US2598669A - Current responsive acceleration control for electric motors - Google Patents

Description

June 3, 1952 E. BATTILANA 2,598,659

CURRENT RESPONSIVE ACCELERATION CONTROL FOR ELECTRIC MOTORS Filed Feb. 16. 1949 Patented June 3, 1952 CURRENT RESPONSIVE ACCELERATION CONTROL FOR ELECTRIC MOTORS Emilio Battilana, Genoa-Cornigliano, Italy, as-

sign'or, by me'sne assignments, to Soc. Per Azio'ni Stabilimenti Elettromeccanic'i Riuniti Ansal'do San Giorgio, Genoa, Italy, a company of Italy Application February 16, 1949, Serial No. 76,674 In Italy February 23, 1948 4 Claims. I

In an electric traction equipment, the manner of producing the sequence of remote control switchings', called telerupters, for cutting out resistances is well known, as efiected by means of an auxiliary motor which drives a cylinder con trolling in turn the remote switches and of a relay, called acceleration relay, which for a given value of current is set into a certain operative position and, responsive to the opening of electric circuits, stops the auxiliary motor and consequently the sequence of remote control switching.

During the starting period of the motor, the current therethrough is reduced and thereby the acceleration relay is caused to take another oper ative position which, as a result of electric circuit connections, sets the auxiliary motor in motion again, thereby closing the sequence of the remote control switching for starting again.

Sometimes it is desirable to assign several calibrations to the acceleration relay and therefore it happens that during the starting operation, in passing from one calibration value to another, there is no gradual passage between the two or more values of the acceleration relatingto the two or more values of calibration current.-

Accordingly, it is an object of the present invention to eliminate this drawback and to enable the accomplishment of a starting which graduates the increase in acceleration between certain limits.

A further and more particular object is to enablea starting havinga constant variation of acceleration as a function of time. 7 v v In the sheet of drawings having a single figure hereto annexed there is illustrated, only by way of example, an embodiment of a device according to the present invention. I

The device heredisclosed in effect very advantageously substitutes for the said auxiliary motor, the control cylinder and the acceleration relay andthe several calibrations as known.

Referring to the drawing, which is a circuit diagram, there is shown an acceleration relay having two connected magnetic circuits constituted by cores HI, H2 and I I3} the yoke H4 and armature I I5 slightly biased by spring I' I6 in the position shown in the figure. Said armature oscillating on core H2 operates the closing and opening of contacts H1 and H8 alternatively. On the: cores III and H3, there are two copper tubes, H9 and I20, constituting two short-circuit windings which serve to delay the release of armature H5 by a predetermined and constant time value. The voltage coil I 2| acts to generate a magnetic flux in the circuit composed by' cores II I and H2 closed by yoke H4 and the armature I I5. Coil I22 acts similarly respecting the circuit composed by cores H2, H3, yoke H4 and armature H5.

Coil I23 through which the traction current passes, has the function of generating a magnetic flux in both circuits, one circuit including ele ments HI, H5, H2 and H4, and the other including elements H2, H5, H3 and HA. In these magnetic circuits there will circulate two fluxes of widely different values, owing to the differences in the values of their respective reluctances. If the armature be considered in the position shown in the figure and the 0011 I2! be fed, if now this feeding be interrupted and the voltage coil I22 be fed, core I I3 may attract armature I Ilionly after the retardation time caused by tube H9 has elapsed, if the current value in current coil I23 will have such a value as to allow it, because the flux generated by this coil will prevailingly cir culate in the circuit consisting of elements H2, H5, III and H4 which will be opposed to the armature motion. The result is that the armatur'e oscillations are under the control of the traction current and, therefore, of the car load. The stabilization of the current increase is of importance in the operation of the subdivisions of the starting resistance I24.

The reaction moment caused by spring I I6 has a negligible value, especially because there isa change of sign when core I I I attracts the arma ture, which gives rise to a slight inequality of time in the oscillation of the armature.

Consider now the description of the starting of a trackless trolley car, the equipment of which is constituted by a continuous current traction m'otor I26 with series excitation I25, a starting resistance- I24, control apparatus III-J23, a remote'control line switch I, to which corresponds contacts II, I2 and I3, a set of remote control sequence switches 29 wherein for switch 2 there corresponds contacts 2I2B, for switch 3 there corresponds contacts 3'I-'36, and so on. Said set of remote control switches is divided into two groups which are operated by cross-coupled contacts in connection with feeding and locking of coils I2I and I22 alternatively. The main operating organ is the pedal which as shown in the diagram is represented by contacts ll" to IX. Said pedal has the following positions:

State of rest, by whichall circuits are open;

First position, by which the motor runs on resistance I24;

II to IX positions, by which the exclusion of the starting resistance takes place.

Starting the car In the first position of the pedal, it closes contact I thereby feeding the remote control switch I of the line; the latter closes contacts II and I2 putting motor I25 in circuit with the network, and closes contact I3 preconditioning the feeding of remote control switch 2. Motor I26 starts through the whole series resistance I24.

Suppose now the case in which the pedal is put directly into the IX position and contacts 0 and II to IX are closed; contacts II to IX precondition the circuit for the feeding of remote control switches 25.

