JPH0639334Y2 - Mechanical sensor - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a mechanical quantity sensor that detects the amount of bending of a bending member due to an input load and measures acceleration and the like.

B. Prior Art FIG. 3 is a plan view and FIG. 4 is a IV-IV sectional view thereof.
A conventional mechanical quantity sensor will be described with reference to the drawings.

In FIG. 3, the central portion of the disk-shaped sensor body 1 is approximately C.
A tongue-shaped bending member 2 is formed by hollowing out in a letter shape. The additional mass 3 is fixed to the free end side of the bending member 2 to improve the sensor sensitivity. The additional mass 3 is composed of a mounting base portion 3a and a fork portion 3b having a two-pronged shape extending outward from the mounting base portion 3a, and an inner edge portion of the sensor body 1 is located between the forks of the fork portion 3b. And the bending member 2
On the fixed end side of, the mechanical quantity detection elements 4a to 4d such as four strain gauges connected in bridge are provided. In addition, 5 is a hollow hole of the bending member 2.

When a load acts on the mechanical quantity sensor configured as described above in the direction A of FIG. 4, the flexure member 2 flexes, and a detection signal corresponding thereto is taken out from the mechanical quantity detection elements 4a to 4d. Here, an excessive impact (such as a drop load) on the mechanical quantity sensor (for example,
100G to 1000G), the bending member 2 bends greatly,
The fork portion 3b of the additional mass 3 comes into contact with the sensor main body 1, whereby the amount of bending of the bending member 2 is regulated.

C. Problems to be solved by the device However, as shown in FIG. 5, a rotational moment acts on the additional mass 3 counterclockwise about the contact point between the fork portion 3b and the sensor body 1, The amount of deformation of the bending member 2 increases. For this reason, the mechanical quantity detection elements 4a to 4d may be destroyed, or the bending member 2 may be damaged or cracked. Therefore, there is a problem in the durability and reliability of the sensor.
Further, when manufacturing such a sensor, since the bending member 2 or the additional mass 3 needs complicated processing, there is a problem that the manufacturing cost is high.

An object of the present invention is to prevent a rotational moment from being generated in the added mass when an excessive load acts to regulate the amount of bending,
An object of the present invention is to provide a mechanical quantity sensor that solves the above-mentioned problems by reducing the amount of deformation of the bending member when an excessive load is input.

D. Means for Solving the Problems Referring to FIG. 1 showing an embodiment, the present invention provides a bending member 11 which bends by an input load, an additional mass 14 attached to the bending member 11, and a bending member. It is applied to a mechanical quantity sensor having a mechanical quantity detection element 13 which obtains a signal corresponding to the amount of bending of the member 11. And the above-mentioned problem is that when the excessive load acts, the additional mass 14 comes into contact with the regulating member 12a for regulating the bending amount of the bending member 11 within the allowable range, and the additional mass 14 is set to an arbitrary amount of the bending member 11. This can be solved by forming the cut surface that is parallel to the plane including the locus of movement of one point and that includes the portion that comes into contact with the regulation member 11 when regulating the bending amount with a substantially circular object (for example, a cylindrical object).

E. Action When an excessive load acts in the load detection direction, the additional mass 14 attached to the free end side of the bending member 11 contacts the regulation member 12a, and the amount of deflection is regulated. At this time, since the additional mass 14 is formed by an object whose cut surface is substantially circular, the restriction member
Since the line of action of the reaction force Fr acting on the additional mass 14 from 12a passes through the center of gravity OX of the additional mass 14 or in the vicinity thereof, the bending member
An undesired rotational moment does not act on 11, and the amount of deformation can be reduced.

F. Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, one end of the flexible member 11 is fixed to one side surface of the rectangular parallelepiped container 12, and its free end portion extends in the opposite side surface direction. A mechanical quantity detection element 13 such as a strain gauge for obtaining a signal corresponding to the amount of bending of the bending member 11 is provided on the fixed end side of the bending member 11, and a second end is provided on the upper and lower surfaces of the free end.
As is clear from the figure, a pair of semi-cylindrical additional masses 14 are fixed. Here, a pair of semi-cylindrical additional masses 14
Thus, a substantially columnar additional mass is formed. The center of gravity of the entire load mass including the bending member 11 is at the position OX. The gap between the additional mass 14 and the upper and lower wall surfaces (regulating member) 12a of the container 12 is the bending member 11 when a load within the mechanical quantity detection range is applied.
The bending amount is set to be less than or equal to the allowable bending amount.

Next, the operation of this embodiment will be described.

When a load acts on the mechanical quantity sensor configured as described above in the direction A (load detection direction) in the figure, the bending member 11 bends, and a signal corresponding to the amount of bending is obtained from the mechanical quantity detection element 13.

When an excessive load acts in the direction A, the bending member 11 is largely bent, and the additional mass 14 abuts the upper and lower wall surfaces 12a of the container 12 to restrict the amount of bending. At this time, the bending member 11 and the load mass
The line of action of the inertial force Fi acting on 14 equivalently passes through their center of gravity OX, and the generatrix l (second
(Fig.) Contacts the upper and lower wall surfaces 12a of the container 12. Therefore, the line of action of the half force Fr that the additional mass 14 receives from the upper and lower wall surfaces 12a passes through the center of gravity OX, and therefore the conventional bending moment does not act on the bending member 11, and the amount of deformation can be reduced. As a result, the bending member 11 and the physical quantity detection element 13 are prevented from being damaged.

The same effect can be obtained by forming each of the pair of additional masses into a hemisphere and forming a spherical additional mass as a whole. Although the upper and lower wall surfaces 12a of the container 12 are the regulating members, they may be provided separately.

G. Effect of the Invention According to the present invention, the additional mass is parallel to the plane including the motion locus of any one point of the bending member, and the cutting surface including the portion that comes into contact with the limiting member when the bending amount is restricted is substantially circular. Since it is composed of an object, regardless of the position of the restricting member at the time of restricting bending, the line of action of the reaction force acting on the additional mass from the restricting member always passes through the center of gravity of the additional mass or its vicinity
An undesired rotational moment does not act on the flexible member under any condition, and the amount of deformation thereof is regulated, so that a mechanical quantity sensor with high reliability and durability can be obtained. In addition, since the additional mass does not require complicated processing, the manufacturing cost is reduced.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a sectional view of a sensor, and FIG. 2 is a partial perspective view of a flexible member on a free end side. 3 to 5 show a conventional example, FIG. 3 is a plan view, FIG. 4 is a sectional view taken along the line IV-IV, and FIG. 5 is a view showing conventional rotation of an additional mass and deformation of a bending member. Is. 11: Flexible member, 12: Container 12a: Wall surface, 13: Physical quantity detection element 14: Additional mass

Claims (1)

[Scope of utility model registration request] 1. A dynamic quantity sensor having a flexure member that bends due to an input load, an additional mass attached to the flexure member, and a mechanical quantity detection element that obtains a signal corresponding to the flexure amount of the flexure member. Is provided with a restricting member that abuts against the additional mass and restricts the amount of bending of the bending member within an allowable range, the additional mass being parallel to a plane including a motion locus of any one point of the bending member. The mechanical quantity sensor is characterized in that a cut surface including a portion that comes into contact with the regulation member when the deflection amount is regulated is formed of a substantially circular object.