WO2017178376A1

WO2017178376A1 - Position sensor device

Info

Publication number: WO2017178376A1
Application number: PCT/EP2017/058419
Authority: WO
Inventors: Steffen Hoppe
Original assignee: Hella Kgaa Hueck & Co.
Priority date: 2016-04-13
Filing date: 2017-04-07
Publication date: 2017-10-19
Also published as: DE102016106779A1

Abstract

The invention relates to a position sensor device (2), which comprises two magnetic circuits (26, 28), a magnet (18), a sensor (20), a reference guide plate (16), and two measurement guide plates (10, 12), wherein the first magnetic circuit is a reference circuit (28) and the second magnetic circuit is a measurement circuit (26). In order to describe a position sensor device (2) that is extensively insensitive to environmental influences and to changes to the material properties of the position sensor device (2) itself, the magnet (18) is designed as an easily magnetizable magnet and the sensor (20) is designed as a magnetic field line direction sensor, wherein the magnet (18) and the sensor (20) are each part of both magnetic circuits (26, 28). The reference circuit (28) additionally comprises the reference guide plate (16) and the measurement circuit (26) additionally comprises the measurement guide plates (10, 12) and a measurement gap (14) is formed between the two measurement guide plates (10, 12). Variations of the width of the measurement gap (14) lead to a change in the distribution of the field lines (22) between the reference circuit (28) and measurement circuit (26) and can be converted into an electrical output signal by means of a sensor (20) which measures the field line direction (24).

Description

Displacement sensor device

description

The present invention relates to a displacement sensor device referred to in the preamble of claim 1 Art.

Such displacement sensor devices are already known from the prior art.

For example, from US 3,329,012 a differential travel sensor in the form of a torque sensor unit is known. In this case, two turntables with overlapping slots are rotated by the constant wide air gap of a magnetic circuit of a differential transformer. Depending on the degree of overlap of the slots, the magnetic circuit is influenced accordingly and thus closed to the torque. In this case, the degree of overlap leads to an altered magnetic resistance, which in turn influences an alternating voltage with variable amplitude, which is evaluated as an electrical signal.

The known sensors usually require high-quality materials, ie materials with a low magnetic resistance. Due to the measurement of absolute magnetic quantities, there is also a susceptibility to environmental influences, such as temperature fluctuations, or to the aging of the magnet.

The present invention has for its object to provide a displacement sensor device which is largely insensitive to environmental influences and changes in the material properties of the displacement sensor device itself. Furthermore, it should be possible to use less high-quality materials, ie materials with higher magnetic resistances. This should be both cost advantages and an improvement of other parameters, such as strength and toughness, can be achieved. This object is achieved by a displacement sensor device having the features of claim 1. The dependent claims 2 to 9 relate to advantageous developments of the invention.

Although a position sensor using a magnetic field line direction evaluation is already known from US Pat. No. 9,207,100 B2. However, this is a partially differently magnetized permanent magnet, which is moved. On the basis of the different magnetization directions along the magnet can be closed by means of the evaluation of the magnetic field line direction on the position of the permanent magnet and thus the moving part of a device.

In contrast, a significant advantage of the displacement sensor device according to the invention is in particular that simpler and therefore less expensive magnets can be used. There are no complex magnets with partially different magnetization directions required. Also, the known from the aforementioned prior art permanent magnets are not bendable, which makes it difficult application of such magnets or makes the measurement technology for certain measurement tasks not applicable at all.

An advantageous development of the teaching according to the invention provides that the magnet is designed as a permanent magnet. Permanent magnets are cheaper than electromagnets. In addition, eliminates electrical leads and the supply of electrical power. Just the elimination of electrical leads allows applications under difficult installation u. Operating conditions, such as those at or near rotating or moving parts in general. Another advantage is the overall lower power consumption of the sensor, because the otherwise required energy for generating a magnetic field is not needed.

Another advantageous embodiment provides that the magnet, the sensor and the Referenzleitblech are mutually stationary. This ensures that the conditions in the reference circuit during operation substantially stay the same. Changing conditions in the reference circle would otherwise have to be taken into account in the subsequent evaluation of the measurement signals.

