US2118930A - Electrical closure control system - Google Patents

Description

E. D. LILJA ELECTRICAL CLOSURE CONTROL SYSTEM 3 Sheets-Sheet 1 May 31, 1938.

Filed Nov. 16, 1935 Fig. 1. I

INVENTOR ATTORNEYS E. D.- LILJA ELECTRICAL CLOSURE CONTROL SYSTEM May 31, 1938.

Filed Nov. 16, 1935- 3 Sheets-Sheet 2 "mull IJF l lllll.

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To LINE 0 WJ L R N m Mm N Er n W0 A J Y A May 31, 1938. E. D. LILJA ELECTRICAL CLOSURE CONTROL SYSTEM Filed Nov. 16, 1935 3 Sheets-Sheet 3 To LINE w L ,T Y D R T 0 m Mn V A my PM mm Patented May 31, 1938 ELECTRICAL CLOSURE CONTROL SYSTEM Edgar D.

Lilia, Rockford, Ill., assignor to Howard D. Colman, Rockford, Ill.

Application November 16, 1935, Serial No. 50,192

Claims.

This invention relates to an electrical control system whereby the operation of a power driven closure operator at one point may be initiated under manual control from another point, and it has particular reference to a control system of this character adapted for use under conditions which render it impractical to employ a direct metallic control circuit between the two points.

More specifically considered, the invention relates to an electrical control system especially adapted for use in the control from a moving or stationary vehicle of power driven mechanism for opening and closing garage doors, driveway gates, and the like.

The primary object of the invention is to provide a new and improved electrical control system of the above general character which is simple in construction and dependable in operation, and which is relatively inexpensive to manufacture and install.

Another object is to provide a control system of the above general character in which the various elements are so combined and coordinated that the system may be operated on low voltage current such as is supplied by the storage battery of a motor vehicle and which, by reason of the entire absence of special current generators, induction coils, vacuum tubes, etc., may be of very simple and inexpensive construction and capable of operating indefinitely without requiring attention or replacement of parts.

Another object is to provide an improved control system of simple and relatively inexpensive construction adapted to initiate the operation of the closure operator only in response to a signal of predetermined frequency whereby unauthorized operation of the same is prevented and false operation by stray currents, lightning discharges, etc. is effectually avoided.

A further object is to provide an improved electrical control system employing signalling current of relatively low frequency such as can be readily supplied by a simple interrupter or vibrator operating from the storage battery of a motor vehicle, the system being sufilciently sensitive so that extremely accurate positioning of the signal transmitting means with respect to the receiving means is unnecessary.

Still another object is to provide an improved signal receiving relay adapted to operate on extremely feeble signal currents of predetermined low frequency.

Other objects and advantages will be apparent from the following description taken in connection with the accompanying drawings wherein the invention is illustrated in a preferred embodiment. It will be understood, however, that changes may be made in the construction and arrangement employed and in the particular application of the system without departing from the spirit and scope of the invention as expressed in the appended claims. 4

In the drawings:

Fig. l is a perspective view of a garage having a driveway leading thereto and showing a motor vehicle equipped with signal transmitting apparatus in accordance with my invention.

Fig. 2 is a diagrammatic view of the signal transmitting apparatus.

Fig. 3 is a vertical sectional view of the vibrator comprising a part of the signal transmitting apparatus.

Fig. 4 is a. schematic view of the receiving apparatus and door operator.

Fig. 5 is a transverse sectional view through the antenna.

Fig. 6 is a schematic view of a modified form of the receiving apparatus.

