JPH02218965A - Impact sensor - Google Patents

Abstract

PURPOSE:To provide the title sensor withstanding impact force and made repeatedly usable by positioning a movable permanent magnet between the fixed permanent magnets in a main body case in a manner freely movable in the longitudinal direction of said case and making the magnetic poles thereof opposed to the fixed permanent magnets the same with each other. CONSTITUTION:Fixed permanent magnets 3, 3 are inserted in the main body case 2 of this sensor 1 so that the magnetic poles thereof become parallel to the longitudinal direction of the case and the same poles thereof are in the same direction and mounted to both side ends of said case 2. A movable permanent magnet 4 is arranged between said magnets 3, 3 in a state freely movable in the longitudinal direction so that the magnetic poles thereof opposed to the magnets 3, 3 are same and become repulsive each other and becomes a levitated stage almost at the center of the case 2. When external force is applied to this sensor 1, impact force acts on the magnet 4 and the magnet 4 reciprocally moves within the case 2 in the axial direction. At this time, the flux density piercing a Hall element 5 is changed by the displacement of the magnet and Hall voltage is generated in the element 5 and impact force can be measured on the basis of this change.

Description

[Detailed Description of the Invention] [Table of Contents] Overview Industrial Application Fields Conventional Technology Problems to be Solved by the Invention Means for Solving the Problems Embodiments Effects of the Invention [Summary] The present invention mainly focuses on portable type shocks. Our goal is to provide an impact sensor that does not break even when excessive impact force is applied to the sensor, can withstand repeated use, has low dissipated power, and is easy to incorporate into portable equipment. A main body case, a pair of fixed permanent magnets supported by the main body case, whose magnetic axes are the same as the longitudinal direction of the main body case, and poles with the same name are arranged in the same direction, and between the fixed permanent magnets in the main body case. a movable permanent magnet that is located and movable in the longitudinal direction of the main body case and arranged so that the magnetic poles facing each fixed permanent magnet are the same; a Hall element that measures changes in magnetic flux density within the main body case; It is characterized by consisting of.

Problem solved.

The present invention was devised to solve the above problems, and provides a shock sensor that does not break even when excessive impact force is applied, consumes less power, and is easy to incorporate into portable equipment. The purpose is to

[Industrial Field of Application] The present invention is mainly applied to portable type impact sensors.

[Prior Art] Conventionally, a pressure sensor using a piezo element or a semiconductor, a strain gauge using a load cell, etc. have been used as a vibration/impact detection sensor.

[To solve the problem that the invention aims to solve '5HE However, since the conventional vibration/shock sensor uses a plastic material, it is brittle, easily damaged when subjected to excessive impact force, and cannot withstand repeated use. The impact sensor of the present invention includes a cylindrical main body case, and a pair of fixed permanent sensors supported by the main body case, whose magnetic axes are the same as the longitudinal direction of the main body case, and whose poles with the same name are arranged in the same direction. a movable permanent magnet located between the fixed permanent magnets in the main body case, movable in the longitudinal direction of the main body case, and arranged so that magnetic poles facing each fixed permanent magnet are the same; and a Hall element that measures changes in magnetic flux density.

[Example code] Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 1 shows an embodiment of a shock sensor according to the present invention.

The impact sensor 1 includes a cylindrical main body case 2, a pair of fixed permanent magnets 3.3, a moving permanent magnet 4, and a Hall element 5.

A pair of fixed permanent magnets 3 are installed on both ends of the cylindrical main body case 20.
．． 3 are fitted and attached to each other. The fixed permanent magnet 3.3 has a magnetic axis parallel to the longitudinal direction of the main case 2,
A movable permanent magnet 4, which is movable in the longitudinal direction of the main body case 2, is inserted between the fixed permanent magnets 3 and 3 in the main body case 2, which are arranged so that the poles with the same name are in the same direction. There is. The movable permanent magnet 4 is arranged so that the magnetic poles facing each of the fixed permanent magnets 3.3 are the same, that is, so that they repel both fixed permanent magnets 3.3.

Therefore, unless an external force is applied to the shock sensor 1, the moving permanent magnet 4 is in a floating state approximately at the center between the fixed permanent magnets 3 and 3. 4 is configured to move only in the longitudinal direction of the main body case 2 and not to come into contact with the main body case 2.

For example, a configuration may be considered in which a rotation stopper made of a non-magnetic material is attached to the inner surface of the main body case 2 facing the outer periphery of the moving permanent magnet 4.

Here, on the fixed permanent magnet 3 side inside the main body case 2,
A Hall element 5 is attached to measure changes in magnetic flux density within the main body case 2.

Next, a configuration example illustrating the principle of the present invention will be explained with reference to FIG.