Reference, coupling and measuring baffles are not just actual plates. Other forms of training which achieve the function of bundling magnetic field lines are also to be understood here. The term "baffle" has become naturalized in the art.

A further advantageous development of the teaching of the invention provides that in the measuring circuit additionally two Kopplungsleitbleche are arranged, one of which is arranged magnetically between one of the two Messleitbleche and the other components of the measuring circuit. In this way, an even better leadership of the magnetic field lines is achieved, so that interference by the environment are further reduced. Particularly advantageous is a stationary arrangement of the coupling baffles, so that the coupling baffles do not move when it comes to a movement of Messleitbleche. As a result, the structural design and the magnetic design is further simplified.

Basically, the use of a single sensor is sufficient. For redundancy, in addition to the sensor, a further magnetic field line direction sensor may be arranged in both magnetic circuits. This is particularly recommended for safety-relevant applications. An increase in safety is moreover possible by using a magnetic field line direction sensor of a different type and / or by arranging the further magnetic field line direction sensor relative to the other magnetic field line direction sensor elsewhere in the position sensor device. Furthermore, it is also possible to use more than two sensors to meet special safety requirements.

The design of the measuring gap between the two Messleitblechen is basically selectable by type, extent and arrangement within wide limits. This also applies to oblong columns. If the measuring gap is of helical design, the largest possible relative displacement and thus the largest possible output signal can be achieved to reach. The more the gap is orthogonal to the direction of movement of the measuring baffles, the greater the output signal.

A particularly advantageous development of the teaching according to the invention provides that the reference guide plate is formed in two parts and both parts are separated by a reference gap, wherein the width of the reference gap coincides with the width of the measuring gap in a zero position of the path sensor device. By "zero position" is meant the position of the displacement sensor device in which there is a defined width, for example, of the measuring gap, which is rated as "normal." Deviations from this width, ie a narrower or wider measuring gap, lead to a strengthening of the magnetic field lines across the measuring circle or over the reference circle and thereby to a change in the summed field line direction in the sensor or the sensors, resulting in a corresponding output signal.A reference gap in the Referenzleitblech is a further approximation of the magnetic conditions in both magnetic circuits in Zero position and thus an improved adjustment of reference and measuring circuit allows, for example, this has an advantageous effect in case of fluctuations in the ambient temperature.

The way sensor device can basically also be used for the measurement of absolute paths or absolute angles. This would be the case if only one of the Meßleitbleche is designed to be movable. Particularly advantageous is the design of the travel sensor device as a differential travel sensor device, so that both Messleitbleche each other and the rest of the travel sensor device are designed to be movable. Often very small relative movements between two components must be detected, each moving in a greater length or angle range. For this purpose, the proposed displacement sensor device is particularly well suited, since the same motion of the two components and thus the two Meßleitbleche not substantially affect the measurement result when the magnet, the sensor or sensors and the baffles are designed and arranged coordinated with each other such that a movement the Meßleitbleche leads in the same direction and the same amount to no change in the width of the measuring gap. A further object of the invention is that a device has a displacement sensor device according to one of claims 1 to 9, wherein at least one of the Meßleitbleche is mechanically coupled to the at least one movable part. Accordingly, it would be conceivable that only one Meßleitblech with a moving part or that both Messleitbleche is each coupled to a movable part.

Reference to the accompanying, rough schematic drawings, the invention will be explained in more detail below. Showing:

1 shows a first embodiment in a partial perspective view.

2 shows the first embodiment in a further perspective view. 3 is a simplified representation of the first embodiment; 4 shows an electrical comparison circuit diagram;

5 shows a second embodiment in a similar representation as in Fig. 3.

Fig. 6 shows a third embodiment in a partial perspective view and

Fig. 7 shows a fourth embodiment in a simplified representation. In the following, the path sensor device according to the invention will be explained in more detail with reference to FIGS. 1 to 7.

Identical or equivalent components are denoted by the same reference numerals.

