JP2006183721A - Cylinder position detecting device and hydraulic and pneumatic cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder position detecting device capable of detecting a position of a piston rod with accuracy corresponding to an accuracy requirement of a detecting position. <P>SOLUTION: In this cylinder position detecting device 7, a magnetic force response part 5 which is formed in the piston rod 4 and of which circumferential position is changed responding to the axial position of the piston rod 4 is read by a sensor part 6 provided in a cylinder main body 2, to detect the axial position of the piston rod 4. Inclination of the magnetic force response part 5 with respect to the axial direction of the piston rod 4 is changed by the axial position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cylinder position detecting device that detects a piston position of a hydraulic or pneumatic cylinder as an absolute value, and an oil / pneumatic cylinder including the cylinder position detecting device.

  Hydraulic cylinders or pneumatic cylinders are used in various fields as drive means in the industry, and depending on the purpose of use, it may be necessary to detect the piston position. The position is detected as an absolute value.

  As such a cylinder position detecting device, the one described in Patent Document 1 is publicly known, FIG. 4A is an external perspective view, and FIG. 4B is a conceptual explanatory diagram of the main part.

  As shown in FIG. 4 (a), this cylinder detecting device is formed on a piston rod 13 of a hydraulic / pneumatic cylinder 11 having a cylinder body 12 and a piston rod 13 provided with a piston at the tip, and is positioned at the axial position thereof. Correspondingly, it is composed of a magnetic response portion 15 whose circumferential position changes proportionally and a sensor portion 16 provided in the cylinder body 12, and the sensor portion 16 reads the circumferential position of the magnetic response portion 15, It detects the axial position of the piston rod.

  FIG. 4B shows the formation position of the magnetic response portion 15 and the detection position of the sensor portion 15 on the surface development view of the piston rod 14. In this apparatus, FIG. As shown, a pair of magnetic response units 15R and 15L and sensor units 16R and 16L are provided on the axis of the piston rod 14, and the output of the pair of sensor units 16R and 16L is used to influence the rotation of the piston rod 14. Try to remove.

  This cylinder position detection device can detect the axial position of the piston rod as an absolute value without being influenced by the rotation of the piston rod, although having such a simple configuration.

  However, in this detection device, it has only been proposed to make the inclination of the magnetic response portion 15 constant (a constant proportionality factor) over the entire length of the piston rod 14, which is important for detection. It was not possible to detect more accurately in the part and to reduce the precision in the unimportant part.

This is because the magnetic response portion 15 is formed on the axis of the piston rod 14 whose circumferential length is relatively smaller than the axial length, and the effective detection length of the magnetic response portion 15 is at most the circumferential length. In this type of cylinder position detecting device, which is limited to less than half of the above, this is an important solution in terms of its effective use or purposeful use.
Japanese Patent Laid-Open No. 11-336713 (FIGS. 1 and 5)

  An object of the present invention is to provide a cylinder position detecting device capable of detecting the position of a piston rod with an accuracy corresponding to a request for accuracy of a detecting position, and an hydraulic / pneumatic cylinder including the cylinder position detecting device.

The cylinder position detecting device of the present invention reads a magnetic response part formed on a piston rod and whose circumferential position changes in accordance with the axial position of the piston rod with a sensor provided in the cylinder body. A cylinder position detecting device for detecting an axial position,
An inclination of the magnetic response portion with respect to the axial direction of the piston rod is changed according to the axial position.

  The hydraulic / pneumatic cylinder according to the present invention includes the cylinder position detecting device.

  According to the cylinder position detecting apparatus of the present invention, the inclination of the magnetic response portion with respect to the axial direction of the piston rod is changed according to the axial position, so that the position of the piston rod can be accurately matched to the accuracy requirement of the detected position. Can be detected.

  Further, according to the hydraulic / pneumatic cylinder of the present invention, the effect of the cylinder position detecting device is exhibited as a cylinder.

  Embodiments (examples) of the present invention will be described below with reference to the drawings.

  1A is a longitudinal sectional view of an example of an hydraulic / pneumatic cylinder provided with a cylinder position detecting device of the present invention, FIG. 1B is a conceptual explanatory diagram of the main part thereof, and FIG. FIG. 3 is a functional explanatory diagram of the sensor unit, FIG. 3B is a diagram showing a conversion graph used in FIG. 3A, and FIG. 3 is a diagram showing a conversion graph for explaining an arithmetic method used in the cylinder position detecting device of the present invention. .

