DE20203298U1 - Measurement value transducer, especially a linear displacement transducer for use in a blowout preventer for an oil or gas well, has a bit pattern generator whose signal is detected and evaluated to indicate component position - Google Patents

Abstract

Measurement value transducer (1) for measuring at least one kinematic measurement value, especially for use in a device (2) for mineral oil and gas production. Said device has a first device part (3) that moves relative to a second fixed device part (4). As the moving part moves along a movement direction (5) a bit pattern is generated, from which position specific bit pattern groups can be sampled by a sampling unit (8).

Description

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TRANSDUCERS

The invention relates to a measuring sensor for at least one kinematic measurement variable, in particular in devices for oil and natural gas extraction, with a first device part which is movable in or through the device and whose kinematic measurement variable is to be determined, and a second device part which is stationary relative to the first device part.

Such sensors are used, for example, to determine the position when the movable part of the device is moved relative to the stationary part of the device. By moving the parts relative to each other, the position of a shut-off device, a blow-out preventer, a rotary adjustment device, a valve, a throttle or the like is determined and displayed as position information at the desired location. The corresponding devices are used in oil and gas extraction to extract along production lines, change the output of the production lines, close the production lines in an emergency, add chemicals to the production lines in a controlled manner or the like. In each case, precise knowledge of the relative position of the movable part of the device and the stationary part of the device is necessary.

Previously, position determination was carried out, for example, by assigning a scale to a spindle, a piston or another movable part of the device, from which the corresponding position of the movable part of the device relative to the stationary part of the device can be read. Another known possibility for determining the position is a potentiometer or a linear resistor, relative to which a contact adjusts when the movable part of the device moves, so that the detected resistance changes.

Finally, there is another way of determining positions in which slots or similar are arranged at the same linear distance on a scale. These are recorded and counted in order to determine corresponding positions. Instead of a linear arrangement of such slots, a turntable with a sliding

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zen at a constant distance in the circumferential direction, which are also detected by light detectors or the like and then counted.

The disadvantage of these well-known sensors is that in addition to scanning the similar and equally spaced divisions on the corresponding scale, such as slots in an encoder disk, the corresponding divisions must be added up in addition to the scanning in order to obtain the corresponding position information. Furthermore, with the previously known sensors it is not immediately clear in which direction the movement is actually taking place, since, for example, in a straight-line movement it is not immediately clear whether the movement is to the left or to the right. The same applies to a rotating encoder disk, where the direction of rotation cannot be easily determined by the sensor.

A further disadvantage is that, for example, if the electronics of the measuring sensor fail, the relative position between the movable part of the device and the stationary part of the device can no longer be determined and must be moved to one end of the possible relative movement range in order to carry out the corresponding position determination again.

The invention is therefore based on the object of improving a measuring sensor of the type mentioned at the outset in such a way that both the direction of movement and the respective position can be determined without returning to the ends of the movement range in a simple, structural and inexpensive manner.

This object is achieved in connection with the features of the preamble of claim 1 in that the first and/or second device part have a bit pattern that changes along a direction of movement, from which position-specific bit pattern groups can be scanned by a scanning device arranged on the respective other device part.

By changing the bit pattern in the direction of movement and the various position-specific bit pattern groups, the actual

Direction of movement can be determined. The way in which the bit pattern changes is known, and by scanning the bit pattern it is therefore easy to determine in which direction the movement is taking place. In addition, since the corresponding bit pattern groups of the bit pattern are position-specific, even in the event of a temporary failure of the corresponding electronics or the like of the measuring sensor, it is still possible to easily record the current relative position between the first and second parts of the device when the device is switched back on. At most, it would be necessary to move the first part of the device so far that the closest bit pattern group can be clearly detected again by the scanning device. Under no circumstances is it necessary to move the first part of the device back to one end of the movement range in order to determine the position or the corresponding kinematic measurement variable again from there.

In particular, in the case of the corresponding devices in oil and gas extraction, such a minimal movement of the first part of the device for re-determining the corresponding kinematic measurement variable is advantageous, since in this way the corresponding devices do not have to be moved completely back into a closed or open position, for example in the case of a valve. Instead, only a minimal movement is necessary to record the next bit pattern group.

Finally, in this context, it is also advantageous that a summation of the scanned subdivisions of a corresponding scale is not necessary. Instead, the relative position between the first and second device parts is uniquely determined by each position-specific bit pattern group.

In order to be able to scan the bit pattern groups more quickly, the scanning device can have a number of individual scanning elements. Depending on the number of these individual scanning elements, the corresponding bit pattern group can be partially or completely captured in one scanning process.

The assignment of scanning device and bit pattern group can preferably be carried out in such a way that an extension of the scanning device or the individual scanning elements in

Direction of movement essentially corresponds to a bit length of each individual bit of the bit pattern. As a result, each individual scanning element also directly records an individual bit, without, for example, a single bit being recorded by adjacent individual scanning elements or several individual bits being recorded simultaneously by a single scanning element. This increases the resolution when recording the kinematic measurement variable and, at the same time, each individual bit can be reliably scanned. In order to increase the resolution using bit patterns and scanning elements if necessary, n individual bits of a bit pattern group can be assigned n+1 or n-1 individual scanning elements. As a result, either the scale with the bit pattern or the one with the individual scanning elements is a vernier scale that is one element shorter. If, for example, 10 individual bits are provided per bit pattern group, the vernier scale of the individual scanning elements can have nine individual scanning elements. The 10 bit patterns are as long as the nine individual sampling elements, so that, for example, the first individual bit is shifted by 1/10, the second by 2/10, etc., relative to the individual sampling element.

