US3834224A - Device for transducing force into pneumatic signal - Google Patents

Device for transducing force into pneumatic signal Download PDF

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Publication number
US3834224A
US3834224A US00379170A US37917073A US3834224A US 3834224 A US3834224 A US 3834224A US 00379170 A US00379170 A US 00379170A US 37917073 A US37917073 A US 37917073A US 3834224 A US3834224 A US 3834224A
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United States
Prior art keywords
air
opening
radius
force
curved surface
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Expired - Lifetime
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US00379170A
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English (en)
Inventor
M Uchida
S Jinno
T Sumi
Y Suzuki
R Itagaki
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Toray Industries Inc
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Toray Industries Inc
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Publication date
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/02—Measuring force or stress, in general by hydraulic or pneumatic means

Definitions

  • a device for transducing a force into a pneumatic signal comprises an air obstructing body composed of a rigid ball and supporting disc against which a force to be transduced is applied, and an air nozzle including an opening facing the rigid ball, the air nozzle being connected to a compressed air supply unit.
  • Back air pressure is measured by an air pressure measuring instrument connected to the air nozzle as a pneumatic signal.
  • PAIENIEI sin man SIIEEI I (If 8 I 2 RADIUS OF RIGID BALL RADIUS OF OPENING 30V mommm RADIUS OF RIGID BALL RADIUS OF OPENING PAIENIEDsw 019%4 sum s or a 30V 9mm mmclmrI INNER RADIUS OF OPENING (mm) INNER RADIUS OF OPENING (mm) PAIENImsmmsn 318 34.224 SHEEI 60F 8 30v mOmmm INNER RADIUS 0F OPENING (Tnm) 90 EDGE ANGLE OF OPENING PAIENTEBSEPIOIBH sum 8 I 3.834.224
  • the present invention relates to a device for transducing a force into a pneumatic signal.
  • the invention provides a force to a pneumatic transducing device which converts the amount of applied force to be transduced into a corresponding air pressure value used as a conventional industrial instrumentation technology pneumatic signal.
  • the basic components comprise an air nozzle 1, an opening 2, an air restrictor 3, air tubings 4, 5, 6 and 7, an air bellows 8, an air pressure measuring instrument 9, an air supply unit 10, a rod 11, a balancing beam 12 and a fulcrum 13.
  • the air nozzle 1 having an opening 2 for flowing compressed air is connected to the air supply unit through the air tubing 4 having an air restrictor 3 therein.
  • the air bellows 8 is connected to the air pressure measuring instrument 9 through the air tubings 6 and 7, and is connected to the air nozzle 1 thhrough the air tubings 5 and 7.
  • One end of the balancing beam 12 is rigidly connected to the air bellows 8 by the rod 11, and the other end of the balancing beam 12 is supported by the fulcrum 13.
  • the balancing beam 12 is placed adjacent the opening 2 of the air nozzle 1.
  • the principle of operation is as follows.
  • a force (F) to be transduced is applied on one end of the balancing beam 12.
  • the balancing beam 12 tends to incline around the fulcrum 13 in a direction to plug the outcoming air flow from the air nozzle 1 (known as the socalled nozzle and flapper mechanism), causing the back air pressure of air nozzle 1 to increase to such an extent that a force produced by the inflation of air bellows 8, with inside air pressure equal to nozzle back air pressure, in the opposite direction to compensate, or balance, the applied force (F) so that the balancing beam movement settles at a new equilibrium position.
  • the balancing beam 12 and relating components act in reverse of the above operation.
  • the conventional device has many metal constructed parts, such as bellows, springs andd hinges, each of which is subjected to the influence of ambient temperature variations, etc.
  • the conventional device has many component parts, none of which can be eliminated without sacrificing the guaranteed performance, and each of which should be insured by accurate and elaborate fabricating technology.
  • One method of suppressing the undesirable results indicated above is to adopt a relatively heavy order of force levels around the balancing beam; the resulting larger dimensions of the main component parts through miniaturization is the recent trend in instrumentation technology.
  • the invention we have developed solved most of those problems with a minimum of component parts and with outstanding simplicity and compactness.
  • the invention has no air bellows, balancing beam, fulcrums or hinges. Nevertheless, the accuracy of force to air pressure conversion performance was improved considerably.
  • FIG. 4 is a schematic cross-sectional view showing the force to air pressure transducing element.
  • FIG. 5 is a graph relating to an applied force to be measured and the pneumatic signal output.
  • FIG. 6 is a graph relating to output air pressure change/supply air pressure change and a radius of supporting disc/radius of the rigid ball.
  • FIG. 7 is a schematic illustration of some variations of the supporting disc.
  • FIGS. 8, 9 and 10 are graphs relating to hysteresis, linearity or error and a radius 'of the rigid ball/radius of the opening.
  • FIGS. 11, 12 and 13 are graphs relating to hysteresis, linearity or error and radius of the opening.
  • FIGS. l4, l5 and 16 are graphs relating to hysteresis, linearity or error and edge angle of the opening.
  • FIG. 17 is a graph relating to output air pressure change and an air resistance of the air restrictor/an air resistance of the air tubing.
  • a force (F) to be transduced is applied downward on the lower end of the vertical rod which is connected with circular suspension ring 21 by an over-load safety spring 24.
  • Force (F) is conveyed in sequence from vertical rod 25, circular suspension ring 21, and supporting disc 22 to air obstructing ball 23.
  • compressed air is supplied from air supply unit 28 through capillary air restrictor 26 and air reservoir chamber 27 to air outflow nozzle 29.
  • the difference of the force (F) to be transduced and a force developed in the opposite direction by a static back pressure within the nozzle opening and an outcoming air flow causes the air obstructing ball 23 to move upward or downward, depending on whether the sign of the difference of the forces is plus or minus,
  • the air pressure between air nozzle 29 and air restrictor 26 shows an exact one-toone correspondence with the force to be transduced, and can be used as a measured pneumatic signal of force (F).
  • the change in the amount of force to be transduced can be converted to the corresponding change in output air pressure at the output air tubing 30 and measured by the air pressure measuring instrument 31.
