US2487313A

US2487313A - Electric controlling apparatus

Info

Publication number: US2487313A
Application number: US652521A
Authority: US
Inventors: Arthur M Cohen
Original assignee: Ward Leonard Electric Co
Current assignee: Ward Leonard Electric Co
Priority date: 1946-03-07
Filing date: 1946-03-07
Publication date: 1949-11-08
Anticipated expiration: 1966-11-08

Description

Nov. 8, 1949 A. M. COHEN 2,487,313

ELECTRIC CONTROLLING APPARATUS Filed March 7, 1946 2 SheetsSheet l @5 77 //l l// //l IN VEN TOR.

Nov. 8, 1949 A. M. COHEN ELECTRIC CONTROLLING APPARATUS 2 Sheets-Sheet 2 Filed March '7, 1946 INVEN TOR. 4/777/d/7/Z 6 06 5 ia A Patented Nov. 8, 1949 ELECTRIC CONTROLLING APPARATUS Arthur M. Cohen, New Rochelle, N. Y., asslgnor to Ward Leonard Electric Company, a corporation of New York Application March 7, 1946, Serial No. 652,521

14 Claims. 1

This invention relates to improved electromagnetic controllers and to regulators for maintaining constant the voltage, or other variable factor, of a dynamo-electric machine.

One object is to provide a compact form of controller which will occupy small space and which is particularly adapted for controlling small units, although it may be utilized for controlling units of large capacity. Another object is to produce a controller of high sensitivity and which-is capable of securing close regulation. Another object is to avoid the objections of a vibrating type of contrailer and to provide regulation by a series of steps which will insure long life and require little or no attention and avoid objectionable sparking and deterioration of the control contacts. Another object is to provide an improved form of structure and relationship of the various parts for securing the above mentioned results, various features of which may be utilized for control purposes other than the particular example herein disclosed. A further object is to provide means for compensating for temperature changes and thereby insure maintenance of the control within close fixed limits regardless of temperature changes. A further object is to mount the variable resistance device and resistive elements in close relation to the controlling magnet with common supporting parts to form a complete unitary structure. Other objects and advantages will be understood from the following description and accompanying drawings which illustrate a preferred embodiment of the invention.

Fig. 1 is a front elevation, the enclosing box being removed except the lower portion of the box; Fig. 2 is an end view looking from the right of Fig. l and showing portions of the enclosin box; Fig. 3 is a horizontal section on the line 3-3 of Fig. 1; Fig. 4 is an end view looking from the left of Fig. l, the prong base not being shown; Fig. 5 is a face view of the fingers which variably engage the contacts to which the resistive elements are connected; Fig. 6 is a face view of the pivot spring, plunger guide and finger controlling bar looking from the left of Fig. 1; Fig. '7 is a top side view thereof; Fig. 8 is an end view thereof; and Fig. 9 is a diagram of electrical connections.

Referring to Fig. 1, the axis of the magnet coil to is horizontal. The magnet frame is formed of two L-shaped sheet iron strips fitted together at I their meeting edges. One strip ll embraces the top and left-hand end of the coil and the other strip Ila embraces the bottom and right-hand end of the coil. A base [2 of insulating material having connecting prongs l2a is located below the magnet and is secured to the bottom l3 of a sheet metal enclosing box preferably made of hard aluminum. The prong base is of the usual radio connecting type. A screw l3a at each side passes upwardly through the prong base and bottom cover and has a threaded engagement with the bottom of the magnet frame for holding the parts together.

Referring to Fig. 3, a hollow cylindrical plug it of iron is welded at its outer end to the frame portion Ila and extends partially within the coil [0. In addition to forming a path for the magnetic fiux, it serves as a stop for the magnetic plunger It in its movement to its unattracted position. A washer l6 of magnetic material is welded to the outer side of the frame II and serves as a stop for the plunger in the fully attracted position. The plunger is yieldably supported and aligned centrally within the coil by means comprising two metal plates I1 and Na of hard aluminum or other non-magnetic material. This supporting means will be later described. A spacing tube [8 of brass extends from the inner end of the plunger to the plate Ila. A spring 1 cup l9 preferably of aluminum, engages at its central projecting portion, the plate l'la. A tube or eyelet 20 of brass extends through the plunger and spacer l8 and through the guidingsupports l1 and Ila. The left-hand end of the eyelet is turned over the outer surface of the plate IT. The right-hand end of the eyelet extends through and is turned over the spring cup ill. The eyelet thus holds these parts firmly together as a movable assembly.

