US3704589A - Method and arrangement for automatically positioning a piston as a function of rotor position in a piston motor - Google Patents

Method and arrangement for automatically positioning a piston as a function of rotor position in a piston motor Download PDF

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Publication number
US3704589A
US3704589A US21418A US3704589DA US3704589A US 3704589 A US3704589 A US 3704589A US 21418 A US21418 A US 21418A US 3704589D A US3704589D A US 3704589DA US 3704589 A US3704589 A US 3704589A
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United States
Prior art keywords
piston
signal
arrangement
rotor
position signal
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Expired - Lifetime
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US21418A
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English (en)
Inventor
Hans Kubach
Gerfried Leberl
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Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH
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Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B9/00—Reciprocating-piston machines or engines characterised by connections between pistons and main shafts, not specific to groups F01B1/00 - F01B7/00

Definitions

  • the piston traveling along a substantially straightline path can thus only be correctly positioned relative to the angular crankshaft position when the amount of fluid within the hydraulic linkage is correct.
  • the piston position relative to the rotary crankshaft position must be adjusted when the motor is first starting up and, because of leakage in the hydraulic system, possibly also during the operation of the motor.
  • the position of the piston isnot related to the angle of rotation of the rotary element by a linear function, but follows a substantially sinusoidal curve for a constant change in angle of rotation, that is for a constant angular speed.
  • thisrelationship must first be simulated by electrical signals.
  • This invention constitutes a method for automatically adjusting the position of the piston in a piston motor as a function of the rotary crankshaft position by changing the amount of hydraulic fluid constituting the linkage between said crankshaft and said piston. While the invention is illustrated by use of a motor having a hydraulic linkage between piston and crankshaft, it can, in general terms, be applied to any system wherein the straight-line motion of a first element (piston) is translated, via a hydraulic linkage into corresponding rotational motion of a second element, herein called a rotor. It comprises the steps of generatinga piston position signal having an amplitudevarying as a predetermined function of said piston position relative to a piston reference position.
  • a difference signal corresponding to the difference between said piston position signal and said rotor position signal is generated and the amount of hydraulic fluid constituting the linkage is varied as a function of said difference signal.
  • the piston position signal is obtained by an instrument transformer whose operation is restricted to furnish a substantially linear output signal as a function of piston position, this linear portion being less than one half a period of the output signal of the instrument transformer.
  • the rotor position signal is also furnished by an instrument transformer.
  • the rotor position signal as a function of rotor position-during a complete cycle of piston operation is a substantially sinusoidal signal.
  • the difference signal after processing and suitable circuitry, is caused to open or close inlet and outlet valves controlling the fluid flow to the hydraulic linkage.
  • the valves are operated in accordance with the polarity and the magnitude of the difference signal until such time as the piston position corresponds to the rotor position and the difference signal goes to zero.
  • the instrument transformers furnishing the piston position signal and the rotor position signal may be substantially identical.
  • synchro generators may be used.
  • a mechanical linkage is used to convert the substantially straight line back'and-forth movement of the piston into a bidirectional rotational movement.
  • the primary excitation of the synchros is furnished by a reference voltage.
  • the amplitudes of the secondary voltages that is of the output signals, depend upon the position of the rotor and the piston respectively.
  • the adjustment of the voltages is necessary, since the two synchros are not driven to the same outputs because of the nonlinear relationship between the rotor position and the piston position, when the same reference voltage is applied to the primaries.
  • the rotor has more than one piston, which often occurs in practice, then a separate instrument transformer is required for each piston, but the same rotor position signal may be used for all pistons. Of course, if the pistons do not all operate in the same phase relationship, then suitable phase correction networks must be supplied.
  • FIG. 2 shows the amplitude variation of the rotor position signal as a function of rotor angle.
  • FIG. 3 is a graph showing piston position signal as a function of piston position.
  • FIG. 4 is a graph showing the output of the phase detector as a function of a difference signal
  • FIG. 5 is a block diagram showing the electrical control arrangement in accordance with the present inventron.
  • FIGS. 7a 7g show a number of curves illustrating phase detector output signals for different deviations between the rotor and piston positions.
  • FIG. 6 Also shown in FIG. 6 is the hydraulic coupling 21 linking piston to crank shaft 22 having a journal 23.
  • the amount of fluid 21 isregulated by a valve 18 having an inlet 19 and an outlet 20.
  • the operation of valve 18 is controlled by a difference signal 13, described below.
  • the rotor position signal is derived from a synchrogenerator 7 whose rotor or secondary winding is connected to journal 23.
  • the middle curve in FIG. 1 shows the piston movement when the quantity of oil in the hydraulic system is correct, while too much fluid is present in the conditions pictured in the upper curve 2 and too little oil is present under conditions pictured in the lower curve, 3.
