US2244234A - Electric heater - Google Patents

Description

JHM 3, 1941- P. a AsHToN ErAL 2.244.234

ELECTRIC HEATER Filed May 9, 1939 2 Sheets-Sheet l xNvENToRs PH/L/P '5. `/flsHTo/v,

AND 5'/ EY L WoLFso/v, @Wj/fromm June v 3, 11941. P. E. "ASHTQN :TAL

ELECTRIC HEATER Filed May 9, 1939 v2 Sheets-Sheet 2 lNvENToRs PHIL/P E. .AsHTo/v,

L. WoLFsa/y,

AND slp SYM? RNEY Patented June 3, 1941 ELECTRIC HEATER Philip E. Ashton and Sidney L. Wolfson, Meriden, Conn.; said Wolfson assignor to said Ashton Application May 9, 1939, Serial No. 272,554

(Cl. 21S-32) 11 Claims.

Our invention relates to devices in which heat is produced by the passage of an electric current through a suitable resistance element and in which the circuit is broken automatically when the heater element has reached a predetermined temperature.

One object is to provide a construction that can be embodied in a form suitable for a socalled cigar or cigarette lighter of the type in which there is a socket or holder for a removable heater carrying member or plug Another object is to provide a construction in which there is a minimum danger of accidental and complete separation of parts when the circuit is broken.

Another object is to provide a device which can be heated and reheated repeatedly without the necessity of waiting a long time between periods but in which the heating is always subject to automatic thermostatic control.

Another object is to minimize the danger of burning out the heater or running down the battery.

Another object is to prevent overheating of the plug knob or handle.

Another object is to provide a construction that is reliable and can be made economically.

Other advantages will be discernible, to those skilled in the art, on reading this specification.

Fig. 1 is a longitudinal sectional view of a device embodying our invention in its preferred form, the parts being in the normal inactive position with the plug fully inserted in the socket but the switch open."

Fig. 2 is a partial section and partial side view showing the switch closed.

Fig. 3 is an end view of the socket contacts and showing a section of the socket on the plane of the line 3-3 of Fig. 2.

Fig. 4 is a side view showing the plug partly inserted into the socket but not in the normal carying position.

Fig. 5 is an end View of the heater coil with the rim of the holder in section.

Fig. 6 is an exploded side view and partial section of parts of the plug member.

Fig. 7 is a cross sectional view of the rear end of the sliding switch member on the plane of the line 1-1 of Fig. 6.

Fig. 8 is an end view of the cup member of the body of the plug.

Fig. 9 is a view of the inner face of parts of the front end of the sliding switch member.

Fig. 10 is a section and side view of the socket abutment contact.

Fig. l1 is a side view of the rear portion of the sliding switch member.

Fig. 12 is a sectional View of an insulating cup of the plug.

Fig. 13 is a fragmentary side view and section of a modified detail in which the thermostatic latch and the switch are independent of each other.

In the preferred form there is a stationary socket or holder which has circuit terminals and a removable plug-in device carrying the heater element or igniter and having contacts slidably connected together, one of which, when the plug is in place in the socket, normally engages one of the socket terminals and the other of which is spring pressed but adapted to be moved to engage the other socket terminal when closing the circuit. A thermostatic bimetal latch holds the movable contact in closed circuit position and releases it when the heater has reached its desired maximum temperature.

The socket is designed to frictionally hold the plug and has a xed contact to be engaged by the heater contact and a thermostatic latch for receiving the switch contact of the movable switch member. This latch also preferably but not necessarily carries current.

The plug is composed of two relatively movable parts with a spring between them. One part includes an insulating body carrying the heater element and its contact and the other part slides in the body and includes a knob connected to the other plug contact which acts as a switch member to engage a socket latch contact.

The socket I0 is preferably cylindrical so that the plug may be inserted at any rotary position and may be rotated in it. The socket wall is provided with a spring tongue II to assist in holding the plug in the socket. A spindle I2 serves as one of the external terminals and the sleeve I3 insulated from it by insulating tube I3 serves as the other outer terminal. A clamping member I4 may be screw threaded on the sleeve and serves to draw the flange I4 against the outer surface of a panel I4 or other support when the front end of the member I4 engages the inner surface of the support.

Inside of the socket are the two terminal contacts I5 and I6 each in the form of a spider stamped from sheet metal with its central part ilxed and insulated from the other by washer Il and tube I3. Contact I5 is mounted on the sleeve I3 and contact I6 is mounted on spindle I2 to which the circuit wire is directly or indirectly secured.