It is possible that a bit pattern contains more individual bits than there are individual scanning elements in the scanning device. This would require the scanning device to be moved relative to the bit pattern in order to fully capture the bit pattern. To speed up the scanning process, each individual bit of a bit pattern group (data word width) can be assigned an individual scanning element. This means that the entire data word width and thus the kinematic measurement variable is captured in one scanning process.

The resolution of the acquisition of the kinematic measurement variable can be further increased if the bit pattern groups are shifted relative to each other by one single bit in the direction of movement. This means that by shifting the scanning device relative to the bit pattern by just one single bit, the next position-specific bit pattern group is acquired, so that the resolution is essentially determined by the width of the single bit or the single scanning element.

If, for example, the first device part in the corresponding devices moves in the longitudinal direction within a housing or the like, wherein the first device part can be a piston, a spindle or the like, it is furthermore

It is advantageous if the bit pattern extends in the longitudinal direction of the device. This allows the bit pattern to be easily scanned during the relative movement of the first and second parts of the device.

The bit pattern can be implemented in different ways. For bit patterns in the binary system, only two different features or states need to be assigned to each individual bit. The corresponding features/states can be determined by the scanning device.

An example of two such states for corresponding individual bits is that the corresponding bit pattern is formed by depressions and/or elevations. This means that individual bits can differ in terms of different depths of the depressions, heights of the elevations or the like. Depressions and elevations can also alternate, whereby the depressions can each be the same depth and the elevations can each be the same height.

In this case, the corresponding scanning device is designed to detect depressions and elevations and, if applicable, their depth or height.

Another possibility for realizing such a bit pattern is areas of different conductivity. For example, a single bit can be formed by a conductive area of the corresponding device part and the next single bit by a non-conductive area. It is also conceivable that the areas are, for example, highly conductive and slightly conductive or the like.

Another possibility for realizing a bit pattern is that it is formed by areas with different reflectivity. In this case, for example, the scanning device could have a corresponding illumination option and record the light reflected from the corresponding areas. Since the reflectivity is different, a distinction can be made between the individual bits.

For areas with different conductivity, an individual scanning element can, for example, have at least one coil. If an alternating voltage is applied to this, the coil has different attenuations depending on the conductivity of the corresponding detected areas, each of which forms an individual bit. This applies analogously to individual bits from different depressions and/or elevations, since these elevations and depressions also have different effects on a coil supplied with an alternating voltage.

In addition, an individual scanning element can have at least one light-emitting diode. This can be used, for example, to distinguish between areas with different reflectivity. A light-emitting diode can also be used to detect the depressions and/or elevations.

In order to be able to determine the kinematic measurement value redundantly, two scanning devices can be arranged, in particular directly adjacent to one another in the direction of movement. If, for example, one of the scanning devices fails, the current position and a change in position can still be determined by the corresponding other scanning device. In particular, for scanning the entire range of movement of the two device parts, it is advantageous if the scanning devices are arranged directly adjacent to one another.

The scanning device and bit pattern are arranged according to the direction of the relative movement between the two parts of the device. If the direction of movement is, for example, straight, the bit pattern and scanning device also extend in a straight line.

Other possibilities for movement directions are a helical or a substantially circular movement direction. The bit pattern and scanning device can be arranged accordingly.

The determination of the kinematic measurement variable can be carried out in such a way that neither the bit pattern nor the scanning device are visible from outside the device. This is useful, for example, if the bit pattern and the scanning device are to be protected from damage.

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are to be protected, or if the devices are to be used under unfavorable environmental conditions, such as underground or in the maritime sector. By arranging bit patterns and scanning devices accordingly, they can also be protected from aggressive substances, pressure or the like. An advantageous arrangement can be seen in the bit pattern being formed along an inner wall of an inner bore of a piston of the device. Instead of inside a piston, it can also be arranged inside a rotary spindle, inside a movable rod or inside another movable or adjustable actuating element.

If the bit pattern is formed on an inner wall of such an inner bore of a piston, the bit pattern would move together with the piston and the scanning device would be arranged accordingly on the stationary part of the device.

Another possibility for forming a bit pattern can be seen in the fact that it is formed along a bit pattern carrier that is attached in particular detachably to a piston. The bit pattern can be formed on the corresponding bit pattern carrier depending on the desired resolution. Due to the possibility of exchanging the bit pattern carrier, a bit pattern can be replaced by a finer or coarser bit pattern.

Depending on the device, the bit pattern carrier can extend from one end of the piston, for example. However, in order to avoid having to make the device larger by using such a bit pattern carrier, the bit pattern carrier can also extend coaxially to an inner bore of the piston, for example. This means that the bit pattern carrier is arranged in the inner bore of the piston and moves together with it.

