US3360185A - Vacuum pump control - Google Patents

Vacuum pump control Download PDF

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Publication number
US3360185A
US3360185A US450434A US45043465A US3360185A US 3360185 A US3360185 A US 3360185A US 450434 A US450434 A US 450434A US 45043465 A US45043465 A US 45043465A US 3360185 A US3360185 A US 3360185A
Authority
US
United States
Prior art keywords
vacuum
tape
box
loop
pressure
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
US450434A
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English (en)
Inventor
Robert S Wooldridge
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.)
Unisys Corp
Original Assignee
Sperry Rand Corp
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 Sperry Rand Corp filed Critical Sperry Rand Corp
Priority to US450434A priority Critical patent/US3360185A/en
Priority to GB15634/66A priority patent/GB1134342A/en
Priority to FR58321A priority patent/FR1476478A/fr
Priority to BE679900D priority patent/BE679900A/xx
Application granted granted Critical
Publication of US3360185A publication Critical patent/US3360185A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B15/00—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function
    • G11B15/56—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function the record carrier having reserve loop, e.g. to minimise inertia during acceleration measuring or control in connection therewith
    • G11B15/58—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function the record carrier having reserve loop, e.g. to minimise inertia during acceleration measuring or control in connection therewith with vacuum column
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D16/00—Control of fluid pressure
    • G05D16/20—Control of fluid pressure characterised by the use of electric means
    • G05D16/2006—Control of fluid pressure characterised by the use of electric means with direct action of electric energy on controlling means
    • G05D16/2066—Control of fluid pressure characterised by the use of electric means with direct action of electric energy on controlling means using controlling means acting on the pressure source

