US3750643A

US3750643A - Multiple position door latch mechanism

Info

Publication number: US3750643A
Application number: US00256093A
Authority: US
Inventors: R Fowler; J White; D Cross
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1972-05-23
Filing date: 1972-05-23
Publication date: 1973-08-07
Anticipated expiration: 1990-08-07
Also published as: DE2325506A1

Abstract

A three-position, sliding latch mechanism for an appliance door such as an oven door. The mechanism includes a latch handle and a hidden latching bolt for swinging out and engaging the door. The first position of the latch mechanism is an unlocked position, and the second position is a locked position. The third position is also a locked position, although the latching bolt remains stationary in this locked position as the latch handle is moved between the second and third positions. There are separate interlock switch means that are operable in either the first (unlocked) or the second and third (locked) positions, whereby different oven operations may be performed as a function of the various positions of the latch handle so as to simplify the control circuitry and components.

Description

14 1 Aug. 7, 1973 Fowler et al.

MULTIPLE POSITION DOOR LATCH MECHANISM 3,540,767 11/1970 Siegel 126/197 Primary Examiner-Carroll B. Dority, Jr.

[75] Inventors: Roland V. Fowler; James A. White;

v Dvid C. Cross a" of Louisville y Attorney Richard L. Caslin et al.

[73] Assignee: General Electric Company, [57] ABSTRACT Lousvluei Y- A three-position, sliding latch mechanism for an appli- 22 Filed; May 23 1972 ance door such as an oven door. The mechanism includes a latch handle and a hidden latching bolt for [2'1] Appl- 256,093 swinging out and engaging the door. The first position of the latch mechanism is an unlocked position, and the 52 us. 01 126/197, 219/413, 292/113, Second Position is a locked Pvsifion. The third Position 292/1316. 69 is also a locked position, although the latching bolt re- 51 .1111. Cl. F23m 7/00, F241; 15/04 mains Stationary in this locked Position as the latch 58 Field of Search 292/97, 196, DIG. 69, handle is moved between the Second and third P s 292 113; 12 197; 2 9 4 3 tions. There are separate interlock switch means that are operable in either the first (unlocked) or the sec- [5 References cited and and third (locked) positions, whereby different UNITED STATES PATENTS oven operations may be performed as a function of the I various positions of thev latch handle'so as to simplify I the control circuitry and components.

3,367,697 2/1968 Fox 292/113 13 Claims, 8 Drawing Figures 7 1 5 5O '5' 4 (a Q6 Q5 7O 7\ I ,1 a: I I (0e 4. r

113 y i H7 74 I 107 88 v 98 4 119 I2 I as Q ris 101 13 S9 82 g, 84- loo I 3 1G3 1 9 S's f 05 155 12 7e =l 14s 61 I 41 M PAIENIEBAUB mu v 3,750,543

sum 3 OF 4 Has r Q MULTIPLE POSITION DOOR LATCH MECHANISM BACKGROUND OF THE INVENTION This invention was specially designed for a door latching system for a microwave oven that is provided with the added convenience of a pyrolytic self-cleaning oven cycle, but clearly the invention is not limited to a maximum of three positions. It is imperative that a microwave oven have its oven door latched during its opetation so as to prevent the leakage of microwave energy from the oven cooking cavity, since such radiation that are formed as metal sheathed resistance heating elementsthat are sold under .the registered trademark of CALROD-heating units. For such conventional cooking, the door latch would be set in its first (,unlocked)position. H I

The oven'is also furnished with a microwave generator and powersupply that may fu rnish microw'ave energy in one of two frequency bands of 915 mI-Iz or x 2,450 mI-Iz for increased speed of cooking. To'accomplish this function, the oven door would be locked, with the latch mechanism set in its second (locked) position.

It is possible to combine the action of the two heating means so as to have both radiant energy and microwave energy furnished to the oven cavity simultaneously I while in this second (locked) position.

When-the oven is to be cleaned of the food soils and grease spatters that accumulate on the inner surfaces of the oven liner and inner'door liner, the door la'tch would be moved to its third (locked) position. Then the radiant heating elements would. be energized to raise the oven temperature to about 900F. for a'sufficient length of time to degrade the food soils with the production of corresponding gaseous degradation products that are returned to the kitchen atmosphere .as harmless gases.

It has been found expedient to provide separate door interlock switches and circuits for operation during the second and third (locked) positions of the door latch fordiscriminating between the microwave cooling operation and the pyrolytic self-cleaning oven cycle so as to simplify the control circuits and reduce the cost of electrical components.

S U MMARY OF "THE INVENTION A multiple-position,sliding latch mechanism comprising a base plate and a latch handle that ispivotally connected to the base plate adjacent the rear thereof so as to'flatten the arc of the path of movement of the outermost portion of the latch handle. The latch mechanism includes a latching bolt that is connected to both the base plate and the latch handle through a latch lever. There are two locked positions of the latch mechanism between which the latching bolt remains substantially stationary. Separate interlocking switch means cooperate with the latch mechanism in either the first (unlocked) or thesecond and third (locked) positions to set up independent controlcircuits.

