JPH0372267A - Acceleration sensor - Google Patents

Abstract

PURPOSE:To obtain a reliable ON-OFF signal by a simple construction, to make also responsiveness excellent and to improve reliability by opening and closing a magnetic path by an impact acceleration. CONSTITUTION:A pillar-shaped permanent magnet 5 having a magnetic fluid added around is disposed with a space enabling movement thereof in a vessel 1 so that it constitutes a magnetic path, and the magnet 5 can move in the direction of A1 or A2 inside the vessel 1. When an impact acceleration of a set value or above is given in the direction of A2 in the front of the vessel 1 or A1 in the rear thereof, the magnet 5 having the magnetic fluid added around is made to move in the direction of A1 or A2 by the acceleration, gets out of positions of magnetic yokes 2a and 2b and moves to a position whereat it collide with the inner wall surface of the vessel, so that an open magnetic path be formed. Accordingly, a reed switch 6 is turned OFF with the impact acceleration applied when the switch is ON initially. By knowing whether the acceleration is applied or not by discriminating the ON-OFF state of the switch 6, therefore, responsiveness can be made excellent and reliability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an acceleration sensor used for detecting the acceleration of a moving object such as an automobile or for sensing the load capacity of an elevator or the like.

(Prior Art) One of the conventional acceleration sensors is disclosed in Japanese Unexamined Patent Publication No. 61-50270, and its configuration is shown in FIG.

This is because a colloidal magnetic fluid made of ferrite (Fe3 04), etc. moves due to acceleration, and the amount of movement is detected by changes in the dielectric constant, or capacitance, of the capacitor.
The acceleration is output as a voltage value.

(Problem to be Solved by the Invention) However, in the conventional example described above, the acceleration is output as a voltage value, so the electrical signal is compared with the voltage value when no acceleration is applied. To display it as acceleration, a logic circuit for difference and conversion is required, and because it is an indirect method of comparing with a reference value, it has a complicated configuration. There was a problem in that a switching circuit, a relay circuit, etc. had to be added to the circuit shown in FIG.

The present invention has a simple configuration and a reliable on-state.

The object of the present invention is to obtain an acceleration sensor that can provide an off signal, has good responsiveness, and is highly reliable.

[Configuration of the Invention (Means for Solving the Problem) In order to achieve the above object, the present invention has the following configuration.

The first configuration includes a columnar permanent magnet around which a magnetic fluid is added, and a container having a space in which the permanent magnet can move.
A pair of magnetic yokes and a reed switch are arranged in a direction intersecting the moving direction of the permanent magnet with respect to the container, and the permanent magnet, the magnetic yoke, and the reed switch form a closed magnetic path. It has been placed.

In a second configuration, a magnetic gap is formed in the path where the magnetic yoke of the first configuration forms the closed magnetic path, and the magnetic attraction force is adjusted by changing the width of this magnetic gap. This is how it was done.

In the third configuration, an external lead terminal is attached to both ends of the reed switch of configuration 1 or 2, and the entire terminal except for the outwardly projecting end is molded with resin.

A fourth configuration is that each of the containers in configurations 1 to 3 is provided with a lid that hermetically accommodates the columnar permanent magnets to which magnetic fluid is applied.

A fifth configuration includes a columnar permanent magnet around which a magnetic fluid is added, and a container having a space in which the permanent magnet can move, the direction intersecting with the moving direction of the permanent magnet with respect to the container. A plurality of pairs of magnetic yokes with one ends facing each other are arranged in a plurality of rows along the moving direction of the permanent magnet, and a reed switch is arranged at the other end of each pair of magnetic yokes.

A sixth configuration includes a columnar permanent magnet to which a magnetic fluid is added around the periphery, and a container having a space in which the permanent magnet can move, and the side surface of the container is arranged in the direction of movement of the permanent magnet. A pair of magnetic yokes are provided with one end facing each other in the intersecting direction, a reed switch is provided on the other end side of the pair of magnetic yokes, one end is facing each other at a position adjacent to the magnetic yokes, and the other end is located adjacent to the magnetic yokes. A magnetic yoke in which the magnetic yokes are connected is arranged, and the columnar permanent magnet is arranged so as to be aligned with the opposing tip of one of the magnetic yokes.

In a seventh configuration, the magnetic yoke in the sixth configuration is
A magnetic gap is formed in a part of the magnetic gap, and the magnetic attraction force is adjusted by changing the width of this magnetic gap.