Definitions

  • a system for regulating the pressure in a tape loop box for magnetic tape handlers is disclosed.
  • a vacuum pump drive by a motor is used to create a partial vacuum between the bottom of the tape loop and the bottom of the loop box.
  • a pressure sensitive switch is used to sense the vacuum in the loop box and to control the average speed of the vacuum pump motor so as to hold the vacuum in the loop box substantially constant.
  • This invention relates to tape loop boxes, and more particularly to means for regulating the vacuum in such tape 100:: boxes.
  • Tape loop boxes wherein loops of magnetic tape are maintained during operation are well known.
  • such loops are provided to permit relatively fast acceleration of the tape.
  • the loops of tape are generally formed by a pressure differential resulting from atmospheric pressure at the top of the tape and a low pressure or vacuum at the bottom of the tape.
  • the low pressure or vacuum is generally created by a vacuum pump which is driven by a pump motor.
  • a vacuum pump which is driven by a pump motor.
  • the motor is driven at different speeds therebv causing changes in the vacuum within the loop box.
  • This causes the tension on the tape to vary resulting in irregular operation. For example, as the tension on the tape varies, the rates of acceleration of the tape also vary causing faulty operation of the read-write circuits.
  • the length of the loop of tape is often controlled by the operation of a vacuum switch.
  • Such switches are re "sponsive to open or close dependent upon the pressure be tween the tape and the bottom of the loop box.
  • switches having special characteristics and designed to operate at selected pressures are necessary to assure uniformity of the length of the loop and tension of the tape.
  • means are provided for regulating pressure in a tape loop box.
  • a vacuum pump driven by a motor, is used to create a relatively low pressure or vacuum between the tape and the bottom of the box.
  • a vacuum switch responsive to the pressure in the loop box, connects a source of voltage to the motor to control the speed of the motor.
  • An adjustable valve is provided to control the pressure at which the vacuum switch opens and closes. The voltage applied to the motor is caused to remain at a relatively constant level and drives the pumpto maintain a relatively constant desired pressure in the loop box.
  • a loop box 10 which corresponds to the one of the tape columns 24 or 26 of Patent 2,792,217, for example, includes a loop of magnetic tape 12.
  • a low pressure of vacuum is created in the area 14 between the bottom surface of the tape 12 and the sides and bottom of the loop box 10.
  • the low pressure area is created by mans of a vacuum pump 16 driven by a DC. series motor 18.
  • a source of voltage is applied from terminal 20 to drive the motor 18 through appropriate circuitry, as will be described.
  • the size or capacity of the pump 16, while not critical, is selected so that when motor 18 is full on, pump 16 will generate the necessary vacuum to pull the tape loop 12 down to its desired operating position in loop box 10 when the tape handler is operating under the designed worse case condition of atmospheric pressure and line voltage variation.
  • the silicon controlled rectifier 22 is appropriately :biased by resistors 25, 27 and 29 so that it is normally cut-off in the absence of an applied gating signal to its gate electrode.
  • a voltage from a vacuum switch unit 30 is applied to make the silicon controlled rectifier 22 conducting.
  • a gating signal is applied to the gate electrode 26 of the rectifier 22, it will become conducting causing current to flow from terminal 20, through the winding 24 of the motor, through the anode and cathode of the rectifier 22, to a point of reference potential, designated as ground.
  • Silicon controlled rectifiers are well known to those skilled in the art. Their main advantage is that they are relatively inexpensive and are capable of drawing heavy current. Such devices act as normal rectifiers, i.e., they include an anode and a cathode, but also include a third electrode for receiving a gating signal. Silicon controlled rectifiers are normally held non-conducting until an appropriate gate signal is applied to its gate electrode. Once a silicon rectifier becomes conducting, it generally remains conducting, even though the control signal applied to the gate electrode is discontinued.
  • the voltage applied at the terminal is an unfiltered, full wave, rectified DC. voltage, as illustrated by a wave form 32. It is noted that while the wave form 32 is positive for a full half cycle, it also goes slightly negative for a short time. This is illustrated by the small portions of the DC. signal falling slightly below the reference level, designated as zero. With the type of signal 32 applied to the silicon controlled rectifier, the rectifier is cut off by the slightly negative portions of the signal 32.
  • the use of such silicon controlled rectifiers, as well as the use of unfiltered DC. voltage to shut them off are well known to those skilled in the art, and are only incidentally related to the present invention.
  • a diode is provided across the motor 18 to receive the high current resulting from the inductive reactance of the motor when the motor is suddenly turned off. This diode is also only incidentally related to the present invention.
  • the silicon controlled rectifier 22 is made conducting by the application of a gating signal from the vacuum switch unit 30 to permit current to flow through the motor in a manner to be described.
  • the vacuum switch unit 30 includes a flexible diaphragm 34 which divides the unit into two chambers 36 and 38.
  • the chamber 36 is exposed to the atmosphere and the chamber 38 is connected through conduits 4t and 42 to the low pressure or vacuum area 14 of the tape loop box.
  • the chamber 38 is also connected to the atmosphere through the conduit 40, a conduit 44 and an adjustable valve 46.
  • a vacuum switch 48 adapted to be normally closed and to be open when a predetermined pressure is present within. the chamber 38.
  • the switch includes a movable contact arm 49 which closes or opens to connect a source of gating voltage from a terminal 50 through the resistor 29 to the gate electrode 26 of the silicon controlled rectifier 22'.
