US3034026A

US3034026A - Time delay device

Info

Publication number: US3034026A
Application number: US789101A
Authority: US
Inventors: Lichtgarn Fred
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-01-26
Filing date: 1959-01-26
Publication date: 1962-05-08
Anticipated expiration: 1979-05-08

Description

May 8, 1962 Filed Jan. 26, 1959 F. LICHTGARN TIME DELAY DEVICE 2 Sheets-Sheet 1 FIG.b

y 1952 F. LICHTGARN 3,034,026

TIME ,DELAY DEVICE Filed Jan. 26, 1959 2 Sheets-Sheet 2 FIG.8

IN V EN TOR.

BY QMQL Lgu m 3,fl3 ,l}26 TE'MIE DELAY DEVEQE Fred Lichtgarn, 34 Franklin St, Northlalre, ill. Filed .lan. 25, 1 59, Ser. No. 789,101 4 Claims. (QB. 317-4175) This invention relates to electro-mechanical time delay devices. At present, these devices are operated by air or liquid leakage, by clock type movements, or by thermal means.

This invention adds a new method to the above in that the alternations in an AC. current are utilized in a novel manner. Alternating current rapidly changes from maximum to almost zero and back to maximum. In 60 cycle current this happens 120 times a second and produces the characteristic humming sound. If A.C. current is used to energize the coil of a solenoid, for instance, the plunger will be magnetically pulled in and released 120 times a second. During the very brief intervals when the current is zero the plunger is free of magnetic attraction. Therefore, if an external rotative force is applied to the plunger, it will slowly rotate in its sleeve during the brief interval that the magnetic flux is zero. However, the plunger cannot rotate very far before the current increases to a maximum and so the plunger is forced to stop its rotation. Thus we have a condition of stop and go that can be used for time delay purposes. 1 term this action A.C. slip." It is a sort of controlled and controllable mechanical slippage or creep.

The A0. slip effect depends on the strength of the external rotative force, on the magnetic efficiency of the electro-magnetic design, on the amount of electrical shading present, on the amount of friction, on the amount of lubrication and other similar contributing factors.

By a combination of the variables above and through the use of gearing, time delays from seconds to minutes and longer may be obtained. Also, by controlling the magnetic flux intensity by an external variac a conveniently adjustable time delay control is possible from a remote point.

It is to be understood that the AC. slip effect is not confined to rotetive designs but may be adapted to other mechanical configurations.

Since it now takes time for a plunger to rotate or a shaft to slide or a disc to rotate, we can couple the moveable parts to any other suitable mechanism and thereby impart a time delay to the control of that mechanism, switch or valve.

The main objective is to provide another means of time delay which operates by a new principle.

Another objective is to make a time delay device that has relatively few parts.

Another objective is simplicity: only one moving part.

Another objective is a low cost device.

Another objective is to make a time delay device that can be varied electrically-and from a remote point.

Another objective is to make a device that is rugged.

Another objective is to make a device that is relatively vibration proof.

ther objects and uses will be apparent from the following description and drawings.

Referring to the drawings,

PEG. 1 is shown to simply and clearly illustrate the working principle of the invention.

FlG. 2 is a cross-section view of one variation utilizing flat frictional surfaces.

MG. 3 is a cross-section view of another solenoid variation utilizing a tapered cone for the frictional surfaces.

aaaaazs iatented May 8, 1932 FIG. 4 is a cross-section view of another mechanical and electrical variation utilizing fiat frictional surfaces and a conventional electro-magnet. It is not a solenoid.

FIG. 5 is a cross-section view of another variation which utilizes an electro-rnagnet Whose polepiece is in contact with a rotatable disc made of a material which can be attracted by an electro-mag'net.

FIG. 6 is a diagrammatic view of another variation in which magnetized bearings grip a shaft moving along the path of the arrow. A force against the shaft causes it to creep slowly through the magnetic bearings.

FIGS. 7 and 8 are top and front views of a complete working apparatus which can produce a time delay in the controlled electric circuit.

Although the above is shown to clearly illustrate a few possible variations, it is understood that many other Variations of utilizin this new principle are entirely possible to anyone skilled in these arts.

Referring again to the drawings, in FIG. 1 We have a conventional solenoid in cross section. If the variac 6 is adjusted to apply full voltage to coil 1 the plunger 2 will be tightly held in its normal position in frictional contact with the polepiece 7 and be almost immovable. Now the rubber band 3 is fastened to the end of the plunger 2 and twisted manually until a positive degree of tension is exerted rotatively when the rubber band is looped over pin 4. The tension will probably not be strong enough to cause plunger 2 to rotate, but if the variac 6 is slowly adjusted to lower the applied voltage on the coil l and thus the frictional pull against the polepiece '7, a point will be reached Where a slight humming sound will be heard. it the plunger 2 is now carefully watched one can see a very slowly creepage in the plunger as it rotates by AC. slip effect. Each time the current goes to zero the plunger moves (rotates) very slightly, but before it can move any distance the current comes on to keep it in place. Thus for each cycle of the current the plunger is impelled by the rubber band to creep a little. This is the time delay. Adjusting the variac will provide faster and slower rotation. When the rubher band unwinds the rotation will stop of course. Instead of the rubber band we may have any external source of energy such as gravity, an electric clock motor, a spring or even compressed air. One design could be made where a clock type electric motor will be operated in a semi-stalled condition to supply the energizing force necessary to cause the AC. slip effect to occur.