For the purpose of illustration, I have shown in the drawings and will hereinafter describe the invention as applied to the control of a power driven garage door operator from a motor vehicle. It will be appreciated, however, that the system may be employed equally well for controlling other closure operators, for example, driveway gates and the like. Generally stated, the control system embodies a signal transmitter 5 carried by a motor vehicle and a signal receiver 6 (Fig. 4) associated with a door operator 1 and efiective to initiate the operation of the same in response to a signal sent out by the transmitter. The transmitter 5 includes a manually controllable signal generating means operative to supply a pulsating or fluctuating current of a predetermined, relatively low frequency to a low resistance antenna 8 comprising, in the present instance, two loops or turns of wire, carried by the vehicle. Connected with the receiver 6, which is located in the garage, is a receiving coil 9 which is suitably placed in or near the driveway by which the vehicle approaches or leaves the garage so as to be inductively infiuenced by the fluctuating magnetic field set up around the antenna by the current flowing therein. Thus, an alternating voltage is induced in I the receiving coil 9, and serves to energize the receiver 6 (Fig. 4) which, as shown herein, is in the form of a sensitive tuned relay adapted to close its switch in upon receiving signal current of a predetermined frequency. The switch Ill, through the medium of a switching device Ii, initiates the operation of the door operator 1 to open or close the garage doors as required.

The signal transmitter 5 is preferably constructed in the form of a compact, enclosed unit for convenient mounting, for example, on the inner side of the instrument panel of the vehicle. It includes a. vibrator l2 (Figs. 2 and 3) adapted to periodically close and open a circuit for the antenna 8 through the medium of a switch I4. While the vibrator I2 may be oscillated manually or in any other convenient manner, I prefer to employ an electro-magnet for this purpose and to this end, provide a switch I3 adapted to be actuated alternately with the switch I4 for controlling the circuit of the magnet. The vibrator I2 preferably is in the form of a comparatively stiff reed of steel or other suitable material which is insulated from and rigidly supported at one end by a supporting post I5 carried on a base plate I6 of insulating material constituting the base of the transmitter unit. Riveted or otherwise suitably attached to the free end of the reed is a weight H of magnetic material suitably proportioned with respect to the stillness of the reed so as to give the reed a desired natural period of vibration. This period may desirably be varied in different transmitters so that each transmitter will be effective to initiate the operation of a particular receiver and door operator only,.

thus providing for selective operation under conditions in which a number of vehicles use the same driveway in approaching the garage.

In the illustrative embodiment, a driving magnet I8 is provided for oscillating the vibrator I2. The magnet may be of any suitable type and, as shown herein, comprises a winding I9 upon a magnetic core 20' from which it is insulated by a spool 2I (Fig. 3) of insulating material. Pole piece members 22 enable the magnet to act upon the weight I! of the vibrator with maximum efficiency. These members may take the form of elongated strips of magnetic material secured at one end to the respective ends of the core 20 and having the other end projecting substantially beyond the outer edge of the winding I9 and spaced apart to provide suflicient clearance to enable the weight I! of the vibrator to pass between them. The magnet may conveniently be supported on the base I6 by non-magnetic brackets 23 so that the projecting ends of the pole pieces 22 will lie adjacent the upper edges of the vibrator weight I! in the idle position thereof. Thus, when the magnet is energized, the pole pieces will attract the weight and raise the same against the flexural restoring force of the vibrator reed.

Operatively associated with the vibrator I2 and adapted to be opened and closed in accordance with its vibrations are the switches I3 and I4 (Fig. 3), which are included, respectively, in the driving magnet circuit and the antenna circuit. As shown herein, the switches are carried respectively by spring members 24 and 25 supported on the post I5 on opposite sides of and insulated from the vibrator I2. Switch I3 is adapted to be closed by the vibrator I2 when the latter is in its normal inactive position, the switch I4 being open at this time. When the vibrator is raised under the influence of the magnet I8, switch I3 is opened and switch I4 is closed. The reverse takes place upon the release of the vibrator, that is, switch I3 is closed and switch I4 is opened.

Accurate adjustment of the switches I3 and I4 is effected by means of adjusting screws 26 and 21, respectively. The adjusting screws are conveniently carried by an arm or bracket 28 supported at one end on the vibrator supporting post I5 and projecting forwardly substantially parallel to the vibrator I2. Adjusting screw 27 is arranged to project through an aperture 29 electrical contact therebetween. Aperture 2! permits the member to move freely upon the closure of switch I4 so that the damping effect on the vibrator I2 is kept at a minimum. Spring member 25, of course, follows the vibrator in its downward movement but in this case, the head of screw 21 defines the limit of downward movement of the member and thereby determines the point at which the switch I4 is opened. Thus, member 25 is enabled to follow the movements of the vibrator I2 without materially interfering with such movement and, at the same time, the opening and closing of switch I4 at the proper time is insured.

