US 3390909 A
Description (OCR text may contain errors)
July 2, 1968 s. w. NAGEL O VEN DOOR LATCH AND LOCK ARRANGEMENT 4 Sheets-Sheet 1 Filed April 28, 1966 FIG-2.
MOVABLE --o- LATCH LINK LOCK MEANS MEANS ASSEMBLY Filed April 28, 1966 July 2, 1968 9 G. w. NAGEL 3,390,909
OVEN DOOR LATCH AND LOCK ARRANGEMENT 4 Sheets-Sheet 2 FIG.8-
July 2, 1968 G. w. NAGEL OVEN DOOR LATCH AND LOCK ARRANGEMENT 4 Sheets-Sheet 3 Filed April 28. 1966- mGI United States Patent 3,390,909 OVEN DOOR LATCH AND LOCK ARRANGEMENT George W. Nagel, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., 21 corporation of Pennsylvania Filed Apr. 28, 1966, Ser. No. 545,967 8 Claims. (Cl. 292201) This invention relates to the type of oven adapted for high temperature cleaning of food soils, and is directed particularly to a latching and locking arrangement for securing the door of the oven cavity.
Both safety requirements and common sense dictate that the oven door of a heat-cleaning type oven be locked shut during the potentially dangerous portions 'of the heat-cleaning cycle, that is, whenever temperatures in the oven cavity are substantially above normal cooking temperatures.
This invention is concerned with a latching and locking arrangement in which the oven door is latched by physically moving a handle to a position in which the door is mechanically restrained from direct opening before the heat cleaning cycle temperatures are experienced, and in which the door is locked shut during the high temperature portions of the cycle. The locked shut condition means that the door is latched shut in the sense of being mechanically restrained from direct opening and that the option of cancelling the restraint (which is available while the door is latched only) is not available to the user. It is also considered a practical requirement that the locked condition for the door be automatically effected as the oven temperature rises into the heat cleaning range, and be automatically cancelled when the oven temperature falls below the range.
In general, the object of the invention is the provision of a rugged, effective, and reasonably inexpensive latching and locking arrangement satisfyin the above requirements.
The attainment of the general object in accordance with my invention was influenced by a number of practical considerations. For example, it is considered desirable to effect the mechanical latching as close as possible to the top of the structure framing the oven door opening. However, the space there is limited and is sub- -ject to high temperatures during the heat cleaning cycle. Accordingly, I locate the means for effecting the locking of the oven door at the rear of the range and locate the latching means at the front. Link means extend from the front to the rear to coordinate the function of the latching and locking means in accordance with the conditions existing. In a sense, my invention may be said to reside in the provision of an arrangement which coordinates these functions while using relatively simple and inexpensive parts, which takes advantage of relatively simple mechanical movements, and which is not readily subject to damage if improper operation is attempted.
In a currently preferred embodiment, a latching and locking arrangement according 'to my invention generally comprises: latching means located generally at the front of the range, lock effecting means located generally at the rear of the range, link means extending from the latching means to the lock effecting means and biased toward one position and movable toward an opposite position in response to operation of the latching means to a latching position, the lock effecting means including electrically-actuated means responsive to movement of the link means to the opposite position to move into a position obstructing the return of the link means to the one position, and responsive to movement of the link means back to the one position to move out 3,390,909 Patented July 2, 1968 of the obstructing position, and means responsive 'to oven cavity temperatures above a predetermined level to disable the electrically-actuated means.
