JPH0635150Y2 - Radial beam type load cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a radial beam type load cell suitable for size reduction and weight reduction, which enables accurate and stable measurement even with an unbalanced load.

[Prior Art] Conventionally, as a load cell using a radial beam as a sensing portion, as shown in FIG. 8, a plurality of holes 3 ( 3-1 and 3-
2, .....) are drilled and adjacent holes, for example hole 3
-1, 3-2 ..... Beams 4 formed (4-1, 4-
2, ...,) are arranged in a radial pattern centered on the load receiving part 2,
Strain gauges 5 (5a, 5b, ...) Are attached to each beam 4.
It is known to have a bonded structure.

[Problems to be Solved by the Invention] However, in the load cell having such a structure, the lower surface 6 (FIG. 8) is fixed to a mounting base by a bolt for use. If it is not perfectly flat, the load is not evenly applied, and especially for an unbalanced load, a cause of lack of reliability is caused, and further, the shape is inevitably large and heavy.

[Means for Solving the Problems] The embodiment of the present invention has an external appearance as shown in FIG. 1, and has a structure similar to that of FIG. The load cell main bodies 11 and 21 having one or more radial beams 14 and 24 are face-to-face connected by bolts (not shown in order to avoid complication), and the load receiving portion 1 is provided above.
2. The structure is such that the installation side receiving portion 22 is arranged below.

Furthermore, the composite type strain gauges 15, 25 that are integrally incorporated on the same substrate are provided on the beams 14, 24 (see FIG. 5) of the main bodies 11, 21 so that elongation and compression can be measured simultaneously. (See Fig. 4
15a is shown as an example), and strain gauges of the same type (elongation or compression) symmetrically arranged with respect to the center, for example, strain gauges 15a1 and 15i1 for elongation measurement are connected in series, It is inserted at the crossroad of the bridge that becomes the measurement circuit.

[Operation] Since the load applied to the load receiving portion 12 is supported by the installation side receiving portion 22, the planes of the connecting surfaces 16 and 26 (FIG. 1) corresponding to the lower surfaces of the two main bodies 11 and 21. The degree does not matter so much, and even if an unbalanced load is applied to the load receiving part 12, since strain gauges of the same kind bonded at symmetrical positions with respect to the center are connected in series, The deviations of elongation or compression with respect to strain are averaged to enable more accurate measurement. Furthermore, the two load cell bodies 11,
Since the 21 are connected face-to-face, it is possible to make the shape relatively small and lightweight when considering the same accuracy and the same weighing.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.
The figure shows a front view of two single-body load cells facing each other and connected by bolts (not shown), FIG. 2 is a plan view thereof, FIG. 3 is a cross-sectional view taken along the center transverse line of FIG. 2, and FIG. Explanatory drawing of a strain gauge in which resistors for measurement and for compression measurement are arranged on the same substrate, FIGS. 5 (a) and 5 (b) show that the point P in FIG. FIG. 6 and FIG. 7 are exploded views opened in the counterclockwise direction and are circuit diagrams showing the wiring positions of the strain gauge.

Therefore, first of all, the structure of the present invention will be described. The load receiving portion 12 and the installation side receiving portion 22 projecting in the center are respectively loaded as load buttons by the screws 17, 27 (Fig. 3) to the main body 11,
A radial beam extending around the cylindrical outer peripheral portion is screwed around the load receiving portion 12 and the installation side receiving portion 22.
Holes 13-1 to 13-8 and 23-1 to 23-8 are provided for forming 14-1 to 14-8 and 24-1 to 24-8, respectively.

Although the number of beams is eight here for the sake of illustration,
The larger the number of beams, the better. Considering the eccentric load, eight is the minimum number because at least one beam is required in the directions other than the horizontal and vertical directions. Also, considering the combination of strain gauges at symmetrical positions, the number of beams is even.

The composite type strain gauges 15a to 15p and 25a to 25p are adhered to the both sides of the beams 14 and 24 of the load cell main bodies 11 and 21, respectively, as shown in FIG.

Then each strain gauge bonded to each beam 14, 24
Strain gauges 15 and 25 of the same type (elongation or compression) located symmetrically with respect to the center are connected in series, and are connected to each branch of the bridge circuit as shown in FIG. Here, P1 and P2 are input terminals, and P3 and P4 are output terminals.

For example, as can be seen in Fig. 5 (a), strain gauge 15a1 for measuring elongation on the main body 11 side (the final digit number 1 indicates elongation).
Is connected in series with the strain gauge 5i1 of the same type (for elongation measurement) that is symmetrical with respect to this and the center of the strain gauge. It is connected to one side of the upper left branch (A1) in the left bridge circuit A (indicated by reference numeral).

Similarly, the strain gauge 15c1 for symmetric elongation measurement
And 15k1 are also connected in series with the strain gauges 15a1 and 15i1 to the same one side.

