U.S. patent application number 11/333664 was filed with the patent office on 2006-06-08 for transducer for measuring a shaft dynamic behavior.
Invention is credited to Imtiaz Ali, Keming Liu, Jing Yuan.
Application Number | 20060117868 11/333664 |
Document ID | / |
Family ID | 32030124 |
Filed Date | 2006-06-08 |
United States Patent
Application |
20060117868 |
Kind Code |
A1 |
Liu; Keming ; et
al. |
June 8, 2006 |
Transducer for measuring a shaft dynamic behavior
Abstract
A transducer comprising an outer member, an inner member, an
arcuate sensor member for sensing a strain, the arcuate sensor
member disposed between the outer member and the inner member, at
least one strain gage disposed on a surface of the arcuate sensor
member, the arcuate sensor member connected to the outer member by
a first connecting member at a first location and connected to the
inner member by a second connecting member at a second location,
the first connecting member and the second connecting member
disposed on substantially opposing sides of the arcuate sensor
member along an axis A-A, the fist connecting member having a
predetermined spring rate and arcuate form compatible with the
dynamic forces borne by the arcuate sensor member to minimize
stresses in the first connecting member, and the outer member and
the inner member are coplanar.
Inventors: |
Liu; Keming; (Sterling
Height, MI) ; Yuan; Jing; (Rochester Hills, MI)
; Ali; Imtiaz; (Rochester Hills, MI) |
Correspondence
Address: |
Jeffrey Thurnau;The Gates Corporation
900 S. Broadway
Mail Stop 31-4-1-A3
Denver
CO
80209
US
|
Family ID: |
32030124 |
Appl. No.: |
11/333664 |
Filed: |
January 17, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10262035 |
Sep 30, 2002 |
7021159 |
|
|
11333664 |
Jan 17, 2006 |
|
|
|
Current U.S.
Class: |
73/862.045 |
Current CPC
Class: |
G01L 1/2237 20130101;
G01L 5/10 20130101 |
Class at
Publication: |
073/862.045 |
International
Class: |
G01L 1/22 20060101
G01L001/22 |
Claims
1. A transducer comprising; an outer member; an inner member; an
arcuate sensor member for sensing a strain; the arcuate sensor
member disposed between the outer member and the inner member; at
least one strain gage disposed on a surface of the arcuate sensor
member; the arcuate sensor member connected to the outer member by
a first connecting member at a first location and connected to the
inner member by a second connecting member at a second location;
the first connecting member and the second connecting member
disposed on substantially opposing sides of the arcuate sensor
member along an axis A-A; the fist connecting member having a
predetermined spring rate and arcuate form compatible with the
dynamic forces borne by the arcuate sensor member to minimize
stresses in the first connecting member; and the outer member and
the inner member are coplanar.
2. The transducer as in claim 1, wherein the arcuate sensor member
and the outer member and the inner member are substantially
coplanar.
3. The transducer as in claim 1, wherein the outer ring comprises
an aperture for accessing the arcuate sensor member.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of and claims priority from
U.S. application Ser. No. 10/262,035 filed Sep. 30, 2002.
FIELD OF THE INVENTION
[0002] The invention relates to a transducer, and more particularly
to a transducer for measuring a shaft dynamic behavior having
concentric members supporting an arcuate sensor member between
them.
BACKGROUND OF THE INVENTION
[0003] Various strain measuring devices are known. Among the known
devices are dual beam sensing members which include spaced end wall
members connected integrally by parallel spaced beam members, which
beam members are relatively flexible or bendable in one direction
only. One of the end walls is generally attached to a support
structure and the other end wall is operatively or directly
attached to a shaft.
[0004] Other devices are known which provide a cantilever
connection between a shaft member and a load sensor device. The
cantilever nature of the connection serves to increase a width or
thickness of the device, thereby increasing the space necessary to
accommodate the device.
[0005] Representative of the art is U.S. Pat. No. 6,324,919 to
Larsen et al (2001) which discloses load transducer for measuring
forces and/or moments on a rotatable member. In one embodiment, the
transducer includes an inner ring member attachable to a wheel hub
and an outer ring member attachable to a wheel rim. At least one
and, preferably, a plurality of beams unitarily extend between the
inner and outer ring members and are circumferentially spaced
apart. Each beam is formed of a stem and a perpendicular crossleg.
