US2364751A - Speed responsive apparatus - Google Patents

Description

Dec. 12, 1944. w PLACE 2,364,751

SPEED RESPONSIVE APPARATUS Filed April 12, 1941 M12 BL g 14 I] EL 01% 55 I 43; C ZA ConZPol Czkwaz'zfir F591.

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H15 ATTORNEY Patented Dec. 12-, 1944- SPEED RESPONSIVE APPARATUS Willard P. Place, Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application April 12, 1941, Serial No. 388,286

4 Claims.

My invention relates to speed responsive apparatus of a type adapted for use on railway vehicles for governing the braking system or motive power or both in accordance with its speed.

While the apparatus provided by this application is especially designed for use on railway vehicles it is not limited to use in this field, andit is contemplated that the equipment may be employed in other situations.

It is an object of my invention to provide improved apparatus of the type described which re quires less apparatus than the systems heretofore known.

A further object of my invention is to provide apparatus of the type described and incorporating improved means to maintain portions of the apparatus energized when the vehicle is standing still or is moving at extremely slow speeds.

I shall describe two forms of apparatus embodying my invention, together with a modification which I may employ, and shall then point out the novel features thereof in claims.

In the drawing,

Fig. 1 is a diagram of one form of speed responsive means embodying my invention,

Fig. 2 is a view showing a modified form of relay which may be employed in the system shown in Fig. 1, and

Fig.3 is a diagram of another form of speed responsive means embodying my invention.

Similar reference characters refer to similar parts in each of the several views.

The system shown in Fig. 1 includes a master relay MR, a transformer T, a control relay OR, a checking relay K and a ballast lamp BL., The master relay MR is provided with two-windings, and is provided with a contactcarrying armature which is moved to one position when one winding of the relay is energized and is moved to its other position when the other winding of the relay is energized. The relay MR is of a type the armature of which when moved to either position remains in that position until energy is supplied to a winding of the relay to move the armature to its other position.

The system shown in Fig. 1 has a contact which is actuated by a cam secured to an axle I I or other moving part of the vehicle to the speed of which the system is intended to respond. The

contact I0 is preferably of the make-before-break typ so that on movement of the contact from one position to the other it establishes one circuit controlled thereby before it interrupts the other circuit which it controls. This insures that when the vehicle is at rest one circuit controlled by the contact ID will be established regardless of the position in which the axle stops. While a movable contact I!) actuated by a cam has been illustrated, the invention is not limited to the use of this structure and any other suitable construction may be employed. For example, the axle may have mounted thereon a commutator having two segments, only one of which is connected to the source of current, while brushes may be provided to control the circuits of the commutator.

The relay CR has a contact which controls a circuit or circuits which may be employed to control the vehicle braking means, or for any other appropriate purpose.

The equipment is shown in the condition which it assumes when the vehicle is moving at a medium speed. At this time contact I0 is reciproeated by the cam on the axle II and alternately engages its front and back contacts. When contact I ll engages its front contact, a circuit is established to supply energy from a suitable source of direct current, such as the headlight generator on a locomotive, the terminals of which are designated B and C, to the upper winding of relay MR in series with the ballast lamp BL, while when contact 10 engages its back contact, energy is supplied to the lower winding of relay MR.

As a result of energization of the upper winding of relay MR, the contacts of this relay are moved to their left-hand position, as shown, while on energization of the lower windingof relay MR the relay contacts are moved to their right-hand position.

On movement of contact I4 to its left-hand position at a time when contact 10 engages its front contact a circuit is established to supply energy to the upper winding of the relay CR. Similarly, when contact I4 is in its right-hand position and contact [0 engages its back contact, a circuit is also established to supply energy to the upper winding of relay CR.

In addition, as a result of movement of contact I 5 of relay MR between its two positions, the two portions of the primary winding of transformer T are alternately energized so that energy is in duced in the transformer secondary winding and is supplied therefrom through the rectifier RX to the lower winding of relay CR.

It will be seen, therefore, that when the vehicle is traveling at a medium speed, the two windings of the master relay MR are alternately energized and the relay contacts are moved between their two positions. As a result of this movement of the relay contacts, energy is supplied to the upper winding of relay CR over the circuit which ineludes Contact M of relay MR, While energy is supplied to the lower winding of relay CR through the transformer T and rectifier RX. Accordingly the contact I "I of relay CR is picked up.

