US2912626A

US2912626A - Electronic time delay relay

Info

Publication number: US2912626A
Application number: US580500A
Authority: US
Inventors: Gugelberg Hans Luz Von
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-06-20
Filing date: 1956-04-25
Publication date: 1959-11-10
Anticipated expiration: 1976-11-10
Also published as: GB791305A; FR1145378A

Description

1959 H. L. VON GUGELBERG 2,912,626

ELECTRONIC TIME DELAY RELAY Filed April 25, 1956 United States Patent ELECTRONIC TIME DELAY RELAY Hans Luz von Gugelberg, Maienfeld, Switzerland Application April 25, 1956, Serial No. 580,500

Claims priority, application Switzerland June 20, 1955 8 Claims. (Cl. 317-142) This invention relates to an electronic time delay relay which comprises a condenser whose change of charge determines the delayed action of the time delay relay, a source of direct current voltage for charging said condenser, and an electronic discharge tube having a control element which induces the tripping action of the time delay relay when the charge of said condenser reaches a definite value.

Objects of the invention are to provide, in an electronic time delay relay of the type stated, an ionization chamber for changing the charge of said condenser, a source of radioactive radiation disposed to emit prodnets of radioactive decay into the discharge space of said ionization chamber, and mechanically controllable means for controlling the quantity of the products of radioactive decay that penetrate into the discharge space of said ionization chamber, whereby the delayed action of the time delay relay can be adjusted to a desired value. Yet another object of the invention is an electronic time delay relay of the kind outlined, wherein said condenser is connected between the cold cathode and the starter electrode of a glow discharge tube, said ionization chamber is connected between said starter electrode and the positive pole of a source of direct current voltage provided to charge said condenser, and a current limiting resistor is provided through which the main discharge circuit of said glow discharge tube is fed from said source of direct current voltage.

These and other objects and the advantages of the invention will best be understood from the following description of specific embodiments when read in connection with the accompanying drawing in which:

Fig. 1 shows a simplified diagram explaining the principle of the mode of operation of the electronic time delay relay, and

Fig. 2 shows a modification of the means for controlling the quantity of the products of radioactive decay that enter the ionization chamber.

The electronic time delay relay shown in Fig. 1 is fed directly from the A.C. supply means through the terminals 1. The metal rectifier elements 2 provide the direct current of 200 to 300 volts required for the operation of the device, the D.C. current being adequately smoothed by a condenser 3 having a capacity of only a few microfarads. The positive pole of the D.C. voltage thus obtained is connected to one contact of a switch 4 by means of which the relay can be put into operation at will. For reasons that will be hereinafter explained a glow discharge tube 5 is provided comprising an anode 6, a cold cathode 7 and a starter electrode 8. The anode 6 is joined to the second contact of the switch 4 through the energizing coil 9 of an electro-mechanical relay. The latter is provided with two well insulated pairs of contacts 10 and 11 which are open when the winding 9 carries no current. The energizing coil 9 also serves as a resistance to limit the current and when .used in conjunction with the normal type of cold cathode tube 5 its ohmic resistance is a few thousand ohms. The

2,912,626 Patented Nov. 10, 1959 ice pair of contacts 11 across the terminals 12 can complete the external load circuit which is to be opened or to be closed at the end of the desired delay period. The other contacts 10 serve to discharge the condenser 13 through the ohmic resistance 14, which has a value of a few hundred ohms, as soon as the glow discharge tube 5 fires and the external load circuit has been closed. The condenser 13 whose change of charge determines the delay period is located between the starter electrode 8 and the cold cathode 7 of the glow dis charge tube 5. The change in charge of this condenser 13 takes place through an ionization chamber, one electrode 16 of which is connected to the starter electrode 8 whereas the other electrode 15 is connected to the main switch 4. The

electrodes

15 and 16 consist of two metal plates of suitable shape and of a few square centimetres superficial area, well insulated the one from the other, and exposed to the free atmosphere. The mean distance between the two

plates

15 and 16 may be between one and five centimetres. This ionization chamber replaces the normally used variable ohmic resistance through which the condenser 13 is gradually charged.

To render the space between the

plate electrodes

15 and 16 conductive for the discharge of an electric current, a source of radioactive radiation 17 is arranged in close proximity thereto. This emits chiefly alphaparticles (helium nuclei with two elementary positive charges) into the discharge space between the

plates

15 and 16. Preferably the source of radioactive radiation is a preparation containing plutonium, radium, or actinium attached to an arm 18 made of metal or an insulating material and facing the discharge space. Plutonium, radium, or actinium are suitable radioactive materials for the purpose in question because their half-value period is sufiiciently long and the alphaparticles emitted have only a limited range of not more than a few centimeters in air at atmospheric pressure. The degree of ionization in the discharge space can be controlled by simple means. As shown in Fig. l the arm 18 may be mounted on a rotatable spindle 19 which allows the distance of the source of radioactive radiation 17 from the discharge space to be varied. Owing to the limited range of the alpha-particles ionization of the air space between the

plates

15 and 16 becomes less as the radioactive preparation 17 is swung further away.