While others have suggested that there is an important advantage in' mounting 'a latch mechanism for this type of range in the range body or door frame structure rather than in the door structure, with anarrangem'ent according to my invention the ,operating portion of the latch mechanism may take an elementary form and be mounted in the door. The movable part of. the latch means is of generally Z-shape in which one legis the operating handle which, when turned, rotates the bight .portion of the Z and turns the other leg into a latched position engaging keeper means secured to the oven door frame or other range structure. The movement of the latching bolt into a latched position is coupled through the link means to the lock effecting means at the rear of the range. The lock effecting means responds to the movement of the link, if electrical power is available to the range, by moving a locking pin into a position obstructing the return of the link means to an unlatched position. The lock pin may be moved out of its obstructing position relative to the link means by simply turning the latchinghandle back toward an unlatched position, unless electrical power is no longer available or the temperature of the oven cavity is in a range in which it is considered unsafe to permit the oven door to be opened. In this latter case, the thermal means responsive to the oven cavity temperature functions to disable that part of the lock effecting means which would permit the locking pin to be withdrawn from an obstructing position relative to the link means.
Since the latched and locked conditions are related to the availability of electric power to the range, my arrangement permits the oven door to be latched without the use of electric power and then be unlatched freely. It also permits the door to be latched when electric power is available and then be unlatched freely if electrical power is still available so long as the cavity temperature is not in the high range. If the oven door is latched while electrical power is available, and electrical power subsequently is not available while the door is still latched, the door may not then be opened. If the oven is at a high temperature when a power failure occurs, a fail-safe situation exists in that the door remains safely locked during cooling of the oven and until power is restored.
In addition to the foregoing advantages, my invention lends itself to an arrangement in which the latching means and linking means cooperates in a manner that unlocking torque applied under a locked condition of the oven door is not transmitted to delicate parts subject to being easily forced out of proper adjustment. That is, forces applied improperly through the manually operated latching means are transmitted directly to the oven frame structure rather than to the lock effecting means, or to the linkage means in a manner which could adversely affect the operating relationship of the parts. operated latching means are transmitted directly to the The invention will be described in connection with the accompanying drawing illustrating a currently preferred 3 corresponding to one taken along the line IIIIII of FIG. 1 and presenting a top view of the lock assembly and the rear part of the link means with the parts shown in a position corresponding to an unlatched condition;
FIG. 5 is a fragmentary vertical sectional view corresponding to one taken along the line V-V of FIG. 3 and illustrating the relationship of the bolt of the latching means relative to a part of the link means;
FIG. 6 is a schematic view in the nature of a force diagram illustrating the operating relationship of the latch ing, linking and locking means;
FIG. 7 is a fragmentary, enlarged rear elevation view of the lock assembly and the rear part of the link means located at the rear of the range;
FIG. 8 is a fragmentary end view, partly broken, of the lock assembly as viewed from the right of FIG. 7;
FIG. 9 is a fragmentary plan view of the lock assembly and the rear part of the link means;
FIG. 10 is a vertical sectional view of a part of a timing mechanism; and
FIG. 11 is a schematic view of a currently preferred electrical circuit for a range incorporating the invention.
RANGE AND OVEN STRUCTURE (FIG. 1)
The general exterior appearance of the illustrated domestic cooking range incorporating the invention is conventional. It includes an outer housing 10 supporting a top wall cooking surface 12 and a control panel 14 extending along the top rear of the range. The outer housing encloses a forwardly open oven cavity 16 provided with top and bottom heating elements 39 and 32, respectively, and various thermostatic means represented by part 34. The oven is adapted to be closed by the hinged drop door 18. A fixed handle 2!) extends across the width of the door near its top edge and is used for opening and closing the door during normal cooking operations. An operable handle 22 is mounted closely below the fixed handle. By rotating the handle 22 about a quarter turn, a bolt is turned up to project out of the top edge of the door and engage a keeper assembly 24 mounted on the oven framing structure.
It is noted that the latch means has all its movable parts carried by the door 18. The lock effecting assembly generally designated 26 is located at the rearof the range and is connected to function in accordance with the operation of the latch means by link means generally designated 28.
