JP4707418B2 - Level measuring device - Google Patents

Description

  The present invention relates to a level measuring device that detects and measures the level of a liquid level or a liquid boundary surface.

  A level measuring device that measures the level of liquid (the height of the liquid level and the height of the liquid boundary surface) with a liquid level sensor is equipped with a liquid level sensor at the tip of a measuring wire wound around a wire drum. The wire drum is rotated in accordance with the level change so that the buoyancy from the liquid acting on the body is constant, and the liquid surface sensing body is moved up and down, and the level is detected and measured from the amount of rotation of the wire drum.

  The level measuring device described above includes a detection shaft coupled to the wire drum via a magnet coupling, detects a deviation between the outer ring magnet and the inner ring magnet of the magnet coupling by a magnetoelectric converter, and according to the deviation. There is a configuration in which a detection value is rotated and a measurement value is obtained (see Patent Document 1).

  However, in the conventional apparatus described above, the magnetoelectric converter must be provided between the outer ring magnet and the inner ring magnet of the magnet coupling. Since both the outer ring magnet and the inner ring magnet are rotating members, the lead wires for supplying power to the magnetoelectric converter and for outputting the output are passed through the slip ring regardless of whether the magnetoelectric converter is attached to the outer ring or the inner ring. Must be derived externally.

  Slip rings may cause contact failure due to wear and contact failure due to use, and this contact failure may cause device malfunction and impair device reliability. .

JP-B-5-31928, page 1-3, FIGS. 1-4

  The present invention eliminates the need for a member that requires electrical energy as a rotating member, and therefore has a simple structure and is unlikely to cause poor contact in the electrical system, and is capable of performing highly stable and accurate level measurement. The issue is to provide.

In order to solve the above-described problems, a typical configuration of the level measuring apparatus according to the present invention includes a wire drum in which a wire having a displacer serving as a liquid level sensor is wound around a tip, and a coaxial relative to the wire drum. And a rotation amount of the wire drum by rotating the detection shaft in accordance with a deviation between the rotational displacement on the wire drum side and the rotational displacement on the detection shaft side caused by a change in level. In the level measuring device that controls the rotation amount of the detection shaft to be the same and detects the level from the rotation amount of the detection shaft, the first gear connected to the wire drum and the detection shaft are connected. A second gear, a planetary gear that connects the first gear and the second gear, a carrier that rotatably supports the planetary gear and revolves coaxially with the detection shaft, and the carrier An attached magnet; a magnetoelectric converter that is disposed in the vicinity of the track of the magnet and detects separation / contact; and an elastic body that applies an urging force in the winding direction of the wire to the carrier. The planetary gear rotates and revolves when there is a difference between the rotational displacement of the rotating shaft and the rotational displacement of the detection shaft side, and the displacement of the magnet that moves due to the rotation of the carrier that is displaced along with the revolution of the planetary gear is converted to the magnetoelectric transducer. Thus detected in the output, by rotating the detection axis allowed rotation and revolution of the planetary gear in the reverse direction, the output of the magnetoelectric transducer to return the position of the magnet to its original position to return to a predetermined value wherein said by rotating the detection axis, the rotation amount of the detecting shaft revolutions and of the wire drum is controlled to be substantially equal to To.

  Further, one of the first gear and the second gear is a sun gear disposed inside the planetary gear, and the other is an internal gear disposed outside the planetary gear.

  In addition, a restriction member that restricts a rotation range of the carrier is provided.

  Further, a plurality of the magnetoelectric converters are provided, and the plurality of magnetoelectric converters are arranged in the vicinity of the orbit of the magnet.

  Embodiments of the level measuring apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining a level measuring apparatus according to this embodiment, and FIG. 2 is a diagram for explaining another embodiment.

  First, the overall configuration of the level measuring apparatus will be described with reference to FIG. The wire drum 1 is wound with a wire 3 having a displacer 2 serving as a liquid level sensor at the tip. In the wire drum 1, a groove 1a for evenly winding the wire 3 is cut into a dense spiral shape. The wire 3 hangs vertically off the groove 1a in the middle.

  When the displacer 2 is in the specified draft, the apparent weight F of the displacer 2 is F = W−B, where W is the weight of the displacer 2 and B is the buoyancy that the displacer 2 receives from the liquid. Since the buoyancy changes when the draft of the displacer 2 changes due to the rise and fall of the liquid level, this apparatus detects the change in the apparent weight F via the tension of the wire 3 and the rotational torque of the wire drum 1, and draft By winding the wire drum 1 around the wire 3 and controlling the rotation in the feeding direction so as to be constant, the amount of rotation is mechanically or electrically integrated to measure the liquid level.

  As shown in FIG. 1, in this embodiment, the shaft 1b of the wire drum is provided with a first crown gear 4 (first gear), and the detection shaft 10 connected to the motor 11 has a second shaft. A crown gear 5 is provided. The shaft 1b and the detection shaft 10 are coaxial, and the tooth surfaces of the first crown gear 4 and the second crown gear 5 are arranged to face each other. Although not shown, the detection shaft 10 is connected to the motor 11 via an appropriate speed reduction mechanism.