A coiled compression spring 2! seats against the spring cup 19 at its inner end and against a metal ring 22 at its outer end. The spring biases the plunger towards its unattracted position. The ring 22 is provided with three outwardly extending projections 22a, as shown in Fig. 2, which extend through inclined slots 23a, shown in Fig. 1, of a fixed metal end cup 23. Thus by turning the ring 22, the spring 2| will be more or less compressed for adjusting the voltage, or other factor,

- which the regulator is to maintain substantially constant. The upper projection 22a is extended and bent to engage a slot 23b in the end cup for convenient adjustment. The upper edge of this slot is notched and engaged by an upset projection on the extension 22a for holding the ring fixed in any adjusted position.

Mechanical damping means for the plunger are provided by a combined spring and dashpot relationship. The dashpot cylinder 24 is shown in Fig. 3 and is fixed in position by being riveted at its center to the end cup 23. The piston which may be of carbon material, is provided with a central eyelet to which is soldered one end of a spring rod 26 preferably of phosphor bronze. This rod extends through the long eyelet 20 and is soldered at its left-hand end to the end of this eyelet. The portion of the rod in the space adjoining the plunger is S-shaped. This combined clamping means has a double acting effect. Upon any change in the exciting current of the magnet, the resilient rod 26 permits the plunger to move quickly to its new position'giving-a rapid corrective response to the controlling means and then the piston is moved less rapidly in following up the movement of the plunger. It thus steadies the movement of the plunger in attaining any adjusted position while permitting high sensitiveness of response.

All the parts are held together by four through studs or posts 21, one at each corner. They pass through outwardly extending portions of the end cup 23 as shown in Fig. 2, through spacing sleeves 21a and through four corners of the magnet frame and coil spacing sleeves 21b. These pins or studs also pass through other parts, later explained, and all the parts are thus held in fixed proper relation by the spacing sleeves and stud nuts and washers.

The yieldable aligning support of the left-hand end of the plunger assembly is shown in Figs. 6, 7 and 8. The previously referred to supporting plate I1 is shown as-having a hole ill) for receivin the end of the eyelet 20. The right-hand end of the plate is secured by a pair of rivets to the outer side of a hollow rectangular shaped thin phosphor bronze spring 28, the plate I'I extending within the hollow central space of the spring. The rear end of the spring, or left-hand portion looking at Fig. 6 is secured by a pair of rivets to a metal strip or bracket 29. This bracket is provided at its ends with holes for the passage of the two rear holding studs 21 for supporting the bracket fixed in place by clamping nuts and intervening lock washers. The aligning plate Ila of the plunger assembly at the right-hand end is similarly supported by a hollow rectangular leaf spring 28 and bracket 29 but its bracket is supported on the two front studs, as well shown in Fig. 1, being reversely supported with reference to the left-hand one. Thus .upon any movement of the plunger assembly, the

aligning support of the two end portions will maintain and guide the assembly in axial align ment while the springs permit yieldable movement upon slight change of the exciting current.

Again referring to Figs. 6, 7 and 8, the left-hand yieldable guide accomplishes a further function of adjusting the step-by-step control of the variable resistance device. For this purpose there is secured to the movable end portion of the spring 28, a finger controllin bar 30. This is formed of a thin sheet of metal bent to the form shown. A reduced central end portion 30a is bent to extend under the end portion of the spring and is secured thereto by the pair of rivets which also hold the plate 11, there being mica sheets or washers 3| introduced on opposite sides of the portion 30a for insulating the bar. The bar is bent at right-angles to the rear portion 30a and extends a short distance outwardly and then is bent inwardly to form the portion 301). As shown in Fig. 8 the part 3% is bent further along its length to form two parts which diverge from the middle, forming a wide obtuse angle between them. The purpose of this will be explained later.