An alternative form of construction for controlling the number of alpha-particles emitted by the radioactive source 17 that penetrate into the space between the two

electrodes

15 and 16 is shown in Fig. 2. This arrangement differs from the one previously described with reference to Fig. 1 inasmuch as the source of radioactive radiation 17 is mounted on a bracket 18 which is fixed in relation to the

plate electrodes

15 and 16. However, a profiled disc 20 is mounted on a rotatable shaft 19 in such manner that it can be interposed to a greater or lesser extent, at will, between the radioactive source and the

plates

15, 16. Since the alpha-particles emitted by plutonium, radium, or actinium have too little energy to penetrate deeply into solids the profiled disc acts as a shutter by means of which the discharge space of the ionization chamber can be controllably screened from the rays of the radioactive preparation 17. The more the radiation from the source 17 is cut off the smaller will be the degree of ionization of the air in the space between the

plates

15, 16. The shaft 19 may be provided with a control knob for turning the shaft 19 with reference to a calibrated scale. By giving the disc 20 a suitable profile any desired functional relation between the subdivisions of the scale and the degree of ionisation can be established.

When the switch 4 (Fig. 1) is closed the plate electrode 15 will assume the full positive D.C. voltage dealpha-particles thatreach the ionisation chamber.

livered by the rectifier elements 2. On the other hand, the plate electrode 16' will"b'e"substantially at the same potential asthatof "thecath'ode 7 since'the capacity of the condenser 13 of say 10,000 lL/Lf. is substantially greater than the capacity between the two plate electrodes .15 and lfifwhicli' may'teer the order of onlya"f ew ,u Lf. The starterelec'trode"8 is therefore at nearly'the same potential as the'cathode T'and the cond'ense'r13 will have practically no char e." No discharge "takesplacebetween theano'de 6 and the cathode'7 so that the energizing 'c'oil 9' ofthe relay remains de energize'd and'th'e contacts and 11 remain open. "Owing to the pene- (ration of alpha-particles emitted by the radioactive some 17 into the "discharge space between" the plate electrodes and 16the 'air between the" plates" will be ionized and an" electric cirr'rent "will pass" between the v two plates and1h'caiisingthecondenser13'to re- 11 soas to complete the external load circuit which is connected to the terminals 12. ,'At the same time the contacts 10 close likewise and allows the condenser 13 to discharge rapidly through the resistor 1 The connections thus established will be maintained so long as the switch4 remains closed. As soon as the switch 4 is opened the main discharge through the glow discharge tube 5 will cease, the contacts 10 and11 open, and the position shown in Fig. 1 will be 're-established, the time delay relay being ready for renewed operation.

The time delay, that is to say the *time that elapses from the closing of switch 4 to the moment the glow discharge tube.5 fires, can be made to be independent of any fluctuations in the voltage of'the AC. supply means. The starting voltage at whicha spark occurs betweeen the starter electrode 8 and the cathode 7 does not in any way depend upon the potential difference between the cathode 7 and the anode 6 in a glow discharge tube. Moreover, the weak electric current that passes between'the

plate electrodes

15 and 16 of the ionization chamber can be made to be entirely'independentof fluctuations in the DC supply voltage by operating the ionization chamber within the saturation range ofits current-voltage-characteristic. To ensure-that this is so the potential difference between the-

plate electrodes

15 and 16 need only'be maintained ata saturation value during the whole period'that the condenser 13 is being charged. Assuming that the potential difference between the

plate electrodes

15 and 16 exceeds 150 volts, at a mean distance between the plate electrodes '15 and 16 of about one-to two centimetres, the current flow will be substantially the saturation current which does not depend upon the applied voltagebut'only upon'the position of the shaft 1% which-controls the number of Once the'position of the shaft 19 has been set the electrical discharge between the-

plates

15 and 16 will be maintained at a'constant level and the voltage acrossthe condenser 13 will increase proportionally-to theelapse of time. The proportionality factor of this rise of potential can be adjusted to any desired value by means of the shaft 19 whose angular position can be indicated by a scale which can be directly calibrated in units'or" time delay. 1 i

By'giving the electrodes 15 and 1-6 a suitable shape becomes withincerta'in'limits practically"independent 0f 5. The" invention as recited in'claim 1, wherein active decay into said ionization chamber.

variations in atmospheric temperature and pressure. To satisfy this requirement the electrodes which enclose the ionizationspacemaybe-curvedordisposed at an angle relative to each other instead of being embodied in fiat parallel plates.

