US3748454A - Pneumatic computing devices - Google Patents

Pneumatic computing devices Download PDF

Info

Publication number
US3748454A
US3748454A US00222257A US3748454DA US3748454A US 3748454 A US3748454 A US 3748454A US 00222257 A US00222257 A US 00222257A US 3748454D A US3748454D A US 3748454DA US 3748454 A US3748454 A US 3748454A
Authority
US
United States
Prior art keywords
input
pressure
force
ball
feedback
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00222257A
Other languages
English (en)
Inventor
D Grier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fischer and Porter Co
Original Assignee
Fischer and Porter Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fischer and Porter Co filed Critical Fischer and Porter Co
Application granted granted Critical
Publication of US3748454A publication Critical patent/US3748454A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06G—ANALOGUE COMPUTERS
    • G06G5/00—Devices in which the computing operation is performed by means of fluid-pressure elements
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/2278—Pressure modulating relays or followers
    • Y10T137/2409—With counter-balancing pressure feedback to the modulating device

Definitions

  • the device includes a force beam supported [58] Field of Search 235/200; 137/85; on a fulcrum, the beam being caused to swing in one 91/359; 92/129 direction by an input force element whose position along the beam relative to the fulcrum is adjustable to [56] References Cited vary the effect of input pressure on the beam. Beam de- UNITED STATES PATENTS flection is sensed by a detector included in a feedback 3,239,139 3/1966 Chapin et al.
  • 235/200 WB Pmducmg mm)t pr'issure is aPPlied I 3,243 112 3/1966 Sorteberg 235/200 WB feedback element tendmg 2 the beam 2,991:006 7/1961 Clarke 235/200 WB the reverse direction.
  • the feedback force being such as 3,072,326 1/1963 Rohmann et al. 235/200 WB to maintain the beam in equilibrium.
  • the input and 3,159,343 12/1964 Hudson 235/200 WB feedback force elements are both constituted by ball- 3,l7l,33 0 3/1965 McCombs 137/85 X andqgylinde elements exerting a force that depends on the ball area and on cylinder pressure.
  • This invention relates generally to pneumatic computing devices, and more particularly to pneumatic arrangements which operate on the force balance principlc and function as ratio devices, analog computers and adders or subtractors.
  • Pneumatically-operated force balance systems are well known, the system acting to algebraically combine torques created by one or more input signal pressures and spring forces to produce an output signal pressure that accurately represents a predetermined mathematical function of the input signals.
  • a force beam mounted on a fulcrum is caused to swing in the clockwise direction by a pneumatic input pressure applied to an input bellows coupled to the beam. Balancing of the beam is effected by a feedback loop including a detector acting to sense any slight beam deflection and coupled to a pneumatic relay to produce an output signal that is applied to a feedback bellows.
  • the feedback bellows operates on the beam to produce a counterclockwise torque balancing the clockwise torque produced by the input bellows, causing the beam to return to its original equilibrium state.
  • the ratio between the input and output signals may be varied by shifting the position at which the input bellows engages the beam.
  • the effect of bellows expansion in response to an applied pressure is expressed by the axial deflection of the bellows from its free length. If a shift in the position of the input bellows along the beam also displaces the axial position of the bellows relative to the beam, this change in the axial position introduces an error.
  • the error is caused by a force change on the beam which is equal to the product of the bellows spring gradient and the axial deflection. While it is possible to align the ratio device to avoid this error, the need for alignment adds to the cost of the instrument.
  • the spring gradient of the bellows also causes another source of error.
  • the input bellows of a ratio device is near the fulcrum of the force beam, its stiffness or gradient is not significant, but when the bellows is shifted to a point well displaced from the fulcrum, the overall gradient of the beam is much higher and therefore less sensitive, particularly since the gradient of the bellows as felt by the beam is proportional to the square of the distance from the fulcrum.
  • the sensitivity of a ratio device undergoes a large change as the bellows is shifted along the beam and beam sensitivity is directly related to the accuracy of the device, the performance of the device becomes progressively poorer as the bellows is shifted away from the fulcrum.