In this context, it is advantageous if the free space between the bit pattern carrier and the inner wall of the piston's inner bore is used for the scanning device. This can be done, for example, by inserting a scanning sleeve between the bit pattern carrier and the inner wall of the inner bore. This is connected to the stationary

assigned to another part of the device and changes its position relative to the bit pattern carrier when the piston moves.

In order to be able to scan the entire range of movement of the piston, the scanning device can be arranged essentially at the free end of the scanning sleeve. If the bit patterns are formed, for example, on the inner wall of the inner bore of the piston or the movable device part, it can also be advantageous if the scanning device is arranged at the free end of a scanner carrier that can be moved relative to the inner bore. This can, for example, project freely, extend to the inner end of the inner bore and scan bit patterns arranged on the inner wall of the inner bore when the movable device part is moved.

In order to supply the scanning device with electricity or to transmit corresponding signals from the scanning device to an associated evaluation device, a corresponding electrical line can be guided from the scanning device along a line bore in the scanner sleeve or the scanner carrier.

In order to protect the scanning device against external influences, the cable hole at the free front end can be releasably closed by an end plug.

To record kinematic measurement variables during a rotary movement, it can be advantageous if the bit pattern has individual bits arranged along a circular path. For example, when the movable part of the device rotates, the individual bits can then be scanned along the circular path on the stationary part of the device using a scanning device that rotates accordingly. It is also possible for the individual bits to be arranged on the movable or rotatable part of the device and for the scanning device to be provided along the circular path of the individual bits on the stationary part of the device.

When arranging or at least assigning the bit pattern to the movable device part, the bit pattern can have individual bits arranged along a circumference of a disk. The individual bits can in turn be separated by areas with different

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different conductivity, with different reflectivity, with depressions and/or elevations or the like. In this context, the corresponding individual scanning elements of the scanning device on the stationary part of the device are assigned to the circumference of the disk.

Instead of scanning from the radial direction, scanning can also be carried out essentially perpendicular to the disk plane if the bit pattern is arranged accordingly. This can be done, for example, by the bit pattern in the disk having individual bits in the form of slots. It is possible for the slots to be designed with a width that increases in the radial direction. In this context in particular, it can be considered advantageous if the individual scanning elements are radially adjustable. The radial adjustment allows an individual scanning element to be precisely adjusted to the load.

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Direction of rotation corresponds to the corresponding extension of the individual scanning element.

A corresponding bit pattern can have a corresponding number of individual bits depending on requirements. For example, the position can be encoded using 4, 5, 6, 7 or more individual bits per bit pattern. The number of individual bits in a bit pattern is determined by the number of individual scanning elements in the scanning device. This means that with four-bit coding, four individual scanning elements are preferably used.

In order to control and, if necessary, check the movements of the first device part relative to the second device part over at least a certain period of time, the measuring sensor can have at least one storage device for storing measurement signals of the scanning device as a function of the position.

In this context, signals from at least a number of individual scanning elements can advantageously be stored as a function of the position. The number of individual scanning elements preferably corresponds to the number of individual bits in a bit pattern.

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In order to obtain information about the entire range of motion, an output measurement signal information for an entire range of motion of the scanning device and/or at least a number of individual scanning elements can be stored at least once in the memory device.

In order to improve the resolution when measuring the kinematic measurement variable, the measuring sensor can have a comparison device for comparing the output measurement signal information with current measurement signal information. The corresponding current measurement signal information can be used by comparing it with the output measurement signal information to determine exactly which area of the output measurement signal information the current measurement signal information corresponds to. This makes it possible to determine the relative position between the movable device part and the stationary device part with greater accuracy than the resolution provided by the individual bits. This corresponding resolution is related to the resolution of the corresponding measurement signal information. If this resolution is sufficiently high, for example, a measurement and evaluation of the current measurement signal information can be carried out essentially analogously or at least quasi-analogously. In this way, the resolution can be significantly increased by the individual bits.

The higher resolution mentioned above also means that it is not necessary to move the first part of the device in the event of a temporary failure of the corresponding electronics or the like in order to re-detect the current relative position between the first and second parts of the device. This also eliminates the need for the previously described movement of the first part of the device to clearly detect a nearest bit pattern group when the device is switched back on. Instead, an absolute encoder is obtained for each position of the first and second parts of the device relative to one another, which allows the corresponding relative position to be determined directly with high accuracy when the device is switched back on after, for example, a failure of the electronics.

In order not to lose any information during the determination of the kinematic measurement quantity when comparing the measurement signal information for precise position determination,

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At least the last current measurement signal information can be stored after its acquisition until it is replaced by subsequent current signal information.

In order to increase the resolution of the determination of the kinematic measurement variable in a simple manner, scanning devices and/or bit patterns can be designed to be interchangeable. This can be done, for example, by replacing the above-mentioned scanner carrier or bit pattern carrier. In connection with the arrangement of two scanning devices, the bit pattern can be replaced by a bit pattern with twice the number of individual bits. These are then recorded by the two scanning devices simultaneously to determine the kinematic measurement variable.

In order to supply electrical power to scanning devices with a number of individual scanning elements in a safe and simple manner, a pressure-resistant multiple cable feedthrough can be provided for the electrical connection of the scanning device. This is preferably arranged in the stationary part of the device and serves to supply electrical power to all individual scanning elements of the scanning device at the same time.