In FIG. 2 we have a solenoid construction also, where 3 is the electro-magnet coil, the plunger 11 has an integral face disc on it which is in frictional contact with stationary frictional face surface 10. The plunger does not quite touch the polepiece 9 because we want the full force of the pull to take place at the fiictional faces of plunger 11 and surface it). With more friction a slower rotative efiect can generally be obtained. In the conven tional solenoid only a limited amount of friction can be obtained. This design is shown Where an increased area of frictional contact is made available. Shaft 12 connects to the associated equipment to be controlled.

in FIG. 3 we have also a solenoid with a specialized cone shaped plunger 16 to provide increased frictional surface area when in contact with fixed frictional surface face 15. The plunger does not quite touch polepiece 14. The coil is 13 and the shaft 17 connects to associated apparatus. it is to be understood that the plunger ll: could be made of a permanent magnet or of a ceramic type magnet so that a sort of amplified A.C. slip can occur due to the mutual attraction and repelling effect of a permanent magnet when used in an AC. circuit.

In PEG. 4 we have an electro-magnet utilizing the full magnetic flux because it is a closed path. Coil 18 magattraction to take place at the frictional faces 19A and thus strongly attracting rotative disc 21 which is connected to shaft 22. Bearing 29 holds shaft so that disc 21. isparallel with faces HA.

In FIG. we have a regular electro-magnet with coil 23 and with extended polepiece 24 in contact with disc 25 which is made of any material attracted by magnetism. Shaft as is attached to disc 25 and rotates with it. If there is no current in coil 23 the disc will be free to rotate. But if current is applied to coil 23 the disc will be strongly attracted to the polepiece and the rotation will be retarded to a very slow rotation due to the AC- slip eifcct. The speed of rotation can be controlled by the strength of the current in coil 23. This then gives a controllable time delay to any equipment which may be attached to shaft 26.

In FIG. 6 We have a coil 27 magnetizing core fill and in turn

hollow polepieces

28 and 28A through which shaft 29 can travel. As shaft 29 is impelled by an external force along the arrow an A.C. slip effect occurs to re tard the free motion to a controlled slow motion which is time delay.

In FIGS. 7 and 8 we have a complete simple operating unit for illustrative purposes mounted on a base ill.

Electro-magnet. coil 36 surrounds solenoid plunger 37 and both are held in place by brackets Rod 38 is attached to plunger 37, and has a weight 39 held in place by set-screw 39A. Microswitch 34 controls the associated external circuit and also the coil magnetism of the electro-magnet 36. In use rod 33 is manually lifted as shown. This immediately causes switch 34 to close its contacts, coil 36 is energized and the external circuit is on. As the rod 33 and weight 3% slowly fall due to gravity and the A.C. slip etfect a time delay occurs so that the external circuit remains on for a predetermined time interval. The timing period may be adjusted by moving the weight 39A along the rod. 41 is a leaf spring which contacts the operating button in the microswitch. Bracket 33 holds switch 3d in place. 32 is the incoming connection block and 31 is the outgoing connection block for the electric current. As the rod slowly falls to reach the position shown in the dotted lines the switch is opened and the coil and external circuit is also opened.

Having thus illustrated the manner in which the principles of this invention may be applied, What is claimed is:

1. A variable time delay device comprising an electromagnetic-solenoid like structure with a hollow core having a fixed magnetic stop at one end, with a movable armature in said hollow core, with separately powered rotative means acting upon said armature and with other separately powered counter-force means also acting upon said armature to exert a force counter to the magnetic attractive forces generated by said electromagnet, with the said rotative means co-operative with the said counterforce means to cause said armature to momentarily free 4;, itself of both frictional restraint and residual magnetic restraint when said electromagnet is at its low point in the changing cycle of periodically varying electrical input so that said armature could then begin to rotate, and with the said rotative and counterforccs nullified when the said electromagnet is energized by an increasing power input in the said changing cycle, and With the rotative speed of said armature being dependent upon and controllable by the amount of electrical energy being fed into said electromagnet.

2. A variable speed timed delay clutching device comprising ari electromagnet having a hollow center, with an armature slidably and rotatively positioned in said hollow center, with said armature having a frictional face can tacting another frictional face attached to said electromagnet, with attachment means to couple an external rotative power source to said armature, with means to connect a periodically cycled varying power input into said electromagnet, with no armature rotation occurring when said elec omagnet is fully energized, and with a degree of rotation occurring when said electromagnet has a reduced magnetic strength due to said varying power input, and with the speed of rotation of said armature controllable by the overall amount of electrical energy fed into said electromagnet.

3. A variable time delay device comprising an electromagnetic structure having two extended polepieces, with a coil in between said pelepieces, with an opening extending through each said polepiece, with a magnetically attractive shaft completing the magnetic circuit and movable in openings, with means by which anexternal propelling force can be coupled to said shaft, with means to connect a periodically varying electrical input into said coil, and with the speed of movement of said shaft being controllable by the amount of electrical energy fed into said coil.

4. A variable time delay clutching device comprising an electromagnetic structure having an electrical coil around a corset magnetic material, with a bearing positioned in a gap in said core, with a shaft extending through said bearing, with a frictional face attached'to said shaft, with means for connecting said shaft to a means for applying a rotative force to said shaft, with said frictional face being magnetically attracted'to the abutting surface of said core when the said coil is energized by a periodically varying electrical input current, and with the rotative speed of said shaft being controllable by the overall power input into said coil.

Germany July 21, 1914