Referrin to Fig. 4, a rectangular plaque, or

plate, 32 of a thin sheet of mica is supported at its four corners by the studs 21 and fixed in position by spacing nuts and washers. At the righthand portion of the plaque is supported a vertical row of contacts 33 projectin from its inside face as shown in Fig. 1. These contacts are preferably made of a silver platinum compound with rounded ends projecting inwardly and having reduced shanks projecting outwardly through the mica plaque. Each shank is split longitudinally and the divided portions spread apart against the outer face of the plaque for clamping the contacts in fixed position. The resistive conductors 34 are connected to the contacts 33 and are located on the front face of the plaque, being connected to the contacts by the clamping shank portions and by soldering. These resistive conductors have no insulating covering and thereby can stand high temperatures. They are held in spaced position on the face of the plaque by passing from the contacts under projections 32a formed on the left-hand edge of the plaque. An additional pair of similar contacts 33a are provided and similarly mounted to form terminals, the terminal leads 35 being connected to these terminals by soldering to the projectin portions on the inner side of the plaque. The circuit from one lead to the other through the resistive conductors may be followed from the lower lead 35 through the lower resistive conductor 34 to its contact, then through another resistive conductor to the next upper contact and so on successively to the contact next to the top, then through the upper resistive conductor 34 to the upper terminal. The

' upper and lower' conductors 36 connecting the terminals to the upper and lower contacts 33 respectively have no appreciable resistance. The resistivity of the resistors 34 are graduated, the outer'on'es having the lowest resistance and the inner ones having the highest resistance between contacts. It is obvious that when all of the contacts are bridged by a low resistance conductor, all of the resistive conductors are short-circuited and the controlled circuit is in a resistance-allout condition. When all except the upper and lower contacts are short-circuited, the upper and lower resistive conductors are inserted in the controlled circuit. Continued removal ofthe shortcircuit towards the middle of the contacts, gives a step-by-step removal of resistance; and when all short-circuiting of the contacts is removed, all of the resistance will be included in the controlled circuit.

There is another resistive conductor 31 mounted on the mica plaque. This is connected between additional terminals 38 from which leads 39 extend. The resistive conductor 31 is positioned on the inner side of the plaque and is held in place by being looped over projections 32b formed in the upper and lower edges of the plaque. This resistive conductor is formed of a material having no appreciable temperature coefllcient of resistance, such as an alloy of nickel and chromium, or of nickel and copper. Its purpose will be explained later.

Fig. 5 shows a face view of the variably controlled spring fingers or resilient contact strips for variably short-circuiting the resistive conductors 34. This is a thin sheet of heat treated spring material such as phosphor bronze, or beryllium copper. The fingers 40 extend from a common connecting base portion 40a. This base portion is covered by a clamping metal strip M of the same size as the base. A pair of rivets 42 pass through the strip 4 I, the base portion and the mica. plaque for holding these parts together.

Thus the resilient fingers 40 extend from the left-hand portion of the plaque on its inner side; and the right ends of the fingers are spring pressed against and respectively engage the contacts 33. The inside face of the fingers and base portion are overlaid with a coating of good conducting and contacting material such as an alloy of silver and platinum.

The function of the finger controlling bar 30b will now be understood. The ends of the fingers 40 extend a short distance beyond the contacts 33 and the inclined side portions of the bar extend over these ends. When the magnet is deenergized, the biasing spring 2| forces the plunger and bar 30b to the left as shown in Fig. 1. Underthis condition the bar does not engage any of the fingers and all of the resistive conductors 34 are then short-circuited. when suificient current passes in the magnet winding, the plunger and bar 30b will be moved slightly to the right and the upper and lower ends of the bar will draw the upper and lower fingers away from their contacts, thus inserting the upper and lower resistive conductors 34 in the controlled circuit. Further movement causes the next inner pair of fingers to be separated from their'contacts and thereby insert another pair of resistive conductors and so on until in the limiting attracted position all of the resistive conductors are inserted in the controlled circult. In practice the plunger will assume a position determined by the value of the magnet current and change slightly according to any slight change of current to increase or decrease the inserted resistance. Thus 'a high degree of sensitivity and refinement of control are obtained. A further refinement of control is obtained by slightly inclining one side of the finger bar more than the other so that a staggered successive action is obtained in the control of the fingers first on one side of the bar and then on the other, giving successive control oi! each resistive conductor 34, instead of a pair at a time.

There is another resistive conductor 43 shown in Fig. 1 located in the space between the magnet winding l and the lower part of the magnet frame. This has a negative coefiicient of resistance such as a carbon block. It is in the form or a small fiat plate with conductor leads secured to its opposite edges and is, as later explained, connected to secure compensation for changes in temperature of the regulator.

In practice these regulators have been built to have overall dimensions including the enclosing box and excluding the prong base of about two inches long, one-and-five eighths inches high and one-and-a-quarter inches deep and have secured close regulation under widely varying speeds of the dynamo-electric machine.