LATCH MEANSKEEPER (FIGS. 2-4) The keeper bracket 24 which receives the latch bolt 40 is mounted on the frame structure 36 which frames the oven cavity front opening. The bracket projects forwardly with the bolt-receiving opening 38 located over the top edge of the closed door 18. The bracket 24 comprises two nesting parts, the underlying one being secured by screws 42 to the oven frame structure 36, and the top one being adjust-ably secured to the underlying one. The forward edge 44 of the keeper opening is angled relative to the plane of rotation of the bolt 40 to provide a cam surface which the bolt engages when the latching means is operated to a latched position. This pulls the oven door 18 toward a sealed position.
LATCH MEANSOPERATING PARTS (FIGS. 2-4) The operating parts of the latch means carried by the door take the general form of a Zsh'aped crank pivotal about the axis of the bight portion 46 which is the connecting shaft between the operating handle 22 and the bolt 49. In an unlatched position with the door closed (FIG. 2) the handle 22 extends horizontally in one direction and the bolt 40 extends horizontally in the opposite direction. When the handle 22 is puShed downwardly at its right end (as viewed facing the oven) toward a latching position, the bolt 40 will be turned upwardly into the keeper opening 38 and move along the LINK MEANS (FIGS. 2-5) In the currently preferred form, the link means generally designated 28 includes: a rearwardly-biased drawbar 48 extending between the front latch means and rear lock effecting means 26; a 'bell crank 59 at the front end of the drawbar, the crank having the end of one leg 56b pivotally secured at 52 to the drawbar, and having the junction of its legs pivotally secured at 54 to the keeper bracket 24; and, a rear link 56 (FIG. 4) having one end pivotally connected to the rear end of the drawbar 48, the link extending at a right angle from the drawbar into the lock assembly structure 26 where it is mounted to pivot about a vertical axis.
The link means tells the lock effecting means 26 what position the latching means is in, and'under a condition requiring locking of the door obstructs the release of the latch. This works as follows: When the latching means is operated from its unlatched FIG. 2 position to its latched FIG. 3 position the bolt it turning through the keeper slot 38 engages the leg 50A of the bell crank and turns the bell crank about its pivotal securernent 54 to the FIG. 3 position. As the bell crank 50 pivots, its leg 50B pulls the drawbar 48 forwardly to place the extreme forward end 43A in a position to obstruct the movement of the bolt 40 back toward an unlatohed position. As is perhaps best seen in FIG. 5, the bolt may not be turned back to an unl atched position until the forward end 48A of the drawbar is retracted.
It is noted that the forward end of the drawbar, and the cooperating bell crank may take alternate forms to that shown. For example, the bell crank may be arranged to operate as a second order lever having a fulcrum at the one end, the drawbar being pivotally attached to the middle portion, and the end of the lever toward which the bolt moves in a latching direction having a forwardly directed part, lying at an acute angle to the lengthwise dimension of the lever, with the bolt moving in camming engagement with the inner edge of the forwardlydirected part to pivot the lever about its fulcrum and accordingly draw the drawbar forwardly. Or the drawbar and crank may be a rigid structure arranged with the drawbar restrained from lateral movement, and the same shape forwardly-directed part, also lying at an acute angle serving to convert the latching movement of the bolt to forward movement of the drawbar.
LATCH, LINK, LOCK OPERATIONAL RELATION- SHIP (FIG. 6)
The schematic view of FIG. 6 shows in simplified form this operational relationship. When the latching means is turned toward a latched position bolt 40 turns the bell crank 50 to draw the bar 48 forward against the force of biasing spring 60. The ear 62 at the rear end of the bar bears against the end of a lock pin 64 to deflect it from a centered position. With power available, the solenoid 66 is energized to retract the pin which then centers itself. This deenergizes the solenoid and the pin moves down past the bar to obstruct the return of the bar to its rearward position. The lock pin is also retractable out of an obstructing position by energization of the solenoid 66. The springs 68 represent forces biasing the lock pin toward engagement with the cooperating parts of the link means, and also biasing the lock pin to a yieldable centered position which permits it to be deflected one way and another as the rear end of the link means moves one way and another in accordance with latch movement.
