JP3009764U - Displacement detection device - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the size, increase the output, and improve the stability of an inductance type displacement detection device. A circuit board is arranged so that the inductance detection elements L ₁ and L ₂ face each other with a minute gap to the plate surface of the conductive disk 21a of the eccentric rotor 21 that is eccentrically rotated by the drive shaft 34. 38. Oscillation circuit and detection circuit components 46 and 47 are mounted on the circuit board 38 and led out to the outside through external terminals 48 such as input terminals and output terminals.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a displacement detection device which is used in various machine tools, measurement and control devices, etc., and detects a minute displacement of a material to be measured as an electrical output proportional to the displacement. This is an inductance displacement detection structure that incorporates an oscillator, displacement detection coil, eccentric rotor, detection circuit, etc., and changes the inductance of the detection coil by the eddy current generated in the eccentric rotor.

[0002]

[Prior art]

 Conventionally, there is an inductance type displacement detecting device of this type disclosed in Japanese Utility Model Publication No. 52-35717.

The principle configuration of this displacement detecting device will be described with reference to FIGS. 11 to 13. In FIG. 11, reference numeral 1 denotes an eccentric rotor, which is formed by mounting a disc 1a made of metal such as brass on an input shaft (rotating shaft) 1b to which an external rotational force is applied, with an eccentricity of Δs from the shaft center. Has been done. The eccentric rotor, that is, a disc (hereinafter referred to as an eccentric disc) 1a that is eccentrically mounted on the input shaft 1b (hereinafter referred to as an eccentric disc) 1a is sandwiched between the input shaft 1b and, for example, 180 ° angular intervals. Inductance detecting elements (displacement detecting coils) L ₁ and L ₂ are arranged, and in the inductance detecting elements L ₁ and L ₂ , coils (insulating coated wires) 3 ₁ and 3 ₂ are provided around the cores 2 ₁ and 2 _2. It is formed by winding.

The inductance detecting elements L ₁ and L ₂ form a bridge circuit 4 with rectifying elements D ₁ and D ₂ as shown in FIG. 12, and a high frequency oscillator 5 that oscillates a frequency of 1 to 10 MHz, for example. Are connected to form an oscillation detection circuit 6.

In this configuration, the inductance detection element L₁, L₂When an alternating magnetic field is applied to the eddy current 1a, an eddy current is generated in the eccentric disc 1a.₁ , L₂Generates a secondary magnetic field in the opposite direction to the alternating magnetic field. In this state, when a rotational force is applied to the input shaft (rotating shaft) 1b of the eccentric disc 1a, the inductance detecting element L ₁ , L₂And the outer peripheral surface of the eccentric disc 1b are different from each other, the inductance detection element L₁, L₂When the effective inductance of changes, and its rotation angle is θ, the rectified output voltage e proportional to sin θ as shown by the curve m in FIG. The output of the oscillation detection circuit 6 is obtained, and the displacement of the measured material can be detected and displayed.

A specific configuration of this displacement detection device will be described with reference to FIGS. 14 and 15. The rotating shaft 1b of the eccentric rotor 1 is rotatably supported by ball bearings 9a and 9b, which are mounted on a base 7 and a cylindrical bottom substrate 8 having a bottom, and the eccentric disc 1a is mounted on the base 7 and the back substrate 8. It is located in the middle part between, and more specifically, in the tubular part 8a of the back substrate 8.

As described above, the inductance detecting elements L ₁ and L ₂ formed by winding the coils (insulating coated wires) 3 ₁ and 3 ₂ around the cores 2 ₁ and 2 ₂ are the cylinders of the back substrate 8. It is attached to a cylindrical holder 9 arranged in the cylindrical portion 8a with an angular interval of 180 ° and faces the outer peripheral surface of the eccentric disc 1a.

Since the inductance detecting elements L ₁ and L ₂ have the same configuration, one inductance detecting element L ₁ will be described with reference to FIG. Core 2 ₁ is formed by planting a columnar portion 2b ₁ integrally with the center of the disc portion 2a _1, insulating coating on the columnar portion 2b ₁ of this is applied a number of turns of the coil 3 ₁ of the required It is wound and its lead wire 3a ₁ is led out to the disk portion 2a ₁ side. The core 2 ₁ of coils 3 ₁ outer periphery of the columnar portion 2b ₁ wound around an outer diameter is made substantially the same diameter as the disc portion 2a _1, a cylindrical coil case 11 having one end opened at The tip of the columnar portion 2b ₁ is exposed and fitted and fixed. Then, the outer core 2 ₁ including a coil case 11, leaving the tip of the pillar-shaped portion 2b _1, which is surrounded by the external thread member 12 made of a synthetic resin material or the like, the lead wires 3a ₁ of the coil 3 ₁ male screw member It is led out from a conduction hole 12a formed in the rear part of the twelve.