Wells are formed in the exterior surfaces of the stem and the
crossleg for mounting a strain gage in a force or moment
measurement orientation. Additional strain gages may be mounted on
the exterior sidewalls of each stem. The strain gages are
inter-connected in a bridge configuration for measuring forces and
moments exerted on the wheel. Bores formed in the stem and the
crossleg provide a passage for the conductors from each strain gage
to an electrical connector mounted between the inner and outer ring
members.
[0006] What is needed is a transducer that comprises concentric and
coplanar inner and outer members supporting an arcuate sensor
member disposed between the inner and outer member. The present
invention meets this need.
SUMMARY OF THE INVENTION
[0007] The primary aspect of the invention is to provide a
transducer that comprises concentric and coplanar inner and outer
members supporting an arcuate sensor member disposed between the
inner and outer member.
[0008] Other aspects of the invention will be pointed out or made
obvious by the following description of the invention and the
accompanying drawings.
[0009] The invention comprises a transducer comprising an outer
member, an inner member, an arcuate sensor member for sensing a
strain, the arcuate sensor member disposed between the outer member
and the inner member, at least one strain gage disposed on a
surface of the arcuate sensor member, the arcuate sensor member
connected to the outer member by a first connecting member at a
first location and connected to the inner member by a second
connecting member at a second location, the first connecting member
and the second connecting member disposed on substantially opposing
sides of the arcuate sensor member along an axis A-A, the fist
connecting member having a predetermined spring rate and arcuate
form compatible with the dynamic forces borne by the arcuate sensor
member to minimize stresses in the first connecting member, and the
outer member and the inner member are coplanar.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The accompanying drawings, which are incorporated in and
form a part of the specification, illustrate preferred embodiments
of the present invention, and together with a description, serve to
explain the principles of the invention.
[0011] FIG. 1 is a perspective view of the transducer.
[0012] FIG. 2 is a perspective view of the transducer.
[0013] FIG. 3 is a plan view of the transducer sensor ring.
[0014] FIG. 4A is a plan view of the transducer.
[0015] FIG. 4B is a cross-sectional view of FIG. 4A at line
B-B.
[0016] FIG. 4C is a side view at 4C-4C in FIG. 4B.
[0017] FIG. 5 is a perspective exploded view of the transducer.
[0018] FIG. 6 is a partial plan view of the self-aligning
portion.
[0019] FIG. 7 is a partial plan view of the self-aligning
portion.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] FIG. 1 is a perspective view of the transducer. The
transducer is relatively compact and may be used in a pulley to
measure a shaft load or shaft dynamic behavior. This includes
measuring a hubload and thereby a belt tension. A hubload is a load
imparted to a pulley and its shaft by a belt tension in a belt
drive system. The transducer may also be used to measure a shaft
vibration.
[0021] Transducer 100 generally comprises an arcuate inner member
or hub ring 101, sensor ring 102 and arcuate outer member or outer
ring 103. Hub ring 101 comprises a bore 104 which acts as a means
for attaching the transducer to a mounting surface. A fastener such
as a bolt engages hub ring 101 through bore 104 to connect the
transducer to a mounting surface. Hub ring 101 is relatively rigid
to provide a firm means of connecting the transducer to a mounting
surface. Hub ring 101 may also comprise an integral shaft for
attaching the hub ring to a mounting surface. Hub ring 101 is
connected to sensor ring 102 by connecting portion or member
108.
[0022] Sensor ring 102 is connected between hub ring 101 and outer
ring 103. Sensor ring 102 has an arcuate shape which concentrically
cooperates with the arcuate shape of hub ring 101 and outer ring
103. The concentric relationship between the hub ring, sensor ring
and outer ring allows the inventive transducer to have a minimal
diameter for better use in confined areas, such as in a pulley.
[0023] Slot 510 is disposed between sensor ring 102 and outer ring
103. Slot 511 is disposed between sensor ring 102 and inner ring
101. Under load sensor ring 102 deforms to become elongated or
elliptically shaped, having a major axis in direction A-A and a
minor axis in direction B-B, see FIG. 3. A width of slot 511 is
determined by a desired total deformation of sensor ring 102 in
direction B-B when under load. A width of slot 511 is also a
function of the thickness T of sensor ring 102. Thickness T is
determined by the dynamic conditions to which the sensor ring is
exposed.