As can be understood from the drawings, reference numeral 10 indicates an oscillator, and the oscillator 10 outputs a pulse signal having a constant waveform and a constant period. Further, a constant current is passed through the Hall element 6. In this state, the Hall element 5, which has received a change in the magnetic field due to the impact, changes its output voltage in proportion to the change in the magnetic field, so this voltage is amplified by the voltage amplification section 9 and sent to the output buffer 7 in the next stage. , a detection signal approximately proportional to the impact force is obtained.

As shown in Fig. 4, it has been confirmed by experimental data that the change in magnetic flux density is proportional to the movement width of the moving permanent magnet 4 moved within the main body case 2, and from this, the change in magnetic flux density, that is, the output of the Hall element. Impact force can be detected by measuring changes in voltage.

Furthermore, a temperature sensor 6 is attached to the outside of the main body case 2.

By attaching the sensor 6, the detected value can be calibrated, and therefore an accurate detected value that is not affected by temperature can be obtained.

In the above configuration, when an external force such as impact acceleration is applied to the impact sensor 1, an impact force F acts on the movable permanent magnet 4, and the movable permanent magnet 4 reciprocates in the axial direction within the main body case 2. At this time, since the magnetic flux density penetrating the Hall element 4 changes due to the displacement of the moving permanent magnet 4, a Hall voltage is generated in the Hall element 4.

Then, as described above, by measuring the change in this voltage, the impact force can be measured.

(The thickness of the Hall element 4 is dl, the Hall coefficient is RH, the current flowing through the Hall element 4 is ■, and the magnetic field applied in a direction perpendicular to the Hall element 4 is B).

In addition, if the impact force to be measured is large, the moving permanent magnet 4
The longitudinal dimension of the main body case 2 is made larger so that the zero stroke can be longer, and the main body case 2 is made larger when the impact force is small.
Reduce longitudinal dimension.

FIG. 2 shows another embodiment of the present invention. In this embodiment, impact sensors are attached to the support part 7 in three directions. Each impact force can be measured. Normally, the one of this embodiment is generally used.

By the way, as shown in FIGS. 5 and 6, the present invention is used for detecting impact during transportation of precision equipment, etc.

Reference numeral 20 is an impact sensor device inserted into the transport package 21 .

The impact sensor device 20 comprises the impact sensor 1, A according to the invention.
/D converter 22, CPU 23, storage unit 24, timer 25, program memory 26, and interface 2
7.

When using this device 20, please be sure to
The allowable impact force for the precision equipment in 1 is input into the program memory 26, and when the impact force generated during transportation exceeds the allowable impact force, the impact force is stored in the storage unit 24 along with the date and time. Let's do it like this.

After the transportation is completed, the stored contents are displayed on a display section 28 such as a CRT which is separately connected via an interface 27.
Alternatively, by outputting the output to the printer 29, it is possible to know in detail what time and minute during transportation the impact exceeded the allowable impact force, and in what direction the impact force was applied.

Therefore, this makes it possible to smoothly readjust the transported precision equipment.

[Effects of the Invention] The present invention has the above configuration, and according to the present invention, it is possible to provide an impact sensor that does not break even when an excessive impact force is applied and can withstand repeated use.

Furthermore, since the impact sensor of the present invention consumes little power, continuous measurement for a long period of time is possible, and it is easy to incorporate into portable equipment.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the impact sensor of the present invention;
Fig. 2 is a perspective view showing another embodiment of the present invention, Fig. 3 is a diagram showing the principle configuration of the impact sensor of the present invention, Fig. 4 is a graph showing experimental data, and Fig. 5 is an example of use of the present invention. A perspective view showing
FIG. 6 is a configuration explanatory diagram showing one application example of the present invention. 1. Shock sensor 2φφ Body case 3. Fixed permanent magnet 4. Movable permanent magnet 5 - Q No. 10 20 ・ 21 ・ 22 φ 23 ・ 24 ・ 25 ・ 27 ・ 28 ・ 29 ・ ・Hall element・Temperature sensor・Support part, oscillator, shock sensor device, transportation packaging - A/D converter, CPU, storage part, timer, program memory, interface, display part, printer

Claims (1)

[Scope of Claims] A cylindrical main body case; a pair of fixed permanent magnets supported by the main body case, whose magnetic axes are the same as the longitudinal direction of the main body case, and whose poles with the same name are arranged in the same direction; a movable permanent magnet located between the fixed permanent magnets in the main body case, movable in the longitudinal direction of the main case, and arranged so that the magnetic poles facing each fixed permanent magnet are the same; and a magnetic flux density in the main body case. An impact sensor comprising: a Hall element that measures changes in;