The operation of the switch I3 is controlled in generally the same manner by the adjusting screw 26. To this end switch member 24is provided along one edge with an upstanding lug 3| out interfering with its free movement in the' other direction.

The electrical connections of the transmitter 5 may be readily seen by reference to Fig. 2 of the drawings. Current for operating the transmitter may be conveniently supplied by a battery 32 having one terminal grounded on the frame of the vehicle and the other terminal connected to the transmitter via a manually operable switch 33. The switch 33 may be of any suitable type and is preferably mounted so as to be within easy reach of the driver of the vehicle. A conductor 34 provides a connection between the ungrounded terminal of the battery 32 and one contact of the switch, the other contact of the switch being connected by a conductor 35 to a terminal lug 36 mounted on the base I6 of the transmitter unit. From terminal lug 3B, the circuit extends through a protecting fuse 31, terminal lug 38, conductor 39 to one terminal of the magnet I8. The other terminal of the magnet is connected by a conductor 40 with the switch member 24 which, in one position of the vibrator I2, is electrically connected with the vibrator by the switch I3. Vibrator I2, in turn is connected by a conductor M with a terminal lug 42 grounded on the frame of the vehicle. It will be apparent that, upon closure of the switch 33, magnet III will become energized and attract the weight II carried by the vibrator I2, thus raising the vibrator and interrupting the magnet circuit by opening the switch I3. To prevent excessive sparking, the switch may be shunted by a condenser 43 and resistance 44 connected in series.

Each energization of the magnet I8, in addition to opening the switch I3 as above described, will also close the switch I4 to complete a circuit through the antenna 8. This circuit may be traced from the battery connected terminal lug 38, through the outer antenna coil, terminal lug 45, inner antenna coil, terminal lug 46, conductor 41, switch member 25, switch I4, and vibrator I2 to grounded terminal 42. Thus, at each closure of the switch I 4, antenna 8 will be connected directly across the terminals of the battery 32.

While the antenna 8 may be of any suitable construction, to facilitate its manufacture and installation, I prefer to employ a multi-conductor cable of the ordinary commercial type having relatively heavy conductors 43 and 44* enclosed in an insulating sheath 8 as shown in Fig. 5.

The cable may be conveniently attached to the running gear of the car to form a flat generally rectangular loop disposed in a plane substantially parallel to the surface over which the vehicle operates and enclosing as large an area as is practicable thus providing a maximum operating range. For connecting the conductors of the cable to form a plurality of serially connected loops, I provide suitable terminal lugs such as the terminal lug 45 on the base l6 of the transmitter. Suitable terminal lugs 38 and 45 provide convenient means for connecting the terminals of the antenna to the transmitting device. The particular improved construction of the transmitting antenna forms no part of my present invention but is described and claimed in my copending divisional application Serial No. 105,560, filed October 14, 1936. When the antenna is connected across the battery 32 by the transmitting device 5 as above described, the current flow therein sets up a magnetic field which pulsates at vibrator frequency and serves to induce an alternating voltage of corresponding frequency in the receiving coil 9 whenever the vehicle is positioned so that the coil lies under the area enclosed by the antenna. By reason of the low resistance of the antenna, a suificiently heavy current flow may be obtained from an ordinary six-volt storage battery to provide effective signalling. The use of special transmitter batteries, step-up transformers or induction coils is thus avoided and by reason of the absence of these elements, an emcient transmitter may be constructed in very compact form and at a minimum cost.