The V-shaped element 70 shown as straddling the lock pin 64 is responsive to movement in either direction of the lock pin to close solenoid switch 72 momentarily when movement of the bar 48 causes fiexure in either way of the lock pin.,The thermostatic switch 74 is normally open and closes in response to a high oven temperature indicating a cleaning cycle is'starting. When it closes, the solenoid switch 72 and solenoid 66 are shunted out of the circuit so thatthe solenoid cannot be energized. In other words, the solenoid is disabled at high temperatures. v
The general operation of the latching and locking arrangement may now be readily appreciated with respect to its operation under various conditions. If the oven door is latched shut in the absence of electrical power to the range, the solenoid 66 does not retract the lock pin 64 away from the ear 62. Hence the pin end moves with the earratherthan moving into an obstructing position as the drawbar 48 is moved forwardly. It will be appreciated then that in the absence of electrical power, the door may be latched and unlatched without any locking taking place. With electrical poweravailable, the usual. case, as the lock pin is deflected by the car it causes switch 72 to closev momentarily by engaging wire lever 70. The
solenoid 66 is energized and the lock pin momentarily retracted as the ear moves forwardly. Upon retraction, the lock pin assumes its undeflected position and is centered relative to wire lever 70. Switch. 72 opens, deenergizing the solenoid, and the lock pin springs into an obstructing position relative to the link means. However, the lock pin may be readily moved out of an obstructing position with electrical power still available by simply operating the latch means toward an unlatched position. This permits the biasing spring 60 to draw the bar rearwardly and again cause energization of the solenoid through deflectionof the lock pin in the other direction and closing of switch 72..This retracts the lock pin out of the obstructing position.
However, if the lock pin 64 is in an obstructing position whilethe oven temperature is in the high heat range, the thermally responsive switch 74 closes and disables the solenoid. Accordingly, the biasing spring 60 is unable to draw the bar 48 rearwardly against the obstruction of the lock pin which may be deflected rearwardly only to a'lirnited extent in the obstructing position because of the stop 75, even though the limited deflection closes switch 72.
One notable feature of the invention is the arrangement of the biasing spring 60 to constitute the sole force for urging the bar 48 rearwardly. No force is exerted by the latching means upon the linkage means to effect the rearward movement of the linkage means. Thus, with the oven door latched and locked, if the user attempts to force the latch to an open position, the latching bolt 40 simply bears against the forward end 48A of the drawbar in a direction'at right angles to the normal direction of movement of the drawbar. This force is carried directly through the connection 52 of the drawbar to the bell crank leg 50B, and to thekeeper bracket and frame structure of the oven. Since such a force is not carried back to the back assembly through the linkage, the drawbar and the cooperating parts in the locking assembly may be of relatively lightweight material not required to resist large stresses.
LOCK EFFECTING MEANS (FIGS. 7-9) The currently preferred arrangement embodying lock effecting means 26 according to the invention is shown in FIGS..79. A lightweight sheet metal shell 76 serves as a base for carrying a number of the parts concerned with locking. The shell is secured to the back face of a vertical rear wall 78 spaced rearwardly from the vertical rear wall of the oven liner. Thermal insulation occupies the space between the liner and the wall 78. The shell is mounted to this rear wall for limited pivotal movement about a vertical axis passing approximately through vertically aligned upper and lower fasteners 80. The fasteners extend through spacers 82 which space the shell from the wall 78 to permit the shell to rock slightly upon the spacers. This mounting arrangement, contributed by another, is used to compensate for thermal expansion and contraction of the range frame, and to prevent the forward end of the drawbar from being pulled out of the unlatching path of the bolt during the heat cleaning cycle. The compensating arrangement includes an arm 84 rigidly connected to two opposite corners of the shell by fasteners 86 (FIG. 7) and a bar 88 connected to the outboard end of the arm. The bar 88 is fixed at its forward end to the keeper assembly and extends rearwardly to its pivotal connection with the outboard end of the arm. The bar is of the same material as the drawbar 48 and preferably is of the same dimensions. For all practical purposes expansion and contraction of both drawbar 48 and bar 88 will be the same since they are subject to essentially the same temperatures. Accordingly, the shell 76 will rock as required to keep the same adjusted relationship between the rear link 56 and the operating parts in the locking assembly and will also prevent the locked condition of the door from being lost.
