JP4918993B2 - Angle sensor - Google Patents

Description

The present invention relates to an angle sensor mounted on a positioner or the like for adjusting a valve opening, and more particularly to a connecting shaft that transmits an improved rotational displacement so that reliability can be maintained even if force is applied to the shaft. The present invention relates to the angle sensor used .

  7 and 8 are explanatory views showing a conventional angle sensor mounted on a positioner or the like as a schematic configuration. 7 shows a side view, and FIG. 8 shows a cross-sectional view.

  The case 1 has a substantially cylindrical shape, and a cylindrical portion 3 for guiding the shaft 2 is formed in a central portion so as to protrude integrally. A shaft hole 4 is opened through the cylindrical portion 3.

  A rotation stopper 5 that prevents the shaft 2 from rotating too much is fixed to the shaft 2 on the outer end side of the shaft 2. On the other hand, a recess 6 is formed in the case 1 on the inner end side of the shaft 2, and an angle detection unit 7 that detects the rotational displacement of the shaft 2 at the inner end side end of the shaft 2 in the recess 6. Is fixed to form an angle sensor.

  As shown in FIG. 9, the angle detection unit 7 includes a pair of ferrite pieces 8A and 8B, a printed circuit board 9, and the like. The ferrite pieces 8A and 8B have a U-shaped cross section and are fixed to the shaft 2 separately on the left and right.

  The printed board 9 has coils 10A and 10B printed on the left and right with the axis of the shaft 2 as the center, and is covered with ferrite pieces 8A and 8B so as to sandwich the coils 10A and 10B vertically.

A pair of coils 10A and 10B and a pair of ferrite pieces 8A and 8B are arranged in the magnetic flux density B. The crossing area where these coils 10A (10B) and the ferrite pieces 8A (8B) intersect is defined as S. A constant current I is passed through the coil 10A (10B), and the mutual inductance M at that time can be expressed as equation (1). However, BS = φ (φ: magnetic flux)
M = BS / I (1)

  Since the intersection area S is configured to change linearly according to the rotation angle, the intersection area S where the coil 10A (10B) and the ferrite pieces 8A and 8B intersect changes linearly with the rotation angle, and mutual inductance M is changed, and the rotation angle is detected from the output signal.

Patent Document 1 listed below discloses a coupling joint for transmitting a rotational driving force capable of absorbing and buffering an axial displacement.
Patent Document 2 listed below describes a non-contact rotation angle sensor based on a change in inductance.

Japanese Patent Laid-Open No. 11-93965 JP 7-139905 A JP 2000-251357 A JP-A-8-297869 JP-A-9-72367

However, the conventional angle sensor using the shaft has the following problems. When a load is applied in the axial direction of the shaft, there is a possibility that the printed circuit board and the ferrite piece come into contact with each other and the low-strength ferrite piece is broken. In an actual working environment, it is assumed that a large load is applied in the shaft axis direction due to careless handling, and in that case, the possibility of destruction increases.

  On the other hand, equipment used in plants and the like is required to have a maintenance-free design that does not break down. Therefore, there is a demand for a structure in which the printed circuit board and the ferrite piece do not contact even in a severe use environment where a load is applied to the shaft.

In addition, if the distance between the ferrite piece and the printed board changes, it causes an error. Therefore, it is required that the distance between the two parts is always constant.

Therefore, the object of the present invention is to use a shaft structure that can maintain the performance of the equipment without being damaged even if a heavy load is applied to the shaft in a severe environment of actual work, and prevents the angle detection unit from being damaged and error. It is an object of the present invention to provide an angle sensor having a structure that does not cause generation.

  Another object of the present invention is to provide an angle sensor that is free from backlash and has a small angle error.

The present invention which achieves such an object is as follows.
(1) a drive shaft held in the case so as to be rotatable;
A driven shaft coupled to the drive shaft;
The drive end is fixed to the drive shaft and the other end to absorb axial displacement of the drive shaft has a high rigidity with respect to the rotational direction of the drive shaft is fixed to the driven shaft A leaf spring connecting the shaft and the driven shaft;
An angle detector provided on the tip side of the driven shaft;
An angle sensor for detecting a rotational displacement of the drive shaft.
(2) The angle detector
It is composed of a ferrite piece fixed to the driven shaft, and a printed circuit board on which a coil arranged on the case so as to face the ferrite piece is printed,
The angle sensor according to (1), wherein the rotational displacement of the drive shaft is detected from a change in mutual inductance caused by a rotational displacement of an intersection area between the ferrite piece and the coil.