The energy for operating the relays MR and CR is supplied through the ballast lamp BL so that the voltage of the energy supplied to these relays is substantiall uniform regardless of fluctuations in the voltage of the source.

The construction of the ballast lamp BL is not a part of this invention and this lamp may be of a suitable type well known in the art. The lamp includes a filament which when heated to a value within the operating range of the device is responsive to fluctuations in the voltage of the source from which energy is supplied through the lamp. On an increase in this Voltage more current tends to flow through the lamp filament with the result that its temperature increases and its resistance correspondingly increases and the voltage of the energy supplied through the lamp remains substantially unchanged. Similarly, on a decrease in the voltage of the source less current tends to flow through the lamp and the temperature of the lamp filament decreases so that there is a corresponding decrease in its, resistance so that the voltage of the energy supplied through the lamp remains substantially unchanged.

The resistance 20 and the relay K together provide a fixed load of substantial value on the lamp BL so that sufficient energy is supplied through the lamp at all times to keep the lamp filament heated to a degree effective to cause the lamp to function to regulate the voltage of the energy supplied through the lamp.

If the load on the lamp BL represented by the resistance 20 and the relay K is removed the lamp may not function to accurately regulate the volt age of the current supplied to the relays MR and CR since the current taken by these relays varies. Accordingly, the operation of these relays would be afiected by fluctuations in the voltage of the source.

The relay K provides a check on the existence on ballast lamp BL of the load represented by the relay and the resistance 20.

The relay K has a contact 2! which controls the circuit of the axle operated contact and of the primary winding of transformer T so that if relay K is. deenergized, energy will not be supplied to the master relay and transformer, and accordingl will not be supplied to the relay CR so that the relay CR is released and creates a safe condition.

picked up, and accordingly the contact H of this relay releases. Release of this contact may be employed to perform any desiredfunction, such as lighting a signal lamp, applying the vehicle brakes or changing the effectiveness of the vehicle braking equipment.

On a subsequent reduction in the speed of the vehicle the relay MR again follows the alternate energization of its two windings and energy is again supplied through the transformer T to the relay CR so that the contact of the relay CR is again picked up.

The system provided by this invention is ar ranged so that the relay OR is picked up when the vehicle is standing still or is moving at extremely slow speeds. When the vehicle is standin still, no energy is supplied through the transformer T to the relay CR, while at slow speeds relatively little energy is supplied to the relay CR through the transformer.

When the vehicle is standing still, however, a circuit including contact Ill and contact M of relay MR is established to energize relay CR so that relay CR is picked up. Similarly, at low vehicle speeds energy is supplied over the circuits controlled by contacts 10 and 14 substantially all of the time so that sufficient energy is supplied to the relay OR to maintain the relay contacts picked up.

This arrangement of the equipment so that the relay CR is maintained picked up at low vehicle speeds is advantageous where the relay is employed to govern the efiectiveness of the vehicle braking equipment. In such a system the relay CR when released causes an increase in the effectiveness of the brake equipment, and if the relay were to release at low vehicle speeds, the resulting increase in braking efiectiveness would cause a rough or harsh stop.

The master relay MR employed in this system is of the type shown in United States Patent No.

2,140,604 to Clarence S. Snavely. This relay is 'On an increase in the speed of the vehicle there Q is an increase in the rate of operation of contact Ill, and a corresponding increase in the rate of operation of the contacts of the master relay MR. However, because of the inductance of the relay windings, there is a decrease in the current supplied through these windings as the vehicle speed. increases, and when the vehicle Speed reaches a predetermined value, the energy supplied to the windings of the master relay MR is reduced to such an extent as to be ineifective to move the relay contacts. Thereafter the relay contacts remain in one position and energy is no longer supplied through the transformer T to the relay CR.