  • a significant advantage of the invention resides in the fact that the zero gradient of the ball obviates the need for critical alignment of the force element and of the beam on which it operates.
  • an object of the invention is to provide a pneumatic ratio device in which input pressure is applied to the beam by a ball-and-cylinder force element and in which a similar element is used to apply a feedback force to the beam to maintain beam equilibrium.
  • Yet another object of the invention is to provide a pneumatic computer operating on the force beam principle and employing ball-and-cylinder input and feedback force elements to carry out multiplying, dividing, squaring and square root functions.
  • a force balance arrangement in which a force beam supported on a fulcrum is caused to swing in one direction by an input force element whose position along the beam relative to the fulcrum is adjustable to vary the effect of input pressure on the beam.
  • a flapper-nozzle detector serves to sense beam deflection, the detector being coupled to a pneumatic relay producing an output pressure which is applied to a feedback force element tending to swing the beam in the reverse direction, the feedback force being such as to maintain the beam in equilibrium.
  • the force elements may both be constituted by ball-and-cylinder elements whose balls exert a force on the beam which depends on the ball area and on cylinder pressure.
  • FIG. 1 is a schematic diagram of a known form of pneumatic ratio device
  • FIG. 2 is a schematic diagram of a ratio device in accordance with the invention.
  • FIG. 3 is a perspective view of a preferred embodiment of a ratio device in accordance with the invention, including a pivoted arm to adjust the position of the input force element along the force beam;
  • FIG. 4 is a schematic diagram of the arrangement shown in FIG. 3;
  • FIG. 5 is a simplified schematic diagram of the arrangement shown in FIG. 3;
  • FIG. 6 separately illustrates the action of the pivoted lever of the FIG. 3 device
  • FIG. 7 separately illustrates the action of the spring of the FIG. 3 device
  • FIG. 8 is a perspective view of a pneumatic analog computer in accordance with the invention operating in the multiplying mode
  • FIG. 9 is a schematic diagram of the multiplier shown in FIG. 8.
  • FIG. 10 is a schematic diagram of the analog computer operating in the dividing mode
  • FIG. 11 is a schematic diagram of an addersubtractor in accordance with the invention.
  • FIG. 12 is a sectional view of a ball and cylinder pressure element in accordance with the invention.
  • FIG. 1 there is illustrated a simple pneumatic ratio device.
  • the purpose of this figure is to explain the deficiencies resulting from the conventional practice in which bellows are used to apply input and rebalancing forces maintaining beam equilibrium.
  • Force balance beam is supported on a fulcrum 11 and is caused to swing in a clockwise direction by a pneumatic input pressure P applied to an input bellows 12.
  • This bellows is slidable along a surface 13 parallel to beam 10.
  • the active end of bellows 12 is provided with a roller 14 which engages the beam at a point to the left of fulcrum 11. The distance between this point and fulcrum 11 is represented by symbol x.
  • Balancing of beam 10 is effected by a feedback loop including a flapper-nozzle detector 15 operatively coupled to the beam adjacent the right extremity thereof to sense any slight beam deflection.
  • Detector 15 is coupled to pneumatic relay l6, producing an output signal P which depends on the flapper position relative to the fixed nozzle.
  • Output signal P is applied to a feedback bellows l7 operatively coupled to the beam at a fixed point to the right of the fulcrum and spaced therefrom by a distance a.
  • the zero position of the beam is maintained by a spring 18 coupled between the right end thereof and ground.
  • Output signal P applied to feedback bellows 17 produces a counterclockwise torque that balances the clockwise torque produced by input bellows l7, causing beam 10 to return to its equilbrium state. In this state, the pressure applied by the input bellows multiplied by distance x" is equal to the pressure applied by the feedback bellows multiplied by distance a.”
  • the ratio between input and output signals P and P may be varied by shifting the position of input bellows 12 along the beam, thereby changing the value of distance x."
  • the mechanical advantage of the lever is very low; hence a large change input signal I produces a very small change in output signal P But if this point is shifted away from the fulcrum so that it is near the left end of the beam, the mechanical advantage is much greater, whereby a small change in input signal produces a very large change in the output signal.