  • the adjustable valve 46 provides a leakage path for the pressure from the low pressure area 14 while the conduit 42 acts as a restrictor whereby the valve 46 and the conduit 42 produce an adjustable pressure drop between the switch 30 and the pressure in chamber 14.
  • the pressure at which the switch 48 is actuated is controlled by the position of the adjustable valve 46. If different atmospheric pressures are involved because of different environments for different tape transport units of the same type, different switches all having the same set response characteristic may still be used by simply adjusting the valve 46.
  • the adjustable valve 46 eliminates the need for special switches for different environmental conditions.
  • the pressure level in the area 14 is dependent upon the degree of tension to be applied to the tape 12. In most situations, it is desirable to maintain the tension on the tape 12 relatively constant.
  • the tension on the tape is dependent upon the pressure difiFerence between the pressure of the atmosphere above the tape and the pressure in the area 14.
  • the movable contact 49 of the vacuum switch 48 is held open thereby disconnecting the source of voltage from the terminal 50 to the gate electrode 26 of the silicon controlled rectifier 22.
  • the silicon controlled rectifier is held non-conducting since no gating signals are present to drive it to conduction.
  • the silicon controlled rectifier is non-conducting, no current flows through the motor 18 causing it to slow down.
  • the slowing down of the motor 18 causes the vacuum pump'to operate at a slower speed thereby permitting the pressure in the area 14 to increase. Consequently the differential pressure across the tape decreases to decrease the tension on the tape to its desired degree.
  • the present invention has provided a relatively simple means for maintaining tension of a tape relatively constant. This is accomplished by standard parts, such as vacuum switches of non-critical types, and may be used in widely varying environments involving different atmospheric pressures. Also, the use of relatively inexpensive motors is possible. The input voltage to drive the motor may also vary over wide ranges because of the compensating features of the present invention.
  • vacuum is to be interpreted as not necessarily being a pure vacuum but simply a source of relatively low pressure with respect to another source of pressure, such as atmosphere.
  • a tape loop control box a tape loop formed in said control box so that one surface of said tape loop is exposed to the atmosphere and the other surface thereof forms a vacuum chamber with said control box, means for regulating the vacuum in the vacuum chamber of said box comprising vacuum producing means for producing vacuum in said box, control means for controlling the operation of said vacuum producing means to control the amount of vacuum in said box, and switching means responsive to the vacuum in said box to actuate said control means, means communicating with both the switching means and the control box for adjusting the vacuum applied to said switching means to maintain a desired vacuum in said loop box.
  • a tape loop control box a tape loop formed in said control box so that one surface of said tape loop is exposed to the atmosphere and the other surface thereof forms a vacuum chamber with said control box
  • means for regulating the vacuum in the vacuum chamber of said box comprising a pump for producing a vacuum in said box, a motor for driving said pump, a signal source to operate said motor, switching means responsive to the vacuum in said loop box to connect said signal source to operate said motor, and means communicating with both the switching means and the control boxes for adjusting the vacuum applied to said switching means to maintain a desired length of tape loop in said loop box.
  • means for controlling the length of tape loop in said loop box comprising a motor for producing a vacuum within said vacuum chamber to maintain said tape loop at a predetermined length, a source of current for driving said motor, a silicon controlled rectifier circuit to control the current through said motor, a switch responsive to the vacuum in said vacuum chamber to control the operation of said silicon controlled rectifier, an adjustable valve for adjusting the vacuum applied to said switch whereby a predetermined length of loop may be maintained in said loop box for diiferent atmospheric pressures.
  • means for controlling the length of tape loop in said loop box comprising a pump for producing a predetermined vacuum within said vacuum chamber to maintain said tape loop at a predetermined length, a motor for driving said pump, the vacuum produced by said pump being dependent upon the speed of said motor, a source of voltage for supplying current to drive said motor, a silicon controlled rectifier circuit adapted to be switched between conducting and non-conducting states to control the current through said motor, a switch responsive to the vacuum in said vacuum chamber to cause said silicon controlled rectifier to be switched from a non-conducting to a conducting state, means for adjusting the vacuum applied to said switch whereby a set predetermined vacuum actuates said switch despite difierent pressures in said vacuum chamber or variations in said pressure differential whereby a predetermined length
  • means for controlling the length of tape loop in said loop box comprising a motor for producing a predetermined vacuum within said vacuum chamber to maintain said tape loop at a predetermined length, a source of voltage for supplying current to drive said motor, a silicon controlled rectifier circuit adapted to be switched between conducting and non-conclucting states to control the current through said motor, a switch connected in a first path to said vacuum chamber and responsive to the vacuum in said vacuum chamber to cause said silicon controlled rectifier to be switched from a nonconducting to a conducting state, and an adjustable valve connected in a second path divergent to said first path for adjusting the vacuum applied to said switch whereby a set predetermined vacuum actuates said switch despite different pressures in said vacuum chamber or variations in said pressure differential whereby a predetermined