  • the limits of the actual piston stroke are indicated by a in FIG. 1 while the available range of piston movement is indicated by V.
  • the abscissa is the angular position of the rotor (crankshaft) in degrees, while the ordinate shows piston position in centimeters.
  • the rotor has an arbitrary position indicated, for example, by b in FIG. 1. Under correct operating conditions, the corresponding piston position is indicated by reference numeral 4.
  • FIG. 6 The mechanical linkage used to restrict the output of the piston position synchro to the range indicated by points 5 and 6 is shown in FIG. 6.
  • the piston is designated with reference numeral 15 and the synchro shaft by reference numeral 17.
  • the piston 15 is shown in its upper extreme position corresponding to point 4 in FIG. 1.
  • the lower extreme of its travel is indicated by the dashed lines. It is seen that the mechanical linkage 16 moves through an angle [3 while the piston moves from its top to its bottom extreme positions.
  • the output signal U shown in FIG. 3 thus results from a movement of link 16 through the angle [3 and the corresponding rotation of shaft 17.
  • the piston position signal and the rotor position signal that is the outputs of the piston and rotor synchros, are then processed as follows. First, they are interconnected in phase opposition in order that the differencesignal is obtained. This difference signal or more specifically difference voltage is then filtered by a filter 10 which removes undesired harmonics. The filtered output of filter 10 is then applied to a phase sensitive rectifier 11. This phase sensitive rectification is required since both the phase and the magnitude of the piston position signal must coincide with the rotor position signal if correct positioning of the piston relative to the rotor is to be achieved.
  • the reference voltage U which is used for primary excitation of all synchros, is used as a reference phase for the phase sensitive rectifier 11, as shown in FIG. 5.
  • the voltage U.,, available at output 13, has, within a certain region, a sign and amplitude which is directly proportional to the deviation r of the piston from its desired position (see FIG. 4).
  • the output signal U, of detector 11 is a measure whether and how much hydraulic fluid must be added or subtracted from the system.
  • FIG. 7 A detailed example of the functioning of the phase sensitive rectifier is shown in FIG. 7.
  • line a shows the variation of the reference voltage U with time.
  • line b values of U and U as a function of time are shown wherein U exceeds U
  • Line 0 shows the variation of U, with respect to time when the signals shown in line b are applied to the input of rectifier 11.
  • lines d and f of FIG. 7. The corresponding signals at output 13 are shown in lines 2 and g of FIG. 7.
  • Phase sensitive rectifiers operating in this manner are well known in the art and many structures carrying out these functions may be found in the literature.
  • each piston must of course have a separate means for furnishing a piston position signal, but a single means for furnishing the rotor positionsignal may be used even when a plurality of pistons are present.
  • the additional piston has a synchro 8, a voltage divider or potentiometer 9', its own filter l0 and its corresponding phase sensitive rectifier 11
  • synchro 7 for characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
  • first synchrogenerator means coupled to said piston and having a selected output phase furnishing a piston position signal varying as a predetermined function of the position of said piston relative to a piston reference position
  • second synchrogenerator means coupled to said crank shaft and having a selected output phase furnishing a rotorposition signal corresponding to the angular crank shaft position relative to a reference crank shaft position
  • initial adjustment means for adjusting the amplitude of said piston position signal with said rotor position signal in such a manner that, for correct position of said piston, the amplitudes of said signals are equal
  • connecting means connecting said selected output phase of said first synchrogenerator and said selected output phase of said second synchrogenerator in phase opposition, thereby furnishing a difference voltage
  • rectifier means having a first input energized by said
  • said first synchro generator means has a shaft; further comprising mechanical linking means linking said piston to said shaft, in such a manner that movement of said piston from a first extreme position to a secondextreme position rotates said shaft of said synchro generator through a predetermined angle less than 7 3.
  • said means for generating a piston position signal comprises means for generating a piston position signal having an amplitude varying as a straight line function of said piston position relative to a reference position.
  • said engine has a plurality of pistons, wherein said crankshaft has a plurality of crankpins, each hydraulically coupled to a corresponding one of said pistons; wherein said means for generating a piston-position signal comprises means for generating a plurality of piston-position signals, one for each of said pistons; wherein said comparing means comprise a plurality of comparing means, each for comparing one of said piston-position signals with said rotor-position signal and generating a corresponding plurality of difference signals; and wherein said means for changing the pressure medium comprising means for changing the amount of hydraulic pressure medium coupling a piston to the corresponding crankpin in response to the corresponding difference signal, in such a manner as to minimize said difference signal.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Servomotors (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Reciprocating Pumps (AREA)
  • Valve Device For Special Equipments (AREA)
  • Hydraulic Motors (AREA)
US21418A 1969-03-22 1970-03-20 Method and arrangement for automatically positioning a piston as a function of rotor position in a piston motor Expired - Lifetime US3704589A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19691914669 DE1914669A1 (de) 1969-03-22 1969-03-22 Verfahren zur Sollpositionsvorgabe eines Kolbens als Funktion der Stellung des Rotors eines Kolbenmotors

