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Publication numberUS3666232 A
Publication typeGrant
Publication dateMay 30, 1972
Filing dateApr 14, 1970
Priority dateApr 18, 1969
Also published asDE1919702A1
Publication numberUS 3666232 A, US 3666232A, US-A-3666232, US3666232 A, US3666232A
InventorsKurt Melcher, Wilhelm Vogel
Original AssigneeBosch Gmbh Robert
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method and means for reducing the response time of magnetic valves
US 3666232 A
Abstract
A method and apparatus for reducing the response times of electromagnetically controlled valves. The operating coil of the valve has a center tap connected to a D.C. supply voltage, whereas the end terminals of the coil are each connected to the collectors of two power transistors. The base supply voltages for the power transistors are derived from a voltage divider, and a control transistor has its emitter-collector path connected across the base voltage supply of the power transistors. The power transistors are connected to function as an astable multivibrator which is turned on and off by the control transistor. The astable multivibrator provides rectangular-shaped alternating voltage to the operating coil of the valve for de-magnetizing the valve before or after operation of actuation of the valve.
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United States Patent Melcher et al. 1 May 30, 1972 54] METHOD AND MEANS FOR REDUCING 3,334,316 8/1967 Price ..331/113 x RESP N E ME 0F MAGNET! I E O S TI C FOREIGN PATENTS OR APPLICATIONS 1,318,728 1 1963 F ..251 141 [72] Inventors: Kurt Melcher, Markgroeningen; Wilhelm fame Vogel, Stuttgart-Bad Cannstatt, Germany Examiner Amold Rosemhal [73] Assignee: Robert Bosch GmbH, Stuttgart, Germany Alt rney-Michael S. Striker 22 Filed: Apr. 14, 1970 [57] ABSTRACT [21] App! 32495 A method and apparatus for reducing the response times of eiectromagnetically controlled valves. The operating coil of [30] Foreign Application Priority Data the valve has a center tap connected to a DC. supply voltage, whereas the end terminals of the coil are each connected to Apr. 18, 1969 Germany ..P 19 19 702.5 the collectors of two power transistors The base supply ages for the power transistors are derived from a voltage di- [52] U.S.Cl Vidal, and a comm transistor has its emittepconecmr path 2; 51/129 137/487 connected across the base voltage supply of the power 1 o 3 17/1 5 l23' 33 1 ll transistors. The power transistors are connected to function as an astable multivibrator which is turned on and off by the con- 56 R f Cited trol transistor. The astable multivibrator provides rectangular- 1 e erences shaped alternating voltage to the operating coil of the valve UNITED STATES PATENTS for de-magnetizing the valve before or after operation of actuation of the valve. 3,458,769 7/1969 Stampfli ..25l/3O X 3,219,095 11/1965 Nilson ..25i/l29 X 3 Claims, 5 Drawing Figures PATENTEDMAY 30 m2 SHEET 10F 2 III" INVENTORS Kurt MELCHER Wilhelm VOGEL their ATTORNEY PATEHIEUmso I972 3.666 232 UUUUUUUUHHHHUUU INVENTORS Kurt MELCHE Wilhe m VOC-E.

their ATTORNEY BACKGROUND OF THE INVENTION The present invention relates to a process for reducing the response time of magnetic valves, and an arrangement for carrying out the process.

It is often required that magnetic valves have an extremely short response time. Magnetic valves with short response times are installed in electronically controlled fuel injection arrangements for internal combustion engines. This applies particularly to high-speed machines. Means for shortening the response time of magnetic valvesare already known in the art. Such conventional means consists, for example, of reducing the masses of the movable parts subjected to the magnetic forces, and to increase the surfaces upon which the magnetic forces are applied. The conventional means, furthermore, involves reduction of the inductance of the operating coils.

It is an object of the present invention, accordingly, to reduce the response times of magnetic valves by reducing the complexity of the conventional arrangements. The solution to the problem resides in a process through which the operating coil of the magnetic valve has applied to it an alternating voltage of predetermined frequency after or before each actuation of the valve. This alternating voltage serves to de-magnetize the valve.