  A trident carrier 6 is arranged between the first crown gear 4 and the second crown gear 5, and three planetary gears 7 are attached to the carrier 6. The planetary gear 7 is pivotally supported on the carrier 6 so as to be rotatable, and the carrier 6 is rotatably supported on the detection shaft 10 so that the planetary gear 7 can revolve around the detection shaft 10. In the figure, for convenience of explanation, the first crown gear 4, the planetary gear 7, and the second crown gear 5 are shown separately, but these mesh with each other to constitute a planetary gear mechanism.

  Further, the carrier 6 is provided with an arm 6a extended in the radial direction, and a magnet 8 is provided at the tip thereof, and a spring 9 as an elastic body is connected thereto. The spring 9 is a helical coil spring in this embodiment, and is in a position balanced by being deformed by a predetermined amount by the apparent weight F of the displacer 2. The carrier 6 can be rotated within the range of expansion and contraction of the spring 9.

  As the carrier 6 rotates, the magnet 8 rotates in a circular arc path. In the vicinity of the track of the magnet 8, a magnetoelectric converter 12 such as a Hall element for detecting the separation / connection is disposed. The magnet 8 has an S pole and an N pole on both sides in the rotation direction, and the magnetoelectric converter 12 is one that operates on both S / N poles.

  Considering the liquid level stationary state, the radius of the wire drum 1 is Rd, the distance (radius) from the center of the detection shaft 10 to the connecting portion of the arm 6a and the spring 9 is Rp, and the biasing force applied by the spring 9 is T. Then, F × Rd = T × Rp. Therefore, the urging force T satisfies T = F × Rd / Rp. A position determined by the extension of the spring corresponding to the urging force T (elongation = biasing force T / spring constant) is the rotational position of the carrier 6.

  When the liquid level falls, the draft becomes shallow, so the buoyancy decreases and the apparent weight F increases. As a result, the carrier 6 rotates in the direction of further stretching against the elastic force of the spring 9 via the tension of the wire 3 and the torque of the wire drum 1. At this time, since the motor 11 is stopped, the second crown gear 5 is fixed, and the carrier 6 is decelerated to 1/2 with respect to the rotation of the first crown gear 4 and rotates.

  Then, the relative position between the magnet 8 and the magnetoelectric converter 12 changes, and the output of the magnetoelectric converter 12 changes. In response to this change in sensor output, the motor control circuit 13 drives the motor 11 in the direction in which the wire drum 1 feeds the wire 3. At this time, the carrier 6 does not move from the balanced position unless friction is taken into consideration. Therefore, the rotation of the first crown-type gear 4 and the second crown-type gear 5 is transmitted in the reverse direction at the same reduction ratio.

  When the draft of the displacer 2 rises due to the feeding of the wire 3, the magnet 8 returns to a position facing the magnetoelectric converter 12 due to the balance. When it is detected from the output of the magnetoelectric converter 12 that the magnetoelectric converter 12 and the magnet 8 are opposed to each other, the magnetoelectric converter 12 stops driving the motor 11 assuming that the displacer 2 reaches the specified draft. As a matter of course, the extension state of the spring 9 at this time, that is, the relative positional relationship between the magnet 8 and the magnetoelectric transducer 12 is the same as the liquid level stationary state.

  When the liquid level rises, the draft becomes deeper and the buoyancy increases and the apparent weight F decreases. As a result, the carrier 6 rotates in the direction in which the spring 9 contracts due to the elastic force of the spring 9 via the tension of the wire 3 and the torque of the wire drum 1. Then, the relative position between the magnet 8 and the magnetoelectric converter 12 changes, and the output of the magnetoelectric converter 12 changes. In addition, since the magnet 8 is provided with the south pole and the north pole on both sides in the rotation direction, it is possible to distinguish and detect whether the spring 9 is rotated in the extending direction or the contracting direction. .

  In response to the change in sensor output, the motor control circuit 13 drives the motor in the direction in which the wire drum 1 winds the wire 3. When the draft of the displacer 2 is lowered due to the winding of the wire 3, the apparent weight F increases, so that the magnet 8 returns to the position facing the magnetoelectric converter 12. When it is detected from the output of the magnetoelectric converter 12 that the magnetoelectric converter 12 and the magnet 8 are opposed to each other, the magnetoelectric converter 12 stops driving the motor 11 assuming that the displacer 2 reaches the specified draft. As a matter of course, the extension state of the spring 9 at this time, that is, the relative positional relationship between the magnet 8 and the magnetoelectric transducer 12 is the same as the liquid level stationary state.

  Although the liquid level indicating mechanism is not particularly illustrated, the liquid level can be supported in the field if a mechanical counter linked to the second crown gear 5 is connected through an appropriate speed reduction mechanism. Further, by replacing the counter with a digital displacement transmitter or counting the number of steps using a stepping motor as the motor 11, remote transmission of the liquid level is possible.

  As described above, by using the planetary gear, the drum side can be rotated even if the motor side is fixed, and if the motor side is rotated (because the carrier 6 does not rotate), the wire drum 1 also follows. Then rotate. That is, the wire drum 1 can be rotated by the weight (apparent weight) of the displacer 2 and can be rotated by driving the motor 11.

