JPH10104092A - Strain-generating body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate influences exerting the zero point-stability of acceleration applied to a movable detection part. SOLUTION: The central part of a planar metal body is cut to have each strain-generating portion 11a, 11b, 11c, 11d to be apexes of a parallelogram, thereby forming a Roberval mechanism. In cutting operation, two substantially elliptical holes 14a, 14b are cut out, and a lever 16 is fixed by a lock nut 17 on a connection part 15 that divides these holes 14a, 14b, and then the end portion of the lever 16 is led outward by piercing through a hole 18 provided on a stationary part 12; in addition, a balance weight 19 is screwed in the end part of the lever 16 in a position adjustable manner. Besides, a part of the connection part 15 is cut off at the lower side of a lever 16 securing position before and after attachment of the lever 16. A moment of the lever 16 being swung about the strain-generating part 11a of the stationary part 12 is controlled by moving the balance weight 19 to be balanced with a moment at the movable detecting part 13 side being swung about the same strain-generating part 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexure element used for a force transducer such as an industrial force measurement and an electronic balance.

[0002]

2. Description of the Related Art As shown in FIG. 6, a conventional double beam type load cell having a roberval mechanism is formed of a parallelogram having a metal flexure element 1 provided with four flexure sections 2 called flexures. A strain gauge 3 is attached to the outside or inside of each strain-generating portion 2 as a roberval mechanism.
Lead wires are respectively derived from.

[0003] One vertical member is fixed, and the other vertical member is a free-end movable detector 4, and a load F applied to the movable detector 4 is defined as a parallelogram deformation of the roberval mechanism. It measures based on the output accompanying the deformation of the strain gauge 3 provided in each strain generating part 2.

[0004]

However, when the load cell is used in a dynamic state, for example, when it is used in a vehicle, or when, for example, measuring the spring force of a coil spring, the load cell is moved upward to move the spring. In the case of stopping after being pushed up, if vertical acceleration is applied to the movable detection unit 4, the apparent self-weight of the members constituting the movable detection unit 4 changes and affects the zero point. If the weight of the movable detection unit 4 is small relative to the measuring force, there is no significant problem. However, when the measuring force is several g to several tens g, the acceleration greatly destabilizes the zero point and makes the measurement difficult. The effect on the value is significant. This acceleration is added to the output as a vibration component stably at the zero point of the load cell, and does not attenuate until about 10 cycles. Therefore, if the measurement is performed after waiting for the decay time, the dead time increases, which is not efficient.

In order to positively attenuate the vibration, a damper using water, oil, or the like can be used, but a time constant is inevitable, and measurement of an excessive phenomenon in particular is almost impossible. In addition, it can be dealt with by an electric circuit, for example, by a CR filter, but there is a similar problem.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a flexure element that eliminates the influence of acceleration on zero-point stability.

[0007]

In order to achieve the above object, according to the present invention, a flexure element is provided at each vertex of a parallelogram comprising two vertical members and two horizontal members. A roberval mechanism provided with one of the vertical members as a fixed portion, the other of the vertical members as a movable detection portion, and a lever facing at least one of the horizontal members facing the fixed portion. And the moment of the movable detection unit having the fulcrum as a fulcrum and the moment of the lever having the fulcrum as a fulcrum is adjusted.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a perspective view of an embodiment, in which a strain-generating body 10 includes strain-generating portions 11a, 11b, 11c, and 11 each having a central portion of a plate-shaped metal body as a vertex of a parallelogram.
A so-called double-beam type roberval mechanism is formed by stripping to have d. A vertical portion at one end of the flexure element 10 is a fixed portion 12 and is fixed to a frame by bolts or the like (not shown), and a vertical portion at the other end is a movable detection portion 13 at a free end. Is applied in the vertical direction.

Each of the strain generating portions 11a, 11b, 11c, 11d
At the time of stripping, for example, two substantially elliptical holes 14a and 14b are stripped so as to connect the upper and lower portions, and a lever 16 is attached to a connecting portion 15 that partitions these holes 14a and 14b. 17 and fix lever 1
The end of the lever 6 is guided outward through a hole 18 provided in the fixing part 12, and a balance weight 19 is screwed to the end of the lever 16 so as to be position-adjustable. Note that a part of the connecting portion 15 is separated below the mounting position of the lever 16 before or after the mounting of the lever 16.