  • A is the effective area, in square inches, of input bellows 12, K, is the spring gradient of the bellows in pounds per inch, and f is the deflection of zero spring 17 from its free length.
  • K the spring gradient of the bellows.
  • a special alloy material is required for the bellows. While such special metals are commercially available, they are quite expensive and add materially to the cost of the instrument.
  • the sensitivity of the device changes markedly as the bellows is shifted along the beam.
  • the sensitivity of the beam or the radient of the beam is directly related to the accuracy of the ratio device.
  • the performance of the device becomes much poorer.
  • the beam is excessively sensitive, the device is rendered penumatically unstable, thereby producing an oscillating output signal.
  • FIG. 2 there is shown a pneumatic ratio device according to the invention.
  • the invention makes use of an input ball-and-cylinder force element 19 and a feedback balland-cylinder force element 20.
  • Ball and cylinder input element is shiftable in a straight line along surface 13 parallel to the beam, the ball engaging the beam surface.
  • the input element may be made to move within a suitable groove or a guide rod may be provided.
  • input element 19 is connected by a bracket 21 to one end of a bias spring 22 whose outer end is secured to a lateral extension 23 on beam on the feedback side of the beam, the spring being parallel to the beam. Hence, as input element 19 is shifted away from fulcrum ll, bias spring 22 is stretched accordingly.
  • the force generated by the ball located at one end of the cylinder is strictly a function of the pressure within the cylinder acting on the area of the ball.
  • the pressure applied to the ball thereof is that produced by input signal P, while in the case of feedback element 20, it is that produced by output signal P
  • the ball of the force element were to move slightly along the axis of the cylinder, no perceptible change in force would occur.
  • the parallelism of the beam and the guiding surface for the input element is not critical and, unlike the bellows arrangement shown in FIG. 1, no adjustment is required to assure parallelism.
  • the input force element has its ball moving in a straight line along beam 10. Though straight line motion is the simplest, from the mathematical point of view, mechanical movement along an arc is easier to accomplish in a practical embodiment. This is the arrangement shown in FIGS. 3, 4 and 5 wherein input ball-and-cylinder element 19 is mounted at the end of a ratio pointer 24 pivoted on a post 25.
  • the pointer acts as a lever, whereby when the pointer is shifted along an arcuate ratio-indicating scale, the ball of the input ball-and-cylinder element 19 swings on an arc on force beam 10.
  • FIG. 6 shows in..plan view the arc through which the input element 19 and the end of spring 22 travel as angle T is changed.
  • FIG. 7 schematically shows how the spring 22 moves through an arc during changes in the ratio pointer 24.
  • Spring length equal to ([F+D sin (T)] [D-D cos )l and cos a F+D sin (T)/([F+D sin (T)] l- [D-D cos nz 1/2
  • the effective force caused by the spring on the beam is equal to the spring length multiplied by cos a (vector angle). Therefore:
  • Pneumatic Analog Computers Pneumatic computers are known for solving simple arithmetic functions. Computations such as those involved in stock blending, flow proportioning and mass flow computing may be accomplished in an arrangement which accepts one or two 3 to 15 psi input signals and transmits a 3 to 15 psi output signal proportional to the product or to the quotient of the two inputs, or to the square or square root of one input.
  • the arrangement is essentially the same as in the ratio device shown in FIG. 3. That is to say, the movable input force element 19 is a ball-and-cylinder element mounted at the end ofa lever 24' pivoted on a post 25, and the feedback force element 20 may also be a ball-and-cylinder element.
  • this shift is effected pneumatically by a capsule 30 or any other suitable form of pressuresensitive transducer operatively coupled to lever 24 to adjust the position of input element 19 as a function of a second input pressure P FIG.
  • the unit In the squaring mode, the unit is the same as in multiplying except that a single input P, is applied to both input elements 19 and 30.
  • the computer unit is similar to the multiplier shown in FIG. 9, but nozzle 15 the of detector is moved to the opposite side of force beam 10 and the feedback element 20 is attached to the movable lever 24' whose position is controlled by capsule 30.