  In the present invention, a driving shaft and a driven shaft constitute a connecting shaft, and these shafts are coupled via a gap space, so that a large load applied in the axial direction of the driving shaft is not driven shaft. In addition, since the leading end of the convex portion and the leading end of the concave portion are coupled with each other in a fitting structure, both the driving shaft and the driven shaft are rotated, and the rotating function is not impaired.

  According to the present invention, since the tip of the convex portion is a plate-like protrusion and the tip of the concave portion is formed with a plate-like groove, the displacement in the rotation direction can be transmitted with a simple structure.

In the present invention, since the flange portion of the drive shaft and the stepped portion of the case are stretched by the spring and fixed to the stopper, the drive shaft does not jump out by the stopper, but is constantly pressed against the stopper by the spring, There is an effect that the axial position of the drive shaft is constant.

  In addition, when a large force is applied in the axial direction, the driven shaft moves in the axial direction in any case because the drive shaft hits the stepped portion of the case via a spring before it hits the driven shaft. There is nothing. Further, when the axial force of the connecting shaft is removed, the drive shaft is returned to the original position by the spring.

  The present invention is an angle sensor for detecting rotational displacement of a drive shaft, and this angle sensor has a connection shaft, and has a structure in which an angle detection part is provided on the tip end side of the driven shaft of the connection shaft. Therefore, it is possible to detect the angle safely while providing all the functions of the connecting shaft.

  Therefore, while maintaining the rotation function of the connecting shaft, even if an excessive load is applied in the axial direction, the angle detection unit is not loaded and is not displaced, so the angle sensor is not damaged and generates an error. As a result, high reliability of the angle sensor can be ensured.

  The present invention has an effect because the angle detection unit of the angle sensor is described as a specific configuration. More specifically, even when a large force is applied to the drive shaft in the axial direction, the force is not transmitted to the non-drive shaft due to the function of the connecting shaft. High reliability can be realized even in

  Also, the drive shaft is constantly pressed against the stopper by the spring, and the axial position of the drive shaft is constant, so the position of the driven shaft is also constant, and as a result, the position of the printed circuit board on which the coil is printed Is also constant. As a result, the distance between the ferrite piece and the printed circuit board is constant, and the occurrence of errors can be prevented.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the following description, parts having the same functions as those of the conventional angle sensor shown in FIGS. 7 to 8 are denoted by the same reference numerals, and description thereof is omitted as appropriate.

FIG. 1 is a schematic configuration diagram showing a reference example of an angle sensor according to the present invention. In FIG. 1, the case 20 has a substantially cylindrical shape, and a cylindrical portion 22 for guiding the connecting shaft 21 is integrally formed at the center portion so as to protrude outward. A shaft hole 23 is opened through the cylindrical portion 22.

  The shaft hole 23 of the case 20 is formed with a shaft hole 23A having a large diameter on the outer side of the case 20 and a shaft hole 23B having a small diameter on the inside thereof. The shaft hole 23A and the shaft hole 23B are connected in a stepped manner. Thus, a step portion 24 is formed.

  A recess 25 is formed inside the case 20 on the inner end side of the connecting shaft 21, and an angle detection unit that detects a rotational displacement of the connecting shaft 21 at the inner end side end of the connecting shaft 21 in the recess 25. 7 is disposed.

  The connection shaft 21 includes a drive shaft 26 and a driven shaft 27, and the angle detection unit 7 is coupled to the driven shaft 27 of the connection shaft 21, and the angle sensor is combined with the connection shaft 21 and the angle detection unit 7. 28 is configured.

FIG. 2 shows the configuration of the drive shaft 26. 2B is a plan view, FIG. 2A is a left side view, and FIG. 2C is a right side view. As shown in FIG. 2B, the drive shaft 26 includes a cylindrical portion 26A, a cylindrical flange portion 40 having a diameter larger than that of the cylindrical portion 26A, and a convex tip 30 forming a plate-like protrusion 29 in this order. It is formed with.