Contact Iii has a number of pairs of inturned lugs or ears l5 with inclined edges to receive the thrust of and to centralise the rim of the plug Contact Iii. Contact l5 is formed of thermostatic bimetal with spring fingers iii adapted to serve as latches to receive and hold the edge of the switch Contact I of the plug when it is pushed fully in to close the circuit.

It will be seen that with this type of construction it is practical to assemble both of the socket terminal contacts into one complete sub-assembly before placing them in the socket. This facilitates adjustment of the thermostat as the complete sub-assembly may be tested and adjusted as needed prior to assembly in the socket and while the thermostat is easily accessible.

The plug body consists of the insulating sleeve 2S, the cup member 2l, the stem 22 and the heater coil carrying parts or heating unit, which will be described later. riveted in the bottom 2l of the cup 2|. 'Ihe sleeve fits smoothly in the socket and has a groove tc receive the tip of the spring tongue IVI and thus assist in holding the plug in the socket in the only position it is supposed to occupy when installed in the socket.

The heater coil carrying parts or heating unit comprises cup contact I8, insulating washers 23, reinforcing washer 23', heater coil 24, screw stud 25 and nut 25. The outer end of the heater coil M is preferably welded to the inside of the rim of the cup Contact, and the inner end of the coil is secured, preferably by welding, to the rear end of screw stud which is insulated from the cup contact by means of insulating washers 23. The reinforcing washer is backed up by nut 25' which fits the screw stud and when tightened up thereon serves to hold the above mentioned parts in a rigid assembly which by means of the forwardly projecting end of the stud may be mounted on stem '22. If desired this heating unit may be left readily detachable from 22 for replacement purposes or the stem 22 may be staked adjacent nut 25 and after receiving the heating unit so as to lock it in place.

The rim of the contact cup i8 is preferably rounded and its front or inner end abuts against the inclined edges of the lugs `I5 on which it may be turned or twisted so as to keep the contact surfaces clean and bright.

The washers 23 and 23 and the bottom of the contact cup are provided with perforations E@ to permit circulation of air to assist in quickly heating the thermostatic fingers when desired. The socket also has perforations or openings 2l adjacent the thermostatic fingers so as to allow for the circulation of air to assist the ngers to cool off quickly when the eater is withdrawn.

The latch member has a lug I6 which eX- tends into a notch I'l in the insulating washer, and the washer has another notch Il which holds the lug it formed in the base of the socket so as to prevent relative rotation. This lug Ill also passes through a hole I5 in the base of terminal contact i5 which may thereby also be held against relative rotation.

The switch contact I9 is a hanged part of the sleeve 28 which has arms 29 which slide inside of the cup 2l and through holes ZI in the bottom of the cup. The ends 29 of the arms are passed through slots 3Q in the flanged disc 3B and are then turned or riveted over. A sleeve 3l is secured directly to the cup or disc 30 by the rivet 32 and washer 32'. The knob 33 is screwed onto the sleeve 3l. A spring 34 is interposed The stem 22 is c between the bottom ZI of the cup 2l and an insulating cup 35 in the disc 3h. This spring is strong enough to hold the parts of the plug in the position of Fig. l when inserting the plug into the socket. If the cup 35 is omitted, the spring wire should be of sufficient cross section to avoid excessive heating up if the current passes through it.

When it is desired to close the circuit and energize the heater, the knob 33 with the attached disc 3i), sleeve 23 and contact I9 are pushed in until the switch flange i9 interlocks with the tips of the fingers iii which holds the circuit closed. The coil then heats up and after a few seconds (say 6 to 8) the thermostatic iingers IG become warped outwardly by the heat from the coil or from their resistance to the pase sage of current or both so as to release the switch contact member i9 and open the circuit and permit the spring Sli to push the switch contact member and attached knob to normally open circuit position. This does not disturb the body of the plug with its heater which however can now be withdrawn for use.

The sleeve 28 may have a spring tongue 23 to ensure contact with the inner wall of the cup member 2I and to prevent rattling. The cup member 2l may have spaced ribs Elx on which the sleeve 28 slides.

By forming the contact spider from the socket, the manufacture is simplified and cheapened and at the saine time a more rugged contact is provided. 'lhis form of contact is also less likely to get clogged with ashes. The latch fingers iii being exposed at 'the outer wall of the socket through the openings 27, it is possible to bend and adjust them so that they will work properly.

