US1861288A - Thermostatic control - Google Patents

Description

May 31, 1932. D. WEILL 1,861,288

THERMOSTATIC CONTROL Filed Oct. 25, 1928 2 Sheets-Sheet 2 11 Ila/w y MQ W Patented May 31, 1932 PATENT OFFICE LEON DAVID WEILL, or PARIS, FRANCE THERMOSTATIC CONTROL Application filed October 25, 1928, Serial No. 315,087, and in Belgium October 28, 1927.

The present invention relates to apparatus for controlling a variable physical factor and, more especially, that of temperature.

One of the objects of the invention is to provide means operable to heat a space to a predetermined temperature and to then cease heating said space for a predetermined regulable time.

Other objects will appear in the course of the detailed description now to be given with reference to the accompanying drawings, in which:

' Figs. 1 and 2 show the temperature control device in diiferent operating positions. Referring to the various figures of the drawings, there is shown an electrically heated furnace a,-heating resistances 6 b for said furnace connected to a source of two phase current c,-a pyrometer or thermometer (l, provided with a contact or contacts (in the case of a mercury thermometer, one contact is always submerged-in the mercury, and the other, only when the temperature is, sufficiently high) ,a circuit 7 carrying a relay e in series which is fed with current from a battery or similar small source g,-a lever k controlled by a core extending into solenoid e and serving to close appropriate switches in a circuit j fed with current from source 0, or, if desired, from an independent current source,a relay I inserted in circuit and provided with an arm m serving to open and close a double contact switch n controlling the flow of current to a relay 0 adapted to open and close a switch or circuit breaker i in circuit with source 0 or a part thereof,-a first timing assembly p consisting of a hooked catch 17 adapted to engage with a corre sponding element m depending from arm m carrying switch a (arm m being actuated by arm m through the intermediary of a catch m a regulable timing mechanism p and an arm 2 to Le actuated by timing mechanism p ,and a second timing assembly u adapted to create a delay between the closing of circuit 0 and the release of element m whereby the inertia in the cooling of furnace a and thermometer d is compensated, and consisting of a regulable timing mechanism u", a hooked arm uadapted to engage with arm 17 and set ofl? timing mechanism u, and arm a adapted to be actuated by mechanism u during a time interval longer than that during which timing mechanism p functions, and a switch 0 adapted to connect relay Z to circuit 70 and thus maintain element m in closed position even after therelease of element m The device operates in the following man- As soon as the maximum temperature for which thermometer d is adjusted is reached, current supplied by battery 9 begins to flow in circuit 7, causing relay 6 to pull element It downward and close the circuit 7:: leading from source 0 to relay Z. The latter exerts a pull on arm m and on arm m through the intermediary of catch m bringing double contact switch n into conductive relation with the leads of circuit 12 and causing current to flow through relay 0 so as to open circuit breaker 8'. First timing mechanism 19 then comes into play to maintain switch 2' open long enough for the furnace to cool through the intermediary of regulable timing element controlling the length of time catch p continues to pull downward on element m The opening movement of arms m, m may be effected by springs, counterweights or equivalent elements opposing the action of catch p 30 In the course of operation it may happen that element m is released while arm m is still being pulled downward by element 10 thus causing heating circuit 0 to remain open too long a time. To remedy this difficulty, it sufiices merely toreadjust timing mechanism 19?. In case the furnace lacks sufiicient time to cool means must be provided for temporarily releasing arm m. This may'be'accomplished by hand by means of a switch 9 intercalated in circuit j or automatically by means of a switch adapted to be brought into action by element p as soon as the latter releases 7 arm m Timing mechanism p may be adjusted so 35 that arms m, m move away from relay Z at the same time to close switch 0, the latter occurring as soon as thermometer (1 opens circuit f. Preferably. however, circuit 0 should close somewhat before the release of arm m' to correct the heat inertia of the furnace and thermometer. The second timing mechanism u is effective to obtain this result and operates in the following manner: when element oscillates to engage with catch m first timing mechanism 2 acts on arm p to raise the latter and set off second timing mechanism u through the intermediary of element 'u which ,isdrawn upward by 32 Timing mechanism to then acts on element u to draw switch '0 over into contact with circut k which maintains arm m in closed position in spite of the fact that circuit a is open. After a predetermined time interval, which is larger than that during which timing mechanism. p operates, mechanism u. draws switch '0 back onto circuit j, the current furnished by 9 stops flowing in circuits 7 and k and arm m is released. In the event that the temperature of the furnace does not descend below the maximum value, contact is maintained by thermometer (1 while arm m is released by timing mechanism us action on switch '0. The catch on arm m, in such a case, will engage with element m of arm m and relays e and Z, switch n and circuit, breaker 0 will recommcnce functioning in the manner already described and will repeat their action until the desired temperature is obtained. If contrariwise, the temperature, as registered by the thermometer, falls below the maximum value before mechanism u has functioned to move switch '0 into contact with circuit j, the thermometer will cut off the flow of current in circuit 70, arm m will be released and move upward into position to be actuated when the temperature again rises above the maximum value. The timing mechanism u may also act, in the same manner as above on circuit 7 of the thermometer, thus preventing a new interruption for a certain period of the flow of energy from the source to the object a when circuit a controlled by timing mechanism p, has been closed again. v