  • FIG. 3 shows the basic system composition of the invention
  • FIG. 4 shows the force to air pressure transducing element, the most essential part of the invention.
  • Each component part is shown as: compressed air supply unit 1, air tubing 2, air restrictor 3, air reservoir 4, air nozzle opening 5, air obstrucing body 6 composed of rigid ball 6A and supporting disc 6B, air pressure outlet 7, air tubing 8, pneumatic signal indicating instrument 9 and the applied force to be transduced (F).
  • compressed air is supplied from a compressed air supply 1 and passed through air restrictor 3 and air tubing 2, reaching air reservoir 4 and flowing out to the atmosphere through nozzle opening 5.
  • the air obstructing body 6 is placed for free movement, especially in a vertical direction.
  • the air obstructing body 6 is composed of a rigid ball 6A and a supporting disc 68 with one side of rigid ball 6A facing closely the nozzle opening 5 and a supporting disc 68 is contacted with rigid ball 6A on theother side of the nozzle opening 5.
  • the air obstructing body 6 reaches a certain equilibrium position depending on the relationship between two forces oppositely exerted.
  • One force is developed on one side of rigid ball 6A by the outflowing air from the air nozzle opening 5, and the other force to be transduced is exertedon the supporting disc 6B.
  • the edge shape of the end of the air nozzle opening 5 assures stable and smooth air.
  • FIG. 5 a force to be transduced as a pneumatic output signal relation is shown.
  • the scale unit of the abscissa axis is in grams and that of the ordinate axis is in percentage.
  • Each dimension of this example is as follows.
  • the radii of nozzle opening, ball and supporting disc are 5.1 mm, 5.1 mm and 14.75 mm respectively.
  • Compressed air pressure is 1.6 kg/cm G.
  • percent of output pneumatic signal corresponds to 1.0 kg/cm G.
  • FIG. 5 shows that the invention assures highly linear conversion characteristics.
  • An interesting dimensional relationship exists between the radii of the supporting disc and rigid ball and the ratio of output air pressure change and supply air pressure change under constant applied force.
  • FIG. 6 shows this relationship as observed in the test using the prototype shown in FIGS. 3 and 4.
  • the air obstructing body was composed of a complete sphere and a disc.
  • the rigid ball need not be completely spherical in shape although the side facing against the air nozzle should have a spherical surface.
  • the supporting disc need not necessarily be completely circular in shape.
  • the projection area of the component parts of the air obstructing body should be defined as the value giving maximum projection diameter considered as having complete circular cross sectional shapes.
  • FIG. 7 shows some variations of supporting disc shapes tested in the experiments.
  • the typical data relating to displacement of the air obstructing body observed in the experiments shows displacement of the air obstructing body to be less than 20 a, and reproducibility of the output signal better than i 0.12 percent and the effect of ambient temperature variation of i 30 C on the output signal variation to be better than i 0.2 percent.
  • FIGS. 8, 9 and 10 show the manner by which the radius ratio of spherical air obstructing body to air nozzle opening affects the performance characteristics with regard to hysteresis, linearity, and error caused by variations in the supply of air pressure respectively.
  • FIGS. 8, 9 and 10 illustrate that the performance error could be suppressed within 1 percent of full scale span if the range in ratio falls between 1 and 10.
  • the abscissa axis of these figures express the angle (0) of the edge shape of the air nozzle.
  • the desirable edge angle is less than l80.
  • a relation also exists between performance characteristics and the air path resistivity of the air restrictor 3 (abbreviated as resistance (A)), and the air path resistivity of the air path beginning from the air restriction outlet via the air reservoir to the air nozzle opening (abbreviated as resistance (Ao).
  • FIG. 17 shows this relation using the prototype shown in FIGS. 3 and 4. Abscissa axis is the ratio of (A) vs. r,in logarithmic scale, and ordinate axis is output signal error readings in kglcm
  • Abscissa axis is the ratio of (A) vs. r,in logarithmic scale
  • ordinate axis is output signal error readings in kglcm
  • the changing amount of air supply was selected as 0.4 kglm based on the certain criteria popular in the industrial instrumentation field: (A) can be properly selected by adjusting air restricting element.
  • Device for transducing force into pneumatic signal which comprises:
  • an air nozzle having an opening connected to said means for supplying compressed air through an air tubing, the opening forming an edge angle at a tip of the opening and the air tubing containing an air restrictor
  • an air obstructing body composed of a member having a curved surface and a supporting disc, the member having the curved surface facing said opening of said air nozzle and the supporting disc contacting the opposite side of said curved surface, said body having a member for transmitting an applied force to be transduced, wherein said air obstructing body moves upward and downward by the difference in force between a force acting upon the curved surface by the compressed air from the air nozzle and the applied force to be transduced, and
  • the radius of the opening of the air nozzle, the radius of curvature of the curved surface, the radius of the supporting disc, the air resistance of the air tubing and the edge angle of the outer side of the opening of the air nozzle have the relationship defined by the expressions of where (r) is the radius of said opening, (R1) is the radius of curvature of said curved surface, (R2) is the radius of said supporting disc, (A) is the air resistance of said air restrictor (A0) is the air resistance of said air tubing and (0) is the edge angle of said opening.
  • a device as described in claim 1, wherein the member having a curved surface is composed of a part of sphere.
  • a device as described in claim 1, the member having a curved surface is a spherical ball.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Aerodynamic Tests, Hydrodynamic Tests, Wind Tunnels, And Water Tanks (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)
  • Supply Devices, Intensifiers, Converters, And Telemotors (AREA)
  • Indicating Or Recording The Presence, Absence, Or Direction Of Movement (AREA)
  • Measuring Volume Flow (AREA)
US00379170A 1972-07-14 1973-07-13 Device for transducing force into pneumatic signal Expired - Lifetime US3834224A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP47069976A JPS4947770A (enrdf_load_stackoverflow) 1972-07-14 1972-07-14

