JPH03243833A - Vibration detector - Google Patents

Abstract

PURPOSE:To detect fine vibration and multi-directional vibration and to miniaturize this detector by providing a magneto-strictive pulse generating element, a magnetic circuit consisting of plural yokes, a permanent magnet which applies a magnetic field to the magnetic circuit, and a means which supports them so that the relative position is changed according to applied vibration. CONSTITUTION:A base body 30 which has projection parts 31 and 32 at both ends is fixed on a base 35 and a vibration body 33 which vibrates freely in a horizontal direction is provided on the center part of the projection part 31. The vibration body 33 consists of the magnetic circuit 20 composed of the yokes 21 and 22 and a WIEGAND element 10 and an arm which connects its coupling part 25 and the projection part 31. Then the circuit 20 vibrates greatly in the horizontal direction together with the horizontal vibration of the base 35. The permanent magnet 1 is fixed on the projection part 32 so that the N and S poles are on the sides of the yokes 21 and 22 and a pulse signal generated by the element 10 is processed by an output circuit 40 and outputted as an electric signal from a terminal 36. Consequently, highly sensitive vibration detection is available and many yokes are provided to enable multi-directional vibration detection.

Description

BACKGROUND OF THE INVENTION The present invention relates to a vibration detection device that extracts displacement caused by vibration as an electrical signal.

Prior Art and Its Problems Some vibration detection devices that output electrical signals representing vibrations utilize changes in capacitance or electromagnetic induction caused by vibrations. However, these devices have a problem in that they cannot detect minute vibrations in extremely low frequency ranges. Another problem is that the device becomes larger.

For example, a vibration detection device using a differential transformer cannot detect minute vibrations because of its large mass. Furthermore, in a vibration detection device that uses electromagnetic induction, the output electric signal is not proportional to mechanical displacement but to displacement speed, so the output becomes extremely small for low frequency vibrations. Furthermore, it is difficult to detect vibrations in multiple directions with a vibration detection device that includes a strain resistance element or the like on a cantilever and detects vibrations based on changes in resistance.

TECHNICAL FIELD SUMMARY OF THE INVENTION OBJECTS OF THE INVENTION An object of the present invention is to provide a vibration detection device that can detect minute vibrations, can detect vibrations in multiple directions, and can be further miniaturized.

Structure 1 of the Invention Functions and Effects The vibration detection device according to the present invention includes a magnetostrictive pulse generating element, and the magnetostrictive pulse generating element is arranged at intervals outside the magnetostrictive pulse generating element, one end of each of which is connected to one end of the magnetostrictive pulse generating element. A magnetic circuit including a plurality of yokes coupled to the magnetostrictive pulse generating element and a plurality of yokes arranged at intervals on the other end side of the magnetostrictive pulse generating element, the magnetostrictive pulse generating element and the yokes depending on their relative positions with the magnetic circuit. It is characterized by comprising a permanent magnet that applies a magnetic field to at least one, and support means that supports the magnetic circuit and the permanent magnet so that their relative positions change in response to applied vibrations.

A magnetostrictive pulse generating element outputs a voltage pulse by changing the direction of a magnetic field applied from a permanent magnet.

According to this invention, when vibration is applied, the relative positional relationship between the magnetic circuit and the permanent magnet is displaced. As a result, a magnetic path in the magnetic circuit is selectively formed, the direction of the magnetic field applied to the magnetostrictive pulse generating element is changed, and a pulse signal representing vibration can be obtained.

According to this invention, even if there is a minute vibration, the relative positional relationship between the magnetic circuit and the permanent magnet changes, the magnetic field applied to the magnetostrictive pulse generating element is reversed, and a pulse signal is output.
Vibration can be detected with high sensitivity. Further, by providing a large number of yokes to form a large number of magnetic paths, vibrations in not only one direction but in many directions can be detected. Furthermore, according to the present invention, only one permanent magnet is required and the structure is relatively simple, making it easy to downsize. Furthermore, since the device according to the present invention operates without a power source, the power consumption of the entire system equipped with this vibration detection device can be reduced.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows a vibration detection device according to an embodiment of the present invention.

The base body 30 is fixedly arranged on a base 35, and has a first convex portion 31 that protrudes upwardly at one end, and a second convex portion 32 that protrudes slightly at the center of the other end. A vibrating body 33 that can freely vibrate left and right is formed integrally with the base body 30 at the center of the first convex portion 31 of the base body 30 . This vibrating body 33 has left and right yokes 2 (and a second yoke 22, a connecting portion 25 that connects these yokes 21 and 22 at one end thereof, and yokes 21, 22, which are provided in parallel with one interval apart). It consists of a thin arm 26 that connects the coupling part 25 to the convex part 31, in the middle between the two yokes 21 and 22.

A Wiegand element 10 is fixed to the coupling part 25 at one end thereof. The other end of the Wiegand element 10 is a yoke 21,
It extends to near the other end of 22. These yokes 21.
22. A magnetic circuit 20 is configured by the coupling portion 25 and the Wiegand element 10. When the base 35 is vibrated in the horizontal direction (left-right direction), the magnetic circuit 20 is supported by the thin arms 26, so the magnetic circuit 20 vibrates largely in the left-right direction.