(Function) According to the above configuration, the contact is normally turned on due to the closed magnetic path generated by the permanent magnet, the magnetic fluid surrounding the permanent magnet, the magnetic yoke, and the reed switch, but impact acceleration is applied. The permanent magnet moves under the resulting inertial force, turning off the contact, and when the impact acceleration disappears, the permanent magnet returns to its original position due to the magnetic attraction force, turning the contact back on.

Moreover, since the periphery of the permanent magnet is covered with magnetic fluid, a reliable closed magnetic path is formed even if there is a gap between the magnetic yoke and the permanent magnet.

Furthermore, since the magnetic fluid has a lubricating effect, when impact acceleration is applied, the permanent magnet moves smoothly,
Malfunctions due to the permanent magnet being caught do not occur.

With these mechanisms, on and off signals can be directly taken out, and the above problems can be solved.

(Example) Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1 is a partially cutaway perspective view showing an embodiment of the present invention.

FIG. 2 is a side sectional view of the above embodiment.

As shown in each figure, this acceleration sensor consists of a box-shaped container 1,
A columnar permanent magnet 5 with a magnetic fluid 4 added to its periphery is housed in a container, and a pair of magnetic yokes 2a and 2b1 are provided facing the side surface of the container 1, and arranged below the pair of magnetic yokes. and a reed switch 6.

The container 1 has a space in which a columnar permanent magnet 5 to which a magnetic fluid 4 is added around the periphery can move, and the permanent magnet 5 can move in the direction A1 or A2 within the container work.

The upper ends of the pair of magnetic yokes 2a, 2b are opposed to each other in a direction intersecting the moving direction A1 or A2 of the columnar permanent magnet 5, and the bent end surfaces of the magnetic yokes 2a, 2b are inserted into a hole provided in the container 1. It is installed so that it faces. Incidentally, the tip of the magnetic yoke may be brought into contact with the wall surface without providing a hole in the container 1.

The reed switch 6 disposed in the hole in the lower part of the pair of magnetic yokes 2a and 2b includes a glass tube and a lead 3a inserted into the glass tube with both ends protruding outward.
3b. 8 is a contact point of the lead. In this case as well, the magnetic yokes 2a, 2b may be arranged so that the lower ends thereof are in contact with the reed switch 6 without providing holes at the lower ends thereof.

In this way, the columnar permanent magnet 5 and the pair of magnetic yokes 2a have the magnetic fluid 4 added around them.

2b and the reed switch 6 constitute a closed magnetic path.

The container 1 is provided with a lid 7 and surrounded by a magnetic fluid 4.
A column-shaped permanent magnet 5 to which is added is covered with a lid 7.

Next, referring also to FIG. 3, the operation of the above embodiment will be explained.

When an impact acceleration equal to or greater than a set value is applied to the front A2 or rear A1 direction of the container 1, the impact acceleration causes the columnar permanent magnets 5 around which magnetic fluid is added to move in the A1 or A2 direction. It moves away from the position of the magnetic yokes 2a and 2b, and moves to a position where it collides with the inner wall surface of the container ↑, as shown by the imaginary line 5'.

Since the permanent magnet 5 is removed from the position of the pair of magnetic yokes 2a and 2b, an open magnetic path is created.

As mentioned above, for example, if the reed switch 6 is initially on, it will be turned off when impact acceleration is applied, so by determining whether the reed switch is open or closed, impact acceleration exceeding the set value can be detected. You can know whether it is true or not.

Note that when the impact acceleration is removed, the permanent magnet is drawn toward the yoke and returns to its original position.

FIG. 4 shows an example designed for actual use of the acceleration sensor configured as described above, in which FIG. 4(a) is a front sectional view and FIG. 4(b) is a plan sectional view. In the actual usage example shown in this figure, the top and bottom are reversed compared to the drawing in FIG. The container 1 is constructed as a rectangular cylinder with flanges on the top and bottom, and the opening surface of the rectangular cylinder is sealed with a lid 7 while a permanent magnet 5 to which a magnetic fluid 4 is added is housed inside the rectangular cylinder. . On the other hand, the reed switch 6 has leads 3a at both ends.

