Valve drive with position sensor

Abstract

The invention relates to a valve drive having a valve slide (2) which can be displaced along a movement axis (100) between a first end position and a second end position, a transmission element (3) which is coupled to the valve slide (2) and can be moved along the movement axis (100) by a drive unit, a sensor element (4) having a sensor region (5), wherein an excitation coil (6) and at least one receiving coil (7, 8) are located within the sensor region, and a control unit designed to actuate the excitation coil (6) and / or evaluate the receiving coil (7, 8), wherein the valve slide (2) and / or the transmission element are electrically conductive, wherein a degree of overlap of the valve slide (2) and / or of the transmission element (3) with the sensor region (5) along the movement axis increases as the valve slide (2) and / or the transmission element (3) move progressively from the first end position to the second end position, and wherein the control unit is designed to detect the degree of overlap and to determine a position of the valve slide (2) and / or of the transmission element (3).

Description

[0001] Valve actuator with position sensor

[0002] Description

[0003] The invention relates to a valve drive. The valve drive has a position sensor. In particular, the valve drive does not require additional detection elements for the position sensor.

[0004] Position sensors are known from the prior art. These include, for example, an excitation coil in the form of a conductor track on a circuit board. The excitation coil generates a changing magnetic field, which in turn induces a voltage in a sinusoidal and a cosinusoidal receiving coil, which is also designed as a conductor track, for example. If a detection element is located on this arrangement, eddy currents are induced due to the changing magnetic field of the excitation coil. The eddy currents counteract the induced voltage in the excitation coils, allowing the position of the detection element to be determined.

[0005] The position sensor is designed so that the detection element always covers a constant portion of the coils and is moved along the coils. This results in a substantially linear behavior of the detection sensor.

[0006] The object of the invention is to provide a valve actuator with a position sensor that enables reliable position detection with simple and cost-effective production and assembly.

[0007] This problem is solved by the features of the independent claim. The subclaims contain preferred developments of the invention.

[0008] The valve drive comprises a valve spool, a transmission element, and a sensor element. Preferably, the valve spool and transmission element are rigidly connected to one another or formed integrally. The valve spool is displaceable along a movement axis between a first end position and a second end position. The transmission element is movable along the movement axis by a drive unit and coupled to the valve spool. The transmission element is, in particular, a toothed rack. The sensor element has a sensor region, with an excitation coil and at least one receiving coil arranged within the sensor region. The sensor region is, in particular, a predefined area within which said coils are arranged. The valve drive also comprises a control unit. The control unit is designed to control the excitation coil and / or evaluate the receiving coil.The valve spool and / or the transmission element are electrically conductive. Furthermore, it is provided that the valve spool and / or the transmission element are guided over the sensor area of ​​the sensor element. The degree of overlap of the valve spool and / or the transmission element with the sensor area along the movement axis increases with increasing movement of the valve spool and / or the transmission element from the first end position to the second end position. In other words, each degree of overlap is characteristic of a position of the valve spool and / or the transmission element between the first end position and the second end position. The degree of overlap changes with the movement of the valve spool and / or the transmission element between the first end position and the second end position and is particularly advantageous because it is never the same for different positions of the valve spool and / or transmission element.

[0009] The control unit is designed to detect the degree of overlap. Because the degree of overlap is characteristic of the position, the control unit is designed to determine a position of the valve spool and / or the transmission element from the degree of overlap. In particular, the control unit is designed to generate a changing magnetic field using the excitation coil. This in turn induces an electrical voltage in the receiving coil. If the valve spool and / or the transmission element is located above the sensor area, the magnetic field is impaired. Eddy currents are induced in the valve spool and / or transmission element, which counteract the magnetic field of the excitation coil. This allows lower electrical voltages to be induced in the receiving coil. The degree of overlap can be determined by evaluating the receiving coil.

[0010] The valve actuator therefore allows the position of the valve spool and / or the transmission element to be determined directly without the need for additional components. In particular, it is not necessary to provide separate detection elements that are detected by a sensor. The valve actuator is therefore designed to save space, while at the same time allowing the valve position to be reliably detected based on the position of the valve spool and / or the transmission element.