According to the activity of the source of radioactive radiation 17 the electrical discharge current between the

electrodes

15 and 16 may be of the order 10-' to 1 0 amperes. Currents of this magnitude will charge a condenser 13 of-"10,000 [.L/Lf. to volts in the course of 10 to 10 seconds. It follows that the electronic time delay relay according to theinvention 'hereinbefore described is'capable'of giving delays ranging between a few seconds to over a day although its action relies upon an"extremely"cheap' and small'condenser 13. Shorter delays can be readily obtained simply by using a condenser 13 of even smaller capacity. However, the electrical components which primarily control the electronic delay action must have the required high leakage resistancewhich according to the'time delay that may be desired should range between 10 and 10 ohms. This applies more particularly to the control'e'lement 8 of the valve 5. Moreovenif the minimum power output delivered by the valve 5 to the'windi'ng 9 of. the electromechanical relay is required to be at least one hundred milliwatts the necessary high leakage resistance can only be obtained by using a glow discharge tube witha cold cathode 7 and a starter electrode 8. Hotcathode valves fail because either their operating voltages are too low or because their grid leakage currents are too high.

The invention is not limited to the particular embodiment's here shown and described. Various modifications maybe made in the electronic delay relay withoutdeparting from the spirit and scope of the invention'as set forth in the following claims.

'I claim: o

1; An electronic time delay relay for closing relay contacts in an electric circuit comprising a source of direct current, an energizing coil connected in series with said current source for closing the relay contacts, an electronic discharge tube connected in series with said energizing coil, said tube having a control element, condenser means connected to said control element to cause said tube to be conductive when the charge on said condenser means reaches a predetermined value, an ionization chamber having spaced electrodes connected in series with said condenser means,-a source of radioactive radiation adjacent said ionization chamber I for emitting products of radioactive decay within said chamber to develop a progressively increasing charge onsaid condenser, and mechanically adjustable means for controlling the quantity of the products of radioactive decay that penetrate into said ionization chamber so that the delayed action of the time delay relay can be adjustedto adesired value.

2. An electronic time delay relay as defined in claim 1 wherein said condenser means has a capacity on the order of 10,000 ref.

3. The invention as recited in claim 1, wherein said mechanically adjustable means comprise a shutter movably disposed between said source of radioactive radiation and said ionization chamber.

- 4. The invention as recited in claim 1, wherein said mechanically adjustable meanscomprise an arm which can be moved with respect to the discharge space of said ionization chamber, and said source ofradioactive radiation is attached to said movable arm. 7 4

said source of radioactive radiation contains radioactive materials which emit alpha-particles as products of radio- *6. An electronic time delay relay for closing relay contacts in'an electric circuit comprising a source of direct current; an'energizing coil'connected in series with current source for closing the relay contacts," a glow discharge tube connected in series with said energizing coil, said tube having a cold cathode, an anode and a starter electrode, a condenser connected between said cold cathode and said starter electrode to cause said tube to fire when the charge on said condenser reaches a predetermined value, an ionization chamber having a pair of electrodes, one of said ionization chamber electrodes being connected to said starter electrode and the other chamber electrode being connected to a positive terminal of said direct current source, a source of radioactive radiation adjacent said ionization chamber for emitting products of radioactive decay within said chamber to develop a progressively increasing charge on said condenser, and mechanically adjustable means for controlling the quantity of the products of radioactive decay that penetrate into said ionization chamber so that the delayed action of the time delay relay can be adjusted to a desired value.

7. An electronic time delay relay as defined in claim 6 wherein said energizing coil functions as a current limiting resistor through which the main discharge circuit of said glow discharge tube is fed from said direct current source, and further including means for discharging said condenser upon the firing of said glow discharge tube.

8. An electronic time delay relay as defined in claim 7 wherein the geometric dimensions of the ionization chamber are chosen so as to cause said chamber to operate within the saturation range of its current-voltage characteristic.

References Cited in the file of this patent UNITED STATES PATENTS 2,360,721 Rose Oct. 17, 1944 2,549,058 Constable Apr. 17, 1951 2,567,928 Farmer Sept. 18, 1951 2,596,956 Nierman May 13, 1952 2,606,296 Simpson Aug. 5, 1952 2,615,063 Brown Oct. 21, 1952 2,760,080 Robinson Aug. 21, 1956 2,783,388 Wintermute Feb. 6, 1957 FOREIGN PATENTS 960,955 France Apr. 28, 1950