US3514674A

US3514674A - Device for electromagnetically controlling the position off an armature

Info

Publication number: US3514674A
Application number: US637155A
Authority: US
Inventors: Toshio Ito; Toshimoto Okura; Toshiji Takami
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1966-05-18
Filing date: 1967-05-09
Publication date: 1970-05-26
Anticipated expiration: 1987-05-26
Also published as: DE1614159A1; JPS4413461B1; GB1182313A; DE6609827U

Description

May 26, 1970 TOSHIO n- ETAL 3,514,674

DEVICE FOR ELECTROMAGNE ALLY CONTROLLING THE POSITION OF AN ARMATURE Filed May 9 1967 s Sheets- Sheet 1 May 26, 1970 TOSHIO ITO ET AL 3,514,674

DEVICE FOR ELECTROMAGNETICALLY CONTROLLING THE POSITION OF AN ARMATURE Filed May 9, 1967 3 Sheets-Sheet 2 Fig.2

May 26, 1970 TOSHIO ITO ET AL 3,514,674

DEVICE FOR ELECTROMAGNETICALLY CONTROLLING THE POSITION OF AN ARMATUR'E Filed May 9, 1967 5 Sheets-Sheet S Fig.

MAGNETIC FIUX DENSITY Br I I l l l I l I I I l I I I i ""I |H I I HI MAGNETIC FIEID I I I I I l I I l l I I I I l I I I l I I I l I I I I I --Br .-=i.

3,514,674 DEVICE FOR ELECTROMAGNETICALLY CONTROLLING THE POSITION OFF AN ARMATURE Toshio Ito, Toshimoto Okura, and Toshiji Takami, Amagasaki, Japan, assignors to Mitsubishi Denkr Kabushiki Kaisha, Tokyo, Japan Filed May 9, 1967, Ser. No. 637,155 Claims priority, application Japan, May 18, 1966, ll/31,707 Int. Cl. H01h 47/00 US. Cl. 317155.5 Claims ABSTRACT OF THE DISCLOSURE The disclosed operating device for moving, for example, a movable contact of a current interrupter from its closed position to its open position and vice versa comprises a pair of stationary magnetic cores of permanent magnet material disposed in spaced relation to opposed internal Walls of a magnetic housing and a movable armature movably disposed between the stationary cores to move the movable contact. Each stationary core is surrounded by an exciting coil having a parallel combination of currentlimiting resistor and a semi-conductor diode. In the closing operation a closing switch is closed to discharge a charge with one polarity on one of two capacitors into both coils through the respective resistor and diode combinations. The particular stationary core by which the armature is to be attracted is completely magnetized because of conduction of the associated diode while the other core magnetized oppositely. to the particular core is substantially completely demagnetized by means of the action of the associated limiting resistor with the result that the armature is moved to contact the movable contact with the associated stationary contact. Therefore, the armature and hence the movable contact is maintained at its moved position even after deenergization of the coils. In the interrupting operation, a process reversed from that above described is effected.

This invention relates in general to an operating device and more particularly to such a device utilizing an electromagnet to move an element to be operated from one to the other of a pair of its positions and vice versa and to maintain the element at its moved position until it is desired to return back to its original position.

The conventional type of operating devices referred to is very disadvantageous in View of the economical standpoint in that means should be provided for maintaining elements to be operated in their operated state. For example, such an operating device associated with a current interrupter and employing an electromagnet has been commonly required to include a mechanical mechanism for anchoring the interrupter to its operated position, in addition to the electromagnet. In the conventional, relatively small-sized switches and the like, such a mechanically anchoring mechanism has not been used but the operating coil involved has been forced to have a current continuously flowing therethrough.

It is, accordingly, a general object of the invention to provide a new and improved operating device for moving an element to be operated from one to the other of its two positions and vice versa, simple in construction, compact, light in weight and inexpensive in which a movable part reduces in weight as well as the operative speed characteristics are greatly improved.

Briefly, the invention accomplishes the above cited objects by the provision of an operating device for moving an element to be operated from one to the other of a pair of its position and vice versa, comprising at least one United States Patent 0 operating electromagnet controlled by an exciting coil to move the element, characterized by a stationary magnetic core member of permanent magnet material disposed in a magnetic circuit around the electromagnet, and means for controlling energization of the exciting coil to alternately magnetize and demagnetize the magnetic core member thereby to move the element and to maintain it at its moved position after deenergization of the exciting coil.