If desired, the apparatus may be provided with a signalling system for indicating whether the maximum temperature has been attained or not. To this end, a lamp 1' is intercalated in circuit f or inserted in a special circuit 8 connected to circuit 0 and arranged to be opened and closed by arm 72.. Lamp 7' may also serve to calibrate the length of time that timing mechanism 1) cut heating circuit .0. To regulate mechanism 79. timing mechanism ,u is first temporarily eliminated, thermometer d is adjusted to the maximum temperature desired, and element p regulated so that arms m, m are released at the end of an interval, say of 40 seconds, after they have been closed. The furnace is then heated to the maximum temperature and elements 1", Z and p set in action. If it is found that lamp 1' remains lighted after mechanism 19 releases arm m timer p is readjusted to lengthen the non-heating interval. If, contrariwise,

lamp 9" is extinguished before arm m is released, mechanism p is readjusted toshorten the non-heating period. Once mechanism 1) has been adjusted, it is easy to set mechanism at to actuate switch '0 for a period longer than that during which mechanism p functions.

In the above example the period of the tim-' ing mechanism u, being the sum of the period of timing mechanism p plus a certainlperiod, is longer than that of said timing mec anism p but it may be understood that if the period of mechanism u starts at the end of the period of mechanism p, instead of at the beginning, it must not necessarily be longer.

It will be noted that one of the notable advantages in the present apparatus is the set ting off of the circuit-breaking mechanismi by a secondary circuit f fed from a battery or other relatively feeble current source. This saves the various contacts and permits a large number of makes and breaks to be made without serious deterioration of the various moving'and contacting parts.

What I claim is 1. A system of the class ing a main circuit including a main source of electrical energy and a heater operated by said main source; a-switch controlling said main circuit; a secondary circuit connected to said main source and including an electrically responsive device controlling the operation of said switch; an auxiliary circuit including a thermally'responsive element. an auxiliary source of energy and another electrically responsive device; means operable by said last mentioned device to control said secfor electrically connecting the same to said auxlliary circuit for a predetermined period of time.

2. A svstem of the class described comprising a main circuit including a main source of electrical energy and a heater operated by said main source: a switch controlling said main circuit; a secondary circuit connected to said main source and including an electrically responsive device controlling the operation of said switch; an auxiliary circuit including a thermally responsive element. an auxiliary source of energy and another electrically responsive device: means operable by said last mentioned device to control said secondary circuit: and a timing mechanism operable by said first mentioned electrically resnonsive device for electrically connecting the same to said auxiliary circuit for a predetermined period of time.

3. A svstem of the class described compris ing a main circuit including a main source of electrical energy and a heateroperated b said main source; a, switch controlling said main circuit; a secondary circuit connected to described comprisly'responsive device controlling the operation of said switch; an auxiliary circuit including a thermally responsive element; an auxiliary source of energy and another electrically responsive device; means operable by said last mentioned device to control said secondary circuit; a first timing mechanism operable by said first mentioned electrically responsive device to control said switch; and a second timing mechanism operable to electrically connect said first mentioned electrically responsive device to said auxiliary circuit and thereby put the same under the direct control of said thermal element for a predetermined period of time.

In testimony whereof I have signed this specification.

LEON DAVID WEILL.

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