Furthermore, the permanent magnet 1 is fixed on the second convex portion 32 of the base body 30 so that the N pole or the first yoke 21 side is the S pole or the second yoke 22 side, thereby forming the magnetic circuit 20. It faces the yokes 21 and 22 and the other end (free end) of the Wiegand element 10 with a slight distance therebetween. On the substrate 30, below the magnetic circuit 20.

An output circuit 40 (the circuit element is shown in the figure) is provided to perform predetermined processing on the pulse signal generated from the Wiegand element 10, and an electrical signal representing vibration is output from the output circuit 40. Output terminal 36
It is output to the outside through. Furthermore, a case 37 is placed over the base 35 to protect the vibration detection device from external forces.

Details of the magnetic circuit 20 are shown in FIG.

Wiegand element (magnetostrictive pulse generating element) 10 is an inner core 11 and an outer shell surrounding the outside (cladding)
12, and the outer shell part 2 is set to have a larger coercive force. As a specific example of the magnetostrictive pulse generating element, for example, Picaloy (IOV-52 Co-38Fe
) (trade name: Leigandt Wire), permalloy (50Ni-50Fe) and other so-called Wiegand effect devices, and amorphous magnetostrictive wires that produce the large Barkhausen effect or Matteuccj effect.

A coil 13 is wound around such a Wiegand element io in order to extract a voltage pulse generated when the magnetic pole is reversed. There are various ways to extract the voltage pulses other than winding the coil 13.

3(A) and 3(B) are plan views of the magnetic circuit 20, and the permanent magnet 1 is also shown. Also the fourth
Figures (A) and (B) respectively show pulses generated in the detection coil 13 when the direction of magnetization of the inner core 11 of the Wiegand element IO is reversed in the states shown in Figures 3 (A) and (B). There is.

As shown in FIG. 3(B), the Wiegand element IO has an inner core portion 11. It is assumed that both the outer shell portion 12 are magnetized in the same direction.

In this state, as shown in FIG. 3(A).

When horizontal vibration is applied to the vibration detection device and the N pole of the permanent magnet 1 approaches the first yoke 21, the yoke 2
A magnetic path is formed through Wiegand element 1 and Wiegand element 10, and the magnetization direction of inner core portion 11 is rapidly reversed. The outer shell 12 is not inverted due to its strong coercive force. This results in the fourth
As shown in Figure (A), a voltage pulse is induced within the detection coil 13.

Next, as shown in FIG. 3(B), horizontal vibration is applied to the vibration detection device, and when the S pole of the permanent magnet 1 approaches the second yoke 22, the second yoke 22 and the Wiegand element 10 forms a magnetic path.

The magnetization direction of the inner core portion 11 suddenly returns to its original state. This induces a voltage pulse in the opposite direction to the voltage pulse shown in FIG. 4(A), as shown in FIG. 4(B).

FIG. 5 is a perspective view showing another embodiment. In this figure, the same components as those shown in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted.

As shown in detail in FIG. 6, the magnetic circuit 20 of the vibration detection device shown in FIG. 5 has first yokes 21. Second yoke 22. Third
A yoke 23 and a fourth yoke 24 are arranged. These yokes 21 to 24 and Wiegand element I
O is bonded at one end.

A vibrating body 33 is provided to support this magnetic circuit 20.
has an almost square shape when viewed from the front.

The vibrating body 33 can be displaced vertically and horizontally.

Further, the permanent magnet 1 disposed at a position facing the magnetic circuit 20 has a large number of N poles and S poles corresponding to these yokes 21 to 24. In order to support this permanent magnet 1, the second convex portion 32 has a shape that protrudes compared to the second convex portion 32 of the vibration detection device shown in FIG.

When vertical or horizontal vibration is applied to the vibration detection device shown in FIG.
The relative position with the As a result, the direction of magnetization within the Wiegand element IO is reversed and a pulse signal is output.

In the embodiment described above, the magnetic circuit 20 is fixed to the vibrating body 33 and its relative position with respect to the permanent magnet 1 is changed. A relative displacement may be applied between them.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the invention, FIG. 2 is a perspective view showing the positional relationship between a magnetic circuit and a permanent magnet, and FIG.
) and (B) are plan views showing the operation of the Wiegand element, and FIGS. 4(A) and (B) are waveform diagrams showing generated pulses. FIG. 5 is a perspective view showing another embodiment, and FIG. 6 is a perspective view showing the positional relationship between the magnetic circuit and the permanent magnet in the device shown in FIG. 1...Permanent magnet. lO... Wiegand element. 13...Detection coil. 20...Magnetic circuit. 21゜22゜23゜24... Yoku. 25...Joining part. 26... Arm. that's all

Claims (1)

[Claims] A magnetic circuit including a magnetostrictive pulse generating element and a plurality of yokes arranged at intervals around the magnetostrictive pulse generating element and having one end of each yoke coupled to one end of the magnetostrictive pulse generating element; a permanent magnet that is arranged at a distance from the other end of the magnetostrictive pulse generating element and applies a magnetic field to at least one of the magnetostrictive pulse generating element and the yoke according to a relative position with respect to the magnetic circuit; A vibration detection device comprising: support means for supporting the permanent magnets so that their relative positions change according to applied vibrations.