It should also be noted that the output measurement signal information can also be determined by only a few individual sampling elements, whereby this is compared with corresponding current measurement signal information from the same individual sampling elements. For redundancy reasons, corresponding measurement signal information from all sampling elements can be compared.

The individual bits described so far are characterized by two possible states (features). It is also possible for the individual bits to have more than two states and for all of these states to be detectable by corresponding individual scanning elements. It is of course also possible to determine other kinematic measurement variables in addition to the position, such as speed and acceleration. Appropriate electrical devices for differentiating the position values over time and thus the recorded distance traveled can be assigned to the sensor.

In the following, advantageous embodiments of the invention are explained in more detail with reference to the figures attached to the drawing.

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Fig. 1 is a longitudinal section through a device with a first embodiment of a measuring sensor according to the invention;

Fig. 2 is a longitudinal section analogous to Fig. 1 with a second embodiment of a measuring sensor according to the invention;

Fig. 3 is a longitudinal section through a further device with a third embodiment of a measuring sensor according to the invention;

Fig. 4 shows a fourth embodiment of a measuring sensor according to the invention;

Fig. 5 is a view of a detail "X" from Fig. 3 without redundant design of the measuring sensor according to the invention;

Fig. 6 shows two further embodiments of a measuring sensor according to the invention in connection with a coding disk;

Fig. 7 two further embodiments of the measuring sensor according to the invention in connection with a slotted coding disk;

Fig. 8 shows two further embodiments of the measuring sensor according to the invention in connection with a rotating device;

Fig. 9 is a side view of the embodiments according to Fig. 8;

Fig. 10 shows an example of different bit patterns for position determination in an embodiment of the measuring sensor according to the invention;

Fig. 11 shows total movement information recorded by a single scanning element of a scanning device according to the sensor according to the invention, and

Fig. 12 is a sketch explaining scanning devices and bit patterns.

Fig. 1 shows a longitudinal section through a device 2 for oil or natural gas extraction with a first embodiment of a measuring sensor 1 according to the invention. The device 2 has a piston 24 that can be pushed out of a cylindrical housing 43 as a movable first device part 3. The housing 43 with an attached further part forms a stationary second device part 4. The piston 24 is slidably mounted within the housing 43. The housing has an inlet 44 and an outlet 45 for a pressure fluid. If pressure fluid is supplied to the inlet 44, the piston 3 moves in the direction of movement 5 to the right in Fig. 1. The movement takes place in the longitudinal direction 14 of the device 2.

At its free end 42, the piston 24 is connected in a movement-connected manner to actuate a valve, a rotary adjustment device, a so-called blow-out preventer, a throttle or other devices for oil and natural gas extraction.

The piston 24 has, at least in its section arranged in the housing 43, an inner bore 23 with a corresponding inner wall 22. A scanner carrier 28 is inserted into this inner bore 23. This extends coaxially to the inner bore 23. The scanner carrier 28 extends from one end 60 of the housing 43 in the longitudinal direction of the device 2. A line bore 30 within the scanner carrier 28 is connected to a line feedthrough 46 at an end facing the housing end 60. Electrical connecting lines 29 are laid through the line feedthrough 46 and the line bore 30 between a scanning device 8 arranged at the free end 27 of the scanner carrier 28 and an evaluation and control device of the measuring sensor 1 arranged remotely from the device 2.

The control and evaluation device 61 in Fig. 1 has a comparison device 38, a storage device 36, a display device 41 and optionally further devices.

The scanning device 8 has a series of individual scanning elements 9 which are arranged directly next to one another in the longitudinal direction 14 of the device 2. In the embodiment shown, the individual scanning elements 9 are formed by coils 19, see the following figures. A total of eight individual scanning elements 9 are provided. An end plug 32 is placed on the front end 31 of the line bore 30 directly adjacent to the scanning device 8.

A bit pattern 8 is formed along the inner wall 22 and is composed of a series of bit pattern groups 7 comprising a number of individual bits. The scanning device 8 with its individual scanning elements 9 can each be assigned to a bit pattern group 7. Adjacent bit pattern groups are each shifted relative to one another by one individual bit 13.

When the piston 24 is pushed out to the right in Fig. 1, the bit pattern 6 also moves to the right in Fig. 1 relative to the scanning device 8. As a result, the scanning device 8 scans the various bit pattern groups 7 and the relative position between the scanning device 8 and the bit pattern 6 can be determined by the changes in the bit pattern or the corresponding position-specific bit pattern groups and the displacement path of the piston 24 to the right or left in Fig. 1 can be determined accordingly.

In the embodiment according to Fig. 1, it should also be noted that the bit pattern groups have areas of different conductivity. A corresponding bit length 13, see also Fig. 10, which can be assigned to each individual bit 13 of such an area, results from a corresponding width or extension 11 (see, for example, Fig. 4) of the individual scanning elements 9. It should be pointed out again that such an individual scanning element 9 is formed by an electrical coil 19.