An arrangement for carrying out the process, in accordance with the present invention, consists of providing an oscillator which is connected to the operating coil of the magnetic valve and which may be turned on and off, in accordance with the actuation of the valve. An advantageous operation of the valve is realized when, in accordance with a further feature of the present invention, the output voltage of the oscillator is substantially of rectangular-shaped form. The power received by the operating coil of the magnetic valve within a predetermined time interval, is as a first approximation, proportional to the time integral of the applied voltage. The time integral is evidently larger for a rectangular-shaped alternating voltage, without gaps, than for a sinusoidal-shaped voltage of equal amplitude and otherwise comparable conditions. An astable multivibrator is used to provide simple and reliable operation of an oscillator.

SUMMARY OF THE INVENTION A method and arrangement for reducing the response time of an electromagnetically operated valve. The valve has a center-tapped coil, with the center tap connected to a source of D.C. operating voltage. The end terminals of the electromagnetic coil of the valve are each connected to one collector of two power transistors which function together in the form of an astable multivibrator. The base voltage supply for the power transistors is derived from a voltage divider having one common resistor connected to the D.C. voltage source. Two separate resistors are connected to the bases of the power transistors and to the common resistor. A control transistor is connected across the base voltage supply for the two power transistors. The astable multivibrator serves to apply a substantially rectangular-shaped alternating voltage to the coil for the purpose of de-magnetizing the ferromagnetic parts of the valve. De-magnetization of the valve is applied either before or after actual operation or actuation of the valve in usage.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an electrical schematic diagram for de-magnetization of a magnetic valve through the use of an oscillator, in accordance with the present invention;

FIG. 2 and FIG. 2a illustrate the magnetic characteristics relative to the operation of the circuit arrangement of FIG. 1;

FIG. 3 is a voltage-time diagram of the control voltage of the oscillator, whereby the oscillator is switched on and off in FIG. 1; and

FIG. 4 is a graphical representation of the flux density and magnetization as a function of time of the magnetic valve in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, and in particular to FIG. 1, the magnetic valve 10 includes a pretensioned spring 11 which operates in the closing direction, upon an armature 12 which is movable subjected to a magnetic field. The closure of the magnetic valve results from the aid of a closing member or closure member 13 which is operatively connected to the armature 12. The closure member 13 has a conically shaped portion which is fitted into a valve seat 14. The fuel to be sprayed by the magnetic valve is applied through the entrance 15. The operating coil 16 of the magnetic valve has a center tap 17, as well as the two terminals 18 and 19. The center tap 17 is connected directly to the positive terminal of a voltage operating source U,,. The terminals 18 and 19 are each connected to collectors of transistors of the npn type in the form of power transistors T10 and T11. Thus, the terminal 18 is connected to the collector of T10, whereas terminal 19 is connected to the collector of T11. The emitter of the power transistor T10 is connected to the emitter of the power transistor T11, and both emitters are joined to the voltage supply line 25 connected to ground potential.

The base of each power transistor T10 and T11 leads to the voltage supply line 25, through a circuit consisting of a resistor connected in parallel with a capacitor. Thus, for the power transistor T10, the resistor R10 is provided in parallel combination to the capacitor C10. Similarly, associated with the transistor T11, is the parallel circuit of resistor R11 and capacitor C11. The collector of a control transistor T12 is connected to a circuit junction 26, whereas the emitter of this control transistor T12 is also connected to ground potential through the voltage supply line 25. Connected, furthermore, to the circuit junction 26, is the base of transistor T10, through the series circuit consisting of resistor R12 and diode D10. The base of transistor T11 is similarly connected to the circuit junction 26, through the series circuit of resistor R13 and diode D11. The cathode of the two diodes D10 and D11 are directly connected to the bases of the two transistors. The power transistor T10 operates in conjunction with the diode D10 and resistor R12, whereas the power transistor T11 operates in conjunction with the diode D1 1 and resistor R13. Connected, furthermore, to the collector of the transistor T11, is the series circuit consisting of capacitor C12 and resistor R14. This series circuit of the latter components is, moreover, connected to the anode of the diode D10, the cathode of which is connected to the base of the power transistor T10. Similarly, the collector of the power transistor T10 is coupled to the anode of the diode D11, through the series circuit consisting of capacitor C13 and resistor R15. The cathode of the diode D11 is directly connected to the base of the power transistor T11. The collector of the control transistor T12 which is joined to the circuit junction 26, leads to the power supply voltage U,, through a resistor R16. The emitter of the control transistor T12 is directly connected to the ground voltage line 25.

