JP2006138713A - Tuning fork oscillation type load sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enlarge a load measuring range by providing a lever part having a plurality of steps. <P>SOLUTION: This tuning fork oscillation type load sensor is processed integrally from the same metal plate body, and the first lever part 12 is supported on the upper part of a base part 11 through the first fulcrum 12a comprising a thin-walled part. Similarly, the second lever part 13 is supported on the base part 11 through the second fulcrum 13a. A load receiving part 15 is connected to a load point 12b of the first lever part 12 through a tensile piece 14. A power point 12c of the second lever part 13 is connected to a load point 13b of the second lever part 13 through the thin-walled part 16, and a tuning-fork oscillator 17 which is a sensor is connected between the power point 13c of the second lever part 13 and a projection part 11c of the base part 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tuning fork vibration type load sensor that detects a load received by a load receiving portion with a tuning fork vibrator via a plurality of lever portions.

  For this type of conventional tuning fork vibration type load sensor, for example, a load conversion mechanism made of the same metal plate material as disclosed in Patent Document 1 by the present applicant is used. As shown in FIG. 3, a lever portion 2 is supported via a fulcrum 3 on a part of the base portion 1 of the load conversion mechanism. A load receiving portion 5 that receives a load is connected to a load point 4 of the lever portion 2 via a tension piece 6, and a tuning fork vibrator 8 is disposed between a force point 7 of the lever portion 2 and a fixed portion of the base portion 1. Yes.

Japanese Patent Publication No. 3-49059

  However, the tuning fork vibration type load sensor described above has restrictions on the load range that can be measured from its shape. For example, in the case of a tuning fork vibrator 8 having a thickness of 3 mm, the maximum measurable load is about 2 to 3 kg, and even if the force is expanded / reduced using an integrally assembled lever portion. The measurement range remains in the range of 5 to 1/5 times.

  An object of the present invention is to provide a tuning fork vibration type load sensor that solves the above-described problems and can increase or decrease the overall lever ratio by combining a plurality of lever portions to expand the load measurement range. is there.

  To achieve the above object, the technical feature of the tuning fork vibration type load sensor according to the present invention is that a tuning fork vibration type load sensor formed of a metal plate material has a plurality of stages each connected to a part of a base portion via a fulcrum. It has a lever part, and the load receiving part is connected to the load point of the first stage lever part via a tension piece, the load point of the latter stage part is sequentially connected to the force point of the previous stage lever part, and the last stage part is connected. A tuning fork vibrator is connected between the power point of the lever portion and the fixed portion of the base portion.

  According to the tuning fork vibration type load sensor according to the present invention, the load measurement range can be expanded by providing the levers in a plurality of stages.

  The present invention will be described in detail based on the embodiment shown in FIGS.

  FIG. 1 is a front view of Embodiment 1, and this tuning fork vibration type load sensor is integrally processed from the same metal plate. For example, two mounting holes 11 a and 11 b are formed in the base portion 11, and a first lever portion 12 is supported on the upper portion of the base portion 11 via a first fulcrum 12 a formed of a thin portion. Similarly, the second lever portion 13 is supported on the base portion 11 via the second fulcrum 13a.

  A load receiving portion 15 is connected to the load point 12 b of the first lever portion 12 via a tension piece 14. The load receiving portion 15 is provided with a hole 15a to which a member (not shown) for receiving the load F to be measured is attached. Further, the force point 12 c of the second lever portion 13 is connected to the load point 13 b of the second lever portion 13 through the thin portion 16, and between the force point 13 c of the second lever portion 13 and the protruding portion 11 c of the base portion 11. Is connected to the tuning fork vibrator 17.