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Fig. 2 shows the device 2 from Fig. 1 with a second embodiment of a measured value sensor 1 according to the invention. This differs essentially from the first embodiment in that the bit pattern 6 is formed on a bit pattern carrier 25 which is connected to the piston 24 by means of a screw bolt 47. The bit pattern carrier 25 extends coaxially to the inner bore 23 of the piston 24. A scanner sleeve 26 is inserted between the bit pattern carrier 25 and the inner wall 22 of the inner bore 23. This has two directly adjacent scanning devices 8, 21 at its free end 27. The scanning device 8 corresponds to that according to Fig. 1. The scanning device 21 is designed redundantly. Each of the two scanning devices 8, 21 has six individual scanning elements 9. The scanner sleeve 26 is connected at its end opposite the scanning devices 8, 21 to the housing end 20 as a stationary second device part 4, analogously to Fig. 1.

The bit pattern carrier 25 has a bit pattern 6 formed from depressions 15 and elevations 16. This means that the different areas of the bit pattern are formed by these depressions, wherein each depression or elevation can comprise an individual bit 13 or a number of individual bits 13.

Corresponding electrical lines 29 for supplying the scanning devices 8 and 21 and for determining corresponding signals in the direction of the control and evaluation unit 61, see also Fig. 1, are laid along an outer surface of the scanner sleeve 26 in the direction of the housing end 60. There, the scanner sleeve 26 has a bore 62 through which the electrical lines 29 are guided in the direction of the line guide 46.

In Fig. 3, a third embodiment of a measuring sensor 1 according to the invention is shown in connection with a device 2 having a rotary spindle 63 as a movable first device part 3. The rotary spindle 63 can be rotated manually, electrically or in another way and is used to adjust a valve, a throttle or the like. A bit pattern carrier 25 is inserted into the rotary spindle 63. This in turn has areas with depressions 15 and/or elevations 16 which form a corresponding bit pattern 6. The bit pattern carrier 25 can be adjusted together with the rotary spindle 63 in the direction of movement 5.

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A scanner carrier 28 is inserted into the bit pattern carrier 25 from its free end as part of a stationary second device part 4. At its free end 31, the scanner carrier 28 has a scanning device 8. This is formed by a series of coils 19 as individual scanning elements, analogous to the two previous examples, see also Fig. 4 and 5. A line bore 30 is arranged within the scanner carrier 28, through which a series of electrical lines 29 are led to each of the coils 19. The scanner carrier 28 is fastened to a housing 48 with its end opposite the scanning device 8. A pressure-resistant multiple cable feedthrough 40 is arranged within this housing, through which the corresponding electrical lines 29 are led.

It should be noted that the scanning device 8 according to Fig. 3 can be formed from twelve individual scanning elements 9. However, it is also possible for the twelve individual scanning elements 9 to each form half of the scanning device 8 and half of the redundant scanning device 21, see also Fig. 2.

Two further embodiments of the inventive measuring sensor 1 are shown in Fig. 4 and 5. These differ essentially in that in Fig. 4 the bit pattern carrier 25 is the movable first device part or is associated with it, while in Fig. 5 the scanner carrier 28 is the movable first device part 3 or is associated with it.

In both embodiments, the corresponding scanning device 8 has four individual scanning elements 9, which are formed by light-emitting diodes 20. These light-emitting diodes 20 emit light and receive light reflected by the respective individual bit of the bit pattern 6, with different amounts of light being reflected by the different areas of the bit pattern 6 or the individual bit pattern groups 7. In this case, the different areas are formed by depressions 15 and elevations 16. In connection with the elevations 16, it should be noted that these only arise relative to the depressions 15 and, in the embodiment shown, are not formed by elevations 16 protruding over an inner surface 64. However, in other embodiments, the elevations 16 on the inner surface 64

so that the depressions 15 only arise relative to these elevations or are formed in the inner surface.

An extension 11 of the individual scanning elements 9 in the direction of movement 5 essentially determines a bit length 5 of an individual bit 13. Accordingly, the individual scanning elements 9 arranged next to one another determine an extension 10 of the scanning device 8 as a whole in the direction of movement 5. The extension 10 of the scanning device corresponds to the length of a bit pattern group 7, so that in the embodiments of the measuring sensor 1 shown in Figs. 4 and 5, a four-bit coding of the bit pattern 6 is present.

Instead of the light-emitting diodes 20, the individual scanning elements 9 according to Fig. 4 and 5 could also be formed by electrical coils 19. When supplied with a corresponding alternating voltage, these would emit different signals to the outside depending on the scanning of a depression or elevation.

As already explained in the preceding embodiments, instead of elevations and depressions, regions of different conductivity, different reflectivity or the like could also be formed, which in this case would form the individual bits 13 or groups of individual bits.

Each of the light-emitting diodes 20 or electrical coils 19 is connected via corresponding electrical lines 29 to a voltage source for supply or for signal transmission to the control and evaluation unit 61, see also Fig. 1.

6 to 9 show further embodiments of a measuring sensor 1 according to the invention. In these embodiments, the movable first device part 3 carries out a rotary or screwing movement, while the stationary second device part 4 extends at least partially along the circumference of the first device part 3.

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Furthermore, in Figs. 6 to 9, it should be noted that in one half of the figure, electrical coils are arranged as examples of individual scanning elements 9 and in the other half, light-emitting diodes 20 are arranged as individual scanning elements 9.