Publications (1)

Publication Number Publication Date
US3704589A true US3704589A (en) 1972-12-05

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US21418A Expired - Lifetime US3704589A (en) 1969-03-22 1970-03-20 Method and arrangement for automatically positioning a piston as a function of rotor position in a piston motor

Country Status (5)

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US (1) US3704589A (enrdf_load_stackoverflow)
JP (1) JPS5111751B1 (enrdf_load_stackoverflow)
DE (1) DE1914669A1 (enrdf_load_stackoverflow)
DK (1) DK130851B (enrdf_load_stackoverflow)
GB (1) GB1250437A (enrdf_load_stackoverflow)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5416466U (enrdf_load_stackoverflow) * 1977-07-06 1979-02-02

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1229443A (en) * 1912-10-05 1917-06-12 Westinghouse Electric & Mfg Co Accelerator and system of control.
US1560492A (en) * 1921-02-02 1925-11-03 A L Powell Power Co Inc Internal-combustion engine
US2380973A (en) * 1943-08-11 1945-08-07 Fed Electric Company Inc Control for fluid operated motors
US2742763A (en) * 1950-12-11 1956-04-24 Keelavite Co Ltd Apparatus for providing synchronization between hydraulically operated members
US2771845A (en) * 1955-01-11 1956-11-27 Philadelphia Pump & Machinery Proportioning pump
US3017865A (en) * 1959-02-16 1962-01-23 Martin Marietta Corp Infinitely variable hydraulic damper and locking mechanism
DE1146757B (de) * 1959-07-28 1963-04-04 Short Brothers & Harland Ltd Elektrohydraulischer Steuer-Servomechanismus
US3095784A (en) * 1959-07-28 1963-07-02 Short Brothers & Harland Ltd Electro-hydraulic control servomechanisms
CA674057A (en) * 1963-11-12 J. Conrad Hans Arrangement for converting a reciprocatory movement into a rotary movement
DE1157876B (de) * 1961-11-02 1963-11-21 Beteiligungs & Patentverw Gmbh Vorrichtung zur Regelung des Gleichlaufs von Hubverdraenger und Rotationsverdraenger bei Bewegungswandlern
US3135094A (en) * 1961-08-23 1964-06-02 Beteiligungs & Patentverw Gmbh Drive for conversion of a reciprocating movement into a rotary movement with a liquid as conversion means
US3263572A (en) * 1963-10-17 1966-08-02 Gen Electric Failure correcting device
US3477346A (en) * 1967-10-24 1969-11-11 Bendix Corp Integrated vacuum modulator and actuator

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA674057A (en) * 1963-11-12 J. Conrad Hans Arrangement for converting a reciprocatory movement into a rotary movement
US1229443A (en) * 1912-10-05 1917-06-12 Westinghouse Electric & Mfg Co Accelerator and system of control.
US1560492A (en) * 1921-02-02 1925-11-03 A L Powell Power Co Inc Internal-combustion engine
US2380973A (en) * 1943-08-11 1945-08-07 Fed Electric Company Inc Control for fluid operated motors
US2742763A (en) * 1950-12-11 1956-04-24 Keelavite Co Ltd Apparatus for providing synchronization between hydraulically operated members
US2771845A (en) * 1955-01-11 1956-11-27 Philadelphia Pump & Machinery Proportioning pump
US3017865A (en) * 1959-02-16 1962-01-23 Martin Marietta Corp Infinitely variable hydraulic damper and locking mechanism
DE1146757B (de) * 1959-07-28 1963-04-04 Short Brothers & Harland Ltd Elektrohydraulischer Steuer-Servomechanismus
US3095784A (en) * 1959-07-28 1963-07-02 Short Brothers & Harland Ltd Electro-hydraulic control servomechanisms
US3135094A (en) * 1961-08-23 1964-06-02 Beteiligungs & Patentverw Gmbh Drive for conversion of a reciprocating movement into a rotary movement with a liquid as conversion means
DE1157876B (de) * 1961-11-02 1963-11-21 Beteiligungs & Patentverw Gmbh Vorrichtung zur Regelung des Gleichlaufs von Hubverdraenger und Rotationsverdraenger bei Bewegungswandlern
US3263572A (en) * 1963-10-17 1966-08-02 Gen Electric Failure correcting device
US3477346A (en) * 1967-10-24 1969-11-11 Bendix Corp Integrated vacuum modulator and actuator

Also Published As

Publication number Publication date
GB1250437A (enrdf_load_stackoverflow) 1971-10-20
JPS5111751B1 (enrdf_load_stackoverflow) 1976-04-13
DK130851C (enrdf_load_stackoverflow) 1975-09-22
DK130851B (da) 1975-04-21
DE1914669A1 (de) 1970-10-08

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