At this time on movement of the contact l0 to one of its positions, the one depending upon the position of contact M of relay MR, energy is supplied to the upper winding of relay CR. Under these conditions energy is supplied to the re ay CR only a portion of the time. However, this energy is insuflicient to maintain the rela CR extremely sensitive and will respond to changes in energization of the relay winding even when these changes occur very rapidly. If the axle controlled contact I0 is operated once for every revolution of the vehicle axle, the rate of alternate energization of the relay windings will not increase to the point at which the relay ceases to respond until an extremely high vehicle speed is reached. It has been found that the relay operating characteristics can be improved by mounting a copper sleeve on the relay armature. This renders the relay less sensitive and retards its response to changes in energization of its windings so that the relay will cease to operate at lower speeds than it otherwise would.

Fig. 2 is a diagram showing the way in which the copper sleeve is mounted on the relay armature. The parts shown in Fig. 2 are identified by the same reference characters as are employed the Snavely patent. As shown in Fig. 2, the armature 24 is pivotally supported between yokes 5 and 8, while a copper sleeve 25 surrounds the armature and may be secured in place in any appropriate manner.

Instead of mounting the copper sleeve on the relay armature the same result may be secured by providing a copper bushing within the relay windings.

InFig. 3 there is shown a modified form of speed responsive apparatus embodying this invention. This apparatus is similar to that shown in Fig. 1 but differs therefrom in that the master relay is energized through a filter circuit to render more positive the cut-off point of the code following master relay- MRA. In the system shown in Fig. 3 the axle operated contact l controls the supply of energy to the primary winding of the filter transformer Fl, while the secondary winding; of this transformer is connected to the primary winding of an impedance matching transformerMT. A condenser Q is connected across the terminals of the secondary winding of transformer FT, while the secondary winding of transformer MT is connected to the operating winding of the polarized master relay MRA.

The filter transformer FT has a core providing a magnetic shunt between the primary and secondary windings so that ther is little mutual inductance between these windings. This transformer together with the condenser Q form a band-pass filter which on a predetermined increase in the frequency of the energy supplied thereto permits lessenergy to be supplied through the circuit of the filter.

over the circuit controlled by contact ll of relay MRA only a portion of the time. As pointed out in connection with the system shown in Fig. 1, this energization of relay GR is not effective to maintain the relay contact picked up, and contact ll therefore releases to produce whatever control function is desired.

On a subsequent reduction in the speed of the vehicle suflicient energy is again supplied to relay MRA to operate the relay and energy is again supplied to the relay CR. to pick up the contact of this relay.

The system provided by this modification of the invention, like that shown in Fig. 1, operates so that the relay GR is maintained picked up when the vehicle is standing still or is moving at extremely low speeds.

When the vehicle is moving at low speeds, the

' contact I0 is operated and the contacts of relay MRA are moved between their two positions so that energy is supplied substantially all of the The secondary winding of the filter transformer FT is provided with taps to enable the filter cir suit to be adjusted to operate in different ranges lam-p BL and resistance Zll so that the voltage is maintained substantially constant.

As a result of energization of the primary winding of transformer FT, energy is induced in the transformer secondary and is' supplied therefrom through the transformer MT to the relay MRA so that relay MBA is supplied with impulses of energy of alternate relative polarity. The various parts of the equipment are arranged so that on movement of axle operated contact In into engagement with its upper contact the polarity of the energy supplied to relay MBA. is suchas to cause the contacts l4 and i5 of this relay to move to their-left-hand position as shown. Accordingly, contact 14 establishes a circuit which also includes contact It for supplying energy to the winding of relay CR. Similarly, when contact it engages its lower contact, the polarity of the energy supplied to relay MRAis such that contacts M and I5 are moved to their right-hand position so that contact I4 establishes a circuit to supply energy to relay CR In addition, as a result of movement of contact 15 of relay MRA between its two positions, ener y is supplied through transformer T and rectifier RX to the control relay CR. As a result of the supply of energy to the two windings of relay CR. the contact I! of this relay is maintained picked up.

On a predetermined increase in the speed of the vehicle the frequency of the alternating current induced in the secondary winding of filter transformer FT is increased to such an extent that. because of the band-pass filter characteristics of the transformer and condenser Q, too little energy is supplied to the relay MRA to effect movement of the relay contacts. Accordingly, the relay contacts remain in one position so that energy is no longer supplied through the transformer T to the lower winding of relay CR, while energ is supplied to the upper winding of the relay CR Iii) time to relay CR over the circuit controlled by contact M of relay MRA. This energy is sufficient to maintain the relay CR picked up.