The balance weight 19 is moved so that the moment of the lever 16 having the fulcrum 11a of the fixed portion 12 as a fulcrum is balanced with the moment of the movable detecting portion 13 having the same fulcrum 11a as a fulcrum. Has been adjusted.

At the time of use, each strain generating portion 11a, 11
b, 11c, and 11d, a strain gauge is attached to the inside, a lead wire is drawn out to form a load cell, the fixing unit 12 is fixed to a frame or the like, and the load F applied to the movable detection unit 13 is measured by the strain gauge 1
It measures based on the output of 1a, 11b, 11c, 11d.

At this time, even if a vertical acceleration is applied to the load cell, the acceleration is applied to the movable detector 13 and also to the lever 16 at the same time, so that the moments are balanced and the horizontal balance is not lost.

This can be understood by considering the Roberval mechanism described below. FIG. 2 shows a basic roberval mechanism similar to the conventional example, in which a roberval mechanism having four beams A to D and having a vertex of a parallelogram as a fulcrum is formed. As described above, the balance is lost when acceleration is applied.

However, as shown in FIG. 3, the beam C is extended to the opposite side to the beam A, and the balance weight E is attached.
If the moment on the beam B centering on the fulcrum G is made equal, it is clear that the balance is maintained even if acceleration is applied to both the fulcrum G at the same time.

Further, by developing this, as shown in FIG.
The same function can be obtained even if a lever L is attached to the center of the head, and the lever L is turned in the opposite direction to the beam B, and a balance weight E is attached to the end thereof.

The embodiment of the present invention is exactly the same as the mechanism of FIG. 4 except that the mechanism of FIG. 4 is formed from a metal block. Having will be easily understood.

The balance weight 19 of the lever 16
It is convenient to adjust the position after performing a load cell by attaching a strain gauge to the strain body. That is, in a state where the load cell is horizontal and a state where the load cell is turned upside down, the balance weight 1 is placed at a position where the output of the strain gauge is balanced.
9 can be moved.

Although the provision of the lever 16 gives a shearing stress to the strain generating portion 11a, the stress is small, so that the measurement accuracy of the load cell is not affected at all.

In this embodiment, the lever 16 is attached to the horizontal member on the upper side. However, the lever 16 may be attached to the horizontal member on the lower side. Thirteen moments need to be balanced.

Further, as shown in FIG. 5, levers 16 and 16 'can be attached to upper and lower horizontal members.
In this case, the combined moment of the two levers 16 and 16 ′ is balanced with the moment of the movable detection unit 13.

[0021]

As described above, in the flexure element according to the present invention, the lever is provided so as to maintain a horizontal balance with respect to the movable detection unit, so that the performance of the conventional flexure element is not impaired at all. It operates and has little effect on zero-point stability when acceleration is applied.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment.

FIG. 2 is a configuration diagram of a conventional basic roberval mechanism.

FIG. 3 is a principle explanatory diagram of the embodiment.

FIG. 4 is a principle explanatory diagram of the embodiment.

FIG. 5 is a perspective view of another embodiment.

FIG. 6 is a perspective view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Flexure element 11a, 11b, 11c, 11d Flexure part 12 Fixed part 13 Movable detection part 16 Lever 19 Balance weight

Claims (3)

[Claims] 1. A parallel bar having two vertical members and two horizontal members, each of which is provided with a straining portion at each vertex of a parallelogram, and one of the vertical members is a fixed portion. The other of the vertical members is a movable detecting portion, a lever is attached to at least one of the horizontal members toward the fixed portion, and the moment of the movable detecting portion is a fulcrum about the strain generating portion on the fixed portion side. And the moment of the lever having the fulcrum as a fulcrum is adjusted so as to be balanced. 2. The flexure element according to claim 1, wherein the lever is provided with a balance weight whose position is variable in order to adjust the moment of the lever. 3. The strain body according to claim 1, wherein a strain gauge is attached to the strain section.