[0024] At least one strain gage is attached to the sensor ring as
described in FIG. 3. A hubload force vector is represented by
vector 600. Sensor ring 102 is sufficiently flexible to cause a
surface strain to be realized at a strain gage location upon
application of a hubload to the hub ring. Sensor ring 102 is
connected through arcuate connecting members 512 to outer ring 103
and portion 107. Portion 107 and connecting member 108 are disposed
on substantially opposing sides of sensor ring 102. Connecting
sensor ring 102 to outer ring 103 at members 512 enhances a
deformation of sensor ring 102, and therefore enhances surface
strains in sensor ring 102 when subjected to a hubload force 600
along axis A-A. Although vector 600 is showing having a particular
direction, the transducer is capable of detecting loads having
vectors in any direction. Of course, an overall sensitivity may be
affected depending upon the spatial relationship between vector 600
and the strain gage(s) position with respect thereto.
[0025] Each member 512 partially deforms in conjunction with sensor
ring 102 when the transducer is under load. Members 512 have a
predetermined spring rate that is a function of the dynamic loading
to be borne by the transducer, and more particularly, by sensor
ring 102. The predetermined spring rate in turn determines an
arcuate form of each member 512.
[0026] One can appreciate that during operation sensor ring 102
will be constantly subjected to vibrations and cyclic loading. This
will in turn impose stresses on the connection between sensor ring
102 and outer ring 103. Hence, the arcuate form of members 512
enhances a transducer operating life by distributing and
dispersing, thereby reducing, stress risers that might otherwise be
present at a connection between the sensor ring 102 and the outer
ring 103. This, in turn, minimizes potential fatigue cracking that
may otherwise be caused by stress risers at the connection.
[0027] Apertures 105, 106 in outer ring 103 are used to facilitate
installation of strain gages 301 and 304 on sensor ring 102, see
FIG. 3.
[0028] Bracket 500 may be used to accept a strain-gage signal
conditioner. Bracket 500 is attached to outer ring 103. Bracket may
be formed or cast as an integral part of outer ring 103 as
well.
[0029] Outer ring 103 provides structural strength to the device as
well as provides a means for engaging the transducer to a bearing
and pulley. Outer ring 103 is press fit into a pulley bearing,
which bearing is in turn engaged with a pulley for engaging a belt.
Outer ring 103 is sufficiently rigid to permit rotational operation
of a pulley about the transducer in a belt drive system.
[0030] Hub ring 101, sensor ring 102, and outer ring 103 are
substantially coplanar. More particularly, each of the rings is
concentrically nested within the other. Nesting the rings reduces a
thickness of the inventive device to a minimum, thereby allowing
use of the transducer in a pulley, for example, in an existing
vehicle front end accessory drive where equipment space may be
confined. The inventive transducer can be used to replace an
existing pulley in a belt drive system, thus allowing retrofit for
instrument installation with little or no modification to an
existing system. The transducer may also be used in a tensioner
between a tensioner pulley and tensioner arm on a tensioner pulley
shaft in order to measure a shaft dynamic behavior or a tensioner
arm dynamic behavior.
[0031] In the preferred embodiment the inventive transducer can be
machined from a single piece of material, such as metal. The device
may also be cast from a suitable material such as plastic or
ceramic depending upon the load to be born by the transducer.
[0032] In another embodiment, it may comprise three pieces, i.e.,
hub ring, sensor ring, and outer ring joined by adhesives or
screws, see FIG. 4a. In an embodiment, the hub ring and the outer
ring comprise a ceramic material and the sensor ring comprises a
metallic material. In yet another embodiment the hub ring and the
outer ring may comprise a plastic material in particularly low load
applications. The plastic need only have a sufficient modulus and
have a sufficient resistance to the operating temperature of the
engine to which it is mounted.
[0033] In yet another embodiment, the sensor ring and the outer
ring comprise a single machined piece, with the hub ring attached
by screws or adhesives to the sensor ring. In this embodiment the
sensor ring and outer ring may comprise a metallic material and the
hub ring may comprise a ceramic material. The hub ring may also
comprise a plastic material in a relatively low load application.
The plastic need only have a sufficient modulus and have a
sufficient resistance to the operating temperature of the engine to
which it is mounted.
[0034] FIG. 2 is a perspective view of the transducer. Transducer
100 is shown contained within a pulley 200. A bearing or bearings
205 are pressed onto the outside of outer ring 103 to occupy an
annular space between outer ring 103 and pulley 200. Bracket 500 is
attached to transducer 100 with fasteners 501, 502.
[0035] FIG. 3 is a plan view of the transducer sensor ring. Sensor
ring 102 is shown with strain gages 301, 302, 303, 304 mounted
thereto in a full bridge configuration. As such the strain gages
are connected by wires 401, 402, 403, 404. Wires 402 and 403 are
routed to bracket 500 for connection to an instrument lead wire.