  • the pneumatic pressure P is taken as an output from pneumatic relay 16, whereas the input pressure P is applied to input element l9 and the input pressure P to input element 20.
  • a pressure-responsive capsule is added to the ratio device, which capsule serves to change the position of the lever carrying the input force element to cause this element to shift its position along the force beam.
  • the multiplying capability comes from pneumatically shifting this lever in accordance with input pressure P;, while applying input pressure P, to the input force element. Consequently, we have two factors-a length and a force-both of which are variable. The product of these factors, when rebalanced by the feedback mechanism, causes the device to carry out a multiplying function.
  • an additional detector nozzle is provided on the opposite side of the force beam.
  • Pneumatic adders and subtractors are available commercially, the devices being adapted to effect summation or subtraction of two or more input signals. These are used industrially, for example, to totalize a number of flow loops to obtain the total flow from a multiple flow system. They usually employ a force-balance system operating in conjunction with bellows to produce a single modified output pressure.
  • FIG. 11 there is shown a pneumatic adder-subtractor in accordance with the invention and including a force beam 10 supported in a fulcrum 11, the position thereof being sensed by a flapper-nozzle detector coupled to a pneumatic relay 16 to provide an output pressure P
  • input pressure P, and P are applied to one end of the beam by ball-and-cylinder force elements 31 and 32 engaging the beam on opposite sides thereof at fixed locations.
  • the output pressure P is applied to the feedback ball-and-cylinder force element disposed at the other end of the beam on the upper side thereof, the lower side having a ball-andcylinder force element 33 to which an input pressure P, is applied.
  • Elements 20 and 33 are all at fixed positions.
  • this arrangement :
  • H0. 12 there is shown a preferred form of ball-and-cylinder element comprising a cylindrical housing 35 having an upper head portion 36 provided with a circular groove 36A adapted to receive a snap ring for mounting the element.
  • head 36 may be threaded for mounting purposes.
  • the housing is provided with a lateral opening 37 and a fitting 38 for pressure connection.
  • the ball 40 Received within the main hole 39 is the ball 40, the diameter of the hole being closely controlled to avoid pressure leakage.
  • the ball-and-cylinder element is most advantageous when this element is movable relative to the beam.
  • the pressure-responsive element is fixedly mounted, one need not use a ball-and-cylinder element and one may use other known forms of pressureresponsive elements, such as bellows.
  • a pneumatic computing device comprising:
  • c. means to apply a first input pressure to said input element whereby an input torque is produced tending to swing said beam in one direction, the magnitude of the input torque depending on said input pressure, input element area and the distance between the input element and the fulcrum;
  • a detector operatively coupled to said beam to sense any deflection thereof
  • a pressure-responsive feedback element responsive to said output pressure and engaging said beam to produce a torque in the reverse direction to an extent counteracting said input torque to maintain said beam in equilibrium, said feedback torque having a magnitude depending on output pressure, feedback element area and the distance between said feedback element and the fulcrum;
  • the shiftable element being a ball and cylinder element whose ball engages said beam
  • said ball and cylinder element being constituted by a cylinder having a circular hole forming a socket for the ball, the diameter of the hole substantially matching the diameter of the ball to avoid pressure leakage, and a duct communicating with said hole to apnly a pneumatic pressure thereto whereby the fOI'Ct. znerated by the ball is strictly a function of the pressure within the cylinder acting on the area of the ball.
  • a device as set forth in claim 4 further including a span spring extending between said arm and a point on said beam adjacent said feedback element.
  • transducer is a capsule secured to one end of a pivoted arm, the other end of which is attached to said input element.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Supply Devices, Intensifiers, Converters, And Telemotors (AREA)
US00222257A 1972-01-31 1972-01-31 Pneumatic computing devices Expired - Lifetime US3748454A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US22225772A 1972-01-31 1972-01-31