  The hydraulic / pneumatic cylinder 1 is used in various fields as drive means in the industry. As shown in FIG. 1A, a cylinder body 2 and a piston slidably accommodated in the cylinder body 2 3 and a piston rod 4 that includes the piston 3 at the tip and outputs a driving force generated by the slide to the outside.

  A magnetic response portion 5 whose circumferential position changes corresponding to its axial position is formed on the outer circumference of the piston rod 4, and detects a magnetic change compared to other portions of this magnetic response portion 5. A sensor unit 6 is provided in the cylinder body 2.

  The sensor unit 6 includes a magnetic detection unit 6a, which is a plurality of magnetic detection elements. These magnetic detection units 6a are arranged in the circumferential direction of the cylinder body 2, and the circumference of the magnetic response unit 5 is determined from these detection data. The point where the direction position can be obtained is the same as that of the conventional example in FIG.

  Thus, the magnetic response unit 5 and the sensor unit 6 constitute a cylinder position detection device 7.

  FIG. 1B shows the formation position of the magnetic response portion 5 and the installation (detection) position of the sensor portion 6 on the surface development view of the piston rod 4, as shown in the development view. The x axis is set in the axial direction, and the y axis is set in the circumferential direction.

  Further, as shown in this figure, the magnetic response parts 5R and 5L and the sensor parts 6R and 6L are provided as a pair on the axis target, and the influence of the rotation of the piston rod 4 can be excluded from the conventional example of FIG. Common.

  As shown in FIG. 2A, the sensor unit 6 outputs the output from the magnetic response unit detection unit 6a, which is a magnetic sensor, as a pair, and outputs the graph of FIG. The axial position x of the piston rod 4 is calculated from the circumferential position y.

  This hydraulic / pneumatic cylinder 1 is different from the conventional example in that the characteristic point is that, as shown in FIGS. 1B and 2B, the shape of the magnetic response portion 5 is The inclination with respect to the axial direction differs depending on the axial position depending on the axial position x instead of a straight line.

  Specifically, in this example, the inclination indicates a proportional relationship, and more accuracy is required at the intermediate portion of the entire length of the piston rod 4, and therefore, the inclination at the intermediate portion (y in FIG. 2B) '): B (proportional coefficient = (circumferential position change of the magnetic response unit 5: Δy) / (axial change of the magnetic response unit 5 position: Δx)) is greater than the inclination of other portions: a It has become.

  Then, the functional position between the axial position: x and the circumferential position: y is x = 1 / b (y−c2), and the axial position can be calculated from the circumferential position. The ratio of the change in the axial position with respect to the change becomes smaller, and the axial position of the piston rod 4 can be detected with higher accuracy at this intermediate portion.

  That is, according to this cylinder position detection device 7, the position of the piston rod 4 can be detected with an accuracy corresponding to the accuracy requirement of the detection position, and the hydraulic / pneumatic cylinder 1 provided with this cylinder position detection device 7 According to the above, the effect of the cylinder position detecting device 7 can be exhibited as a cylinder.

  By the way, as will be described below with reference to FIG. 3, when the inclination of the magnetic response unit 5 with respect to the axial direction changes at the axial position as in the present invention, the axial position is calculated from the circumferential position. In addition, it should be noted that a correct result cannot be obtained unless operations are performed in a predetermined order.

  In FIG. 3, although the inclination is different from the graph of FIG. 2, a graph showing specific numerical values is shown for the central portion having a larger inclination.

As can be seen from these numbers, when considering the positive side of the y-axis, this graph is
y = x + 30 (0 ≦ x ≦ 10) Equation 1
y = 2x + 20 (10 ≦ x ≦ 20) Equation 2
y = x + 40 (20 ≦ x ≦ 30) Equation 3
(The minus side is an expression symmetric with respect to the x-axis.) The points at which the slope changes first are a0 and b0, and the midpoint of the central portion is c0 and d0. That is, the respective coordinates are a0 (10, 40), b0 (10, −40), c0 (15, 50), d0 (15, −50).
).

  Here, the piston rod 4 is located at an axial position x = 10, which is a position where the inclination of the magnetic response portion 5 with respect to the axial direction changes (referred to as “inclination point”). When not rotating in the circumferential direction, the magnetism detecting unit 6a detects the magnetism at the points a0 and b0 and outputs data “40, −40” at the circumferential position: y. Thus, the half of the distance between them = 40 can be obtained, and the axial position to be obtained: x = 10 can be calculated from Equation 1 or Equation 2 from this.

