JPH0678804U - Displacement detector - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a small transformer displacement detector that can be installed and used in a narrow space. [Structure] A screw sleeve 3 is provided so as to project from a front portion of a case 14 having a built-in displacement detection coil 4, and the displacement detection rod 1
This screw sleeve, which doubles as a slide guide, is used to fix the detector. Further, the pushing spring 2 of the rod 1 is concentrically housed in the screw sleeve. This spring 2
Are formed of a non-magnetic material and are arranged so as to extend over both the inner region and the outer region of the coil 4. Further, the displacement detection coil 4 also has a configuration in which the secondary coil 4b is wound around the outer circumference of the primary coil 4a. Thereby, the length of the detector can be sufficiently shortened, and the detector can be installed in a narrow space to detect the displacement amount of the object.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a transformer type displacement detector.

[0002]

[Prior art]

 A differential transformer type displacement detector, which can be called a typical example of a transformer displacement detector, inserts a magnetic material displacement detection rod in the center of the differential coil and changes the displacement of this rod to the output change of the differential coil. Then, the displacement amount of the detection object that moves the rod is detected. In this case, the main body of the detector having the differential coil needs to be fixed to an object serving as a reference for displacement detection. Therefore, conventionally, as shown in Japanese Utility Model Laid-Open No. 2-144716, a method has been adopted in which a case that constitutes the main body is provided with a fixing collar and the collar is bolted to a reference object for detection. .

Further, when the displacement detection rod is pressed against an object to be detected by an extruding spring and the displacement of the object is transmitted to the rod, as shown in Japanese Patent Laid-Open No. 57-82701, there is a magnetic effect on the detection accuracy. The spring was placed outside the differential coil to eliminate the effect of the body spring.

[0004]

[Problems to be solved by the device]

 If the above-mentioned fixing collar is provided, the size of the detector is increased by that amount, and the reference object to which the main body is attached also needs a seat for receiving the collar, which increases the size.

The structure in which the push-out spring is arranged outside the differential coil also causes an increase in size because the detector corresponding to the installation space of the spring becomes long in the displacement direction.

For detecting the stroke of the brake pedal of an automobile, etc., it is necessary to incorporate the detector in a limited space, and therefore, the conventional displacement detector as described above cannot be expected to be advantageous.

[0007]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention provides a screw sleeve for fixing the detector, which also functions as a slide guide of the displacement detection rod, is provided at the front of the case accommodating the displacement detection coil. Displacement detection rod and push-out spring of this rod are arranged concentrically.

Further, the displacement detection rod push-out spring allows the push-out end side of the rod to be extended into the screw sleeve, and the push-out spring is made of a non-magnetic material so that the reaction force receiving end of the spring can be separated. It is more desirable to place it inside the moving coil.

[0009]

[Action]

 The displacement detection rod needs a movement guide when it is moved by pressing it against an object to be detected with a spring. The detector of the present invention originally forms this moving guide with a threaded sleeve, and inserts this threaded sleeve into the shaft hole provided in the reference object for detection to pass the displacement detection rod. Fix it to the reference object by screwing it directly into the hole or by screwing the tightening nut into the shaft sleeve through end of the screw sleeve. Therefore, the fixing collar that has been conventionally provided is unnecessary.

Further, since the pushing spring of the displacement detecting rod is housed in the screw sleeve, the length of the detector does not increase due to the installation of the pushing spring.

In the case where the push-out spring is made of a non-magnetic material and the reaction force receiving end side of the spring is arranged inside the displacement detection coil, the length of the screw sleeve is required for sliding the displacement detection rod. It can be shortened to the minimum length, and the effect of miniaturization is enhanced.

[0012]

Embodiment FIG. 1 shows an example of the displacement detector of the present invention. Reference numeral 1 in the figure shows a displacement detection rod formed of a ferromagnetic material, SUS430. This rod receives the force of the push-out spring 2 at the part of the flange provided midway in the longitudinal direction, and is pushed out of the detector from the tip of the screw sleeve 3. The push-out spring is pushed in by the displacement detection target while compressing the push-out spring. It is

When the object to be detected is displaced, the relative positional relationship between the displacement detecting coil 4 and the displacement detecting rod 1 changes according to the amount of displacement, and the coil inductance changes. It is generally easy to convert the change in the inductance into a voltage change by an electric circuit. Therefore, in the illustrated detector, an electric circuit therefor is provided on the circuit board 5 to output the movement amount of the detection target as a voltage signal.

The screw sleeve 3 supports the flange portion of the displacement detection rod 1 on the inner surface and the outer periphery on the tip side of the flange, and also functions as a rod movement guide. Further, here, the screw sleeve 3 is formed of SUS304, which is a non-magnetic material, and its rear end is extended to near the other end of the displacement detection coil 4, and the displacement detection coil 4 is concentrically fitted to the outer periphery of this extended portion. ing. With this arrangement, the screw sleeve 3 serves as a position reference to increase the concentricity of the coil 4 and the rod 1, and the screw sleeve 3 and the displacement detection coil 4 can be integrated in advance so that the detector Easy to assemble. The screw sleeve 3 is made of a non-magnetic material so that the extending portion inserted in the coil does not affect the change in the inductance of the coil.

The push-out spring 2 is also made of SUS304, which is a non-magnetic material, so as not to affect the inductance change in the coil, and is arranged over both the inner region and the outer region of the displacement detection coil 4. This spring 2 is fitted on the outer circumference of the displacement detection rod 1 and arranged substantially concentrically with the screw sleeve 3 and the displacement detection rod 1. One end pushes the rod and the other end is supported by the spring receiver 6. .