  The tuning fork vibrator 17 includes two long piece-like vibrating pieces 18a and 18b that are symmetrical and parallel to the axis, and a substantially U-shaped connecting portion 19a that connects the upper and lower ends of the vibrating pieces 18a and 18b. , 19b and thin plate-like support pieces 20a, 20b for supporting the coupling portions 19a, 19b on the axis, respectively. The upper support piece 20 a is connected to the force point 13 c of the second lever portion 13, and the lower support piece 20 b is connected to the protrusion 11 c of the base portion 11.

  For example, piezoelectric elements 21 a and 21 b for generating continuous vibration are attached to both side surfaces of the coupling portion 19 b below the tuning fork vibrator 17. An input portion and an output portion of an amplifier (not shown) are connected to the piezoelectric elements 21a and 21b, respectively, one piezoelectric element 21a is for vibration, and the other piezoelectric element 21b is for pickup. Then, a frequency counter (not shown) is connected to the amplifier, and when the gain and frequency characteristics of the amplifier are appropriately selected, the resonator elements 18a and 18b vibrate symmetrically at the natural frequency corresponding to the load applied to the tuning fork vibrator 17. The load F can be detected by the frequency counter.

  The tuning fork vibration type load sensor of the first embodiment is a force expanding mechanism because of the lever ratio. When a load F to be measured is applied to the load receiving portion 15, the load F is applied to the tension piece 14 and the first lever portion 12. The tensile fork vibrator 17 acts on the tuning fork vibrator 17 via the second lever portion 13 and a tensile load expanded by the lever ratio is applied to the tuning fork vibrator 17.

  As a result, the vibration pieces 18a and 18b of the tuning fork vibrator 17 vibrate symmetrically at the natural frequency corresponding to the tensile load F, and this vibration is input to the amplifier, and a numerical value proportional to the load F is obtained from the frequency counter. .

  When the lever ratio of the first lever portion 12 is 1 / a and the lever ratio of the second lever portion 13 is 1 / b, the overall lever ratio is (1 / b) · (1 / a) = 1 / (a · b). For example, if a and b are 5, the measurement load range can be greatly expanded by 25 times or 1/25 times.

  FIG. 2 shows the force reducing mechanism of the second embodiment. The second lever portion 13 is disposed below the base portion 11, and the same reference numerals as those in the first embodiment indicate equivalent members.

  In this case, the load applied to the load receiving portion 15 is transmitted to the tuning fork vibrator 17 via the first lever portion 12, the tension piece 22, and the second lever portion 13, and the load is sufficiently applied as in the first embodiment. It can be measured by being reduced. The second lever 13 is different from the first embodiment in that the load point 13b and the force point 13c are arranged on both sides of the fulcrum 13a.

  In the present invention, the tuning fork vibrator 17 is integrally formed of the same metal plate material together with the base 11 and the lever parts 12 and 13 that support the tuning fork vibrator 17, so that the influence of disturbing external force other than the measurement load can be removed, and good measurement Accuracy is guaranteed. Moreover, since it is manufactured as an integral structure, there is an advantage that almost no assembly work is required.

  Note that the lever portion is not two-stage as in the first and second embodiments, and may be further multistage.

1 is a front view of Example 1. FIG. 6 is a front view of Example 2. FIG. It is a front view of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Base part 12, 13 Lever part 12a, 13a Support point 12b, 13b Load point 12c, 13c Force point 15 Load receiving part 17 Tuning fork vibrator

Claims (2)

  A tuning fork vibration type load sensor formed of a metal plate has a multi-stage lever connected to a part of the base part via a fulcrum, and receives the load via a tension piece at the load point of the first stage lever part. Connecting the parts, connecting the load point of the latter lever part to the force point of the former lever part in turn, and connecting the tuning fork vibrator between the last point lever part and the fixed part of the base part. A tuning fork vibration type load sensor.   The lever portion has two stages, the load receiving portion is connected to the load point of the first lever portion, the force point of the first lever portion and the load point of the second lever portion are connected, and the force point of the second lever portion The tuning fork vibration type load sensor according to claim 1, wherein the tuning fork vibrator is connected to the tuning fork vibration sensor.

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