The parts in FIGS. 7-9 which correspond to the parts in the schematic of FIG. 6 carry the same numeral. The locking member 64 takes the form of a pin normally biased downwardly by the helical compression spring 68 which bears against the lower face of the solenoid 66 mounting. The pin is mounted for lateral deflection by a sleeve-shaped, tight helical spring 68A. The part 62 which engages the lower end of the locking pin 64 is located at the right end (FIG. 7) of the link extension 56. When the drawbar 48 is moved forwardly or rearwardly the linkage extension 56 pivots about the vertical axis 58 (FIGS. 7-9) formed by several notches (also designated 58) in rearwardly-directed flanges of the shell 76. The forward edge of a vertical run of the extension link 56 seats in these notches.
The right end of the link extension moves toward the rear (i.e., toward the viewer of FIG. 7) when the drawbar is pulled forwardly during latching, and conversely moves toward the front when the drawbar retracts during unlatching. A raised shoulder 62A engages the end of the downwardly-biased locking pin 64 and deflects the pin toward the rear when the drawbar is moved forwardly. This carries the locking pin into engagement with the V- formed wire 70 and results in closure of switch 72 in series with the solenoid 66. The locking pin is retracted against the bias of spring 68, and assumes a vertical position which again centers it with respect to the wire form V. This permits the switch 72 to again open. The force of the biasing spring 68 then drives the pin downwardly past the link end 62.
The sequence of movements of the locking pin relative to the movement of the end 62 as the link extension 56 is moved between its positions is perhaps most clearly shown in FIG. 8. The solid line representation of the link end 62 and pin 64 corresponds to anunlatched condition. The dash-dot showings represent successive positions. As the link end 62 moves to the left as viewed in FIG. 8, the locking pin is deflected to a position 64B by engagement of the shoulder with the end of the locking pin. This deflection, as explained before, energizes the solenoid momentarily, and the pin takes the centered depressed position 640. If the link end 62 is moved back toward its solid line position, its leading side engages the end of the locking pin 64 and carries it toward a 64D position. If the solenoid 66 is not then disabled in response to a high oven temperature, the solenoid is again energized to retract and recenter the pin which then moves down under its bias onto the link end 62. However,if the solenoid is disabled the end 62 forces the locking pin end over to the 64D position against the edge of a flange and prevents the return of link end 62 to its solid line position. It is noted that the movement of the link end 62 from the dashed line position to its solid position is effected by the force of the biasing spring 60 and not by any force transmitted back through the linkage mech- A timing arrangement for terminating the supply of heat to the oven is also provided in connection with the lock assembly. A timer motor 94- mounted on the shell 76 has its output shaft flexibly connected through a helical spring sleeve 98 to a drive shaft 96. The shaft 96 is slidably supported at its left end (FIGS. 7 and 9) in a horizontal slot 100. A tension spring 102 urges the slidable left end of the shaft 96 in a direction toward the a front of the range. The output shaft includes a wormthread drive section 104 (FIG. 9) adapted to be engaged by a wheel 106 carried by the extension link 56 for movement therewith and provided with teeth on its periphery adapted to mesh with the teeth of the Worm drive section 104. The function of the timer, timer drive, and wheel is to cause the opening of a normally-closed switch 108 after a predetermined period of engagement of the drive shaft and the wheel, when the door is latched shut. In the current arrangement, the timer drive and wheel are designed so that after one hour of engagementthe switch 108 will be opened to terminate the supply of heat.