Strain gages 301 and 304 may be attached to sensor ring 102 through
apertures 105 and 106. The strain gages are oriented so that a
force vector axis A-A is perpendicular to an imaginary line B-B
between the strain gages.
[0036] FIG. 4A is a plan view of the transducer. This is the
embodiment using a separate hub ring 101, sensor ring 102 and outer
ring 103 as described elsewhere herein. Sensor ring 102 is fastened
to outer ring 103 using screws 203 and 204. Hub ring 101 is
fastened to sensor ring 102 using screws 201 and 202. Other means
of fastening the rings may comprise welding, adhesives, riveting,
or other appropriate means known in the art. Screws 201, 202, 203,
204 are oriented as shown with respect to a hubload axis A-A.
[0037] FIG. 4B is a cross-sectional view of FIG. 4A at line 4B-4B.
Screws 201 and 204 are shown connecting sensor ring 102 to outer
ring 103. Bracket 500 provides a means to connect the strain gage
wires to an instrument lead wire as described elsewhere herein.
[0038] FIG. 4C is a side view at 4C-4C in FIG. 4B. Screws 203 and
204 are shown connecting outer ring 103 to sensor ring 102.
[0039] FIG. 5 is a perspective exploded view of the transducer.
Bearings 205 are pressed on outer ring 103 of transducer 100.
Pulley 200 is pressed onto bearings 205.
[0040] FIG. 6 is a partial plan view of the self-aligning portion.
In order to optimize a sensitivity of the transducer, it is
desirable that the sensor ring be disposed to the hubload vector
600 such that vector 600 aligns with axis A-A, thereby aligning the
strain gages with an axis B-B, see FIG. 3. This can be accomplished
using a self-aligning member 700.
[0041] More particularly, an eccentric self-aligning member 700 is
disposed in inner ring bore 104. By way of example and not of
limitation, eccentric member 700 is press fit into bore 104. One
can also appreciate that member 700 may also simply comprise an
integral part of arcuate inner member 101, namely, arcuate inner
member comprises a bore 701 having a center 705 which is not
aligned with a transducer geometric center.
[0042] Eccentric member 700 comprises a bore 701. Center 705 of
bore 701 is eccentrically disposed a distance from an eccentric
member geometric center 704. Eccentric member geometric center 704
also coincides with a transducer geometric center and sensor ring
geometric center. Bearing 702 is pressed into bore 701. A fastening
member 703, such as a bolt, projects through and attaches bearing
702, and thereby the transducer, to a mounting surface (not shown).
By action of bearing 702 the transducer is freely rotatable about
fastening member 703.
[0043] In an exemplary situation, a hubload vector 600 is shown
acting upon the transducer. The hubload is caused by a belt BT
having a tension. In the exemplary configuration vector 600 is
initially laterally offset from bore center 705 by a distance (D).
Immediately upon application of a hubload 600, the self-aligning
feature of member 700 operates to properly align the transducer.
More particularly, distance (D) acts as a lever arm which causes a
torque to be applied to eccentric member 700. The torque causes
eccentric member 700, and thereby transducer 100 and sensor ring
102, to rotate about bearing 702 until vector 600 aligns with
center 705, thereby eliminating the self-aligning torque and
restoring equilibrium. This manner of operation of self-alignment
applies regardless of the direction of vector 600.
[0044] FIG. 7 is a partial plan view of the self-aligning portion.
Vector 600 is aligned with bore center 705. This orientation
results in strain gages 301, 302, 303, 304 being in an optimum
sensing position, that is, aligned with axis B-B as described in
FIG. 3.
[0045] One can appreciate that the transducer can operate with or
without the self-aligning member 700 as described in FIGS. 6 and 7.
Use of the self-aligning member 700 depends upon a desired
sensitivity for the transducer. This may also depend in part upon a
range of movement of vector 600 during operation. The sensitivity
of the transducer is a function of the alignment of the strain
gage(s) with a load vector 600. For example, if the inventive
transducer is used with an idler with a narrow range of directions
for vector 600, the need for the self-aligning member may be less
important. In the alternative, where the transducer is used on a
tensioner having a relatively large range of movement caused by a
tensioner arm movement, use of the self-aligning member is
advantageous to maintain a desired sensitivity for the
transducer.
[0046] Although forms of the invention have been described herein,
it will be obvious to those skilled in the art that variations may
be made in the construction and relation of parts without departing
from the spirit and scope of the invention described herein.
* * * * *