[0011] The excitation coil and / or the receiving coil are preferably formed as conductor tracks on a substrate. This makes the coils easy to manufacture. The excitation coil and / or the receiving coil are preferably designed two-dimensionally. This enables detection of the position of the valve spool and / or the transmission element. The substrate is particularly preferably part of the control unit. Thus, the sensor element is particularly integrated into the control unit. For example, a circuit board can be manufactured for the control unit, and the coils of the sensor element can also be manufactured in the same way. This achieves simple and cost-effective production on the one hand, and a compact design on the other.

[0012] Particularly preferably, the excitation coil encloses the receiving coil on the substrate. In particular, the sensor area is defined by the excitation coil. Furthermore, an electrical voltage can be induced more easily and reliably in the receiving coil, thus achieving a reliable and precise measurement.

[0013] At least two receiving coils are advantageously arranged in an overlapping manner. Furthermore, the excitation coils are electrically insulated from each other. This allows precise and reliable detection of changes in the degree of coverage.

[0014] Preferably, the degree of coverage in the first end position is greater than 0%. Alternatively or additionally, the degree of coverage in the second end position is less than 100%. This ensures that any movement of the valve spool and / or transmission element can lead to a change in the degree of coverage. In particular, the sensor area is not completely covered or not covered at all.

[0015] Advantageously, the sensor region has a first end and a second end along the movement axis. The receiving coil has a supply conductor running from the first end to the second end and a return conductor running from the second end to the first end. The supply conductor and the return conductor form a continuous loop, with the supply conductor and the return conductor overlapping in an electrically insulated manner at at least one intersection point. In this way, a voltage can be optimally induced in the receiving coil, whereby a lower than expected induced voltage can be reliably detected. If the voltage is lower than expected, the degree of overlap corresponding to the reduction can be reliably determined.

[0016] Particularly advantageously, a first receiving coil and a second receiving coil are provided. The first receiving coil has, starting from the first end or second end, a sinusoidal first feed conductor and a sinusoidal first return conductor. The second receiving coil is different from the first receiving coil. The second receiving coil has a cosinusoidal second feed conductor and a cosinusoidal second return conductor. The use of two receiving coils makes it possible, in particular, to calculate out interfering magnetic fields. This leads to an improvement in the accuracy of the measurement results. The sinusoidal shape and / or cosinusoidal shape is preferably stretched and / or compressed. As a result, an electrical voltage induced in the receiving coils exhibits, in particular, a linear change when the degree of coverage changes. This simplifies the evaluation of the induced voltage and the determination of the degree of coverage.This also leads to an accurate determination of the valve position.

[0017] The at least one receiving coil is designed symmetrically with respect to a center point of the sensor surface. In particular, all existing receiving coils are designed symmetrically with respect to the center point. This allows for simple and reliable evaluation and determination of the degree of coverage.

[0018] Preferably, the valve spool and / or the transmission element completely cover the sensor area in the transverse direction, perpendicular to the movement axis. This ensures maximum coverage in the transverse direction at all times. This leads to an optimally measurable influence on the magnetic field of the excitation coil by the valve spool and / or the transmission element.

[0019] Further details, advantages, and features of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawings. It shows:

[0020] Fig. 1 is a schematic view of a valve drive according to an embodiment of the invention,

[0021] Fig. 2 is a schematic view of a sensor element of the valve drive according to the embodiment of the invention, which is covered by a valve slide,

[0022] Fig. 3 is a schematic view of a first alternative of a sensor element of the valve drive according to the embodiment of the invention,

[0023] Fig. 4 is a schematic view of a second alternative of a sensor element of the valve drive according to the embodiment of the invention,

[0024] Fig. 5 is a schematic view of a first alternative of a measuring arrangement of the valve drive according to the embodiment of the invention,

[0025] Fig. 6 is a schematic view of a second alternative of a measuring arrangement of the valve drive according to the embodiment of the invention, and

[0026] Fig. 7 is a schematic view of a third alternative of a measuring arrangement of the valve drive according to the embodiment of the invention.

[0027] Figure 1 schematically shows a valve drive 1 according to an embodiment of the invention. The valve drive 1 has a valve spool 2, which is displaceable along a movement axis 100 between a first end position and a second end position. The valve spool serves in particular for adjusting a valve position of a valve, for example, a hydraulic valve.