In Fig. 6, a disk 35 as a movable first device part 3 or as a disk connected to this device part for movement has depressions 15 and/or elevations 16 along its circumference, which form a corresponding bit pattern 6. The length of bit pattern groups 7 forming the bit pattern 6 results accordingly from the extension of the scanning device 8 in the circumferential direction or along the circular path

33 of the disk 35. In this case, each bit pattern 6 is formed from four individual bits 13, whereby each individual bit can be assigned to an individual scanning element 9.

While the direction of movement 5 in Fig. 1 to 5 was straight, in Fig. 6 to 9 it is circular or helical.

In these embodiments, the bit pattern also changes along the circumference

34 of the disk 35 and comprises corresponding position-specific bit pattern groups. It also applies to these embodiments that neighboring bit pattern groups differ by one individual bit 13.

While in Fig. 6 the scanning by means of the scanning devices 8 takes place radially from the outside, with the depressions and elevations 15, 16 being arranged in the circumference 34 of the disk 35, in Fig. 7 the scanning takes place perpendicular to the disk plane. In this case the individual bits 13 or bit pattern groups 7 are formed by slots in the disk surface. It should be noted, however, that the areas lying between the slots also form individual bits or bit pattern groups, see for example the bit pattern group 7 assigned to the light-emitting diodes 20.

The slots formed in the disk expand radially outwards. In order to be able to precisely scan a single bit, the individual scanning elements 9 are arranged so that they can be adjusted in the radial direction. If, for example, smaller scanning elements 9 are used, they can be moved radially further inwards in order to be able to be assigned precisely to a single bit 13.

In Fig. 8, openings are formed in the circumference 34 of the disk 35, so that the corresponding bit patterns 6 are formed by areas 17 with openings and/or areas 18 without openings. The scanning devices 8, which in turn are formed by light-emitting diodes 20 or electrical coils 19, are movable along the circumference 34. The individual scanning elements 9 scan the different areas 17, 18 and thus the individual bits 13. In accordance with the number of individual scanning elements 9, the embodiment according to Figs. 8 and 9 also has a four-bit coding, whereby in this case each bit pattern group 7 has four individual bits 13.

Fig. 9 corresponds to a side view of the embodiment according to Fig. 8. In this side view, the areas 17 of the circumference 34 of the disk 35 formed by openings can be seen in particular.

It should also be noted that the disk 35 according to Fig. 8 and 9 has a disk base surface which is connected to a rotation axis 50. An annular flange protrudes from this disk base surface, the outer side of which forms the circumference 34 according to Fig. 8 and 9. The corresponding regions 17, 18 are formed along the annular flange.

In connection with Figs. 6 to 9, it should also be noted that it is also possible for the corresponding disks to be stationary and for the scanning devices to move in a circular or helical manner around the disks 35.

In Fig. 10, a four-bit coding of a corresponding bit pattern 6 is described in connection with an embodiment of a measuring sensor 1.

The sensor 1 comprises the movable first device part 3, of which essentially only the scanning device 8 is shown. This is inserted into an inner bore 23 of the stationary second device part 4, which can be, for example, a piston according to Figs. 1 and 2. However, it is again possible for the scanning device 8 to be movable and the bit pattern 6 to be stationary.

On the inner wall 22 of the inner bore 23, the bit pattern 6 is formed by regions 17 of different conductivity. For example, the regions 17 are conductive and the regions 18 are non-conductive. The bit pattern 6 comprises a series of bit pattern groups 7 which can be scanned one after the other by the relative movement of the scanning device 8 and the bit pattern 6. In the starting position of the scanning device 8 relative to the bit pattern 6 shown in Fig. 10, a bit pattern group 17 is scanned which is formed from a conductive region 17. The bit pattern group 7 comprises four individual bits corresponding to the number of individual scanning elements 9 of the scanning device 8. These have a bit length 12 which is determined by a corresponding extension 11 of the individual scanning elements 9. This means that the area 17, which is scanned in Fig. 10 as the first bit pattern group 7, comprises four individual bits 13, which together form the conductive area 17. An extension 10 of the scanning device 8 corresponds precisely to a corresponding extension of the bit pattern group 7 or the conductive area 17.

The next bit pattern groups 7, see the various number combinations in the lower part of Fig. 10, are created by shifting the scanning device 8 by one individual bit 13 to the right in Fig. 10. If an individual bit 13 falls into a non-conductive area 18, this is represented by a "1", while individual bits 13 in the conductive area 17 are represented by a "0". This sequence of "0" and "1" results in the coding 51 of the bit pattern 6, which determines the position-specific bit pattern groups 7.

If the four-bit coding 51 of the various bit pattern groups 7 is converted into a decimal numerical value 52, the numerical values shown in the corresponding column range from 0 to 15. This means that each of the bit pattern groups 7 can be assigned a different decimal numerical value from 0 to 15. Regardless of the order of the decimal numerical values 52, each of the bit pattern groups 7 that are passed through one after the other is assigned a specific position value 53. The position values 53 are ordered and numerical values from 1 to 16 are assigned to them.

To obtain more position values 53, for example, a five-bit coding, a six-bit coding, a seven-bit coding, etc. can be used. It is

It is known that due to the corresponding number of bits for a code and the two states or features for a code in the embodiment shown, the corresponding position values for each individual bit are 2 DWB, where DWB corresponds to the data word width, which includes, for example, 4 bits, 5 bits, 6 bits, etc. The data word width corresponds to a bit pattern group.