Both of the inductance detecting elements L ₁ and L _{2 configured} as described above are screwed into the female screw portions 10a and 10b formed on the peripheral wall portion of the cylindrical holder 10 described above with an angular interval of 180 ° to form an eccentricity. When the disc 1a is rotated, it does not come into contact with the outer peripheral surface of the disc 1a, and the gap between the outer peripheral surface of the eccentric disc 1a and the gap adjustment is adjusted by the screwing depth of the female screw portions 10a, 10b.

The cylindrical holder 10 has its one end edge side pressed by the set screw 13 screwed into the bottom surface 8 b of the back substrate 8 and the other end side pressed against the base 7 to regulate the position. It is designed to do.

A circuit board 15 is attached to the outer surface side of the bottom surface portion 8b of the back substrate 8 via columns 14 at required intervals, and the circuit component of the oscillation detection circuit 6 described above is attached to the circuit board 15. An external terminal 17 is mounted on the circuit board 15 and is projected to the outer surface side of a case 18 which covers all the assembled members assembled as described above. Through the external terminal 17, inputs of the inductance detection elements L ₁ and L ₂ are applied and outputs are taken out.

According to the displacement detection device configured as described above, a detection signal corresponding to the rotation of the eccentric disc 1a is obtained at the external terminal 17 as in the case of the principle configuration described in FIGS. The change of the material to be measured can be detected.

[0013]

[Problems to be solved by the device]

 In the conventional displacement detection device configured as described above, the magnetic flux is not sufficiently converged by the inductance detection element, so that the eddy current value generated in the eccentric disc of the eccentric rotor is small due to this magnetic flux, and this eddy current causes The secondary magnetic field in the opposite direction to the alternating magnetic field generated in the inductance detection element also becomes smaller, and as a result, the output voltage cannot be made large and there is the problem of lack of clarity in detection and display.

Further, the gap between the inductance detecting element and the outer peripheral surface of the eccentric disc of the eccentric rotor varies depending on the part of the detecting element due to the circular outer peripheral surface of the eccentric disc. However, there is a limit to how much it can be made, depending on the processing accuracy of each member. For example, the minimum limit is about 0.3 mm, which results in a small output voltage and a problem with stability.

Since the inductance detecting element is located on the outer peripheral side of the eccentric disc of the eccentric rotor, the outer diameter of the entire apparatus becomes large and the apparatus becomes large in size, which requires a lot of space for installation. The department was restricted.

The present invention has been made in view of the above points, and it is possible to reduce the influence of lateral and axial loads applied to the rotary shaft and reduce the size by increasing the output and improving the stability. An object of the present invention is to provide a displacement detecting device.

[0017]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the displacement detecting device of the present invention is provided with a plurality of inductance detecting elements with a small gap with respect to a conductive plate surface of an eccentric rotor which is eccentrically rotated by a drive shaft. Are arranged face-to-face with each other so that a detection signal proportional to this rotation angle can be obtained as the eccentric rotor rotates.

Further, it is preferable that the inductance detecting element itself causes the generated magnetic flux to form a closed circuit.

Further, the drive shaft and the eccentric rotor may be indirectly connected via an engagement connecting member.

Further, it is preferable that the main body case having the detection mechanism including the eccentric rotor and the inductance detection element has a sealed structure.

Further, it is preferable that the gap width between the conductive plate surface of the eccentric rotor and the inductance detecting element can be adjusted.

[0022]

[Action]

 The magnetic flux generated by the inductance detection element intersects with the conductive plate surface of the eccentric rotor, which causes an eddy current on the conductive plate surface of the eccentric rotor, which causes a secondary magnetic field in the inductance detection element. When the drive shaft rotates the eccentric rotor, a detection signal proportional to this rotation angle is obtained with this rotation.

In this case, the inductance detection element has a high convergence rate of the magnetic flux by allowing the generated magnetic flux to form a closed circuit by itself, which is accompanied by the miniaturization of the facing gap with the conductive plate surface of the eccentric rotor. Can take a large output.