FIG. 2 shows two diagrams with two magnetizing characteristics which apply to the magnetic valve 10, and in particular to the ferromagnetic parts thereof. The left diagram in FIG. 2, provides the general magnetizing characteristics for a magnetic valve which is not demagnetized. In the state in which current flows, a maximum field strength Hm prevails, and a corresponding flux density Bs prevails correspondingly to the field intensity I-Im at the armature, for example. The flux density Bs appears at the beginning of saturation of the iron.

When the current is now turned off, the field intensity H becomes zero, so that the magnetic flux density B takes the path of the upper curve in the direction from ES to Br. The flux density Br is the residual flux remaining when the field intensity H is zero. The iron parts of the arrangement used in the operation of the magnetic valve, therefore, always possess magnetic properties in the un-excited state of the associated electromagnetic coil. This remaining magnetic property in the form of residual magnetic flux, causes an attractive force between the armature and the remaining ferromagnetic parts of the valve. In order that the magnetic valve remains securely closed in the unexcited state of the coil, however, the force resulting from the residual magnetism must be supplemented through the oppositely directed force applied by the spring 1 1.

The diagram at the right hand of FIG. 2, shown as FIG. 20 on the drawing, shows the function of the flux density or magnetization B as a function of the field intensity H when the ferromagnetic parts of the magnetic valve are de-magnetized. The flux density B then becomes zero when the voltage applied to the electromagnetic coil is removed or turned ofl". As a result, the closure force which is required to retain the magnetic valve in the closed state, can then be made considerably smaller. If a de-magnetized valve is connected to the operating voltage source again, considerably larger forces may be used for accelerating the armature, when the construction of the magnetic valve remains the same. This is because the magnetic forces opposite to the force applied by the spring 11, may be reduced as a result of the decrease or complete dropout of the residual magnetism. When taken in conjunction with the diagrammatic characteristics in FIG. 2, the operational function of FIG. 1 may be readily described. This operation of the arrangement of FIG. 1 is as follows:

The resistor R16 which is connected between the junction point 26 and the operating voltage U serves as the collector resistance for the control transistor T12. When the control transistor T12 becomes turned off through the control voltage U applied to its base, a potential is applied to the bases of the power transistors T and T1 1 through the resistor R16. This voltage applied to these bases is transmitted through the feedback branches R14, C12, and R15, C13. With these feedback branches, the circuitry functions as a multivibrator. The diodes D10 and D11 protect the base-emitter paths of the power transistors T10 and T11, from being subjected to voltages of excessive magnitudes. Since the construction and operation of multivibrator circuits are well known in the art, the details of this circuit are not further described here. The transistors T10 and T11 are alternatingly in the conducting and cut-off state. As a result, current flows alternatingly through each half winding of the tapped coil of the magnetic valve. With each switching of the multivibrator, the flux density changes in the magnetic circuit of the valve. The change of the flux density, in this manner, is with respect to its sign or polarity. If, now, such a control voltage is applied to the control transistor T12, so that the latter becomes conducting, a voltage drop appears across the resistor R16 to the extent that the power transistors T10 and T1 1 become turned off through the voltage divider consisting of resistors R12, R10 and R13, R11. The multivibrator commences thereby to cease operation by ceasing to oscillate. The oscillations of the multivibrator are thereby related with the rise of the control voltage U so that the ferromagnetic parts of the magnetic valve 10 become thereby de-magnetized.

These processes are illustrated graphically in FIGS. 3 and 4. FIG. 3 shows the voltage U as a function of time, whereas FIG. 4 shows the resulting magnetic flux density B as a function of time, when prevailing, for example, at the armature of the magnetic valve 10. The function of the flux density or magnetization of FIG. 4 is represented in ideal form. The selfinduction of the operating coil which has the effect of providing rounded comers on the curve, has been neglected. These simplified curves, however, are very close to the actual function, since the inductance of the operating coils is to be maintained substantially small.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in magnetic valve operating circuits, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential 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.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

1. An arrangement for reducing the response time of a magnetic valve comprising, in combination, an electromagnetic coil in said magnetic valve for operating said valve upon applying an actuating signal to said coil; a source of alternating voltage providing an alternating voltage of predetermined frequency; connecting means between said source of alternating voltage and said electromagnetic coil for applying said voltage to said coil before or after operation of said valve, so that said valve is de-magnetized through application of said alternating voltage to said coil, whereby residual magnetism in said electromagnetic coil is substantially removed through said demagnetization of said valve prior to a subsequent operation of said valve, said residual magnetism increasing the response time of said valve to said actuating signal, said source of alternating voltage comprising an oscillator; controlling means connected to said oscillator for turning said oscillator on and off, the output voltage of said oscillator being substantially rectangular-shaped, said oscillator comprising an astable multivibrator, said astable multivibrator comprising two power transistors and a control transistor connected across the base supply voltage for said power transistors; voltage dividing means connected to each base of said power transistors for providing a supply voltage thereto; and a source of operating voltage connected to said voltage dividing means.