In Fig. 1, a device 1 is partially shown, in which two pistons 4 and 6 of the device 1, not shown, are reciprocally movable along an imaginary axis, which is symbolized by a double arrow 8. In this embodiment, the two pistons 4 and 6 can each move along the symbolized by the double arrow 8 axis. The pistons 4 and 6 are each mechanically coupled to a Meßleitblech 10 and 12. In the example, the measuring guide plate 10 is fixed on the piston 4 and the measuring guide plate 12 on the piston 6. Between the Messleitblechen 10 and 12 is a measuring gap 14 which is formed helixformig and along the helical course has a constant width b. A reference baffle 16 is also recognizable. The baffles 10, 12 and 16 are part of a Wegsensorvorrichtung invention, which will be explained in more detail below.

Fig. 2 shows the device 1 in a comparable representation, but in a different operating position than in Fig. 1st The pistons 4 and 6 were moved towards each other along the double arrow 8, so that the Meßleitbleche 10 and 12 have been compared to the operating position in Fig. 1 to each other. The width b of the measuring gap 14 is reduced accordingly.

In Fig. 3, the displacement sensor device 2 of the device 1 shown in Figs. 1 and 2 is roughly schematically illustrated. The path sensor device 2 is formed in the first embodiment as Differenzwegsensorvorrichtung. In addition to the baffles 10, 12 and 16 already discernible in FIGS. 1 and 2, FIG. 3 also shows a magnet 18 designed as a permanent magnet and a sensor 20 designed as a two-dimensional Hall sensor. The magnetic field lines are symbolized here by lines 22. In general:

The space in which a magnet exerts force is known as the magnetic field. The magnetic field lines indicate the direction of the acting force in a magnetic field.

The magnet 18, the sensor 20 and the Referenzleitblech 16 are fixed to the device 1, so that they do not move during a movement of the pistons 4 and 6, not shown in FIG. 3, but are stationary.

The displacement sensor device 2 is matched to the design and the material selection such that in the zero position shown in FIG. 3, that is to say the width b of the measuring gap 14 shown in FIG. 3, the summed field line direction detectable by the sensor 20 moves to the right in the plane of the page shows. See arrow 24, which symbolizes the summed field line direction 24. The illustrated summed field line direction 24 is purely exemplary; any other summed field line direction 24 would also be eligible for the null position. Depending on the application or measuring range, the specialist will determine the zero position.

Now, if the Meßleitbleche 10 and 12 moves toward each other by a movement of the pistons 4 and 6 along the double arrow 8, the width b of the measuring gap 14 is reduced. See also Figs. 1 and 2. This also reduces the magnetic resistance of the The magnetic field lines 22 along the measuring circle 26 -the magnet 18, the sensor 20, the Meßleitbleche 10 and 12 and the measuring gap 14 are compared to the magnetic field lines 22 along the reference circle 28 -der the magnet 18, the sensor 20 and the Referenzleitblech 16 includes stronger. The summed field line direction 24 would in this case run in the leaf plane to the top right. This is detected by the sensor 20 and converted into a corresponding output signal. In the other case, ie when the width b of the measuring gap 14 is increased by the movement of the pistons 4 and 6, the magnetic field lines 22 along the measuring circle 26 are weakened compared to the magnetic field lines 22 along the reference circle 28, which leads to the summed field line direction 24 would be in the leaf plane to the bottom right; followed by a corresponding output signal of the sensor 20.

The relationships in the two magnetic circuits 26 and 28 can also be explained with an electrical comparison circuit diagram according to FIG. 4. For the sake of simplicity, the sensor 20 was not considered.

This is because magnetoresistance, also referred to as reluctance, is, according to Hopkinson's law, the proportionality factor R _m between the magnetic voltage U _m and the magnetic flux Φ. This equation

U _m = R _m ^* Φ is analogous to Ohm's law for the electric current U = R ^* I.