Fig. 9 shows the electrical connections of one application of the invention to the voltage control of a variable speed generator, such as a hand driven generator. The small circles designated A to H represent the prongs lZa of the prong base. The parts indicated within the prongs A to H represent the parts of the regulator already described and are correspondingly numbered. The parts shown outside the prongs A to H are connected to the usual prong socket; and the diagram shows the connections when the prongs are inserted in the socket. The armature 44 of the generator is shown connected at one terminal to ground and at the other terminal to the prong B. The field winding 45 oi the generator is connected from the ground side of the armature to the prong G. Prongs B, C and D are directly connected together by leads on the upper side of the prong base, there being more prongs than necessary in the standard prong base. Prongs E and F are similarly connected together and likewise prongs H and A.

The magnet coil I0 is connected at one terminal to ground by prong A. The other terminal is connected to prong F and then through resistive devices 31 and'43 in parallel to prongs C and B and thence to the ungrounded side of the motor armature. The magnet coil is thus subjected to the armature voltage. The variable resistors are connected in series with the generator field winding by a circuit from oneside oi the generator armature through the field winding to prong G, then through the resistors to prong B and to the other side of the armature.

When the generator is not running, the plunger of the regulator is biased by spring 2| to cause the short-circuiting of all the resistors 34, as already explained; and when in operation the regulator will vary the resistance of the field circuit to maintain the generator voltage within close limits. Compensation for changes in temperature of the regulator is provided for by the parallel connection of the resistors 31 and 43 in series with the magnet coil l0. Otherwise increase in temperature would reduce the voltage maintained at the armature terminals due to increase in resistance of the magnet coil and of the resistors 34. The compensation is secured by reason of the fact that any increase in temperature will not materially affect the resistance of the resistor 31 but will decrease the resistance of the resistor 43. This permits a proper amount of increased current to pass through the resistor 43 and through the magnet winding l0 and thereby short-circuit a correspondingly increased amount of the resistors 34 to compensate for the temperature increase. Upon decrease of temperature, the reverse action takes place.

It is apparent that this improvement results in the production of a regulator unit having all the parts closely related in compact form which mutually cooperate to produce the desired results.

Although a particular embodiment of this invention has been shown and described, it will be understood that various modifications may be made without departing from the scope thereof.

I claim:

1. Electric controlling apparatus comprising a supporting plate, a plurality of resistors mounted on one side thereof, an aligned row of fixed insulated contacts positioned on the opposite side of said plate and between which said resistors are respectively connected, resilient contact fingers biased to engage said fixed contacts respectively for short-circuiting the fixed contacts, said fingers being mounted and supported on the said opposite side of said plate, and a movable bar having a surface inclined to said aligned fixed contacts for engaging said fingers to successively move said fingers from engagement with the fixed contacts.

2. Electric controlling apparatus comprising a supporting plate of insulating material, a plurality of bare resistive conductors mounted on one side thereof, an aligned row' of fixed contacts positioned on the opposite side of said plate and between which said resistive conductors are respectively connected, resilient contact fingers biased to engage said fixed contacts respectively for short-circuiting the fixed. contacts, said fingers being'mounted and supported on the said opposite side of said plate, and a movable bar having a surface inclined to said aligned fixed contacts for engaging said fingers to successively move said fingers from engagement with the fixed contacts.

3. Electric controlling apparatus comprising an electromagnet having a magnet frame, a winding and a movable plunger, a support of insulating material mounted on an end portion of the magnet frame, an aligned row of fixed contacts on said support, resilient contact fingers mounted on said support biased to engage said aligned contacts respectively, and a movable bar having a surface inclined to said aligned contacts forsuccessively engaging said fingers to successively move the fingers from engagement with the:

aligned contacts, said, bar being mechanically connected to said plunger.

4. Electric controlling apparatus comprising an electromagnet having a magnet frame, .a winding and a movable plunger, a support of insulating material mounted on an end portionof the magnet frame, an aligned row of-fixed contacts on said support, resilient contact fingers mounted on said support biased to engage said aligned contacts respectively, a movable bar having a surface inclined to said aligned contacts for successively engaging said fingers to successively move the fingers from-engagement with the aligned contacts, said bar being mechanically connected to said plunger, and a yieldable support mounted on said end portion of the magnet frame between said first named support and said end portion of the magnet frame for yieldably guiding said bar and plunger.