2. An arrangement for reducing the response time of a magnetic valve comprising, in combination, an electromagnetic coil in said magnetic valve for operating said valve upon applying an actuating signal to said coil; a source of alternating voltage providing an alternating voltage of predetermined frequency; connecting means between said source of alternating voltage and said electromagnetic coil for applying said voltage to said coil before or after operation of said valve, so that said valve is de-magnetized through application of said alternating voltage to said coil, whereby residual magnetism in said electromagnetic coil is substantially removed through said demagnetization of said valve prior to a subsequent operation of said valve, said residual magnetism increasing the response time of said valve to said actuating signal, said source of alternating voltage comprising an oscillator; controlling means connected to said oscillator for turning said oscillator on and off, the output voltage of said oscillator being substantially rectangular-shaped, said oscillator comprising an astable multivibrator, said astable multivibrator comprising two power transistors and a control transistor connected across the base supply voltage for said power transistors; voltage dividing means connected to each base of said power transistors for providing base supply voltage thereto; a source of operating voltage connected to said voltage dividing means, said voltage dividing means comprising a first resistor connected to said source of operating voltage, a second resistor connected between said first resistor and the base of one of said power transistors, and a third resistor connected between said first resistor and the base of the other one of said power transistors, said first transistor having one terminal connected to a terminal of each of said second and third resistors.

3. An arrangement for reducing the response time of a magnetic valve comprising, in combination, an electromagnetic coil in said magnetic valve for operating said valve upon applying an actuating signal to said coil; a source of alternating voltage providing an alternating voltage of predetermined frequency; connecting means between said source of alternating voltage and said electromagnetic coil for applying said voltage to said coil before or after operation of said valve, so that said valve is de-magnetized through application of said alternating voltage to said coil, whereby residual magnetism in said electromagnetic coil is substantially removed through said demagnetization of said valve prior to a subsequent operation of said valve, said residual magnetism increasing the response time of said valve to said actuating signal, said source of alternating voltage comprising an oscillator; controlling means connected to said oscillator for turning said oscillator on and off, the output voltage of said oscillator being substantially rectangular-shaped, said oscillator comprising an astable multivibrator, said astable multivibrator comprising two power transistors and a control transistor connected across the base supply voltage for said power transistors; and a source of DC. operating voltage, said coil for operating said valve being a center tapped coil with center tap connected to said source of DC. operating voltage, each end terminal of said center tapped coil being connected to one collector of said power transistors.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3219095 *Jun 21, 1962Nov 23, 1965Hoganasmetoder AbPulsed oil feeding system for industrial furnaces
US3334316 *Aug 13, 1964Aug 1, 1967Minnesota Mining & MfgFeedback modulator oscillator
US3458769 *Aug 16, 1966Jul 29, 1969Lucifer SaElectrically controlled valve
FR1318728A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4453652 *Sep 16, 1981Jun 12, 1984Nordson CorporationControlled current solenoid driver circuit
US5190223 *Mar 20, 1991Mar 2, 1993Siemens Automotive L.P.Electromagnetic fuel injector with cartridge embodiment
US5402760 *May 20, 1993Apr 4, 1995Nippondenso Co., Ltd.Fuel injection control apparatus for internal combustion engine
EP0245540A2 *Dec 2, 1986Nov 19, 1987VDO Adolf Schindling AGMethod for actuating an injection valve
WO2013041283A1 *Aug 2, 2012Mar 28, 2013Zf Friedrichshafen AgMethod and drive apparatus for driving an electromagnetic actuator
Classifications
U.S. Classification251/129.15, 331/113.00R
International ClassificationF02M51/06, H01F7/18, F02M51/08, F02D41/20
Cooperative ClassificationF02M2051/08, F02D2041/2079, F02M51/061, F02M51/0671, F02D2041/2044, H01F7/1811, F02D2041/2072, F02D41/20
European ClassificationH01F7/18B1, F02M51/06B2E2, F02D41/20, F02M51/06B