A current limiter may advantageously be connected in series to the exciting coil to decrease a flow of current through the exciting coil upon demagnetizing the operating electromagnet as compared with that upon magnetizing the latter thereby to perform the magnetizing and demagnetizing operations by the common exciting coil.

In a preferred embodiment of the invention the operating device may comprise a housing made of a magnetic material, a pair of stationary magnetic core members of permanent magnet material rigidly secured in spaced relationship on the opposed internal wall surfaces of said housing, a movable armature member of magnetic material movably disposed between said pair of stationary magnetic core member and including a control rod controlling the position of said element to be operated, one exciting coil surrounding each of said stationary magnetic core members, a current limiter means connected in series circuit relationship to each of said exciting coils, and means for simultaneously energizing both of said exciting coils through said current limiters, said current limiter means being operative not to limit a flow of a current zfiowing through one exciting coil associated 'with the particular stationary magnetic core member by which said movable armature member is now to be attracted thereby to permit that stationary core member to be magnetized but to limit a current flowing through the other exciting coil to such a magnitude that the remaining stationary magnetic core member is substantially demagnetized.

The invention as its organization and its mode of operation as well as other objects and advantages thereof will become readily apparent from the following detailed description when read in conjunction with the accompanying drawing in which:

FIG. 1 is a side elevational view, in cross section of an operating device constructed in accordance with one embodiment of the invention;

FIG. 2 is a schematic diagram of a circuit which may be used with the operating device illustrated in FIG. 1, and

FIG. 3 is a graph useful in explaining the principles of the invention.

While the invention will now be described in terms of a current interrupter it is to be understood that it is equally applicable to any other apparatus including an element to be driven from one to the other of its two positions and vice versa and to be maintained at its driven position for any desired interval of time.

Referring now to the drawing and FIG. 1 in particular, there is illustrated an operating device constructed in accordance with the teachings of the invention. An arrangement illustrated comprises a housing 10 of any suitable magnetic material, an apertured stationary magnetic core member, or attracting and holding element, 12 made of any suitable permanent magnet material and rigidly secured to one internal wall surface, in this case, an upper internal wall surface as viewed in FIG. 1 of the housing 10, a stationary magnetic core member, or attracting and holding element, 14 of the same material as the core member 12 and rigidly secured to the opposed or lower internal wall surface of the housing 10, and a movable armature member 16 of any suitable magnetic material movably disposed between the upper and lower

stationary core members

12 and 14. The movable armature member 16 is provided on that side facing the upper core member 12 with a central control rod 18 loosely extending through aligned apertures formed in both the upper core member 12 and the upper wall of the housing and having mounted at the extremity an element to be operated, in the illustrated example, a movable contact member 20 of the associated current interrupter (not shown). The movable contact member 20 is adapted to engage and disengage from a stationary contact member 22 opposing to the same. The upper core member 12 may be called a closing stationary core member and the lower core member 14 may be called an interrupting stationary core member for the reasons as will be apparent hereinafter.

Disposed within the housing 10 are an exciting coil 24 surrounding the upper or closing stationary core member 12 and another exciting coil 26 surrounding the lower or interrupting stationary core member 14 as shown in FIG. 1. Further a flange-shaped protrusion 28 made of the same magnetic material as the housing 10' extends from the lateral internal wall surface of the housing toward the movable armature member 16.

With the arrangement illustrated it will be appreciated that the upper stationary core member 12, the top housing wall, the upper half of the lateral housing wall, the protrusion 28 and the movable armature member 16 form a magnetic circuit through which a magnetic flux due to the upper coil 24 flows with a permanent magnet composed of the core member 12 disposed in the magnetic circuit. Similarly the lower stationary core member 14, the bottom housing wall, the lower half of the lateral housing wall, the protrusion 28 and the movable armature member 16 form another magnetic circuit including a permanent magnet.

Referring now to FIG. 3 solid curve designates an initial magnetization curve along which the material of the upper stationary magnetic core 12 may be first progressively magnetized in one direction, for example, in a positive direction and then gradually demagnetized until it is substantially completely demagnetized and dotted curve designates a similar curve for the material of the lower stationary magnetic core member 14 in the case the core is first magnetized in a negative direction.