Further, by indirectly engaging and connecting the drive shaft and the eccentric rotor, the influence of various loads applied to the drive shaft is reduced and the stability of the output is increased.

[0025]

【Example】

 Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 10, and first, a basic configuration of a displacement detection device according to the present invention will be described with reference to FIGS.

In FIGS. 1 and 2, reference numeral 21 denotes an eccentric rotor, which is formed by mounting a disc 21a formed of a conductive metal plate on a rotary shaft 21b as an input shaft with an eccentricity of Δs from the center of the shaft. Has been done.

On the other hand, the inductance detection element L of this example₁, L₂Is the central portion 22a₁, 22a ₂ Winding groove 22b around₁, 22b₂Vase-shaped core 22₁, 22₂Winding groove 22b₁, 22b₂Coil (insulated wire) 23₁, 23₂Is wound around the center part 22a₁, 22a₂The generated magnetic flux is configured to create a closed circuit by itself.

The inductance detecting elements L ₁ and L ₂ have a magnetic flux below or above a disc eccentrically mounted on the rotation shaft 21b of the eccentric rotor 21 (hereinafter referred to as eccentric disc) 21a. The eccentric discs 21a are made to face each other with a uniform gap maintained so as to intersect with each other, and when one of the inductance detection elements L ₁ or L ₂ has a maximum eddy current value, the other is disposed at a position where it is minimum.

In this case, the gap between the eccentric disc 21a and the inductance detecting elements L ₁ and L ₂ is set to be the minimum in a range where they do not contact each other.

As shown in FIG. 3, the inductance detecting elements L ₁ and L ₂ arranged to face the eccentric disc 21a are connected to the high frequency oscillation circuit 24 and the detection circuit 25, as shown in FIG. In this configuration, when an alternating magnetic field is applied to the inductance detecting elements L ₁ and L ₂ by the high frequency oscillating circuit 24, an eddy current is generated in the eccentric disk 21a, and based on this, an alternating magnetic field is applied to the inductance detecting elements L ₁ and L _2. A secondary magnetic field in the opposite direction is generated. In this state, when a rotational force is applied to the rotating shaft 21b of the eccentric disc 21a and the eccentric disc 21a is eccentrically rotated, the crossing area of the eccentric disc 21a with respect to the magnetic flux generated by the inductance detection elements L ₁ and L ₂ is increased. Changes, which changes the eddy current value and changes the effective inductance of the inductance detection elements L ₁ and L ₂ .

As a result, the output voltage corresponding to the rotation angle of the eccentric disc 21a is obtained at the output of the detection circuit 25, and the change of the material to be measured can be detected and displayed. Next, a specific embodiment of the present invention will be described with reference to FIGS. FIG. 4 shows the entire displacement detecting device of this example, in which 32 is a case whose lower surface side is open, and the bearing metal 33 as a bearing is press-fitted into the central bearing cylindrical portion 32b of the upper surface portion 32a. A drive shaft 34 serving as an input shaft is inserted through the bearing metal 33 and is retained by a C ring 35 so as to be retained and airtight by an O ring 36. The inside of the case 32 of the drive shaft 34 is retained. A coupling gear 37 as a connecting member is fixed to the end of the.

A circuit board 38 is fitted to the open lower surface 31c of the case 31, and the eccentric rotor 21 and the inductance detection elements L ₁ and L _{2 are} arranged at the center of the inner surface of the circuit board 38. The detection mechanism 39 is mounted.

In this detection mechanism 39, as shown in FIG. 7, the stepped fixed shaft 40 is fixed to the circuit board 38 in the axial direction of the drive shaft 34 by screws 41, and the stepped fixed shaft 40 is fixed. interposed therebetween inductance detecting element L _1, L ₂ is fixed on the circuit board 38, i.e., an inductance sensing element L _1, L ₂ is pot-shaped core 22 _1, 22 ₂ have you on the lower surface side on the circuit board 38 secured by an adhesive, the open side upper surface of the coil 23 _1, 23 ₂ winding groove 22b ₁ wound around the, 22b ₂ upward and rotatably supported in place by the stepped fixing shaft 40 eccentric It faces the lower surface of the eccentric disc 21a of the rotor 21 with a required space.