With the plate terminals Ta and Tb for external extraction connected to 3b, the entire plate terminals Ta and Tb except the tips are covered with resin M.
It has a structure that protects the glass tube by molding it with. With the thus molded reed switch placed horizontally on the upper flange of the container 1, the tips of the reed switch 6 face both ends of the permanent magnet 5.
A pair of L-shaped magnetic yokes 2a and 2b are attached so that the other end faces the position where the magnetic yokes 2a and 2b are arranged. In the above-mentioned combined state, the whole is assembled by a U-shaped metal fitting P attached from one side of the lower flange IB of the container 1 to the upper end of the resin molded part M and further to the other side of the lower flange IB of the container 1. Tightening is fixed.

This tightening and fixing is performed using screws or the like that are attached through holes Pa provided at both ends of the metal fitting P and screw holes provided in the lower flange portion IB of the container 1.

FIG. 5 is a partially cutaway perspective view showing another embodiment of the present invention.

The difference between the embodiment and FIG. 1 is that three pairs of magnetic yokes 12 (12a, 12b) and 13 (13a) are arranged along the two moving directions A I and A of the permanent magnet 5.

13b) and 14 (14a, 14b) are placed side by side, and a reed switch 15°16.1 is placed below the magnetic yoke.
This is the point where 7 is placed.

According to such an embodiment, in the initial state, the permanent magnet 5 to which the magnetic fluid 4 is added around the periphery, the pair of magnetic yokes 13a,
13b and the reed switch 16 form a closed magnetic path, and the portions to which the other two pairs of magnetic yokes 12 and 14 are attached form an open magnetic path.

When an impact acceleration exceeding the set value is applied, the above permanent magnet 5
moves in the A1 or A2 direction, and the other two pairs of magnetic yokes 1
Either one of the parts where 2.14 is attached becomes a closed magnetic circuit. By checking whether the reed switch 15.17 is on or off, it is possible to know whether an impact acceleration greater than a set value has been applied and from which direction, A2 or A1, the impact acceleration has been applied.

FIG. 6 shows yet another embodiment, and the difference from the embodiment shown in FIG. 5 is that the magnetic yokes 12 (
12a, 12b), 14 (14a.

14b) and reed switches 15 and 17 have the same structure as in the previous embodiment, but the reed switch is not provided and a magnetic yoke 18 whose lower side is connected is placed in the center.

With this configuration, reed switch 1
By checking the ON or OFF state of 5 or 17, it is possible to know that an impact acceleration exceeding a set value has been applied, and also the direction in which the impact acceleration has been applied, as in the embodiment shown in FIG.

Furthermore, as shown in FIG. 7, a magnetic gap is provided by cutting out the lower center part of the magnetic yoke 18, and a spacer 9 is inserted therein.
By providing this, the amount of magnetic flux can be reduced.

Therefore, by changing the width of the spacer 9, the amount of magnetic flux can be adjusted, and the sensitivity of detecting impact acceleration can be adjusted.

FIG. 8 shows yet another embodiment, which is different from the embodiment shown in FIG.
21a, 21b) and the reed switch/edge 16 are the same as in the previous embodiment, but the difference is that no reed switch is provided and magnetic yokes 19 and 20 connected at the lower sides are arranged at both ends.

With this configuration, if impact acceleration is applied, the permanent magnet 5 moves in the direction of A1 or A2, but since no reed switch is provided on the magnetic yoke 20 or the workpiece 9, impact acceleration greater than -window , it becomes possible to obtain the same effect as described above by utilizing the point where the closed magnetic path deviates.

Furthermore, if an external permanent magnet or an external coil magnetic field is installed in the acceleration sensors shown in FIGS. 1, 5, 6, and 8, they can be used as acceleration sensors with a reset function.

In each of the above embodiments, it is possible to adjust the magnetic attraction force by providing a magnetic gap in a part of the magnetic yoke, and the position where the magnetic gap is provided is not limited to that shown in FIG. 7, but may be provided anywhere. .

In addition, as shown in FIG. 9, if magnetic yokes 22 and 23 having tapered parts 22A and 23A that are tapered toward the tips are placed facing the side surface of the container 1, the magnetic attraction force at the center of the tapered parts can be reduced. Since the magnetic attraction force is at its maximum and becomes weaker toward the periphery, the permanent magnet 5 can be easily returned to its original position when resetting after the permanent magnet 5 has moved. .