In the embodiment herein disclosed, the receiving coil 9 is located in the driveway so that a vehicle must pass over it to enter the garage. To provide the necessary protection for the coil, it is preferably sealed in a non-magnetic annular casing member 48 of generally U-shaped cross section (Fig. 4) adapted to fit tightly against the surface of the driveway. The casing may be secured in place by means of suitable screws passing through the external flange 49 of the casing and anchored in the driveway. Thus, the coil may be installed in existing driveways with a minimum of labor and expense. An electrical connection between the receiving coil 9 and the exciting coil of the receiving relay 5 is provided by a suitable two conductor cable 50 which may conveniently be located underground. While only one receiving coil has been shown in the preferred embodiment, it will be apparent that a plurality of such coils connected in series with the receiving relay may be employed if desired. For example, by providing a coil 9 in the floor of the garage, the door opening and closing mechanism can be conveniently controlled from the car after theisame is run into the garage. Two receiving coils 9 would of course be necessary where the system is applied to the opening and closing of the gate in a driveway in which case the two coils would be mounted on opposite sides of the gate at any desired distance therefrom.

Referring now to Fig. 4 of the drawings, the construction of the receiving relay 6 and the apparatus controlled thereby will be described. The actuating element of the relay comprises an exciting coil 5| wound on one leg of a generally 0 shaped iron core member 52 which is preferably of laminated construction. To insure the delivery of maximum energy to the relay, the impedance of the coil 5| is matched with that 'remains parallel to the pole faces.

of the coil upsets this balance, pole pieces 53 and of the receiving coil 8, both coils comprising a relatively large number of turns so that the current in the receiving system will be low and the losses in the cable 50 between the coils will be negligible. The open ends of the member 52 are bifurcated and disposed so as to face each other across a narrow air gap and thus constitute opposed pole pieces 53 and 54 between which a permanently magnetized armature 55 is suspended.

By reason of the bifurcated construction of the pole pieces, the alternating flux will be concentrated at the ends of the armature where it will be most effective in producing armature torque. As shown herein, the armature is carmm by a flexible ribbon 56, preferably in the form of a flat steel spring, supported at opposite ends by a'frame mounted on the core 52.

In its preferred form, the frame comprises side members 51 and 58 of bakelite or other suitable insulating material secured in any suitable manner between the bifurcated ends of the respective pole pieces 53 and 54 with the inner faces of the members substantially flush with the ends of theassociated pole pieces. Secured to the upper ends of the frame members is a top plate 59 of brass or other non-magnetic electrically conductive material provided with a slot 60 for anchoring the ribbon 55. The ribbon may be anchored securely to the plate 59 by means of a screw 5| threading into the plate and adapted to clamp the ribbon against the back wall of the slot 50. A similar plate 63 secured to the lower ends of the frame members 51 and 58 provides a suitable anchorage for the other end of the ribbon 56. Armature 55 is thus suspended midway between the pole pieces 53 and 54 and is free to rock about an axis defined by the ribbon 5B.

The circuit controlling function of the relay is effected through the medium of the switch I, one contact point of which is carried by an arm 64 formed on the armature 55. The other contact point of the switch may conveniently comprise a contact screw 55 threading into a metal bracket 55 supported on the frame member 58. Adjustment of the contact points of the switch is effected by turning the screw 65. By rocking the armature about its axis, the switch in is opened and closed thus effecting switching operations to be described hereinafter.

When no current is flowing in the exciting coil 5|, the magnetic forces acting on the armature 55 are substantially balanced and the armature Energization 54 attracting opposite ends of the armature, each end being attracted by the two pole pieces alternately at twice vibrator frequency as a result of the polarity reversals produced in the pole pieces by the alternating exciting current. Thus the armature is caused to oscillate angularly at exciting frequency about the ribbon as an axis, and against the torsional restoring force exerted by the ribbon. It will be appreciated, however, that the armature oscillations will attain maximum amplitude only when the frequency of the exciting current corresponds to the natural frequency of vibration of the armature assembly. This natural frequency of vibration is a function of the moment of inertia of the armature 55 and the torsional stiffness of the ribbon 55. Excitation of the coil 5| by an alternating or pulsating current of a corresponding frequency will thus cause the armature 55 to vibrate and the vibrations will quickly attain maximum amplitude. Switch ll may conveniently be adjusted to close when the armature vibrates substantially at maximum amplitude and thus becomes effective to complete the control circuits. On the other hand, the armature vibrations will not attain sufllcient amplitude to close the switch ll when the coil 5| is excited by an alternating or pulsating current of a frequency differing materially from the natural frequency of the armature assembly. Thus, the relay is operable only by signal currents of a predetermined frequency, and false operation from stray currents, lightning discharges, etc. is effectually avoided. At the same time, the relay is extremely sensitive, the low mass of the armature and the small amount of unlaminated material in the magnetic circuit perniitting it to operate on a very feeble current of the proper frequency.

