Axial force sensor

Patent metadata

Field	Value
Publication number	US-9417142-B2
Application number	US-201314401167-A
Country	US
Kind code	B2
Filing date	Apr 30, 2013
Priority date	May 16, 2012
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

A low-cost, compact, high-precision axial force sensor is provided. The axial force sensor includes a pair of parallel pressing plates and a strain gauge sandwiched therebetween. The strain gauge includes a plurality of strain-sensitive resistive elements around its periphery, and is provided with a spacer that transmits a pressing force from the pressing plates to some of the strain-sensitive elements but blocks the pressing force to the rest of the strain-sensitive elements. The output signal of the strain-sensitive elements blocked from the pressing force provide an accurate baseline to compare the output signal of the strain-elements subjected to the pressing force. The spacer has a uniform pattern of open and closed portions. On the strain gauge, the strain-sensitive elements are provided at both the open and closed portions of the spacer.

First claim

The invention claimed is:

1. An axial force sensor, comprising:
a pair of pressing plates;
a strain gauge arranged in parallel with, and sandwhiched between, the pair of pressing plates, the strain gauge having a plurality of strain-sensitive elements including resistors, and
a transmitting and blocking mechanism that transmits a pressing force from the pair of pressing plates to at least one of the plurality of strain-sensitive elements and blocks the pressing force from the rest of the strain-sensitive elements,
wherein the transmitting and blocking mechanism is a plate-like spacer arranged between the pair of pressing plates together with the strain gauge, the plate-like spacer having at least one open, force-blocking portion and at least one closed, force-transmitting portion; and
wherein one or more strain-sensitive elements of the strain gauge are respectively aligned with the at least one open, force-blocking portion and the at least one closed, force-transmitting portion.

2. The axial force sensor according to claim 1 ,
wherein the spacer is formed in a ring shape, and has a plurality of alternating open, force-blocking portions and closed, force-transmitting portions arranged at constant angular intervals in a circumferential direction, and
wherein the plurality of strain-sensitive elements of the strain gauge are arranged at constant angular intervals at positions corresponding to the open, force-blocking portions and positions of the closed, force-transmitting of the ring shaped spacer.

3. The axial force sensor according to claim 1 , further comprising a Wheatstone bridge circuit wherein the strain-sensitive elements to which the pressing force is transmitted are arranged on opposite sides to each other and wherein the strain-sensitive elements to which the pressing force is blocked are arranged on opposite sides to each other.

Assignees

• A&D Co Ltd
• A&D Co Ltd

Inventors

• Ichige Tatsuo
• BANNO Masaaki
• ISHIMORI Tomoyuki

Classifications

• G01N3/08

  by applying steady tensile or compressive forces (G01N3/28 takes precedence) · CPC title

• G01L1/246

  using integrated gratings, e.g. Bragg gratings · CPC title

• G01L1/22 Primary

  using resistance strain gauges · CPC title

• G01L1/2231 Primary

  the supports being disc- or ring-shaped, adapted for measuring a force along a single direction · CPC title