And the collar part 40 is hold | maintained so that rotation with the axial hole 23A of the case 20 is possible, and the spring inserted between the step part 24 and the collar part 40 of the case 20 as shown in FIG. 31 is held.

Further, the flange portion 40 comes into contact with the peripheral edge portion of the flange portion 40 from the outside of the case 20 to a cylindrical stopper 39 inserted and fixed to the shaft hole 23A of the case 20 from the outside, so that the drive shaft 26 is exposed to the outside. Avoid jumping out.

  FIG. 3 shows the configuration of the driven shaft 27. 3A is a plan view, and FIG. 3B is a right side view. As shown in FIG. 3A, the driven shaft 27 has a cylindrical part 32 on the left side, a disc-shaped dish part 33 having a diameter larger than that of the cylindrical part 32 at the center, and a diameter from the dish part 33 on the right side. The recess tip 35 is integrally provided as a cylinder formed in a slit shape with a small center as a plate-like groove 34.

  A plate-like projection 29 at the convex tip 30 of the drive shaft 26 has a fitting structure with the space 36 shown in FIG. 1 held in the concave tip 35 formed as the plate-like groove 34 of the driven shaft 27. Has been inserted. Due to the presence of this space 36, when a large axial load is applied to the drive shaft 26, it is possible to block the shock so that an impact is not transmitted to the driven shaft 27.

  The cylindrical leg portion 37 of the recess tip 35 is fixed to the case 20 via a bearing 38, which helps the driven shaft 27 to rotate and displace smoothly by the bearing 38, and the axis of the driven shaft 27 is centered. Hold exactly.

  In the recess 25 formed inside the case 20, the angle detection unit 7 fixed to the tip of the cylindrical portion 32 of the driven shaft 27 is disposed. Then, ferrite pieces 8A and 8B having a U-shaped cross section fixed to the cylindrical portion 32 are fixed on the disc-shaped dish portion 33 of the driven shaft 27, and the ferrite pieces 8A (8B) are fixed. A printed circuit board 9 fixed to the case 20 is inserted and fixed in the space between the U-shapes.

  Then, the ferrite pieces 8A and 8B rotate with the rotation of the driven shaft 27, rotate with the printed circuit board 9 interposed therebetween, and change the mutual inductance M corresponding to the rotational displacement as in the prior art, thereby changing the angle from the output signal. Is detected.

  According to the above configuration, since the bearing 38 is attached between the driven shaft 27 and the case 20, the driven shaft 27 rotates without receiving a frictional force.

The drive shaft 26 and the driven shaft 27 are combined at the concavo-convex portions (29, 34), and this portion has a fitting (gap fit) structure, so that it can be driven without friction. Since the shaft 26 moves in the axial direction and has an uneven structure, the rotation of the drive shaft 26 is transmitted to the driven shaft 27 as it is.

  Further, since the drive shaft 26 does not jump out by the stopper 39 but is constantly pressed against the stopper 39 by the spring 31, the axial direction of the drive shaft 26 is constant.

Then, the drive shaft 26 when rotated around the axial direction, the force is transmitted to the driven shaft 27, by the rotational angle of the drive shaft 26, the driven shaft 27 is rotated.

  Here, if a force is applied to the drive shaft 26, the drive shaft 26 moves in the axial direction. However, since there is a space 36 between the drive shaft 26 and the driven shaft 27, the driven shaft 27 moves in the axial direction. There is no. When a large force is applied, the drive shaft 26 has a structure (24, 31, 40) that hits the case 20 before hitting the driven shaft 27. Therefore, the driven shaft 27 moves in the axial direction in any case. There is no.

  When the axial force of the drive shaft 26 is removed, the drive shaft 26 returns to the original position by the force of the spring 31.

  The connection shaft 21 described above has been described as an example of coupling to the angle detection unit 7 used in a positioner for adjusting the valve opening, but this structure can be applied to shaft structures of various products.

  Moreover, although the angle detection part 7 demonstrated above demonstrated as an example the angle detection part of the structure using the printed circuit board 9 and the ferrite pieces 8A and 9B, not only this but the angle detection part which operate | moves on various principles is used. Can do.

Hereinafter, the present invention will be described in detail with reference to FIGS. 4, 5, and 6. 4 is a schematic configuration diagram showing an embodiment of the angle sensor according to the present invention, FIG. 5 is a configuration diagram showing a configuration of the drive shaft shown in FIG. 4, and FIG. 6 is a driven type shown in FIG. It is a block diagram which shows the structure of a shaft.