Accordingly, the magnetic flux can be t> R _e f in the reference circuit 28 in analogy to the electrical current I through U _m / _Re R f and the magnetic flux <t> measurement in the measuring circuit 26 determined by To / Riviess. As can be seen from the electrical comparison diagram, U _m = URef = Ui iess- Simplified, R _Re f corresponds to the magnetic resistance of Referenzleitblechs 16 and Riviess the sum of the magnetic resistances of Messleitbleche 10, 12 and here filled with air measuring gap 14. Simplifies therefore, because between the individual components of the displacement sensor device 2 in addition to the measuring gap 14 practically even more gaps, which are filled here with ambient air, are available. The ratio of the magnetic fluxes t> R _e f / <t> measurement between reference circuit 28 and measuring circuit 26 is determined by the equation _Re f / <t> measurement = (RMessieitbieche / RRef + RMessspait / RRef) - since the summand (RMessieitbieche / RRef) is constant, a direct statement about the magnetic resistance RMessspait of the measuring gap 14 can be made. The magnetic voltage U _{m is} shortened.

The reference resistance R _Re f is to be tuned to the expected in the respective measurement task conditions in the measuring circuit 26. The magnetic resistors of the measuring baffles 10 and 12 should be as low as possible in order to keep the summands RMessieitbieche RRef as small as possible.

Of course, in practice, the gaps between the magnet 18 and the sensor 20, between the magnet 18 and the reference baffle 16, between the sensor 20 and the reference baffle 16, between the magnet 18 and the baffle 10 and between the baffle plate 12 and the sensor 20 must be taken into account in the dimensioning. An advantageous development of the teaching of the invention provides to make this unavoidable gap as closely as possible, so as small as possible. All gaps of the first embodiment, including the measuring gap 14, are filled with air.

Fig. 5 shows a second embodiment of a differential path sensor device 2 similar to that of the first embodiment. In contrast to the first exemplary embodiment, the differential travel sensor device 2 here additionally has two coupling guide plates 30. Depending on one of the coupling baffles 30 is magnetically disposed in the measuring circuit 26 between the Meßleitblech 10 and the magnet 18 and between the Meßleitblech 12 and the sensor 20 and in comparison to the Meßleitblechen 10 and 12 stationary; analogous to the Referenzleitblech 16. See also the comments on the first embodiment. The basic mode of operation corresponds to that of the first exemplary embodiment.

The coupling baffles 30 are magnetically coupled to the measuring baffles 10 and 12 such that a movement of the measuring baffles 10 and 12 in the same direction and the same amount -also both Meßleitbleche 10 and 12 move around the same amount in the image plane to the left or to the right to no metrologically relevant change in the magnetic resistance of the measuring circuit 26 leads. This is shown by the dashed line 31, which symbolizes the magnetic coupling of the coupling baffles 30 with the two Messleitblechen 10 and 12. In this case, the coupling guide plates 30 are coupled to the two measuring guide plates 10 and 12 via the magnetic field lines 22 indicated at both ends of the dashed line 31. The dashed line 31 symbolizes the rigid coupling of the two magnetic couplings.

If the measuring baffles 10 and 12 move in the same direction and with the same amount along the double arrow 8 to the coupling baffles 30, the magnetic resistance in the measuring circuit 26 remains unchanged since the path of the magnetic field lines 22 remains the same through the matter and through the air. This is clarified when the dashed line 31 mentally moves along the double arrow 8 in the image plane to the left or right. Where the magnetic field lines 22 have to traverse less path through the matter at one point, the magnetic field lines 22 now additionally pass through this matter through matter.

Such a movement in the same direction and the same amount has no effect on the width b of the measuring gap 14 and should thus also have no effect on the output signal of the Differenzwegsensorvorrichtung 2. Therefore, the above tuning of the coupling baffles 30 with the measuring baffles 10 and 12 is important.