Furthermore, as shown in FIG. 10, a container 21 having a space 2↑A that is an inclined surface rising from the center to the left and right is used, and a permanent magnet 5 to which a magnetic fluid 4 is added is placed in the center of the container 21. This allows the permanent magnet 5 that has moved due to the impact acceleration to be easily returned to its original position at the time of reset.

[Effects of the Invention] As described above, according to the present invention, the magnetic path consisting of a permanent magnet, a magnetic fluid surrounding the permanent magnet, a magnetic yoke, and a reed switch is a mechanism that opens and closes due to impact acceleration. Even if there is a gap between the magnetic yoke and the permanent magnet, a reliable closed magnetic path is formed, and the permanent magnet moves smoothly due to impact acceleration, so that malfunctions due to the permanent magnet getting caught will not occur. It has good responsiveness, and
Highly reliable.

Furthermore, since a reed switch is used for the contact portion, on and off signals can be directly taken out, and a reliable operating signal can be obtained.

Further, since there is no need to add a special circuit to obtain on/off signals, it is possible to obtain an acceleration sensor with a simple configuration and a small number of parts.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing one embodiment of the present invention, and FIG.
The figure is a side sectional view of the above-mentioned Fig. 1, Fig. 3 is an explanatory view of the operation of the embodiment device of the above-mentioned Fig. 1, and Figs. 4(a) and (b) are front views showing specific embodiments of the above-mentioned embodiment. 5 is a partially cutaway perspective view showing another embodiment of the present invention,
FIG. 6 is a partially cutaway perspective view showing still another embodiment of the present invention, and FIG. 7 is a side sectional view showing a modification of the embodiment shown in FIG. 6.
FIG. 8 is a partially cutaway perspective view showing still another embodiment of the present invention, FIGS. 9 and 10 are cross-sectional views showing modified examples of the present invention,
The first king diagram is a configuration diagram of a conventional acceleration sensor. 1... Container, 2a 2b 12a 12b 13a 13b 14a
, 14b. 18, 19.20.21...Magnetic yoke, 3...Lead, 4...Magnetic fluid, 5...Permanent magnet, 61
51617... Reed switch, 7... Lid of movable container, 8... Contact of reed switch, 9... Spacer of magnetic yoke. -48' (0) po Tb) Figure Figure -489 re≧9・su! ξn is a book

Claims (7)

[Claims] (1) In an acceleration sensor, a columnar permanent magnet having a magnetic fluid added to its periphery, a container having a space in which the permanent magnet can move, and a direction intersecting the moving direction of the permanent magnet with respect to the container. An acceleration sensor comprising a pair of arranged magnetic yokes and a reed switch, the permanent magnet, the magnetic yokes and the reed switch arranged so as to form a closed magnetic path. (2) The acceleration sensor according to claim 1, wherein the magnetic yoke has a magnetic gap formed in a path forming the closed magnetic path, and the magnetic attraction force is adjusted by changing the width of the magnetic gap. (3) The acceleration sensor according to claim 1 or 2, wherein external lead-out terminals are attached to both ends of the leads of the reed switch, and the entire terminal except for the outwardly projecting end portion is molded with resin. (4) The acceleration sensor according to any one of claims 1 to 3, wherein the container is provided with a lid that hermetically stores a columnar permanent magnet to which a magnetic fluid is applied, which is stored inside the container. (5) A columnar permanent magnet with magnetic fluid added around it;
The permanent magnet has a container having a space in which the permanent magnet can move, and a pair of magnetic yokes with one end facing each other in a direction intersecting the moving direction of the permanent magnet are arranged along the moving direction of the permanent magnet. An acceleration sensor that is arranged in multiple rows, with a reed switch arranged at the other end of each pair of magnetic yokes. (6) A columnar permanent magnet with magnetic fluid added around it;
a container having a space in which the permanent magnet can move; a pair of magnetic yokes are provided with one end facing each other in a direction intersecting the moving direction of the permanent magnet on a side surface of the container; A reed switch is provided on the other end side of the magnetic yoke, and a magnetic yoke with one end facing the magnetic yoke and the other end connected is arranged at a position adjacent to the magnetic yoke.
An acceleration sensor in which the columnar permanent magnet is arranged so as to be aligned with an opposing tip of one of the magnetic yokes. (7) The acceleration sensor according to claim 5 or 6, wherein the magnetic yoke has a magnetic gap formed in a part thereof, and the magnetic attraction force is adjusted by changing the width of the magnetic gap.