The construction is such that the circuit is normally broken automatically after it has been closed manually and the plug left to heat. In case an effort is made, intentionally or through ignorance, to hold the plug in the closed circuit position, the thermostatic latch lingers I6 will distort b-y the heat created by the coil and immediately leave the rirn i9 of the switch member and break the circuit. As soon as the fingers cool sufficiently to allow them to contract and engage the rim I Q of the switch member, they will immediately expand again and open the circuit before the heater gets dangerously hot. This breaking and making the circuit may be continued indenitely without overheating the heater coil.

Although it is preferred that the bimetallic latch fingers it shall also carry current and therefore act as members of the switch for controlling the circuit, one or more latch fingers 40 might be electrically insulated as in Fig. 13 and a supplemental contact Iii provided in the socket to be engaged by the sliding contact I9 of the plug and thus form an electrical connection with the stem i2. With this modified construction however it would be possible to hold the plug in circuit as the breaking and making action described in the previous paragraph would be absent.

It will be seen that the direct thrust of the plug when inserted into the socket is taken by the engagement of the rim I of the heater against the heavy lugs I5' which are so shaped as to accurately center the rear end of the heater in the rear of the socket when the body or insulating sleeve 20 is in the socket. When the plug is in the socket the heater is held in this l5 separately innermost position at all times by the spring finger II which engages in the groove 20' of the insulating sleeve 20 except when the plug is removed for use.

When the lighter is in its proper closed circuit position the thrust of the spring 34, tending to move the sliding switch assembly forward is held by the engagement of the rim I9 against the latches I6 and reacts through the cup 2I, stem 22 and the associated parts of the heating unit against the terminal I so that the spring pressure is utilized to hold the two plug terminals I8 and I9 in firm contact with the cooperating terminal contacts of the socket I5 and I6.

The thermostatic latch arms are so proportioned that outward distortion caused by rearward or forward movement of rim I9 is well within their elastic range and causes no damage or setting. Excess rearward travel of the switching member is arrested by engagement of the rim 30" of cup 30 with the forward face of the bottom 2|" of cup 2l.

It will also be noted that the circuit is completed and broken between the thermostatic latches I6 and the switch contact rim I9 at some distance from the heater coil. There is therefore no chance of ionizing the arc formed when the circuit is broken as would be the case if the circuit was broken at the rim of the heater cup I8 adjacent the red hot coil.

By keeping the thermostatic members out of conductive relation with the heater per se, with an intervening air space and with the insulation I1 between the bases of the spiders I5 and I6, we avoid the objectionable overheating or soaking of the latches. They are therefore free to cool oil rapidly when the heater is removed. It will be understood that the latches are heated by resistance, convection and radiation and not by conduction,

The proper way to energize the heater is to press on the knob so as to thrust the sliding switch member I9 into interlocking engagement with the thermostatic latches I6 and then release the knob so that the rim I9 will be sure to engage the rear faces of the nclines I6. If the knob is held pressed in, the latches may not engage the rim unless the latches are bent inward enough to engage the outer wall of the cylindrical part of the switch member.

The plug has only one proper position in the socket as shown in Figs. 1 and 2, the knob and switch member I9 being slidable in the body of the plug to open and close the circuit. It will be seen that the spring 34 which serves to move the switch member to open the circuit is located as far as possible away from the heater so that it will not be damaged by the repeated heating of the coil 24.

The heating action of the coil 24 is highly effective in controlling the operation of the thermostat although neither the coil nor the cup I8 touches the thermostatic member since air freely circulates around and through them within the sensitive area of the thermostatic latch fingers.

We claim:

1. The combination of a socket and a plug, the socket having an electric terminal and having a stationary contact in the bottom and a number of thermostatic latches arranged around the axis of the socket nearer to the mouth of the socket than the stationary contact and having a circuit terminal, the plug having a body removably supported in the socket, a heater element fixed to said body for engaging the stationary contact, and a spring pressed member slidably supported in said body and having a projecting conducting rim electrically connected to said heater element and adapted to be pressed inwardly for electrically engaging and interlocking with the latches when the slidable member is moved inwardly beyond its normal position of rest, the spring acting to press the heater element against the stationary contact when the rim is interlocked with the latches.

2. A plug type heater member having an insulating body with a cup secured therein and a projecting stem, a heater element with a resistance coil mounted on said stern, and having passages for the circulation of air through the element and around the stem and a contact sleeve slidable in the body cup toward and from the heater element, a spring for moving the sleeve away from the heater element and a knob for moving the sleeve against the pressure of the spring.