In Fig. 6, a third embodiment is shown. The distance sensor device 2 is likewise designed here as a differential travel sensor device. However, in this embodiment, a rotational movement and thus a differential rotation angle sensed. The Meßleitbleche 10 and 12 are attached to not shown rotatable components of a device, also not shown. In order to determine the differential rotational angle of these two components, the inventive principle explained above can also be used. To change a width b der measuring gap 14, the Meßleitbleche 10 and 12 are formed as shown in FIG. 6 and rotatable about an axis 32. Again, an angle-like rotation in the same direction is unattractive metrologically. Accordingly, the measuring baffles 10 and 12 are to be designed and matched to one another such that the width b of the measuring gap 14 does not change in the same direction when the baffles 10 and 12 rotate in the same direction. If a measurement baffle 10, 12 rotates less or both measuring baffles 10, 12 rotate in opposite directions, however, the width b of the measurement gap 14 changes, which leads to an output signal in the desired manner. Incidentally, the operation is identical to that of the first and second embodiments.

Fig. 7 shows a fourth embodiment, which is similar to the third embodiment. Analogous to the second exemplary embodiment according to FIG. 5, coupler baffles 30 are also used here in order to bundle the magnetic field lines 22 even better and to further reduce disturbing influences. Again, a vote of Kopplungsleitbleche 30 with the Meßleitblechen 10 and 12 is required to avoid unwanted influences on the output signal of the Wegsensorvorrichtung 2. This tuning causes only a rotational movement of the two Meßleitbleche 10 and 12 without changing the width b of the measuring gap 14 is still no change in the magnetic resistance of the measuring circuit 26 and thus no weakening or amplification of the magnetic field lines 22 of the measuring circuit 26 in comparison to the reference circle 28th triggers. Again, analogous to the second embodiment shown in FIG. 5, the magnetic coupling of the coupling baffles 30 to the Meßleitbleche 10 and 12 symbolized by the dashed line 31. An angularly equal rotational movement in the same direction of rotation, symbolized by double arrow 36, here analogous to the second embodiment does not increase the magnetic resistance in the measuring circuit 26. Again, a mental displacement of the dashed line 31 along the double arrow 36 helps to illustrate this , See also the comments on Fig. 5.

In contrast to the third exemplary embodiment according to FIG. 6, the differential displacement sensor device 2 here has a redundancy sensor 34, which has the same design as the sensor. Sor 20 is formed. However, it would also be conceivable, for example for even higher safety requirements, to use a magnetic field direction sensor of a different design. The redundancy sensor 34 is part of both the measuring circuit 26 and the reference circuit 28.

The invention is not limited to the present embodiments. By way of example, other movements, absolute and relative movements, can also be detected by the travel sensor device according to the invention. It is only necessary that the quantity to be measured can be transformed into a change in the width b of a measuring gap. In addition to permanent magnets and electromagnets are used. The control can be carried out here with DC voltage, AC voltage, as well as with special other signals or controlled to achieve, for example, to achieve a certain field strength in the sensor.

The displacement sensor device according to the invention and the device according to the invention are less susceptible to interference from environmental influences such as, for example, temperature fluctuations. In addition, they are also robust against the inevitable aging of the magnets, since no absolute magnetic quantities are measured, but the summed magnetic field line direction change of a measuring circuit and a reference circle.

Furthermore, the use of a wide range of sensors is possible. In addition to the exemplary two-dimensional Hall sensors, for example, one or more three-dimensional Hall sensors, but also AMR, GMR, CMR and TMR are conceivable. Important in this context is only that the selected sensor (s) can measure in two dimensions and the measuring direction is selected according to the changes. This allows a very wide range of applications. Also, the use of cheap materials is possible. High-quality materials with low magnetic resistance or complex magnetizable magnets can be dispensed with. Another advantage is that the magnetic fields are largely in baffles. As a result, a low radiation of the field strengths is achieved, whereby, for example, reduces the total field strength and the total radiation can be minimized. The influence of external homogeneous interference fields on the output signal of the path sensor device according to the invention should be negligible. By choosing a correspondingly high magnetic field strength, an additional reduction of the sensitivity to such interference fields can be achieved.

However, as with other magnetic sensor devices, it is imperative that saturation in the baffles be effectively avoided. For this purpose, depending on the application, a compromise between the strength of the magnet used, the geometric shape of the baffles and their material and the dimensioning of the measuring gap to find.