The structural arrangement of the timer wheel assembly is perhaps best understood from the vertical sectional view of FIG. 10 taken through the wheel and associated structure. The wheel 105 is mounted for rotation about a bolt 110 which secures it to the link extension 56. A helical return spring 112 has one end pinned to the wheel 106 and the other end connected to the link 56 to exert a force urging the wheel 106 in a counterclockwise direction (as viewed from above) to a start (i.e., reset) position. A U-shaped wire form member 114 is carried at the ends of its legs from the bolt for turning movement relative to the bolt. The wheel 105 includes one or more depending lugs 116 disposed to engage the lower leg of the wire form 114 when the wheel rotates sufficiently in either direction. The bight of the wire form 114 is confined between a stop 118 (FIG. 9) on the one side, and the actuating lever for the switch 108 on the other side.
When the link extension 56 is in an unlatched position, the wheel 106 is out of engagement with the worm drive section 104, and the return spring 112 urges the wheel 106 in a counterclockwise direction until a depending lug 116 engages a leg of the wire form 114 and is stopped by the Wire form engaging the limit flange 118. When the link extension 56 is moved to a latched position, the wheel is carried into engagement with the worm drive section. With the timer 94- energized, the wheel is slowly rotated in a clockwise direction and carries the depending lugs around. After the leading lug engages the lower leg of the wire form 114, it carries the bight portion of the wire form into engagement with the actuating lever of normally-closed switch 108. When switch 108 opens, heat-cleaning energization is terminated, and the timer motor 94 is denergized. Subsequently, after the oven has cooled sufficiently, and after the latch means is operated to an open position, the wheel will be moved back away from the drive worm section 104 and the return spring will act to reset the wheel to its initial position from which it started.
OVERALL CIRCUIT (FIG. 11)
The relationship of the lock assembly circuitry to theremainder of the oven circuitry as concerned with a heat cleaning cycle or operation is generally illustrated in FIG. 11. A three-wire power source is indicated by the conductor terminals N, L1, and L2. A stepdown transformer 120 and the timer motor 94 are energized across neutral and L2 when the clean position contacts 122 of the selector switch are closed, and the latching means .have been operated to a latched position to effect closure of the normally open interlock switch 92 engaged by the locking pin 64. The secondary of the transformer 120 provides power through another set of contacts 123 in the selector switch in a clean position to operate control relay means 124 to a position energizing the top heating element 30 in the oven. Until the temperature in the oven rises above a level, such as 550 F., normally encountered in cooking, the normally-open lock thermostat switch 74 remains open. Above that temperature, the thermostatic switch 74 closes to shunt out the solenoid 66 and the solenoid switch 72 so that these elements are disabled. Thus, the oven door will be locked shut (since the lock pin 64 cannot be retracted out of the way of the link means) until the switch 74 subsequently opens as the oven temperature falls into the normal cooking range of temperatures. Closing of lock switch 74 also energizes an indicating light and ventilating fans.
After the latching means have been in a latched position with the selector switch in a clean position for about an hour, the timer operated switch 108 is opened in the manner previously explained. This deenergizes the transformer 120 and results in opening the circuit to the element supplying heat to the oven cavity. Then when the oven temperature cools below the set temperature of the lock switch 74, this switch opens and the solenoid 66 may again be energized by operating the latching means toward an unlatched position. Further details as to the functioning of the various parts of the circuit may be found in Kastovich U.S. patent application Ser. No. 552,663, entitled, Oven, and filed Apr. 26, 196(, a continuation-in-part of US. patent application Ser. No. 521,932.
It will be appreciated from the foregoing that in accordance with my invention there is provided an arrangement in which the mechanical latching function can be accomplished with a simple and straightforward latching structure, at the front of the range, the link means may also take a relatively simple form, and the lock effecting means may be concentrated at the rear of the range in essentially package form and positioned conveniently near the control panel. The arrangement is such that forcing the latching means improperly does not result in the transmission of stress to parts subject to misadjustment or maladjustment in the locking assembly. The arrangement further is such that latching and unlatching may be accomplished either with or without electrical power but a failure of electrical power while the door is locked does not permit the door to be opened without restoration of the electrical power.