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Advancing Webs (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
US450434A 1965-04-23 1965-04-23 Vacuum pump control Expired - Lifetime US3360185A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US450434A US3360185A (en) 1965-04-23 1965-04-23 Vacuum pump control
GB15634/66A GB1134342A (en) 1965-04-23 1966-04-07 Vacuum control particularly for a tape loop box
FR58321A FR1476478A (fr) 1965-04-23 1966-04-20 Système de réglage du vide
BE679900D BE679900A (cs) 1965-04-23 1966-04-22

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US450434A US3360185A (en) 1965-04-23 1965-04-23 Vacuum pump control

Publications (1)

Publication Number Publication Date
US3360185A true US3360185A (en) 1967-12-26

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Family Applications (1)

Application Number Title Priority Date Filing Date
US450434A Expired - Lifetime US3360185A (en) 1965-04-23 1965-04-23 Vacuum pump control

Country Status (3)

Country Link
US (1) US3360185A (cs)
BE (1) BE679900A (cs)
GB (1) GB1134342A (cs)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5008051A (en) * 1989-03-01 1991-04-16 Decoursey Robert T Vacuum sizing tank with electronically controlled vacuum pressure
US5242404A (en) * 1992-02-12 1993-09-07 American Cyanamid Company Aspiration control system
US5549139A (en) * 1989-10-27 1996-08-27 Storz Instrument Company Pneumatic controls for ophthalmic surgical system
US5624394A (en) * 1994-10-28 1997-04-29 Iolab Corporation Vacuum system and a method of operating a vacuum system
US5810766A (en) * 1995-02-28 1998-09-22 Chiron Vision Corporation Infusion/aspiration apparatus with removable cassette
ES2209567A1 (es) * 2001-02-28 2004-06-16 Guillermo Aguirre Dispositivo automatico para regular la presion de vacio variando la velocidad de rotacion de las bombas de vacio mediante la variacion de la frecuencia electrica.

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4397610A (en) * 1981-03-09 1983-08-09 Graco Inc. Reciprocable pump with variable speed drive

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US440375A (en) * 1890-11-11 Fred s
US862696A (en) * 1905-03-21 1907-08-06 Pearsall Pneumatic Tube And Power Company Governing mechanism for pneumatic-tube systems.
US1073276A (en) * 1911-12-05 1913-09-16 Otto H Mohr Preserving apparatus.
US1132777A (en) * 1915-03-23 Lamson Co Automatic pressure-controller.
US1347194A (en) * 1919-04-29 1920-07-20 Washington Elwood Vacuum-cabinet
US3151796A (en) * 1961-06-29 1964-10-06 Ibm Web feeding device
US3156423A (en) * 1962-05-18 1964-11-10 Potter Instrument Co Inc Tape loop control
US3258183A (en) * 1964-02-26 1966-06-28 Potter Instrument Co Inc Tunable tape velocity-fluctuation damper

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US440375A (en) * 1890-11-11 Fred s
US1132777A (en) * 1915-03-23 Lamson Co Automatic pressure-controller.
US862696A (en) * 1905-03-21 1907-08-06 Pearsall Pneumatic Tube And Power Company Governing mechanism for pneumatic-tube systems.
US1073276A (en) * 1911-12-05 1913-09-16 Otto H Mohr Preserving apparatus.
US1347194A (en) * 1919-04-29 1920-07-20 Washington Elwood Vacuum-cabinet
US3151796A (en) * 1961-06-29 1964-10-06 Ibm Web feeding device
US3156423A (en) * 1962-05-18 1964-11-10 Potter Instrument Co Inc Tape loop control
US3258183A (en) * 1964-02-26 1966-06-28 Potter Instrument Co Inc Tunable tape velocity-fluctuation damper

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5008051A (en) * 1989-03-01 1991-04-16 Decoursey Robert T Vacuum sizing tank with electronically controlled vacuum pressure
US5549139A (en) * 1989-10-27 1996-08-27 Storz Instrument Company Pneumatic controls for ophthalmic surgical system
US5857485A (en) * 1989-10-27 1999-01-12 Perkins; James T. Pneumatic controls for ophthalmic surgical system
US5979494A (en) * 1989-10-27 1999-11-09 Bausch & Lomb Surgical, Inc. Pneumatic controls for ophthalmic surgical system
US5242404A (en) * 1992-02-12 1993-09-07 American Cyanamid Company Aspiration control system
US5429601A (en) * 1992-02-12 1995-07-04 American Cyanamid Company Aspiration control system
US5624394A (en) * 1994-10-28 1997-04-29 Iolab Corporation Vacuum system and a method of operating a vacuum system
US5795328A (en) * 1994-10-28 1998-08-18 Iolab Corporation Vacuum system and a method of operating a vacuum system
US5810766A (en) * 1995-02-28 1998-09-22 Chiron Vision Corporation Infusion/aspiration apparatus with removable cassette
ES2209567A1 (es) * 2001-02-28 2004-06-16 Guillermo Aguirre Dispositivo automatico para regular la presion de vacio variando la velocidad de rotacion de las bombas de vacio mediante la variacion de la frecuencia electrica.
ES2209567B1 (es) * 2001-02-28 2005-09-16 Guillermo Aguirre Dispositivo automatico para regular la presion de vacio variando la velocidad de rotacion de las bombas de vacio mediante la variacion de la frecuencia electrica.

Also Published As

Publication number Publication date
GB1134342A (en) 1968-11-20
BE679900A (cs) 1966-10-03

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