The configurations of FIGS. 4, 5, and 6 correspond to the configurations of FIGS. 1, 2, and 3, respectively. The same elements as those in the reference example of FIG.

  The feature of the embodiment of FIG. 4 is the configuration relating to the leaf spring 53 which is an elastic means.

  One end of the leaf spring 53 is fixed to the drive shaft 26, and the other end of the leaf spring 53 is fixed to the driven shaft 27. That is, the drive shaft 26 and the driven shaft 27 are connected by the leaf spring 53.

  For this reason, when the drive shaft 26 rotates, the driven shaft 27 also rotates in synchronization. Specifically, when the drive shaft 26 rotates half, the driven shaft 27 also rotates half. Therefore, the embodiment of FIG. 4 can transmit rotation without rattling.

  At this time, the rotation direction is a direction in which the leaf spring 53 is twisted, and the leaf spring 53 has high rigidity. Therefore, the leaf spring 53 is not twisted, and the rotation angle of the drive shaft 26 and the rotation angle of the driven shaft 27 are equal.

  Further, the leaf spring 53 generates a repulsive force between the drive shaft 26 and the driven shaft 27. Then, the drive shaft 26 is pressed against the stopper 39. With such a configuration, the leaf spring 53 absorbs the axial displacement of the drive shaft 26.

Specifically, when a force is applied in the axial direction of the drive shaft 26, the drive shaft 26 is displaced in the axial direction, and the leaf spring 53 contracts in the axial direction. Further, when a large force is applied in the axial direction of the drive shaft 26, the drive shaft 26 is displaced in the axial direction, the stepped portion 24 and the flange portion 40 come into contact with each other, and the displacement of the leaf spring 53 is limited. The load is limited.

  Therefore, the embodiment of FIG. 4 does not apply an excessive load to the driven shaft 27 and exhibits stable characteristics.

  And the structure of this invention shows a suitable characteristic with respect to the angle sensor mounted in the positioner which adjusts a valve opening degree.

  The present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

It is a typical block diagram which shows the reference example of the angle sensor which concerns on this invention. It is a block diagram which shows the structure of the drive shaft shown in FIG. It is a block diagram which shows the structure of the driven shaft shown in FIG. It is a typical block diagram which shows one Example of the angle sensor which concerns on this invention. It is a block diagram which shows the structure of the drive shaft shown in FIG. It is a block diagram which shows the structure of the driven shaft shown in FIG. It is a side view which shows the typical block diagram of the conventional angle sensor. It is sectional drawing which shows the typical block diagram of the conventional angle sensor. It is explanatory drawing explaining the typical structure of the conventional angle sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,20 Case 2 Shaft 3,22,32 Cylindrical part 4,23,23A, 23B Shaft hole 6 Concave part 7 Angle detection part 8A, 8B Ferrite piece 9 Printed circuit board 21 Connection shaft 24 Step part 25 Convex part 26 Drive shaft 26A Cylindrical Part 27 Driven shaft 28 Angle sensor 29 Plate-like protrusion 30 Protrusion tip 31 Spring (elastic means)
32 Cylindrical part 33 Dish part 34 Plate-like groove 35 Recessed tip 36, 54 Space 37 Leg part 38 Bearing 39 Stopper 40 ridge part 51 Bearing 52 Holding plate 53 Leaf spring (elastic means)

Claims (2)

A drive shaft held in the case so as to be rotatable;
A driven shaft coupled to the drive shaft;
The drive end is fixed to the drive shaft and the other end to absorb axial displacement of the drive shaft has a high rigidity with respect to the rotational direction of the drive shaft is fixed to the driven shaft A leaf spring connecting the shaft and the driven shaft;
An angle detector provided on the tip side of the driven shaft;
An angle sensor for detecting a rotational displacement of the drive shaft. The angle detector
It is composed of a ferrite piece fixed to the driven shaft, and a printed circuit board on which a coil arranged on the case so as to face the ferrite piece is printed,
2. The angle sensor according to claim 1, wherein the rotational displacement of the drive shaft is detected from a change in mutual inductance caused by a rotational displacement of an intersection area between the ferrite piece and the coil.

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