In general, if a magnetic field applied to a permanent magnet material varies in both magnitude and direction the residual magnetic flux density thereof may have any desired magnitude. For example, if a magnetic field having a strength of H is applied to the closing stationary magnetic core member 12 through suitable energization of the closing coil 24 then the core member will have a residual flux density of B while a magnetic field having a strength of '-H will result in the core member 12 being substantially completely demagnetized or having the null residual flux density. Therefore alternate switching of the stationary magnetic core member 12 between its magnetized and non-magnetized or demagnetized states permits the movable armature member 16 to be alternately attracted to and released from the stationary core member 12. This is true in the case of the interrupting stationary magnetic core member 14. It is, however, to be noted that the interrupting core member 14 should be put in its magnetized state quite reversed from the closing core member 12.

More specifically, upon closing the associated current interrupter (not shown), the closing coil 24 is energized such that it establishes in the material of the closing stationary magnetic core member 12 a magnetic field (H having such magnitude and direction that the core member 12 has a residual magnetic flux density of B while at the same time the interrupting coil 26 is energized such that it establishes in the material of the interrupting stationary magnetic core member 14 a magneitc field (H having such magnitude and direction that the core mem- 4 her 14 has the null residual flux density (see FIG. 3). Under these conditions, the movable armature member 16 is released from the interrupting core member 14 to be permitted to be attracted by the closing core 12 thereby to close the associated interrupter through contacting of the movable contact 20 directly connected to the control core rod 18 with the stationary contact 22. After the deenergization of both the

coils

24 and 26 the movable armature member 16 is maintained in contact with the closing core member 12 to hold the interrupter close until the subsequent interrupting operation is performed.

If the closed interrupter is to be open, an operation reversed from the closing operation just described is performed. More specifically, the interrupting coil 26 is energized such that it establishes in the material of the core member 14 a magnetic field (=-H having such magnitude and direction that the core member 12 has a residual flux density of B while at the same time the closing coil 24 is energized such that it establishes in the material of the closing core member 12 a magnetic field (-H having such magnitude and direction that the core member 12 has a null residual flux density (see FIG. 3). This permits the movable armature 16 to be released from the upper core 12 and to contact the lower core 14 thereby to open the interrupter. Then the armature holds the interrupter in its open position after deenergization of the

coils

24 and 26.

In order to repeat the closing and interrupting operations as above described, the closing and interrupting

coils

24 and 26 can be alternately driven into their predetermined energized states under which each coil alternately establishes in the material of the associated stationary magnetic core a magnetic field having respectively such magnitudes and directions that the core is magnetized and demagnetized respectively. Then with the coils driven in such energized states, the closing and interrupting operations are alternately performed and the associated current interrupter is alternately held in its closed and open positions after deenergization of the coils. The operating device illustrated in FIG. 1 can be effectively operated as above described by means of an electric circuit shown in FIG. 2.

As shown in FIG. 2, the closing coil 24 has one end connected to one terminal of any suitable source 30 of alternating current and the other end connected to the other terminal of the source through a current limiter network generally designated by the reference numeral 32, a series combination of normally open resettable switch 34 for use in the closing operation, a charging semiconductor diode 36 and a limiting resistor 38. The serially connected switch and

diode

34 and 36 are electrically connected in parallel to a similar serial combination comprising a normally open, resettable switch 35 for use in the interrupting operation and a semiconductor diode 37 with both diodes poled reversely from each other. The current limited network 32 is shown as comprising a current limiting resistor R and a unidirectional conduction element or a semiconductor diode D connected in parallel to each other.

Similarly the interrupting coil 26 has one end connected to the one terminal of the source 30 through a current limiter network 33 of the same construction as the network 32 and the other terminal connected to the other terminal of the source 30 through the abovementioned parallel combination of serially connected switches and diodes, and the resistor 38. Since the

limiter network

32 and 33 are of the same construction the components of the network 33 are designated the same reference characters sufiixed with the numeral 2 rather than 1.

A capacitor 40 is connected between a junction of the switch and

diode

34 and 36 and the source 30 while another capacitor 41 is connected between a junction of the switch and

diode

35 and 37 and the source 30. It is noted that the capacitors 40- and 41 are charged with opposite polarities from the source 30 respectively, as shown in FIG. 2.