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US (1) US3834224A (enrdf_load_stackoverflow)
JP (1) JPS4947770A (enrdf_load_stackoverflow)
GB (1) GB1404523A (enrdf_load_stackoverflow)
IT (1) IT999523B (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2703796A4 (en) * 2011-04-26 2015-01-21 Tokyo Inst Tech POWER SYSTEM CALCULATION

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU158120A1 (enrdf_load_stackoverflow) *
US2960097A (en) * 1956-05-09 1960-11-15 Junkalor Veb Fluid-pressure operated device
US3001538A (en) * 1956-06-22 1961-09-26 Manning Maxwell & Moore Inc Error detector for pneumatic transmission system
US3237633A (en) * 1961-11-09 1966-03-01 Ass Elect Ind Pneumatic transducers

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU158120A1 (enrdf_load_stackoverflow) *
US2960097A (en) * 1956-05-09 1960-11-15 Junkalor Veb Fluid-pressure operated device
US3001538A (en) * 1956-06-22 1961-09-26 Manning Maxwell & Moore Inc Error detector for pneumatic transmission system
US3237633A (en) * 1961-11-09 1966-03-01 Ass Elect Ind Pneumatic transducers

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2703796A4 (en) * 2011-04-26 2015-01-21 Tokyo Inst Tech POWER SYSTEM CALCULATION
US9091605B2 (en) 2011-04-26 2015-07-28 Tokyo Institute Of Technology Force calculating system

Also Published As

Publication number Publication date
IT999523B (it) 1976-03-10
GB1404523A (en) 1975-09-03
JPS4947770A (enrdf_load_stackoverflow) 1974-05-09

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