5. Electric controlling apparatus comprising an electromagnet having a magnet frame, a winding and a movable plunger, a support of insulating material mounted on an end portion of the magnet frame, a plurality of bare resistive conductors mounted on said support, an aligned row of fixed contacts mounted on said support and between which said resistive conductors are respectively' connected, resilient contact fingers mounted on said support biased to engage said aligned contacts respectively, and a movable bar having a surface inclined to said aligned contacts for successively engaging said fingers to successively move the fingers from engagement with the aligned contacts, said bar being mechanically connected to said plunger.

6. Electric controlling apparatus comprising an electromagnet having a magnet frame, a winding and a plunger, supporting posts extending from said frame, a plate of insulating material supported on said posts, an aligned row of fixed contacts on said plate, resilient contact fingers mounted on said plate biased to engage said aligned contacts respectively, a movable bar having a surface inclined to said aligned contacts for successively engaging said fingers to successively move the fingers from engagement with said contacts, said bar being mechanically connected to said plunger, and a yieldable support mounted on said posts between said plate and said frame for yieldably guiding said bar and plunger.

7. Electric controlling apparatus comprising an electromagnet having a magnet frame, a winding and a plunger, supporting posts extending from said frame, a, plate of insulating material supported on said posts, a plurality of bare resistive conductors mounted on said plate, an aligned row of fixed contacts on said plate between which said resistive conductors are respectively connected, resilient contact fingers mounted on said plate biased to engage said aligned contacts respectively, a movable bar having a surface inclined to said aligned contacts for successively engaging said fingers to successively move the fingers from engagement with said contacts, said bar being mechanically connected to said plunger, and a yieldable support mounted on said posts between said plate and said frame for yieldably guiding said bar and plunger.

8. Electric controlling apparatus comprising an. electromagnet having a magnet frame, a winding and a plunger, a dashpot for retarding the movement of the plunger, and a resilient connection between the plunger and the piston of the dashpot.

9. Electric controlling apparatus comprising an electromagnet having a magnet frame, a winding and a plunger, a dashpot for retarding the movement of the plunger, a coiled spring outside'the cylinder of the dashpot for biasing the plunger in one direction, an enclosure around said spring, and a ring at one end of said spring having projections extending through inclined slots in said enclosure for adjusting the force exerted by the spring on the plunger.

10. Electric controlling apparatus comprising an electromagnet having a magnet frame, a winding and a plunger, a variable contact device controlled by movement of the plunger fixed to an end portion of the frame, a dashpot for retarding the movement of the plunger fixed to the opposite end portion of the frame, and a prong base fixed to a side portion of the frame, the prongs of said base being electrically connected to said device and said winding.

11. Electric controlling apparatus comprising an electromagnet having a magnet frame, a winding and a plunger, 5. variable contact device controlled by movement of said plunger, and a pair of resistors connected in parallel with each other and in series with said winding for compensating for change in temperature, one of said resistors having a negative temperature coefiicient of resistance and the other of said resistors having approximately no temperature coeflicient of resistance.

12. Electric controlling apparatus comprising an electromagnet having a magnet frame, a winding and a plunger, a variable contact device controlled by movement of said plunger, a pair of resistors connected in parallel with each other and in series with said winding for compensating for change in temperature, one of said re sistors having a negative temperature coemcient of resistance and the other of said resistors having approximately no temperature coeflicient of resistance, and an enclosing casing for all of said apparatus.

13. Electric controlling apparatus comprising an aligned row of fixed contacts, resilient movable contact strips biased to engage said fixed contacts respectively at one end portion of each of said strips, said resilient strips being electrically connected together at their other end portions, and a movable bar having a surface inclined to said aligned fixed contacts for engaging said movable contact strips to successively move the movable contact strips from engagement with the fixed contacts.

14. Electric controlling apparatus comprising an aligned row of fixed contacts, resilient movable contact strips biased to engage said fixed contacts respectively at one end portion of each of said strips, said resilient strips being electrically connected together at their other end portions, and a movable bar having two surfaces inclined to each other at an obtuse angle and also inclined to said aligned fixed contacts for successively engaging said movable contact strips to successively move the movable contact strips from engagement with the fixed contacts, the said inclination of the two surfaces extending in opposite directions from the middle of the movable bar along its length.

ARTHUR M. COHEN.

REFERENCES crrEn The following references are of record in the file of this patent:

UNITED STA'I'ES PA'I'ENTS Number Name Date Re. 10,944 Weston July 17,1888 505,241 Waterhouse Sept. 19, 1893 10 1,980,734 Sadtler Nov. 13, 1934 2,064,621 McNairy Dec. 15, 1936