In addition, strain gauges 15e1 and 15ml for elongation measurement are also connected in series to the other side of the same upper left branch (A1) in the bridge circuit A (parallel connection with the above-mentioned one side), and similarly. , 15g1 and 15o1 which are in a symmetric relationship are also inserted in the same other side in a series relationship, and the parallel connection circuit of these one side and the other side constitutes a bridge branch A1.

Further, strain gauges 15d1 and 15j1 and 15d1 and 15l1 for extension measurement, which are in a symmetrical relationship, are inserted on one side of the lower right branch of the same bridge circuit A, and the other side of the parallel connection is extended on the other side. Strain gauges 15f1 and 15n1 for measurement, and 15h1
15p1 each inserted in series relation, bridge crossroad A4
Is configured.

The same applies to the strain gauges for compression measurement. At the lower left branch of the bridge circuit A, strain gauges 15a2 for compression measurement (the last digit number 2 indicates compression) and 15i
2, and 15c2 and 15k2 are connected in series to form one side, and strain gauge 15e2 for compression measurement and
The other side is formed by the series connection of 15m2 and 15g2 and 15o2, and the bridge branch A3 is configured by the parallel connection of the one side and the other side.

Further, at the upper right branch of the bridge circuit, one side is composed of strain gauges 15b2 and 15j2 for compression measurement, and 15d2 and 15l2, and strain gauges 15f2 and 15n2 for compression measurement and 15h2 and 15p2.
And the other side is formed respectively, and the bridge branch A2 is configured as a parallel circuit of the one side and the other side.

This is the lower load cell body 21 [see FIG. 5 (b)].
The same applies to the right bridge circuit B (see FIG. 6).
Each crossroads B1 to B4 are configured. In this case, the directions of the strain gauge adhered to the upper load cell body 11 and the strain gauge adhered to the lower load cell body 21 may be the same or may be opposite.

With such a configuration, if an unbalanced load is applied to the load receiving portion 12 as the load button, one strain gauge with respect to the center, for example, 15a1 changes due to deviation, and the other is in a symmetrical position with this. Since the strain gauge, for example, 15i1 fluctuates with a negative sign opposite to that, by connecting these in series, the bias is canceled and the vertical load is accurately measured.

Although the measurement circuit in which the bridge circuits A and B are connected in parallel has been described above, as shown in FIG.
It is also possible to connect the corresponding branches of B to each other in series and use this as a new branch to form one bridge circuit.

[Advantage of the Invention] The present invention has a large number of beams to be the sensing section in a radial pattern, and the load receiving section and the installation side receiving section also have a protruding projecting button shape. Since the strain gauges of (1) are inserted in the crossroads of the bridge in a series connection relationship, they have the advantages of being able to perform accurate and stable measurements and being suitable for downsizing and weight reduction.

[Brief description of drawings]

FIG. 1 is a front external view showing an embodiment of the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a sectional view taken along the center transverse line of FIG. 2, and FIG.
FIG. 5 is an enlarged explanatory view showing a composite type strain gauge, FIGS. 5 (a) and 5 (b) are development views in which the connecting portion of FIG. 1 is opened, and FIG.
FIG. 7 is a circuit diagram of an embodiment of the present invention and another embodiment, and FIG. 8 is a perspective view showing the appearance of a conventional example. 11, 21 …… Main body of load cell, 12 …… Load receiving part, 22 ……
Installation side receiving part, 13, 13-1 to 13-8, 23, 23-1 to 23-8
... Hole, 14, 14-1 to 14-8, 24, 24-1 to 24-8 ...
Beam, 15, 25, ... Strain gauge, 15a1 to 15p1,25a1 to 25p
1 …… Strain gauge for elongation measurement, 15a2 to 15p2,25a2 to 25p2
...... Strain gauges for compression measurement, 16, 26 …… Connecting surface, P
1, P2 …… input terminal, P3, P4 …… output terminal.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tatsuo Yoshizawa 2-16-404 Wakabadai, Asahi-ku, Yokohama-shi, Kanagawa Examiner Tokio Goto (56) Reference JP 60-249025 (JP, A) JP Sho 59-126221 (JP, A) JP-A-54-158281 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A load cell main body having an even number of eight or more beams extending substantially radially from around a receiving portion projecting upward in a central portion toward a cylindrical outer peripheral portion, The respective outer peripheral portions are connected to each other so as to form a load cell having a load receiving portion and an installation side receiving portion, each of which is a receiving portion protruding in the vertical direction. Strain gauges for elongation measurement and compression measurement are adhered to each beam, and the strain gauges belonging to each of the load cell bodies are connected in series with strain gauges of the same kind located symmetrically with respect to their centers. A radial beam load cell characterized by offsetting the bias due to load and then inserting it at the crossroad of the bridge circuit that is the measurement circuit.