In order to adapt the relay 6 for service with various transmitters and to provide for its accurate tuning, means are provided whereby the natural period of vibration of' thearmature assembly may be conveniently adjusted. As herein shown, the adjusting means includes a screw 81 disposed in a vertical slot 68 formed in the frame member 51, the screw being journaled at one end in a bearing formed in the frame member and rotatably anchored at the other end in the top plate 59 of the frame assembly. Threaded onto the screw 61 is an arm 89 having a slot 18 in its projecting end for slidably receiving the ribbon 58. By turning the screw 81, the position of the arm 69 with respect to the armature 55 can be varied as desired, the effective length of the ribbon 56 being likewise varied with a corresponding variation 'in the natural period of vibration of the armature assembly. Thus, the vibrating elements of the relay may be adjusted or tuned to make the relay responsive to alternating currents of any desired frequency within the limits imposed by the character of the parts involved.

It will be appreciated that only a very small force is required to set the armature 55 of the relay in motion and to prevent this from occurring accidentally, means are provided for protecting the relay mechanism from mechanical vibration or shock which might be transmitted through the garage or other structure on which the relay is mounted. To this end, the relay mechanism is resiliently supported on a bracket H of generally U shaped form which is adapted to be attached to the wall or other part of the garage. As shown herein, the resilient support for the relay mechanism is provided by springs 12, there being a pair. of such springs connecting between the relay mechanism and each leg of the bracket H. One spring 12 of each pair is anchored at one end to the bracket leg adjacent its upper edge and the other end is anchored to a lug or ear 13 attached to the upper side of the core 52. The other spring 12 is anchored at one end to the bracket leg adjacent its lower edge and the other end is anchored to a lug or ear H attached to the lower side of the core 52. Thus, the core is yieldably suspended in a substantially horizontal position between the two legs of the bracket H and the relay mechanism is protected against mechanical vibration or shock by reason of the resiliency of the springs 12.

The relay 8, through the medium of its switch l0, initiates the operation 01' the door opening and closing mechanism I upon receiving the proper signal impulses. Cooperating with the relay 8 to effect the required door opening or closing operation of the mechanism I is the switching device ll comprising electromagnetic relays I5 and 18. The relays l5 and 18 are preferably so inter-connected with the door operating mechanism that relay 15 is effective to control the opening of the garage door and relay I8 is effective to control the closing of the door.

The door operating mechanism 1 may be of any suitable and well known type and, as shown herein, comprises a reversible motor 11 adapted. to drive a door actuating device 18 through the medium of a drive shaft 19. A suitable brake 80 for insuring quick stopping of the mechanism is provided and is adapted to be released by means of a solenoid 8| under control of the relays l5 and 15. Also included in the operating mechanism I is a switching device 82 having one switch 83 which is closed as the garage door moves into closed position and a second switch 84 closed when the door moves into open position. Upon closure of one of the switches, the other switch, of course, is opened.

As shown herein, the switch 83 is adapted, when closed, to connect one terminal of relay 15 to conductor 85 of the power line over which current from any suitable source is supplied to the door operator. Switch 84, when closed, is adapted to connect the corresponding terminal of relay 16 to line conductor 85. The other terminals of the relays 15 and 16 are connected in multiple to one side of the switch in by way of a conductor 88 and the metal bracket 86. The other side of switch III is electrically connected to conductor 81 of the power line, the connection including the switch arm 84, armature 55, ribbon 58, supporting plate 59 and conductor 88 which is electrically connected to the plate. It will thus be appment that the closure of switch will complete a circuit for one or the other of relays 15 or 18 depending upon the position of the garage doors and the switching device 82. fI'hus, if the doors are closed, switch 83 will likewise be closed and switch III will complete a circuit for relay 15. If the doors are open, switch 84 will be'closed, hence switch ID will complete the circuit for relay 18. Similar control may be effected manually by means of the auxiliary manually operable switch 89 connected in shunt with the switch Ill and which, for convenient manipulation, may be mounted on one ofthe walls of the garage.