However, it is also possible that each individual bit can have 3 different states or properties, so that the coding can be done differently accordingly.

It should also be noted here that, for example, if the state or characteristic of the individual bits is conductive/non-conductive, each of these individual bits can be formed by a metal ring (conductive) or plastic ring (non-conductive). If several individual bits are in the same state in this context, the corresponding metal or plastic ring can be made wider.

In Fig. 11, a measurement signal information 37 is shown in connection with an electrical coil 9 as a single scanning element 9 and conductive/non-conductive areas 17, 18 as a bit pattern 6. This results when the bit pattern 6 is scanned by the corresponding scanning device 8 or by scanning an individual scanning element 9. The path 9 is shown on the abscissa and an analog resolution 54 of a signal voltage 58 for an electrical coil 19 is shown on the ordinate. This means that the course of the measurement signal information 37 is evaluated analogously or quasi-analogously in the area of the signal voltage 58. This results in a very precise course of the measurement signal information 37 depending on the path 59.

A measurement signal information 37 can be stored in the memory device 36 of the control and evaluation device 61 of the measuring sensor 1 during a first scan of the bit pattern 6, for example. If a measurement signal information is subsequently obtained during a current scan, this can be compared with the stored measurement signal information. By comparing the two measurement signal information, the relative position of the movable first device part and the stationary second device part can be determined with a higher resolution over the bit length 12 of a single bit 13.

For example, the measurement signal information from one, two, three, four or more individual scanning elements 9 is compared with one another and aligned with one another, so that not only can the position be determined with bit precision, but also transitions between bits, sections between the bits, etc. can be detected. The corresponding resolution of the position essentially results from the analog bit resolution 54 according to Fig. 11 and a corresponding bit width 12, see for example Fig. 10.

By recording the measured value signal information 37 during a first scan and by recording a corresponding current measured value information, it is also possible, if this is stored in a non-volatile memory device, to retrieve it later when the electrical device fails and to compare it with one another and to determine the relative position between the first and second device parts precisely and directly. This is also possible with the bit patterns themselves, whereby the specific bit pattern group closest to the position may only have to be approached when the device is put back into operation if there is no precise assignment of scanning device and bit pattern group.

Fig. 12 shows a simple embodiment of a measuring sensor 1 according to the invention to explain some measuring parameters. The measuring sensor 1 comprises a movable device part and a stationary device part, one of these device parts being, for example, the scanner carrier 28 and the other device part being the bit pattern carrier 25. Electrical coils 19 (not shown) are arranged next to one another on the scanner carrier 28 as individual scanning elements 9, the number of individual scanning elements 9 determining the total length of the scanning device 8 and also the length of the bit pattern group.

Each individual scanning element 9 can be assigned a so-called mechanical bit width 56. The total data word width 55 or extent 10 of the scanning device 8 results from the number of individual scanning elements.

In this context, the resolution is the quotient of an analog bit resolution, see reference numeral 54 in Fig. 11, and the mechanical bit width

56. For example, the analog bit resolution is given in steps per bit and the mechanical bit width in mm per bit.

The length to be measured by the sensor 1 is the product of the mechanical bit width 56 and the maximum number of possible positions 53 minus one, see Fig. 10.

The total length of a path to be traveled by the scanning device is essentially determined by adding the length of the measuring path and the extension 10 of the scanning device 8.

The maximum length of a region 17, see the right half of Fig. 12, also results from this extension 10 or sensor length 57 of the scanning device 8.

Claims (36)