  At this time, from the data “40, −40” in the circumferential position: y detected by the magnetic detection unit 6a, the data “10, 10” having the axial position: x is first calculated using Expression 1 or 2. And then obtaining a half of the sum of the x data, the correct axial position: x = 10 can be calculated.

  However, as shown in FIG. 3, when the piston rod 4 is rotated so that the axial position x = 10 remains as it is and the circumferential position y is decreased by 4, the magnetic response unit 5 moves to the magnetic sensor 6a. On the other hand, when positioned at the points a1 (10, 36) and b1 (10, -44), the above-described method of calculating a half of the circumferential distance obtained from y = 40 is correct. : X = 10 can be obtained, but in the method of calculating the axial position: x first, this data becomes “6, 12” as shown in the figure, and is a half of the sum of the data of x = 9 Thus, the correct axial position cannot be obtained.

  When the piston rod 4 is rotated in this way, the points a1 (10, 36) and b1 (10, -44) are shown as the illustrated points a2 (6, 36), b2 (12 , −44) is detected, and the relational expression between y and x is different from the expression 1 for the point a2 and the expression 2 for the b2.

  In addition, in the graph of FIG. 3, it is clear that the rotation is in the downward direction at the inflection point, so mathematically, by using different equations corresponding to the points a2 and b2. It is possible to obtain the correct axial position: x, but in actuality, only the data of the circumferential position: y, which is the detection output of the magnetic sensor 6a, indicates which direction rotation at which axial position. It is impossible to determine whether or not there is a correct axial position. Therefore, it is necessary to calculate x after the calculation of y.

  As shown in the graph of FIG. 3, the magnetic response unit 5 is not the inflection point of the inclination, and even if the piston rod 4 is rotated, the corresponding point is within the same inclination range. In other words, as shown in the figure, the correct axial position can be calculated by either of the above-described calculation methods.

  That is, when the inclination of the magnetic response unit 5 does not change as in Patent Document 1, the above-described calculation method is not limited.

  Further, when both the pair of magnetic response units 5 are detected by either one of the pair of sensor units 6 (6R, 6L), correct detection cannot be performed. It is necessary to be careful not to make such arrangement.

  Note that the magnetic response unit 5 and the sensor unit 6 of the cylinder position detection device 7 described above are restricted so that the piston rod 4 does not rotate, or when some accuracy error due to rotation does not matter. It is sufficient to provide only one place instead of a pair. Even in this case, the effect of the cylinder position detecting device 7 is exhibited as a single body or as a cylinder.

  The cylinder position detecting device of the present invention can be used when the position of the piston is required in the hydraulic / pneumatic cylinder, and the hydraulic / pneumatic cylinder of the present invention requires a driving force by the hydraulic / pneumatic pressure. And can be used in any industrial field in which detection of the position of the piston is required.

(A) is a longitudinal cross-sectional view of an example of the hydraulic / pneumatic cylinder provided with the cylinder position detection apparatus of this invention, (b) is a conceptual explanatory drawing of the principal part. (A) is function explanatory drawing of the sensor part of FIG. 1, (b) is a figure which shows the graph for conversion used by (a). The figure which shows the graph for conversion for demonstrating the calculating method used with the cylinder position detection apparatus of this invention (A) is an external perspective view of a hydraulic / pneumatic cylinder provided with a conventional cylinder position detecting device, and (b) is a conceptual explanatory diagram of the main part thereof.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic / pneumatic cylinder 2 Cylinder body 3 Piston 4 Piston rod 5 Magnetic response part 6 Sensor part 7 Cylinder position detection apparatus

Claims (4)

Cylinder position detection that detects the axial position of this piston rod by reading the magnetic response part that is formed on the piston rod and changes in the circumferential position corresponding to its axial position with the sensor provided in the cylinder body A device,
A cylinder position detecting device characterized in that an inclination of the magnetic response portion with respect to an axial direction of the piston rod is changed by the axial position.   The cylinder position detecting device according to claim 1, wherein the inclination is made larger at a portion where higher accuracy of the axial position of the piston rod is required.   A pair of the magnetic response parts are provided on the axis object of the piston rod, and the sensor part is also provided in a pair corresponding to the magnetic response part thus provided, and the output of the pair of sensor parts is used by using the outputs of the pair of sensor parts. 3. The cylinder position detecting device according to claim 1, wherein the influence of rotation is removed.   An oil / pneumatic cylinder comprising the cylinder position detecting device according to any one of claims 1 to 3.

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