It will be observed that each of the relays l and I6 is provided with three switches designated 90, SI, and 82, and 90, 9| and 92, respectively.

Switch 90 is adapted upon closure to complete a. holding circuit for relay so as to maintain the relay energized independent of the switch l0 or the switch 89 which efi'e'cts its initial energization and thus insure the operation of the control mechanism through a complete door opening cycle. Switch till functions in the same manner for relay 15. Switch 9|, upon closure, completes a circuit over conductor 93 for operating the motor Tl in a direction such that the garage doors will be moved from closed to open position. Switch ill completes a circuit for the motor 11 over a, conductor 94 so as to cause the motor to move the doors from open to closed position. Switches 92 and 92 complete an operating circuit for the solenoid 8| to release the brake 8!! whenever the motor 11 is operated.

The control system comprising the present invention, as will be appreciated from the foregoing description, provides a convenient means whereby the driver of a motor vehicle is enabled to open or close the doors of a building, such as a garage, without leaving the vehicle. Assuming that the garage doors are closed as the vehicle approaches,

the driver will close the manual switch 33 for a short interval, several seconds for example, when the vehicle is passing over the receiving coil 9 in the driveway. Closure of switch 33 sets the transmitter in action whereby a pulsating current of a predetermined low frequency is sent through the antenna 8. The pulsating magnetic field surrounding the antenna induces an alternating current in the circuit including the receiving coil 9, which current causes the armature of relay 6 to vibrate at its natural frequency so as to close its switch I8.

, Since it is assumed that the garage doors are closed at this time, the switch 83 associated with the door operator will necessarily be closed and switch I8 will therefore complete an initial energizing circuit for relay 15. The relay upon energizing closes a holding circuit for itself at switch 98 so as to maintain its energized condition independently of switch I8 until the garage doors are completely opened. Relay 15 also completes operating circuits for the door operating motor 11 and the brake releasing solenoid 8|, and the motor, accordingly, moves the doors to open position. When the doors reach the limit of their movement to open position, switch 83 is opened thereby deenergizing relay 15 and interrupting the operation of the motor 11.

If it is desired to close the doors with the vehicle in the garage, the manual switch 89 is closed momentarily. The doors being open at this time, switch 84 will necessarily be closed so that relay 16 will energize in response to the closure of switch 89. Relay 16 completes its holding circuit at switch 98 and likewise completes operating circuits for the motor 11 and brake releasing solenoid 8|. These circuits are automatically interrupted by the opening of switch 84 as the doors reach the closed position.

In taking the vehicle from the garage, the above described sequence of operation in opening and closing the doors will be reversed. Manual switch 89 will be operated to open the doors. As the vehicle passes over receiving coil 9, the actuation of switch 33 will initiate .the door closing operation.

In some cases, in order to insure positive opera tion of the switching relays 15 and 16 in response to the momentary closure of the switch I8, I have found it desirable to employ relay coils designed for use with a substantially lower volt-age'than the voltage employed for operating the closure mechanism. Under such conditions, it is desirable that provision be made for preventing excessive heating of the coils due to sustained energization at high voltage. A control system adapted to employ relays of this character is illustrated in Fig. 6 of the drawings. In this figure of the drawings, parts which correspond to those shown in the preferred system as illustrated in Fig, 4 have been designated with corresponding reference characters. The sensitive relay 6 and the receiving coil 9 have been shown diagrammatically, but it will be understood that these elements are similar in construction to those shown in Fig. 4.