1. A measurement sensor ( 1 ) for at least one kinematic measurement variable, in particular in devices ( 2 ) for oil and natural gas extraction, with a first device part which is movable in or through the device ( 2 ), the kinematic measurement variable of which is to be determined, and a second device part ( 4 ) which is stationary relative to the first device part ( 3 ), characterized in that the first and/or second device part ( 3 , 4 ) have a bit pattern ( 6) which changes along a direction of movement (5 ) , of which position-specific bit pattern groups ( 7 ) can be scanned by a scanning device ( 8 ) arranged on the respective other device part ( 3 , 4 ). 2. A sensor according to claim 1, characterized in that the scanning device ( 8 ) has a number of individual scanning elements ( 9 ). 3. A sensor according to claim 1 or 2, characterized in that an extension ( 10 , 11 ) of the scanning device ( 8 ) or of the individual scanning elements ( 9 ) in the direction of movement ( 5 ) essentially corresponds to a bit length ( 12 ) of each individual bit ( 13 ) of the bit pattern ( 6 ). 4. A measuring sensor according to one of the preceding claims, characterized in that each individual bit ( 13 ) of a bit pattern group ( 7 ) (data word width) can be assigned an individual scanning element ( 9 ). 5. A sensor according to one of the preceding claims, characterized in that n individual bits ( 13 ) of a bit pattern group ( 7 ) can be assigned to n + 1 or n - 1 individual scanning elements ( 9 ). 6. A sensor according to one of the preceding claims, characterized in that the bit pattern groups ( 7 ) are shifted relative to one another in the direction of movement ( 5 ) by one individual bit ( 13 ). 7. Sensor according to one of the preceding claims, characterized in that the bit pattern ( 6 ) extends in the longitudinal direction ( 14 ) of the device ( 2 ). 8. Sensor according to one of the preceding claims, characterized in that the bit pattern ( 6 ) is formed by depressions ( 15 ) and/or elevations ( 16 ). 9. Sensor according to one of the preceding claims, characterized in that the bit pattern ( 6 ) is formed by regions ( 17 , 18 ) of different conductivity. 10. Sensor according to one of the preceding claims, characterized in that the bit pattern ( 6 ) is formed by regions ( 17 , 18 ) of different reflectivity. 11. Sensor according to one of the preceding claims, characterized in that the individual scanning element ( 9 ) has at least one coil ( 19 ). 12. Sensor according to one of the preceding claims, characterized in that the individual scanning element ( 9 ) has at least one light-emitting diode ( 20 ). 13. A measuring sensor according to one of the preceding claims, characterized in that two scanning devices ( 8 , 21 ) are arranged, in particular directly adjacent to one another in the direction of movement ( 5 ). 14. Sensor according to one of the preceding claims, characterized in that the direction of movement ( 5 ) is rectilinear. 15. Sensor according to one of the preceding claims, characterized in that the direction of movement ( 5 ) is helical. 16. Sensor according to one of the preceding claims, characterized in that the direction of movement ( 5 ) is substantially circular. 17. Sensor according to one of the preceding claims, characterized in that the bit pattern ( 6 ) is formed in particular along an inner wall ( 22 ) of an inner bore ( 23 ) of a piston ( 24 ) of the device ( 2 ). 18. Sensor according to one of the preceding claims, characterized in that the bit pattern ( 6 ) is formed along a bit pattern carrier ( 25 ) which is in particular detachably fastened to a piston ( 24 ) of the device ( 2 ). 19. Sensor according to one of the preceding claims, characterized in that the bit pattern carrier ( 25 ) extends coaxially to an inner bore ( 23 ) of the piston ( 24 ). 20. Sensor according to one of the preceding claims, characterized in that a scanner sleeve ( 26 ) is inserted between the bit pattern carrier ( 25 ) and an inner wall ( 22 ) of the inner bore ( 23 ). 21. A measuring sensor according to one of the preceding claims, characterized in that the scanning device ( 8 ) is arranged substantially at the free end ( 27 ) of a scanner carrier ( 28 ) which is displaceable relative to the inner bore ( 23 ). 22. Measuring sensor according to one of the preceding claims, characterized in that electrical lines ( 29 ) for supplying and/or transmitting signals from the scanning device ( 8 , 21 ) are guided along a line bore ( 30 ) of the scanner sleeve ( 26 ) or scanner carrier ( 28 ). 23. Measuring sensor according to one of the preceding claims, characterized in that the line bore ( 30 ) is closed at the free front end ( 31 ) by an end plug ( 32 ), in particular releasably. 24. A sensor according to one of the preceding claims, characterized in that the bit pattern ( 6 ) has individual bits ( 13 ) arranged along a circular path. 25. A measuring sensor according to one of the preceding claims, characterized in that the bit pattern ( 6 ) has individual bits ( 13 ) arranged along a circumference ( 34 ) of a disk ( 35 ). 26. A measuring sensor according to one of the preceding claims, characterized in that the bit pattern ( 6 ) has slot-shaped individual bits ( 13 ) in a disk ( 35 ). 27. A measuring sensor according to one of the preceding claims, characterized in that the individual scanning elements ( 9 ) are mounted radially adjustable. 28. A sensor according to one of the preceding claims, characterized in that the number of individual bits ( 13 ) of a bit pattern ( 6 ) is determined by the number of individual scanning elements ( 9 ) of the scanning device ( 8 , 21 ). 29. A measuring sensor according to one of the preceding claims, characterized in that the measuring sensor ( 1 ) has at least one storage device ( 36 ) for storing measuring signals of the scanning device ( 8 , 21 ) as a function of the position. 30. Sensor according to one of the preceding claims, characterized in that measurement signals of at least a number of individual scanning elements ( 9 ) can be stored as a function of the position. 31. A measuring sensor according to one of the preceding claims, characterized in that at least one measurement signal information item ( 37 ) for a total movement range of the scanning device ( 8 ) and/or at least a number of individual scanning elements ( 9 ) can be stored in the storage device ( 36 ). 32. Measuring sensor according to one of the preceding claims, characterized in that the measuring sensor ( 1 ) has a comparison device ( 38 ) for comparing the measuring signal information ( 37 ) with a current measuring signal information ( 39 ). 33. A measuring sensor according to one of the preceding claims, characterized in that at least the last current measuring signal information ( 39 ) is stored after its detection until it is replaced by a subsequent current measuring signal information. 34. A measuring sensor according to one of the preceding claims, characterized in that measurement and evaluation of the measuring signal information ( 7 , 39 ) can be carried out essentially analogously. 35. Sensor according to one of the preceding claims, characterized in that the scanning device ( 8 ) and/or bit pattern ( 6 ) are designed to be exchangeable. 36. Measuring sensor according to one of the preceding claims, characterized in that a particularly pressure-resistant multiple cable feedthrough ( 45 ) is provided for the electrical connection of the scanning device ( 8 ).