At low vehicle speeds .on a change in the position of the axle operated contact I0 thesupply of energy to one portion of the transformer FT is cut off while energy is supplied to the other portion of the transformer primary winding. As a result an impulse of energy is generated in the transformer secondary winding and is supplied therefrom through the transformer MT to the relay MBA and causes a change in the position of the contacts of this relay. This impulse consists of energy of the fundamental frequency of the rate of operation of the axle operated contact together with energy of frequencies harmonically related thereto combined in such phase relationship and magnitude to make up an impulse effective to operate the contact of relay MRA.

When the vehicle stops, the contacts of relay MRA are moved to a position of correspondence with axle operated contact 10 so that energy is supplied to relay CR over the circuit which includes contact M of relay MRA.

Although I have herein shown and described only two modifications of speed responsive means embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described claim is:

1. In apparatus of the class described, in combination, a polarized master relay, an element movable between a first and a second position in accordance with the speed of a moving member, means effective when said element is in its first position to supply energy to said master relay to cause the movable contacts thereof to move to their normal positions and effective when said element is in its second position to supply energy to said master relay to cause the movable contacts thereof to move to their reverse positions, the master relay movable contacts being capable of responding to changes in the supply of energ to the relay only when such changes occur at less than a predetermined rate, a control relay, means effective to supply energy to said my invention, what I control relay when said element is in its first.

position provided a movable contact of the master relay is in its normal position and to also supply energy to said control relay when said element is in its second position provided said master relay movable contact is in its reverse position, and means responsive to movement of another movable contact of the master relay between its two positions for also supplying energy to the control relay.

2. Inapparatus of the class described, in combination, a polarized master relay, an element movable between a first and a second position in accordance with the speed'of a moving member, means effective when said element is in its first position to supply energy to said master relay to cause the movable contacts thereof to move to their normal positions and effective when said element is in its second position to supply energy to said master relay to cause the movable contacts thereof to move to their reverse positions, the master relay movable contacts being capable of responding to changes in the supply of energy to the relay only when such changes occur at less than a predetermined rate, a control relay having a plurality of windings, a circuit effective to sup ply energy to a winding of said control relay when said element is in its first position provided a movable contact of the master relay is in its normaster relay between its normal and reverse posi- I tions for also supplying energy to a winding of the control relay.

3. In apparatus of the class described, in combination, a polarized master relay, an element movable between a first and a second position in accordance with the speed of a moving member, means effective when said element is in its first position to supply energy to said master relay to cause the movable contacts thereof to move to their normal positions and effective when said element is in its second position to supply nergy to said master relay to cause the movable contacts thereof to move to their reverse positions, the master relay movable contacts being capable of responding to changes in the supply of energy to the relay only when such changes occur at less than a predetermined rate, a control relay having a plurality of windings, circuits effective to supply energy to a winding of said control relay only when said element is in its first position and a movable contact of the master relay is in its normal position and when said element is in its second position and said master relay movable contact is in its reverse position, the energy supplied over said circuits being effective to maintain the control relay picked up only when said circuits are complete substantially mor than one-half of the time, a transformer, a circuit governed by another movable contact of the master relay for supplying direct current to the transformer primary winding, and means for supplying unidirectional energy from the transformer secondary winding to a winding of said control relay.

4. In apparatus of the class described, in com bination, an element movable between a first and a second position in accordance with the speed of a moving member, said element being effective in its first position to establish a first supply circuit and being effective in its second position to establish a second supply circuit, a band-pass filter operative to pass energy of frequencies below a predetermined point, means for supplying energy to said filter at frequencies which vary in accordance with the rate of alternate establishment of said supply circuits and which at times ar below said predetermined point and at other times are above said predetermined point, a polarized master relay receiving energy through aid filter and arranged so that its contacts are moved to their normal positions when said element is in its first position and are moved to their reverse positions when said element is in its second position, a control relay, and means effective when the master relay contacts are in their normal positions to supply energy to the control relay provided said element is in its first position and effective when the master relay contacts are in their reverse p0- sitions to supply energy to the control relay provided said element is in its second position.

WILLARD P. PLACE.

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