In the eccentric rotor 21 of this example, a bearing frame portion 21a ₁ centered on a shaft support portion is formed on the upper surface side of the eccentric disc 21a, and a ball bearing 42 as a bearing is fitted therein. A ball bearing 43 as a bearing is fitted by forming a bearing recess 21a ₂ centered on the shaft support on the lower surface side. The ball bearing 43 on the lower surface is mounted on the step surface 40a of the stepped fixed shaft 40. The ball bearings 42 and 43 are axially supported by being inserted into the stepped fixed shaft 40 so as to be engaged with each other, and the C-ring 44 is fitted to the protruding end of the shaft 40 to prevent the shaft 40 from coming off. .

The eccentric rotor 21 has a coupling lever 45 fixed to the upper surface side of the eccentric disc 21a, which meshes with the coupling gear 37 as the coupling member of the operating shaft 34 described above. The reference numeral 45 includes a fixed surface portion 45a fixed to the eccentric disc 21a and a concavo-convex connecting portion 45b formed in a rising shape from the fixed surface 45a. The connecting portion 45b may be formed by only one convex portion.

By fitting the circuit board 38 into the opening on the lower surface side of the case 32, the connecting lever 45 has a concave-convex connecting portion 45 b and a coupling gear 37 as a connecting member at the inner end of the operating shaft 34. They automatically mesh with each other and are connected to the operating shaft 34.

Further, as shown in FIG. 4, the high frequency oscillation circuit 24 and the circuit components 46 and 47 of the detection circuit 25 are mounted on the inner surface side of the circuit board 38, and the input terminal 48a is mounted on the outer surface side. External terminals 48 such as an output terminal 48b and a ground terminal 48c are attached and electrically connected to the coils 23 ₁ and 23 _{2 of the} inductance detection elements L ₁ and L ₂ .

A moisture resistant coating material 49 that closes the lower surface side opening of the case 32 is pushed into the outer surface side of the circuit board 38, and the external terminals 48 are led out from the coating material 49. The coating material 49 may cover the entire outer periphery of the case 32.

In the displacement detecting device of the present example configured as described above, when the drive shaft 34 is rotated, the eccentric disk 21 a of the eccentric rotor 21 of the detection mechanism 39 is connected to the inner end portion of the drive shaft 34. It is configured so as to be integrally rotated through a coupling lever 45 that meshes with a coupling gear 37 as a material, and the drive shaft 34 becomes a member equivalent to the rotary shaft 21b of the eccentric rotor 21 in the basic configuration described above. As in the case of the basic configuration, when the operating shaft 34 is rotated with a DC voltage applied to the input terminal 48a of the external terminal 48, the output voltage proportional to the rotation angle of the eccentric disk 21a that is interlocked with this is output voltage. Is obtained at the output terminal 48b, and the change of the material to be measured can be detected.

In the above configuration, the eccentric disc 21a of the eccentric rotor 21 is formed of a conductive metal material, but in order to reduce inertia, it may be formed of a lightweight conductive metal material such as brass or aluminum. desirable.

The inductance detecting elements L ₁ and L ₂ have a gap a of 0.1 to 0.05 mm between the eccentric rotor 21 and the eccentric disc 21 a, and an angular interval between the detecting elements L ₁ and L ₂ is 18 mm. The change can be reliably detected by fixing it to the circuit board 38 at a position where the magnetic flux change and the output generated by the eccentric rotation of the eccentric rotor 21 are maximized.

As shown in FIG. 9, a polytetrafluoroethylene (trade name: Teflon) film made of polyethylene terephthalate film is provided in a gap portion a between the inductance detecting elements L ₁ and L ₂ and the eccentric plate 21a of the eccentric rotor 21. By inserting a lubricative film 51 such as a biaxially stretched film (trade name Mylar), smoothness and stability of insulation and rotation can be achieved.