By closing contacts with O, coil I22 is fed and core H3 will be able to attract armature H only when the traction current in coil I23 is equal to, or smaller than, the calibration value.

When core H3 is able to attract armature H5, contact I I8 will close and feed remote switch 2; the latter operating closes contact 2I excluding a portion of the starting resistance I24, it opens contact 24 and closes contact 25 feeding itself therethrough, it closes contact 26 reconditioning the circuit to feed remote switch 3, it

opens contact 22 interrupting the feeding to coil I22, it closes contact 23 thereby feeding coil I2I. If, by the exclusion of the portion of the starting resistance I24, a rush of current is produced in the traction circuit and, therefore, in coil I23, which is of a higher value than that of the calibration of the device, it will have the result of holding armature H5 in contact with the core H3; when said rush of current shall have fallen to the calibration value, armature I I5 will be released by core H3 and attracted by core III; this, however, will happen if the rush of current shall have the same or a longer duration than the retardation produced by popper tube I; otherwise, this time will prevail over the first mentioned time; to insure that the traction current be established sooner than the current in coils I2I and I22, a suitable arrangement of contacts of the remote switches is provided. When armature H5 has been released by core H3 and attracted by core III, contact H8 will open and nothing will happen, because switch 2 has been locked up through contact contact II! will close and feed remote control switch 3; this switch 3 will close some of its contacts and open others in accordance with the analogous function of these contacts in case of remote control switch 2. This will be repeated for remote switches 49, while armature H5 will continue to oscillate with a minimum time period equal either to the retardation caused by the copper tube H9 and I25, or to the duration of the rushes of traction current produced by the exclusion of the portions of starting resistance I24.

By the feeding of remote control switch 9, the exclusion of starting resistance I24 is brought to an end and contact 92 is open; the armature oscillations are definitely stopped, for contact 82 has been already opened by remote control switch 8 and the starting operation may be considered ended.

If the pedal had not been pushed all the way down, but, for instance, only so far as to close contact IV, the exclusion of resistance I24 would have stopped with the closing of remote switch 4, because remote control switches 5-9 are operated by contacts V to IX which are still open. The armature has stopped at the position illustrated in the figure, because remote switch 4 has opened contact 42 and closed contact 43; in

due course, 4H will have attracted armature H5 and, consequently, contact H! has been closed; but the latter cannot feed remote switch 5 because contact V is open. By pushing the pedal still farther, the already described sequence will be resumed, with the possibility of stopping at any predetermined position.

stoppage of car By bringing the pedal from position IX to that of rest, contacts IX to I in decreasing order are opened, while contact 0 opens together with contact 2, so that the restoration of remote switches 9 to I takes place by steps, thereby putting the starting resistance I24 into circuit as far as the opening of remote line switch I which breaks the feeding of traction motor I26. During the restoration of remote switches 9-I, armature H5 oscillates while following them, although it is not connected, and it could even lose some cycles. If when letting the pedal come back it is stopped in an intermediate position, motor I25 will go on running with the corresponding portion of resistance left in circuit; furthermore, it will be readily understood that armature H5 has been placed in such a position that the renewal of a starting operation is possible by pushing the pedal instead of drawing it back.

Braking of the car The control device for braking operates in a similar manner to that of the starting; for the sake of simplicity the arrangement as disclosed has not been provided with the apparatus comprising the braking circuit.

Although for descriptive reasons, the present invention is based on what has been shown and described by way of example, it is obvious that many modifications and additions may be included in the embodiment of the invention, all of them nevertheless being based on the fundamental principles of the invention, as defined in the appended claims.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is too be performed, I declare that what I claim is:

1. In an oscillatory device for controlling the starting of electric motors, the combination of a control circuit having two series of control devices inserted therein, each said control device having two contact elements, a bar of magnetic material mounted for oscillatory movement about a pivot, a contact carried by each end of the bar, respective cooperative contact plates each having circuit connections to one of the contact elements of one series of control devices for said starting, a magnetic bridge the two ends of which are located in operative relation to the respective ends of said bar, like voltage coils carried on each of said bridge ends respectively, one end of the two coils being connected to one pole of the feeding line of the motor and of the control circuit, the other ends of said coils being connected to other contact elements of said control devices and thereby to the other pole of said feeding line.

2. A device according to claim 1, wherein the said magnetic bridge is E-shaped and includes a central core, the upper end of which is magnetically connected to the said magnetic bar at said pivot, said central part having a current coil in series with the motor circuit.

3. A device according to claim 2, wherein the respective extreme ends of said magnetic bridge have short-circuiting sleeves and the said cur- UNITED STATES PATENTS rent coils are so energized that each causes the Number Name Date flux in the same direction in the central core. 1,037,433 Carichofi Sept 3, 1912 4. A device according to claim 1, including 2L 1 0 9 2 Carichofi Nlar. 10 191 tensile spring connected at one of its ends to a 5 2,073,382 Tmfimov Man 9, 1937 fixed point and at its other end to the oscillatory 2,455,060 Holmes Nov. 30, 1948 magnetic bar at a point distant from said pivot.

EMILIO BATTILANA.

REFERENCES CITED 10

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