The closing operation will first be described in conjunction with FIGS. 1 to 3 inclusive. Before the closing operation, the closing stationary magnetic core member 12 has been substantially completely demagnetized while at the same time the interrupting stationary core member 14 has been in its magnetized state in which it has a residual magnetic flux density of B (see FIG. 3) as will be readily understood from the foregoing description. Also the capacitor 40 has been charged with one polarity while the capacitor 41 has been charged with opposite polarity from the source 30.

Under these circumstances, the switch 34 for use in the closing operation can be enclosed to permit the charge on the capacitor 40 to discharge. The discharge current from the capacitor 40 flows into both the closing and interrupting

coils

24 and 26. However, since the upper capacitor side is positive with respect to the lower side, this discharge current flows forwardly with respect to the diode D of the current limiter network 32 of the coil 24 to cause it to short circuit the resistor R whereas the current flows reversely with respect to the diode D of the current limiter network 33 for the coil 26 to render it non-conducting whereby the resistor R of the network 33 remains serially connected to the coil 26. Therefore, the closing coil 24 has flowing therethrough a current suflicient to produce in the material of the closing core member 12 a magnetic field having a magnitude of H for magnetizing the latter to saturation, but the interrupting coil 26 has flowing therethrough a current reduced in magnitude by the resistor R so as toestablish a magnetic field having a magnitude of H in the material of the interrupting core member 14. In this connection it is to be noted that the resistor R should have a magnitude of resistance capable of establishing in the magnetic core material 14 a magnetic field having a magnitude of H in which the residual magnetic flux density of the core 14 just decreases from -B to Zero.

As a result, the closing core member 12 has a residual flux density of B while at the same time the interrupting core member 14 completely demagnetized to have substantially a null residual flux density. This causes the movable armature member 16 to be released from the interrupitng core member 14 to be attracted by the closing core member 12 whereupon the movable contact 20 contacts the stationary contact 22 to close the current interrupter. As previously described, the interrupter is held in its closed position after deenergization of the

coils

24 and 26, through opening of the switch 34.

Upon performing. the interrupting operation, the switch 35 for use in that operation is closed to permit the capacitor 41 to discharge. As in the closing operation a discharge current from the capacitor 41 will flow through both the closing and interrupting

coils

24 and 26. In this case, however, as the capacitor 41 has its polarity opposite to that of the capacitor 40 the discharge current flows forwardly with respect to the diode D of the current limiter network 33 for the interrupting coil 26 to conduct it to short circuit the associated resistor R while the current flows reversely with respect to the diode D to render it non-conducting whereby the associated resistor R remains serially connected to the closing coil 24. Therefore the interrupting coil 26 has flowing therethrough a current suflicient to produce in the material of the interrupting core member 14 a magnetic field having a magnitude of H for magnetizing the latter to saturation, but the closing coil 24 has flowing therethrough a current reduced by the resistor R to such a magnitude that a magnetic field having a magnitude of -H is produced in the material of the closing core member 12. As the resistor R the resistor R has a magnitude of resistance preselected to impart to the magnetic core material 12 a magnetic field having a magnitude of H in which the residual magnetic flux density of the core 12 just decreased from B to zero.

As a result, the interrupting core member 14 has a residual flux density of -B,. while at the same time the closing core member 12 is demagnetized to have substantially a null residual flux density. This permits the movable armature member 16 to be separated from the closing core 12 to contact the interrupting core 14 thereby to disengage the movable contact 20 from the stationary contact 22 resulting in an interruption of the interrupter. As previously described, the interrupter is held in its open position after opening of the switch 35 and until the subsequent closing operation is performed.

From the foregoing, it will be appreciated that by alternately discharging the charges of alternate polarity on the

capacitors

40 and 41 intothe closing and interrupting coils '24 and 26, each of the closing and interrupting

stationary core members

12 and 14 can be repeatedly magnetized and demagnetized. The magnetization and demagnetization of both cores causes the movable armature 16 to move in either of the directions thereby to perform the closing or interrupting operation of the associated current interrupter as well as maintaining the latter in its closed or open position until the subsequent interrupting or closing operation is performed.