Then, as shown in A, B, and C of FIG. 10, the inductance detection element L₁, L ₂ In order to adjust the gap a between the eccentric disc 21a and the eccentric disc 21a of the eccentric rotor 21, the inductance detection element L₁, L₂Vase-shaped core 22₁, 22₂Male thread 22c on the circumference of ₁ , 22c₂And the female screw recess 38a is formed on the circuit board 38 correspondingly.₁, 38b₂Is formed in advance, and this female screw concave portion 38a is formed.₁, 38a₂Vase core 22₁ , 22₂Or a male screw 40b is formed in the lower portion of the fixed shaft 40 that supports the eccentric rotor 21, and a female screw hole 38b is formed in the circuit board 38 correspondingly. The structure is such that it is screwed into the hole 38b (FIG. 9B), and further between the upper or lower part or the upper and lower parts of the eccentric disc 21a of the eccentric rotor 21 and the C ring 44 at the tip of the fixed shaft 40 or the step surface 40a. Alternatively, the adjustment washer 52 may be inserted between the both to change the number and the thickness thereof (C in the same figure) to enable fine adjustment of the gap a.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above-described embodiment, two inductance detecting elements L ₁ and L ₂ are arranged at an angular interval of 180 °, but four and six detecting elements are arranged at an angle of 90 ° and 60 °. It is also possible to have a configuration in which they are arranged at intervals.

The eccentric rotor 21 and the operating shaft 34 are engaged and connected via the connecting members 37 and 45 to transmit the rotation of the operating shaft 34 to the eccentric rotor 21. The operation shaft 34 can be directly connected to the eccentric rotor 21 to directly rotate the operation shaft 34.

[0047]

[Effect of device]

 In the change detecting device according to the present invention configured as described above, a plurality of inductance detecting elements are arranged facing each other on the plate surface of the eccentric rotor with a minute gap, and are arranged at an angular interval of a required angle. The depth is shortened and downsizing is possible, making it easy to mount on equipment.

In addition, the inductance detection element has a high convergence rate because the generated magnetic flux creates a closed circuit by itself, and a large output can be obtained due to the miniaturization of the facing gap with the eccentric rotor, which enables displacement detection. It can be done reliably.

The eccentric rotor is not directly connected to the drive shaft, but is indirectly connected via the engagement connecting member, so that the influence of various loads applied to the drive shaft is reduced and the output stability is stabilized. And reliability is improved.

Further, by making the apparatus main body case a sealed structure, the influence on the internal function is reduced even when the apparatus main body case is used in a bad environment, and displacement detection can be reliably performed for a long period of time.

Further, by adjusting the movement of one or both of the eccentric rotor and the inductance detecting element in the axial direction, the gap width between the two can be set accurately.

[Brief description of drawings]

FIG. 1 is a plan view of the basic structure of the device of the present invention.

FIG. 2 is a vertical sectional view of the same.

FIG. 3 is an electric connection diagram of the same.

FIG. 4 is a vertical sectional view of an example of the device of the present invention.

FIG. 5 is a bottom view of the same.

FIG. 6 is an exploded perspective view of the same.

FIG. 7 is a vertical cross-sectional view of the same part.

FIG. 8 is a perspective view of the same part.

FIG. 9 is a longitudinal sectional view of another example of the main part of the same.

FIG. 10 is a vertical cross-sectional view of still another example of the main part.

FIG. 11 is a configuration diagram for explaining the principle of a conventional device.

FIG. 12 is an electric circuit diagram of the same.

FIG. 13 is an output waveform diagram of the same.

FIG. 14 is a sectional view of a conventional device.

FIG. 15 is a cross-sectional view of an inductance detection element applied to the same device.

[Explanation of symbols]

21 yen plates L ₁ as eccentric rotor 21a electroconductive plate surface, L ₂ the inductance detecting element 22 _1, 22 ₂ Core 23 _1, 23 ₂ coil 34 drive shaft 37 coupling gear 38 circuit board 40 fixed shaft 45 connecting member

Claims (5)

[Scope of utility model registration request] 1. An eccentric rotor which is eccentrically rotated by a drive shaft, and a plurality of inductance detecting elements are arranged face-to-face with a small gap at an angular interval of a required angle, and the eccentric rotor rotates. A displacement detection device characterized in that a detection signal proportional to the rotation angle is obtained. 2. The displacement detecting device according to claim 1, wherein the magnetic flux generated by the inductance detecting element itself forms a closed circuit. 3. The displacement detecting device according to claim 1, wherein the drive shaft and the eccentric rotor are indirectly connected via an engagement connecting member. 4. The displacement detecting device according to claim 1, 2 or 3, wherein a main body case containing a detection mechanism including the eccentric rotor and the inductance detecting element has a sealed structure. 5. The gap width between the conductive plate surface of the eccentric rotor and the inductance detecting element is adjusted by moving one or both of the eccentric rotor and the inductance detecting element in the axial direction. The displacement detection device according to claim 1 or 3, characterized in that.