[0028] A transmission element 3 is coupled to the valve spool 2. In the illustrated embodiment, the transmission element 3 is a rack. The valve spool 2 and the transmission element 3 are preferably rigidly connected to one another, whereby the transmission element 3 can be moved together with the valve spool 2. The valve drive 1 also has a drive unit 10, wherein the transmission element 3 can be moved by the drive unit 10 along the movement axis 100. In this way, the valve spool 2 is driven. In the illustrated embodiment, the drive unit 10 is a rotary motor, wherein the transmission element 3, designed as a rack, engages with a toothing of the drive unit 10, in particular with a gear or pinion of the drive unit 10. Movement of the transmission element 3 and the valve spool 2 preferably occurs only translationally along the movement axis 100.

[0029] The valve drive also has a sensor element 4 and a control unit 9. The sensor element 4 has a sensor region 5, wherein an excitation coil 6 and at least one receiving coil 7, 8 are arranged within the sensor region 5, which will be explained below with reference to Figures 2 to 4. The control unit 9 is designed to control the excitation coil 6 and / or evaluate the receiving coil 7, 8.

[0030] Figure 2 schematically shows how the valve spool 2 and / or transmission element 3 are detected by means of the sensor element 4. Figure 3 shows the sensor element 4 without the valve spool 2 and transmission element 3. In the example shown in Figure 2, only the valve spool 2 is detected by the sensor element 4, but not the transmission element 3. Details of this are explained below with reference to Figures 5 to 7.

[0031] The sensor element 4 has a sensor region 5, which is surrounded by the excitation coil 6. Within the sensor region 5 there is at least one receiving coil 7, 8, wherein in the illustrated embodiment, a first receiving coil 7 and a second receiving coil 8 are present. The two receiving coils 7, 8 are surrounded by the excitation coil 6.

[0032] The excitation coil 6 and the receiving coils 7, 8 are formed as conductor tracks on a substrate 11. Thus, the coils 6, 7, 8 can be manufactured easily and with little effort as part of a printed circuit board. Particularly preferably, the substrate 11 is part of the control unit 9, for example, part of a circuit board of the control unit 9. The sensor element 4 is thus preferably integrated into the control unit. This ensures a compact design and simple production. Alternatively, the sensor element 4 is a separate component from the control unit 9, which simplifies the placement of the sensor element 4 and enables it to be positioned at an optimal location for a measurement.

[0033] If the valve spool 2 is moved along the movement axis 100 between the first end position and the second end position, it is provided that the degree of overlap of the valve spool 2 with the sensor area 5 constantly changes. In other words, the degree of overlap is characteristic of the position of the valve spool 2 between the first end position and the second end position. Particularly advantageously, the degree of overlap is more than 0% in the first end position and less than 100% in the second end position. The degree of overlap increases as the valve spool 2 moves from the first end position to the second end position, in particular increases strictly monotonically. By determining the degree of overlap, the position of the valve spool can thus be unambiguously determined.

[0034] To detect the degree of coverage, the control unit 9 controls the excitation coil 6 to generate a changing magnetic field. This magnetic field induces an electrical voltage in the first receiving coil 7 and the second receiving coil 8. The valve spool 2 is electrically conductive. Therefore, eddy currents are induced in the valve spool 2, which in turn generate a magnetic field that counteracts the original magnetic field of the excitation coil 6. Consequently, a lower electrical voltage is induced in the first receiving coil 7 and the second receiving coil 8. Advantageously, the use of additional detection elements that can be detected by the sensor element 4 is dispensed with. Detection takes place directly by means of the valve spool 2, alternatively or additionally by means of the movement element 3 (see explanations of Figures 5 to 7).

[0035] The magnitude of the electrical voltage induced in the first receiving coil 7 and the second receiving coil 8 depends on the degree of overlap. The use of two receiving coils 7, 8 also allows the influence of interfering magnetic fields to be compensated. The control unit 9 is designed to detect the degree of overlap and determine the position of the valve spool 2 based on the induced voltages.