The cleaning cycle may be cancelled or interrupted at will either before or after the oven temperature has risen to a level causing the lock thermostatic switch to close.
I claim as my invention:
1. A latching and locking arrangement for securing the door of an oven cavity adapted to be heated to high temperatures, comprising:
means for latching said door in a closed position, said latching means being located generally at the front of said cavity;
lock effecting means located generally at the rear of said cavity;
link means extending from said latching means to said lock effecting means, said link means being biased toward one position and movable toward an opposite position in response to operation of said latching means to a latching position;
said lock effecting means including electrically-actuated means responsive to movement of said link means to said'opposite position to move into a position obstructing the return of said link means to said one position, and responsive to movement of said link means back toward said one position to move out of said obstructing position; and
means responsive to oven cavity temperature above a predetermined level to disable said electricallyactuated means. i
2. An arrangement according to claim 1 wherein:
said electrically-actuated means includes a solenoidcontrolled locking pin engaged by said link means moving in either direction, said pin being biased toward said obstructing position and adapted to be retracted from said obstructing position upon energization of said solenoid; and
normally-open switch means for said solenoid responsive to said movement of said link means in either direction to operate to a closed position.
3. An arrangement according to claim 1 wherein:
said latching means includes a latching bolt carried by said door and keeper means mounted on said cavity structure to receive said bolt; and
said link means includes one part at its forward end disposed for engagement by movement of said bolt into latching position to elfect said movement of said link means to said opposite position, and includes a second part which, as said link means is moved toward said opposite position, advances into the path said bolt must travel in an unlatching movement.
4. An arrangement according to claim 3, wherein:
said one part of said link means is in the form of a bell crank lever; and
said second part of said link means comprises the forward end of drawbar means connected at its rear end to said lock effecting means.
5. An arrangement according to claim 2, including:
means mounting said locking pin to permit deflection of said pin from its normal position;
said link means includes movable surface means supporting said locking pin in opposition to the biasing force on said locking pin when said latching means is in an unlatched position; and
said surface means includes means for deflecting said locking pin to a position closing said solenoid switch means when said link means is moved toward either position.
6. In an oven adapted to undergoing heat-cleaning;
means defining a forwardly-open oven cavity;
door means for closingsaid cavity;
latching means at the front of said cavity including keeper means rigidly secured to said cavity defining structure, and bolt means carried by aid door for movement generally laterally of said oven into a latching position engaging said keeper means; lock effecting means located remotely and rearwardly rom said latching means; link means extending from said lock effecting means to said latching means for relating the operation of said lock effecting means and said latching means to each other, said link means including a drawbar movable generally longitudinally of said oven in accordance with movement of said bolt; means connecting said drawbar to said keeper means to permit said longitudinal movement; said lock effecting means including means for obstructing said longitudinal movement of said drawbar in response to a high temperature condition of said oven cavity; and said drawbar including means at its forward end obstructing said lateral movement of said bolt from said latching position when said longitudinal movement of said drawbar is obstructed; whereby a force applied in an eifort to operate said bolt to an unlatched position, when said door is locked, is transmitted to said cavity defining structure. 7. In an oven according to claim 6: said lock effecting means includes a solenoid-controlled locking member movable into and out of a position obstructing said longitudinal movement of said drawbar; said lock effecting means further includes normallyopen switch means for said solenoid operable to a closed position in response to predetermined movement of said link means in both a forward and rearward direction. 8. In an oven according to claim 6: means biasing said drawbar in one direction; and said link means includes means disposed for engage ment by said bolt to effect movement of said drawbar in an opposite direction as said bolt is moved toward a latched position.
References Cited UNITED STATES PATENTS 2,575,465 11/1951 Patton 292341.17 X 2,996,323 8/1961 Wood 292-207 3,050,048 8/1962 Scott 23615 X 3,214,567 10/1965 Chisholm 2194l3 3,313,918 4/1967 Barber 219-412 RICHARD E. MOORE, Primary Examiner.