  According to the present invention, in any of the member rotating with the wire drum and the member rotating with the detection shaft, power is supplied to the member for detecting and detecting the rotation and a signal is output. Thus, no element such as a lead wire is required, so that the structure is simple, the possibility of failure such as contact failure in the element can be eliminated, and a highly reliable level measuring device can be provided.

  In the above embodiment, for convenience of explanation, it is easier to understand that the movement of the first crown gear 4 on the wire drum 1 side and the second crown gear 5 on the detection shaft 10 side look equal. It is as a figure using a crown gear. However, in actual production, as shown in FIG. 2, it is easier to work and improve accuracy when the planetary gear mechanism is constituted by a spur gear.

  FIG. 2 is a diagram for explaining another embodiment of the level measuring apparatus according to the present invention. In FIG. 2, the first gear 14 connected to the wire drum 1 is a sun gear arranged inside three planetary gears 17 supported by a carrier 16. The second gear 15 connected to the detection shaft 10 is an internal gear disposed outside the planetary gear 17. If the radius of the first gear 14 is 2R (the number of teeth is double) with respect to the radius R of the planetary gear 17, the amount of rotation of the first gear 14 is twice the amount of rotation of the second gear 15. .

  With the above configuration, manufacturing becomes easy, and the number of steps of the stepping motor of the motor 11 can be increased with respect to the rotation of the wire drum 1 to improve control accuracy, increase torque, or reduce the motor size. Can be achieved.

  Moreover, in the said Example, it demonstrated that the apparatus was comprised by the one magnet 8 and the one magnetoelectric converter 12. FIG. However, a plurality of magnetoelectric converters 12 may be arranged in the vicinity of the track of the magnet 8 and the S pole and the N pole may be arranged in a direction orthogonal to the rotation direction of the magnet 8. Thereby, the detection range can be widened or the direction of rotation can be detected.

  Further, when the drive shaft 10 is rotationally driven, the carrier 6 does not move from the balanced position if originally intended, but a rotational force may be generated due to the frictional resistance of the shaft of the planetary gear 7. At this time, if an excessive load is applied to the spring 9, it may cause damage. Therefore, it is also preferable to provide a regulating member (for example, a protrusion provided on the casing) that limits the rotation range of the carrier 6.

  Moreover, the said Example does not limit the number of planetary gears to three, What is necessary is just one or more numbers. Further, the wire drum 1 and the first crown-type gear 4, the second crown-type gear 5 and the motor 11 may be connected not only directly but also appropriately via a speed reduction mechanism, a link mechanism, a belt transmission mechanism, or the like. .

  The present invention can be used in a level measuring device that detects and measures the level of a liquid surface or a liquid boundary surface.

It is a figure explaining the level measuring apparatus which concerns on an Example. It is a figure explaining another Example.

Explanation of symbols

F ... apparent weight 1 ... wire drum 1a ... groove 1b ... shaft 2 ... displacer 3 ... wire 4 ... first crown gear 5 ... second crown gear 6 ... carrier 6a ... arm 7 ... planetary gear 8 ... magnet 9 ... spring
10… Detection axis
11… Motor
12… Magnetoelectric converter
13… Motor control circuit
14… first gear
15… second gear
16… Career
17… Planetary gear

Claims (3)

A wire drum around which a wire having a displacer serving as a liquid level sensor is wound at the tip, and a detection shaft that can rotate relatively coaxially with the wire drum, The detection shaft is rotated according to a difference between a rotational displacement and a rotational displacement on the detection shaft side, and the rotation amount of the detection drum is controlled so that the rotation amount of the wire drum and the rotation amount of the detection shaft are the same. In the level measuring device that detects the level from
A first gear connected to the wire drum, a second gear connected to the detection shaft, a planetary gear connecting the first gear and the second gear, and a shaft support capable of rotating the planetary gear. And a carrier that revolves coaxially with the detection shaft, a magnet attached to the carrier, a magnetoelectric converter that is disposed near the track of the magnet and detects the separation and connection thereof, and the wire wound around the carrier. An elastic body that gives an urging force in the taking direction,
When a deviation between the rotational displacement on the wire drum side and the rotational displacement on the detection shaft side occurs, the planetary gear rotates and revolves, and the displacement of the magnet that moves by the rotation of the carrier that is displaced along with the revolution of the planetary gear is changed. wherein the output of the magnetoelectric transducers Accordingly detected, by rotating the detection axis allowed rotation and revolution of the planetary gear in the reverse direction, the output of the magnetoelectric transducer to return the position of the magnet to its original position is predetermined The level measuring apparatus is characterized in that the rotation amount of the wire drum and the rotation amount of the detection shaft are controlled to be substantially equal by rotating the detection shaft until it returns to the value of .
  The one of the first gear and the second gear is a sun gear arranged inside the planetary gear, and the other is an internal gear arranged outside the planetary gear. Level measuring device.   The level measuring apparatus according to claim 1, wherein a plurality of the magnetoelectric converters are provided, and the plurality of magnetoelectric converters are arranged in the vicinity of an orbit of the magnet.

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