The displacement detection coil 4 is configured by winding a secondary coil 4b on a primary coil 4a. In the illustrated detector, in order to detect differentially the inductance change due to the displacement of the displacement detection rod 1, a dummy coil 8 is arranged on the outer circumference of the displacement detection coil 4 with a magnetic shield 7 therebetween, and the inductance of this coil is arranged. And the inductance of the displacement detection coil 4 are compared, and the difference is taken out.

As an example, a coated conductor wire having a diameter of 70 μm is wound around the detection coil bobbin 9 having an effective diameter of 10 mm and an effective length of 20 mm for 2000 turns as a primary coil and 2000 turns as a secondary coil. The same coated conductor is wound around the dummy coil bobbin 10 having an effective diameter of 17 mm and an effective length of 20 mm for 2000 turns as a primary coil and 2000 turns as a secondary coil. A displacement detecting rod having a diameter of 3 mm is moved in and out of the detecting section having such a coil structure to detect the displacement amount. Figure 2 shows the output state of the output voltage when a displacement of 20 mm is detected with the above configuration.

Here, the dummy coil 8 is used to differentially detect a change in the inductance in order to remove noise due to a disturbance factor such as temperature. However, if it is not necessary to consider the disturbance factor, displacement detection is performed. Detection by only the coil 4 is also possible.

3 and 4 show an example in which a limit switch is added to the displacement detector of FIG. Displacement detection If there is play in the moving stroke of the object, it is desirable to detect the displacement from the point when the play disappears. For this purpose, it is sufficient to detect that the displacement detection rod 1 is at the end of detection and detect the amount of displacement from that. The illustrated limit switch can be used for such a purpose.

In the limit switch of FIG. 3, the rear end of the displacement detection rod 1 is formed of a non-magnetic insulator 11, and when the displacement detection rod 1 is pushed to the end of detection, the electrical contact 12 is insulated. It is configured to be pushed open and turned off. Further, the limit switch shown in FIG. 4 has a structure in which, when the displacement detection rod 1 is pushed to the end of detection, the electric contact 13 is pushed by the insulator 11 and turned on in the opposite manner to that shown in FIG.

These detectors with limit switches are particularly suitable for detecting the amount of displacement of the brake pedal of a motor vehicle with stroke play.

In the structure as disclosed in Japanese Patent Laid-Open No. 57-82701, the total length of the detector is 3 to 4 times the maximum detected displacement amount. On the other hand, in the structure of FIG. 1 in which the displacement detection coil and the primary and secondary coils of the dummy coil are concentrically arranged, the total length of the detector can be shortened to about twice the maximum detection displacement. Further, since the fixing screw sleeve 3 is projected to the front of the case 14, the length of the detector occupying the installation space (the length from the front surface of the case 14 serving as the fixing surface to the lid 15 of the detecting portion). ) Is even shorter, which is very advantageous in cases where the installation space is limited.

[0023]

[Effect of device]

 As described above, the displacement detector of the present invention can remarkably shorten its length, and when it is necessary to detect the displacement amount of a mechanism or a component in an environment with severe space constraints, For example, a great effect can be expected when the brake pedal stroke of an automobile is detected from the displacement amount of an input rod of a master cylinder that is linked to the pedal.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a displacement detector of the present invention.

FIG. 2 is a diagram showing a relationship between an output voltage and a displacement amount of the detector shown in FIG.

FIG. 3 is a sectional view showing a part of a displacement detector including a limit switch.

FIG. 4 is a sectional view showing a part of a displacement detector incorporating a limit switch.

[Explanation of symbols]

 1 Displacement Detection Rod 2 Extrusion Spring 3 Screw Sleeve 4 Displacement Detection Coil 5 Circuit Board 6 Spring Receptor 7 Shield 8 Dummy Coil 9 Detection Coil Bobbin 10 Dummy Coil Bobbin 12, 13 Electrical Contact 14 Case 15 Detection Part Cover 16 Circuit Section Lid of

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuyuki Sasaki 1-1-1 Kunyo Kita, Itami No. Sumitomo Electric Industries, Ltd. Itami Works

Claims (5)

[Scope of utility model registration request] 1. A transformer-type displacement in which a displacement detection rod partially or wholly made of a magnetic material is inserted into the displacement detection coil, and a displacement amount is obtained from an output change of the displacement detection coil due to the displacement of the displacement detection rod. In the detector, a screw sleeve for fixing the detector, which also serves as a slide guide of the displacement detection rod, is provided projectingly on the front part of the case containing the displacement detection coil, and the displacement detection rod and this rod Displacement detector characterized in that push-out springs are arranged concentrically. 2. The displacement detector according to claim 1, wherein the push-out spring is made of a non-magnetic material, and the reaction force receiving end side of the spring is arranged inside the displacement detection coil. 3. The displacement detector according to claim 1, wherein the rod push-out end side of the push-out spring can be extended into the screw sleeve. 4. The screw sleeve is made of a non-magnetic material, the rear end of the sleeve is extended to near the other end of the displacement detecting coil, and the displacement detecting coil is concentrically fitted to the outer periphery of the extended portion. The displacement detector according to 1, 2, or 3. 5. The displacement detector according to any one of claims 1 to 4, further comprising a switch that is actuated at a push-in end of the displacement detection rod when the displacement detection rod reaches the end of the displacement detection range.