If a movable armature attracted by the associated stationarymagnetic core is to be separated from the latter, it has been previously required to provide a pulling-apart or an interrupting coil, in addition to a closing coil. The invention, however, comprises means for exerting on such a movable armature an opposing force in a direction opposite to the direction of attraction. In addition, upon pulling apart the armature from the closing stationary core, a current flows through the closing coil in a direction reverse from in the closing operation. This flow of current through the coil in the reversed direction causes the residual magnetism in the stationary core to be balanced out by a magnetic flux due to the same, whereby the armature can be automatically separated from the stationary core by the action of the opposing force as above described. As already mentioned, the current limiter network associated with the closing stationary core by which the armature was previously attracted is effective for limiting an interrupting current flowing through the closing coil to such a magnitude that a magnetic flux in that stationary core has an appropriately small value approximating zero without the core magnetized in the opposite direction. This is true in the case of the interrupting stationary core in the closing operation.

In FIG. 2, it is noted that a normally open contacts S or S -are shown as being connected across the unidirectional conduction element or diode D or D by dot-anddash line respectively. This means that the contacts S or S may be used in place of the diode D or D With the contacts S and S used, they should be arranged such that upon closing the switch 40, the contacts S are closed while the contacts S remain open whereas, upon closing the switch 41, the contacts S are closed while the contacts S remain open.

While the invention has been illustrated and described with reference to certain preferred embodiments thereof it is to be understood that various changes in the detail of constructions and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention. For example, either the closing core and

coil assembly

12, 24 or the interrupting core and

coil assembly

14, 26 may be replaced by springloaded operating means to perform the associated operation. Also the present device may be equally applied to any element subject to first drive to perform a first operation and to subject to second drive to perform a second operation.

What we claim is:

1. A device for electromagnetically controlling the position of an armature comprising: a first magnetic circuit including a first ferromagnetic attracting and holding element, and a first exciting coil magnetically coupled to said first ferromagnetic attracting and holding element; a second magnetic circuit including a second ferromagnetic attracting and holding element, and a second exciting coil magnetically coupled to said second ferromagnetic attracting and holding element; a moveable armature disposed between said first and second ferromagnetic attracting and holding elements movable to a first position in response to encrgization of said first magnetic circuit and to a second position in response to energization of said second magnetic circuit; and electric circuit means connected to said first and second coils for alternatively sup-. plying current to one of said exciting coils to render its corresponding ferromagnetic attracting and holding element effective to move said armature to one of said first and second positions and hold it therein while simultaneously supplying a lesser amount of current to the other of said exciting coils to remove any residual magnetism remaining in the other of said ferromagnetic attracting and holding elements when said electric circuit means is connected to a source of potential.

2. A device according to claim 1; wherein said first and second ferromagnetic attracting and holding elements comprise first and second magnetic core elements, respectively.

3. A device according to claim 1; wherein said electric circuit means includes first and second current limiting circuits each connected in series with said first and second exciting coils, respectively; said first and second current limiting circuits each comprising a current limiting impedance element connected in parallel with a diode.

4. A device according to claim 1; wherein said electric circuit means includes first and second current limiting circuits each connected in series with one of said first and second exciting coils, respectively; said first and second current limiting circuits each comprising a current limiting impedance element connected in parallel with a switch.

5. A device according to claim 1; wherein said first and second exciting coils are connected in parallel; and wherein said electric circuit means includes first and second normally open switches, a first capacitor responsive to the closing of said first normally open switch to supply a first discharge current to both said exciting coils, a second capacitor responsive to the closing of said second normally open switch to supply a second discharge current to both said exciting coils in a direction opposite to that of said first discharge current, and current limiting means for successively limiting the flow of current through alternate exciting coils in accordance with the alternate closing and opening of said first and second normally open switches. i

References Cited UNITED STATES PATENTS 2,317,888 4/ 1943 Cypser 317123 2,954,512 9/ 1960 Hardison 317-151 3,445,729 5/1969 McNulty 317-123 3,202,886 8/ 1965 Kramer 335-234 FOREIGN PATENTS 643,832 6/1962 Canada.

I. D. MILLER, Primary Examiner C. YATES, Assistant Examiner U.S. Cl. X.R. 335-234