In the system disclosed in Fig. 6, the momentary closure of the switch III in response to a signal received by the coil 9, energizes either the relay 15 or 16 depending upon the position of the switching device 82 as determined by the open or closed condition of the garage doors. When the doors are closed the relay 15 will be energized over a circuit which includes the line conductor 81, the conductor 88, switch I8, a conductor 99, a normally closed switch I88 adapted to be opened by the relay 15 when energized, a conductor IN, a normally closed switch I82 adapted to be opened when the relay 16 is energized, a conductor I83, winding of the relay 15, a conductor I84, the switch 83, through a circuit breaker I85, to the line conductor 85. The relay 15, on energizing, completes a holding circuit for itself by closing the switch 98, the holding circuit in this case including a suitable resistance I86 which limits the current flow through the coil to a value such that the coil will not become overheated on sustained energization. The relay 15, on energizing, also opens the initial energizing circuit at the switch I88, thereby preventing further energization at high voltage in the event that the switch I8 is closed during the operating cycle of the control mechanism.

When the garage doors are open and the switch 84 is closed, a momentary closure of the switch I8 energizes the relay 16 over a circuit including the line conductor 81, the conductor 88, the switch I8, the conductor 99, the switch I88, the conductor IN, the switch I82, the conductor I83, winding of the relay 16, a conductor I81, the switch 84 and circuit breaker I85 to line conductor 85. Energization of the relay 16 completes a holding circuit for the relay by way of the switch 98* and resistance I86 and interrupts the initial energizing circuit at the switch I82.

The operating circuits for the motor 11 and the brake solenoid M are completed by the relays 15 and 16 as previously described. Relay 15 closes the circuit for the motor at the switch 9I and closes the circuit for the brake solenoid at switch 92. Corresponding circuits are closed by the relay 16 at switches 9i and 92, respectively. 4

It will be apparent that, with the circuit arrangement above described, a relay having a winding of relatively low impedance may be used. By reason of this low resistance, a comparativel-y heavy current impulse will be produced upon the momentary closure of the switch I8, thus assuring positive operation of the relay. At the same time, excessive heating of the relays is prevented by providing for limiting the current by which they are maintained in energized condition.

In the modified control system, I have shown the circuit breaker I85 interposed in one of the line conductors over which current is supplied to the switching elements of the control system. While this circuit breaker may be of any suitable type, I have illustrated a device of the heating coil type embodying a switch I88 which is normally held in a closed position by means of a fusible element I89. Interposed in the line conductor 85 is a resistance element II8 adapted to be overheated by current flow therein and arranged so that, when heated for a predetermined time, its temperature will be suflicient to fuse the element I89. The switch I88 is thereby released and opens to interrupt the supply of current to relays15 and 16 thereby deenergizing the system. Preferably the various parts are so arranged and constructed that the switch I88 will be released only when excessive current is drawn from the line for a considerable length of time.

It will be apparent from the foregoing that I have provided an improved electrical control system for controlling garage door operating mechianisms from a moving or stationary motor vehicle. The control system is extremely simple in construction and relatively inexpensive to manufacture and install and at the same time is efflcient and dependable in operation. Moreover, it employs a minimum number of parts subject to wear and none whatever requiring periodic replacement as is the case with systems employing vacuum tube detectors or the like. Further, the system employs low voltage electric current of a predetermined, relatively low frequency for signalling purposes which current can bereadily generated by a simple interrupter or vibrating device operating from the storage battery of the motor vehicle and the operating mechanism responds only to signals of the predetermined frequency. Thus, opening or closing of the garage doors by unauthorized persons, or false operation due to stray electric currents, lightning discharges, etc., is efl'ectually prevented.