[0036] Figure 2 shows that the valve spool 2 only partially covers the sensor area 5 in the transverse direction 200, transverse to the movement axis 100. Preferably, the valve spool 2 completely covers the sensor area 5. The first receiving coil 7 and the second receiving coil 8 are preferably designed symmetrically with respect to a center point of the sensor area 5.

[0037] The sensor region 5 has a first end 5a and a second end 5b along the movement axis 100. The first receiving coil 7 has a first supply conductor 7a extending from the first end 5a to the second end 5b and a first return conductor 7b extending from the second end 5b to the first end 5a. The first supply conductor 7a and the first return conductor 7b form a continuous loop, with the first supply conductor 7a and the first return conductor 7b overlapping in an electrically insulated manner at an intersection point 12. In this way, two partial loops are formed, which are separated by the intersection point 12.

[0038] The second receiving coil 8 has a second supply conductor 8a extending from the first end 5a to the second end 5b, and a second return conductor 8b extending from the second end 5b to the first end 5a. The second supply conductor 8a and the second return conductor 8b form a continuous loop, with the second supply conductor 8a and the second return conductor 8b overlapping in an electrically insulated manner at two intersection points 12. In this way, three partial loops are formed, which are separated by the intersection points 12.

[0039] In the example shown in Figures 2 and 3, the first receiving coil 7 has a sinusoidal first feed-in conductor 7a and a sinusoidal first return conductor 7b extending from the first end 5a or second end 5b. The second receiving coil 8 has a cosinusoidal second feed-in conductor 8a and a cosinusoidal second return conductor 8b extending from the first end 5a or second end 5b.

[0040] Figure 4 shows an alternative embodiment of the first receiving coil 7 and second receiving coil 8. In this case, the sinusoidal shape and the cosinusoidal shape are stretched and compressed, respectively. In this way, a linear change in an induced voltage is present in the receiving coils 7, 8 when the degree of coverage changes. In this case, the two receiving coils are adapted to the properties of the valve spool 2, so that a desired measurement behavior is present at the receiving coils 7, 8. This desired output behavior is, as described, a linearity between induced voltage and degree of coverage. Alternatively, the desired output behavior can also include the introduction of a targeted non-linearity, for example, to detect only when the valve spool 2 has reached the first end position and / or second end position.

[0041] Likewise, the quality of the output signal of the receiving coils 7, 8 can vary across the sensor range 5. This variance of the output signal, as well as an output signal that is too weak or too inaccurately processed, can be avoided by appropriately adapted shapes of the receiving coils 7, 8.

[0042] As previously described, it is not necessary to provide a separate target component whose sole task is to be detected by the sensor element 4. Rather, the valve spool 2 and / or the movement element 3 itself is detected. This allows the sensor element 4 to be placed close to the valve spool or the movement element 3. If the sensor element 4 is part of the control unit 9, the control unit 9 can be arranged in close spatial proximity to the valve spool 2 and / or the movement element 3. Figures 5 to 7 show various such arrangements.

[0043] In Figure 5, the sensor element 4 is intended to detect only the valve spool 2. The movement element 3 is spaced further apart from the sensor element 4 than the valve spool 2. This prevents the sensor element 4 from detecting the movement element 3. This design corresponds to the previously described variant.

[0044] Figure 6 shows a variant in which the sensor element 4 detects not the valve spool 2, but the moving element 3. The mode of operation is analogous to the variant described above, except that instead of the valve spool 2, the moving element 3 must be electrically conductive in order to generate a counter magnetic field to the magnetic field of the excitation coil 6 through eddy currents. In this embodiment, the valve spool 2 is spaced further apart from the sensor element 4 than the moving element 3. This prevents the sensor element 4 from detecting the valve spool 2.

[0045] Finally, Figure 7 shows a variant in which both the valve spool 2 and the movement element 3 can be detected by the sensor element 4. For this purpose, the valve spool 2 and the movement element 3 are at least approximately the same distance from the surface of the sensor element 4, whereby the valve spool 2 and the movement element 3 can be detected equally.