3. A plug type heater member having a body with a projecting stern, a heater cup with a resistance coil mounted on said stem, and having passages for the circulation of air through the cup and around the stem and a Contact sleeve slidable in the body around the stem and against the heater cup, a spring for moving the sleeve away from the heater cup and a knob for moving the sleeve against the pressure of the spring.

4. A socket and plug combination in which the socket has a centering abutment contact at the bottom and a thermostatic latching contact extending nearer to the front of the socket and in which the plug has a heater rim at its rear to engage the centering abutment contact, a slidable contact for interlocking with the thermostatic latching contact, said plug comprising a housing fitting in the socket and -a spring in the housing pressing the heater rim against the centering abutment contact in the socket when the slidable contact is interlocked with the thermostatic latching contact, the housing and heater rim having only one operable position in the socket, retaining means on the socket yieldably engaging the housing and holding it in said position and a knob attached to the sliding contact for actuating the same against the spring.

5. A heater plug comprising a stationary heater part and a slidable part, the stationary part including a tubular housing, a cup shaped member fixed to the housing, a stem fixed at one end to the cup member and a heater coil fixed to the other end of the stem and spaced away from the cup member, the slidable part including a sleeve slidable in the cup shaped member and having a projecting flange portion surrounding the stem and a knob fixed to the opposite end of the sleeve, and a helical spring interposed between the cup shaped member of the stationary part and the slidable part for maintaining them in normal relationship.

6. A heater plug comprising a tubular housing, a cup sh-aped member fixed to said housing in one end thereof and having openings in its bottom end, a disc slidable in the other end of the housing and spaced from the bottom end of the cup, a. sleeve member slidable in said housing and cup member and having a contact portion outside and adjacent the edge of the cup member and having extensions passing through said openings and secured to said disc, a stem extending outwardly of said cup shaped member and having one end xed to the bottom thereof, a

heater coil xed to the other end of said stem and spaced from said contact portion, a coil spring for maintaining the parts in spaced relationship and a knob ixed to said disc in alignment with the axis of said spring for sliding said sleeve against the action of said spring.

7. In -a cigar lighter having a socket with spaced contacts, the plug comprising a tubular insulating body, a cup member fixed in one end thereof and having openings in its bottom end, a heater coil Xed to the cup member and spaced therefrom, a slidable disc closing the other end of the tubular body, a slidable sleeve enclosed in the housing and having a flange portion in the space between the cup and coil and normally adjacent the outer edge of the cup member and having extensions passing through the openings in the bottom end of the cup member and xed to the slidable disc, a spring in the housing between said bottom end and said disc for normally holding said slidable sleeve with its ange in normal position and a knob member xed to the disc for moving said sleeve against the action of the spring and into engagement with -a contact in the socket.

8. A cigar lighter plug having a cylindrical body for insertion into a socket, an igniter member secured to the body and having a contact rim projecting from one end thereof, a contactcarrying sleeve slidable in the body and having a Contact rim movable between the body and the igniter member, a manually operable knob attached to the sleeve and projecting from the body at the end opposite the igniter member, a spring pressing the contact carrying sleeve and contact rim away from the igniter member and means for limiting the sliding movement of the sleeve and contact rim.

9. A cigar lighter comprising a socket having a contact and also -a spring latch member at one side of the socket, a plug member insertable into the socket and having an igniter unit with a rim for engaging said contact, said rim being of such a diameter as to cause it to engage the contact when the plug is inserted in the socket, spring means for resiliently holding the plug member in the socket, and a switch member slidable in the plug member and having a part adapted to interlock with the latch member.

10. A cigar lighter comprising in combination a socket having two contacts, one of which is a latch located in front of the other contact, a plug, a heater carried on the rear end portion of the plug, a rim around the heater contacting the rear contact of the socket, a second contact carried by the plug in front of the heater and adapted for engagement by said latch and slidable relatively to said plug, and a spring cooperating with said plug and its second contact and adapted on release of the latch to move the second plug contact forwardly, said rear socket contact including inwardly bent longitudinal wall portions adapted to serve also as abutments against which the heater rim is held by said latch and spring.

1l. A cigar lighter comprising a socket having two contacts, a rear contact including a plurality of inwardly bent longitudinal wall portions, a plug longitudinally slidable in the socket for insertion and removal, a heater on the rear end of said plug, a heater rim engaging said inwardly bent wall portions and carried by said plug, cooperative contacts on the plug and socket in front of the heater, said inwardly bent longitudinal wall portions having inclined edge portions adapted to aid in centering said rim.

PHILIP E. ASHTON. SIDNEY L. WOLFSON.

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