Compared to the known displacement sensor devices in which the magnet or magnets are moved, only a small amount of mass has to be moved in the position sensor device according to the invention. This not only leads to higher energy efficiency, but also allows for greater speeds, speeds and accelerations in the movement of the components to be measured. Also, a substantially equal mass distribution is possible on these components. The proposed displacement sensor device is advantageously applicable in particular for smaller displacement measurements, such as in the single-digit angular range or millimeter range.

The path sensor device according to the invention and a device equipped therewith can also be used in a different ambient atmosphere than air. Accordingly, then the column, so also the measuring gap and a possible reference gap would be filled with another gas or gas mixture. LIST OF REFERENCE NUMBERS

1 device

2 way sensor device

4 First piston

6 second piston

8 directions of movement of the pistons 4 and 6

10 First measuring baffle

12 Second measuring baffle

14 measuring gap

16 reference guide plate

18 magnet

20 sensor

22 magnetic field lines

24 Sunned magnetic field line direction

26 measuring circuit

28 reference circle

30 coupling baffles

31 Magnetic coupling

32 axis of rotation

34 redundancy sensor

36 Change of the magnetic coupling by rotary motion without

Measurement gap change

Claims

Distance sensor device claims

1 . Position sensor device (2), the two magnetic circuits (26, 28), a

Magnet (18), a sensor (20), a Referenzleitblech (16) and two Messleitbleche (10, 12), wherein the first magnetic circuit is a reference circle (28) and the second magnetic circuit is a measuring circuit (26), characterized in

the magnet (18) is in the form of a magnet which is simply magnetized, and the sensor (20) is a magnetic field line direction sensor and are respectively part of both magnetic circuits (26, 28), the reference circuit (28) additionally comprising the reference guide plate (16) and the measuring circuit (26 ) In addition, the Meßleitbleche (10, 12) and between the two Messleitblechen (10, 12) a measuring gap (14) is formed and depending on the width of the measuring gap (14), an electrical output signal can be generated.

2. way sensor device (2) according to claim 1,

characterized,

that the magnet (18) is designed as a permanent magnet.

3. way sensor device (2) according to claim 1 or 2,

characterized,

in that the magnet (18), the sensor (20) and the reference guide plate (16) are stationary relative to one another.

4. way sensor device (2) according to one of claims 1 to 3,

characterized,

in that in the measuring circuit (26) additionally two Kopplungsleitbleche (30) are arranged, one of which magnetically between one of the two Messleitbleche (10, 12) and the other components (18, 20, 18, 20, 34) of the measuring circuit (26 ) is arranged.

5. Distance sensor device (2) according to one of claims 1 to 4,

characterized,

a further magnetic field line direction sensor (34) is arranged in both magnetic circuits (26, 28) in addition to the sensor (20).

6. way sensor device (2) according to one of claims 1 to 5,

characterized,

that the measuring gap (14) is helical.

7. way sensor device (2) according to one of claims 1 to 6,

characterized,

that the reference guide plate (16) is formed in two parts and both parts are separated by a reference gap, wherein the width of the reference gap coincides with the width of the measuring gap (14) in a zero position of the position sensor device (2).

8. way sensor device (2) according to one of claims 1 to 7,

characterized,

the travel sensor device (2) is designed as a differential travel sensor device and both measurement baffles (10, 12) are designed to be movable relative to one another and to the remainder of the travel sensor device (2).

9. way sensor device (2) according to claim 8,

characterized,

in that the magnet (18), the sensor (20) or the sensors (20, 34) and the baffles (10, 12, 16; 10, 12, 16, 30) are designed and arranged in such a way that a movement of the Messleitbleche (10, 12) in the same direction and the same amount to no change in the width of the measuring gap (14) leads.

10. Device (1) with at least one movable part (4, 6),

characterized,

in that the device (1) has a displacement sensor device (2) according to one of claims 1 to 9, wherein at least one of the measuring baffles (10, 12) is mechanically coupled to the at least one movable part (4, 6).