I claim as my invention:

1. In a vehicle controlled door operating apparatus of the electromagnetic energy transfer type for effecting the opening of a door or similar closure from a signalling mechanism carried by a moving vehicle and operative while the vehicle is in motion or without accurately timing the actuation of the signal mechanism with the progress of the vehicle, the combination of, cooperating transmitting and receiving coils dis posed respectively on the lower portion of the vehicle and at a point in the path traversed thereby, transmitting means on the vehicle for exciting said transmitting coil with a low frequency interrupted current of a preselected fixed frequency, means operable at will for rendering said transmitting means continuously operative for a relatively long cycle of operation, a closure operating mechanism, and receiver means connected to said receiving coil for initiating the operation of said closure mechanism in response to the electromagnetic induction in said receiving coil of a voltage of predetermined minimum value and of a predetermined frequency corresponding to said fixed frequency for even a small portion of said cycle of operation of said transmitting means as said transmitting coil passes over said receiving coil.

2. An apparatus for effecting the operation of a door or similar closure from a moving vehicle comprising, in combination, a signal transmitter carried by the vehicle and including a source of low voltage direct current, a transmitting coil on the lower portion of the vehicle and an interrupter for producing in said transmitting coil a pulsating current of a predetermined low frequency, a receiving coil disposed in the path of the vehicle when approaching or leaving the closure, a closure operating mec sm having a control switch, and receiver means for actuating said switch during a momentary association of the transmitting and receiving coils in the travel of the vehicle, said receiver means including a relay having a vibrating armature operative to close said switch only when the armature reaches a predetermined maximum amplitude of vibration in response to'the electromagnetic induction in said receiving coil of a voltage of. predetermined minimum value and of a fixed frequency corresponding to said predetermined frequency of the current produced in the transmitting coil.

3. In an apparatus of the electromagnetic energy transfer type for effecting the openin of a door or similar closure from a signalling mechanism carried by a moving vehicle and operative while the vehicle is'in motion or without accurately timing the actuation of the signal mechanism with the progress of the vehicle, the combination oi, cooperating transmitting and receiving coils disposed respectively on the vehicle and at a point in the path traversed thereby, transmitting means for exciting said transmitting coil with a low frequency interrupted current of a preselected ilxed frequency thereby to set up a pulsating magnetic field linking said receiving coil as said transmitting coil passes closely adjacent the same, means operable at will to render said transmitting means operative for a relatively long cycle of operation as the vehicle approaches and passes said receiving coil, a closure operating mechanism, a relay including a vibrating armature member having a natural frequency of vibration equal to said preselected fixed frequency and an actuating winding for said relay connected to said receiving coil for exerting a pulsating magnetic force on said armature, means providing a polarizing field acting on said armature to increase the sensitivity thereof, and means including a pair of electrical contacts arranged to be actuated by said armature only when it reaches a predetermined maximum amplitude of vibration in response to excitation thereof at its natural frequency for initiating operation of said closure mechanism, whereby said relay is effective to operate said closure mechanism in response to the electromagnetic induction in said receiving coil of a voltage of predetermined minimum value and of said fixed frequency for even a small por 5 tion of said cycle of operation of said transmitting means.

4. In a sensitive signalling system for effecting the actuation of a closure operator from a moving vehicle, the combination of, a multi-turn receiving coil mounted stationarily in the path of the vehicle, a frequency responsive relay having an actuating winding connected to said receiving coil, the respective impedances of said receiving coil and actuating winding-being of the same order of magnitude to insure a maximum energy. output to said actuating winding, a closure operating mechanism including an electric energizing circuit arranged to be completed by said relay, a transmitting coil carried by the vehicle and disposed for passage closely adjacent said receiving coil as the vehicle progresses along its path, and means for continuously exciting said transmitting coil for a relatively long interval of time with an interrupted current of the fixed frequency to which said relay responds.

5. In a vehicle controlled closure operating system, a receiver embodying a multi-turn receiving coil arranged for electromagnetic linkage with a relatively moving transmitting coil, a frequency responsive relay embodying a vibratory reed and an actuating winding therefor connected to said receiving coil, said winding being eifectve to move said reed through a predetermined maximum amplitude of movement only when excited with a current of selected frequency, the impedance of said receiving coil and actuating winding being substantially equal, whereby maximum power is supplied to said actuating winding, a closure operating mechanism, and means for initiating the operation of said closure operating mechanism in response to said maximum amplitude vibration of said relay reed.

EDGAR D. LILJA.

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