Publications (1)

Publication Number Publication Date
US3748454A true US3748454A (en) 1973-07-24

Family

ID=22831513

Family Applications (1)

Application Number Title Priority Date Filing Date
US00222257A Expired - Lifetime US3748454A (en) 1972-01-31 1972-01-31 Pneumatic computing devices

Country Status (2)

Country Link
US (1) US3748454A (sv)
JP (1) JPS5540902B2 (sv)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4368750A (en) * 1978-04-28 1983-01-18 Sundstrand Corporation Ball-type feedback motor for servovalves
US4550616A (en) * 1983-09-21 1985-11-05 Honeywell Inc. Pneumatic flow station
US20090206289A1 (en) * 2008-02-19 2009-08-20 Honeywell International Inc. Torque balance servo including electromagnetic force bias mechanism

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2991006A (en) * 1956-09-19 1961-07-04 Foxboro Co Automatic force balance bridge
US3072326A (en) * 1960-01-29 1963-01-08 Honeywell Regulator Co Fluid-pressure-operated computer
US3159343A (en) * 1962-01-22 1964-12-01 Bell Corp Analog computer
US3171330A (en) * 1962-05-18 1965-03-02 Bendix Corp Motion transmitting system
US3239139A (en) * 1961-12-04 1966-03-08 Garrett Corp Pneumatic analog computer
US3243112A (en) * 1963-09-16 1966-03-29 Sorteberg Johannes Weighbeam system

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2521477A (en) * 1948-01-26 1950-09-05 Gulf Oil Corp Apparatus for measuring liquid content

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2991006A (en) * 1956-09-19 1961-07-04 Foxboro Co Automatic force balance bridge
US3072326A (en) * 1960-01-29 1963-01-08 Honeywell Regulator Co Fluid-pressure-operated computer
US3239139A (en) * 1961-12-04 1966-03-08 Garrett Corp Pneumatic analog computer
US3159343A (en) * 1962-01-22 1964-12-01 Bell Corp Analog computer
US3171330A (en) * 1962-05-18 1965-03-02 Bendix Corp Motion transmitting system
US3243112A (en) * 1963-09-16 1966-03-29 Sorteberg Johannes Weighbeam system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4368750A (en) * 1978-04-28 1983-01-18 Sundstrand Corporation Ball-type feedback motor for servovalves
US4550616A (en) * 1983-09-21 1985-11-05 Honeywell Inc. Pneumatic flow station
US20090206289A1 (en) * 2008-02-19 2009-08-20 Honeywell International Inc. Torque balance servo including electromagnetic force bias mechanism
US7971851B2 (en) * 2008-02-19 2011-07-05 Honeywell International Inc. Torque balance servo including electromagnetic force bias mechanism

Also Published As

Publication number Publication date
JPS5540902B2 (sv) 1980-10-21
JPS4888998A (sv) 1973-11-21

Similar Documents

Publication Publication Date Title
US4876524A (en) Six-axis joystick control
GB1364768A (en) Measuring the position of an operating agency in a machine
GB2026704A (en) Device for Measuring Fluid Flow in Tubing
US3748454A (en) Pneumatic computing devices
US4601111A (en) Gear tooth test feeler
US3082622A (en) Angle of attack and sideslip indicator
US3095745A (en) Differential pressure instrument
GB1532192A (en) Mirror-orientating device for a laser levelling instrumen
US3307265A (en) Distance measuring by friction wheel instruments
US3625048A (en) Device for recording width variations of a fabric
US3049007A (en) Force-ratio measuring device
GB2130732A (en) 'servo-controlled surface angle measuring device'
US3401561A (en) Differential pressure responsive apparatus
US2895333A (en) Pressure responsive force-ratio balance apparatus
US3250133A (en) Differential accelerometer
US3718279A (en) Force balance instrument for computing
US2674447A (en) Speedometer
US3264876A (en) Altitude and vertical velocity meter
US4947697A (en) System for measuring force versus position of a flight controller in an aircraft or flight simulator
US3086702A (en) Pneumatic force balance computing apparatus
US2253795A (en) Oscillation scanning and measuring apparatus
US3160007A (en) Force balance measuring instrument
US3335612A (en) Acceleration-sensitive devices and systems
US3742969A (en) Pneumatic force-balance transmitter
US2285500A (en) Dynamometer