[0046] The valve actuator 1 is therefore highly variable and versatile, with a valve position always being reliably determined from the position of the valve spool 2 and / or the movement element 3. The valve spool 2 and / or the movement element 3 can be detected by the sensor element 4, allowing the sensor element 4 to be arranged at different locations, simplifying the design and manufacture of the valve actuator 1. Eliminating the need for additional detection elements for detecting the valve spool 2 also results in a compact design.

[0047] In addition to the above written description of the invention, reference is hereby explicitly made to the drawings in the figures for its supplementary disclosure. List of reference symbols

[0048] 1 valve actuator

[0049] 2 valve slides

[0050] 3 transmission element

[0051] 4 Sensor element

[0052] 5 Sensor area

[0053] 5a first end

[0054] 5b second end

[0055] 6 Excitation coil

[0056] 7 first receiving coil

[0057] 7a first introductory leader

[0058] 7b first repatriation manager

[0059] 8 second receiving coil

[0060] 8a second return conductor

[0061] 8b second introductory leader

[0062] 9 Control unit

[0063] 10 Drive unit

[0064] 10a Gearing

[0065] 11 Substrat

[0066] 12 crossing point

[0067] 100 movement axis

[0068] 200 transverse direction

Claims

Claims 1. Valve drive (1) comprising • a valve slide (2) which can be moved along a movement axis (100) between a first end position and a second end position, . a transmission element (3) coupled to the valve slide (2) which is movable along the movement axis (100) by a drive unit (10), . a sensor element (4) having a sensor region (5), wherein an excitation coil (6) and at least one receiving coil (7, 8) are arranged within the sensor region (5), and • a control unit (9) designed to control the excitation coil (6) and / or evaluate the receiving coil (7, 8), • wherein the valve slide (2) and / or the transmission element (3) are electrically conductive, • wherein a degree of overlap of the valve slide (2) and / or the transmission element (3) with the sensor region (5) along the movement axis (100) increases with increasing movement of the valve slide (2) and / or the transmission element (3) from the first end position to the second end position, and • wherein the control unit (9) is designed to detect the degree of overlap and to determine a position of the valve slide (2) and / or the transmission element (3), wherein the sensor region (5) has a first end (5a) and a second end (5b) along the movement axis (100), wherein the receiving coil (7, 8) has a supply conductor (7a, 8a) running from the first end (5a) to the second end (5b) and a return conductor (7b, 8b) running from the second end (5b) to the first end (5a), and wherein the supply conductor (7a, 8a) and the return conductor (7b, 8b) form a continuous loop, wherein at at least one crossing point (12) the supply conductor (7a, 8a) and the return conductor (7b,8b) electrically insulated overlap, wherein the first receiving coil (7) has, starting from the first end (5a) or second end (5b), a sinusoidal first feed-in conductor (7a) and a sinusoidal first return conductor (7b), and a second receiving coil (8) different from the first receiving coil (7) has a cosinusoidal second feed-in conductor (8a) and a cosinusoidal second return conductor (8b), wherein the sinusoidal shape and / or cosinusoidal shape are stretched and / or compressed in order to preferably change the, AMENDED SHEET (ARTICLE 19) Coverage ratio to exhibit a linear change in an induced voltage in the receiving coils.

2. Valve drive (1) according to claim 1, characterized in that the excitation coil (6) and / or the receiving coil (7, 8) are designed as conductor tracks on a substrate (11), wherein the substrate (11) is in particular part of the control unit (9).

3. Valve drive (1) according to claim 2, characterized in that the excitation coil (6) encloses the receiving coil (7, 8) on the substrate (11).

4. Valve drive (1) according to claim 2 or 3, characterized in that at least two receiving coils (7, 8) are provided, which are designed to overlap and are electrically insulated from one another.

5. Valve drive (1) according to one of the preceding claims, characterized in that a degree of overlap in the first end position is more than 0% and / or in the second end position is less than 100%.

6. Valve drive (1) according to one of the preceding claims, characterized in that the at least one receiving coil (7, 8) is designed symmetrically with respect to a center point of the sensor area (5).

7. Valve drive (1) according to one of the preceding claims, characterized in that the valve slide (2) and / or the transmission element (3) completely cover the sensor area (5) in the transverse direction (200) transverse to the movement axis (100). AMENDED SHEET (ARTICLE 19)

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