measuring principle as compared to the related art. It is possible, in particular, that the sensor system according to the present invention includes a simple measuring principle.

In addition, the sensor system can exhibit a very high sensitivity as compared to the related art. Using the sensor system according to the present invention, it is possible to enhance the reliability of the ascertained values of the at least one rotation characteristic, in particular, of the angular position Φ, as compared to the related art. In addition, the values of the at least one rotation characteristic, in particular, of the angular position Φ, ascertained using the sensor system according to the present invention, can be subject to no influence or very little influence by magnetic interference fields. An influence of magnetic fields on the sensor system according to the present invention due to high currents through electrically conductive materials, in particular, cables, situated close to the sensors can, in particular, be reduced.

The sensor system according to the present invention can provide a significant advantage in installation and removal, in particular, as compared to the related art, in particular, in the utilization of the sensor system according to the present invention for camshaft position detection. Thus, it is possible, in particular, that deviations in the shaping, in particular, manufacturing-related deviations of the geometrical shape, in particular, mechanical tolerances of the components surrounding the sensor system, have no influence on the functionality of the sensor system. Greater mechanical tolerances, in particular, can be permitted as compared to the tolerances usually permitted in the related art, in particular, in the installation of the sensor system. The sensor system according to the present invention could, in particular, be robust regarding tolerances as compared to the related art.

In addition, the provided sensor system can have significantly smaller required installation space as compared to the related art. Moreover, the sinusoidal shaping of the receiver coils generally results in no additional costs. Thus, the sensor system according to the present invention can, in particular, be cost-efficiently designed.

In addition, a measuring range of the sensor system according to the present invention can be expanded to 360° by an evaluation using two or multiple sensor wheels and/or different sensor wheel profiles, in particular, a different number of teeth to include a detection of the angular position, in particular, an absolute angle detection, of a sensor wheel and/or of a rotating element, in particular, of a wave position. A precise measurement can take place, for example, using the Nonius principle or of the Vernier method. The coil arrangement, in particular, the coil arrangement situated on the circuit carrier, can, in particular, cover at least one profile element and at least one gap between two profile elements of the sensor wheel in at least one angular position of the sensor wheel. An opening angle α of the coil arrangement can, in particular, correspond at least to an opening angle ß of the circular segment of the sensor wheel covered by the coil arrangement, encompassing at least one profile element and at least one gap between two profile elements.

In addition, the provided sensor system can enable an availability of the angular position of the rotating element when switching on a power supply. The sensor system according to the present invention can, in particular, have a true-power-on function. A true-power-on function is increasingly demanded by many original equipment manufacturers (OEM).

In addition, the provided device can permit the application of a multitude of methods for determining at least one rotation characteristic such as, for example, the rotational speed or the angular velocity. It can prove advantageous to employ a multitude of such methods, for example, to check a value obtained with a method.

Additional optional details and features of the present invention result from the following description of example embodiments that are schematically depicted in the figures.