The. principle object of the present invention isto provide a multiple-position,sliding latch mechanism having a first (unlocked) position, a second (locked) position and a third (locked) position, and locking means for the latching mechanism to restrict the forward movement from the second (locked)position to the third (locked) position under certain circumstances, as well as to prevent the return movement from the third (locked) position toward the second (locked) position or the first (unlocked)-position when the oven air temperature is above about 600 F.

A further object of the present invention istoprovide a multiple-position, door latch mechanism with a special' latch handle that has an outermost end portion with a flattened are as its path of movement'so as not to constitute an obstruction in its intermediate position.

A further object of the present invention is to provide a three-position, door latch mechanism with separate interlock switch means operablein the'first (unlocked) or the second and third (locked) positions so that the position of the latch mechanism discriminates undifferentiates between the various operating cycles'that the latch mechanism is'to initiate andcontrol. v

BRIEF DESCRIPTION OF THE DRAWINGS .Ourinvention will be better understoodzfrom thefollowing description taken inconjunction with the accompanying drawings and its scopewill-bepointediout in the appended claims.

FIG..I is a right side elevational view of a freestanding electric range with amicrowave oven that -it equipped with a multiple-position, oven door latch mechanism embodying the present'invention.'FIGQZis a fragmentaryplan view onan enlarged scale 'takenon the line 2-2 of FIG. 1 to show the three-'position'latch mechanism of the present invention in 'its'first (:unlatched) position for non-use of the oven orconventionalcooking within the oven.

FIG. 3 is another plan view of the latchmechanism, similar to that of FIG. 2, except the handle hasbeen moved to its second (locked) position for 'microwave cooking or combined microwave and conventional cooking.

FIG. 4 is another plan view of the latch imechanism showing the latch handle in itsthird (locked) position fora pyrolyticself-cleaning oven cycle.

FIG. 5 is a fragmentary elevational view of'the locking' means for the door latching mechanism taken on the line 5-5 of FIG. 2 showing the position of thelocking means when the door latchmechanism-isin itsfirst (unlocked) position of FIG. 2.

FIG. 6 is another fragmentary elevational view, similar to that of FIG. 5, showing the positionzof the locking means when the door latch mechanism is-in its second (locked) position of FIG. .3.

FIG. 7 is another fragmentaryelevational view,;similar to that of FIG. 6, showing the positionof the locking means when the door latch mechanism is in its third (locked) position of FIG. 4.

FIG. 8 is a schematic diagram of boththe powerand control circuitsfor thevarious heating systemsof the oven locating the separate interlock switches for the microwave oven operation and the self-cleaning oven operation toemphasizethat these-various cycles are set up by the alternate positions of the door latch mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to a consideration of the drawings and in particular to FIG. 1, there is shown for illustrative purposes a free-standing electric range having a top cooking surface 11 with a plurality of surface heating elements 12, an oven cooking cavity 13 beneath the top cooking surface, a front-opening oven door 14 hinged along its bottom edge 15, and a backsplash 16 arranged along the back edge of the cooking surface 11 and including in its front face a control panel with all the manual and visual control components 17 mounted therein for governing the energization of the various heating means of the range. The oven cooking cavity 13 includes the'two standard electric heating elements; namely, a lower bake element 18 arranged along the bottom wall of the box-like oven liner 21, and an upper broil unit 19 which is located adjacent the top wall of the oven liner. As in conventional electric ovens, there is a layer 23 of thermal insulation surrounding the walls of the oven liner 21 for retaining the heat generated within the cookingcavity 13. Moreover, the oven door 14 is an insulated door construction so as not to allow excessively high temperatures to exist on the outer surface of the door which might cause a safety hazard. The oven door requires a special door sealing arrangement on its inner surface in the vicinity of the door gap with relation to the front flange of the oven liner 21 in the area marked 25 to prevent both microwave leakage during microwave cooking and smoke, odor and thermal leakage during the self-cleaning cycle. Sincethis door gasketing does not form part ofthe present invention, it has not been illustrated not described in detail.

The microwave features of the oven will now be described briefly with reference to FIG. 1. Beneath the oven 13 is a compartment 27, which in an ordinary range would be a drawer space, but in this particular range. would be the housing for a magnetron generator 29 in combination with a power supply 32, and blower 34 for cooling the magnetron and power supply components under operating conditions. These three assemblies are mounted on a pull-out tray 36 which is provided at its front edge with'a vertical panel 37 which conforms to the appearance of the oven door 14 and serves to close the apparatus compartment 27 and to appear like a drawer structure. In other words, the movable tray 36 serves as the bottom wall of a drawerlike member which is without side walls for ready access to the magnetron, power supply and blower. A waveguide 39 rises vertically from the magnetron generator 29 and extends through the bottom wall of the oven liner 21, generally in the center thereof. An antenna 40 is mounted from the waveguide just above the bottom wall of the oven liner 21 for propagating the microwave energy throughout the oven cooking cavity 13. In order to obtain uniform cooking results, a mode stirrer or parasitic exciter 42 is assembled adjacent the top wall of the oven liner'generally centered above the antenna 40, and it is mounted on a shaft that extends through the top wall of the oven liner for connection to a motor and gear drive assembly 44. The stationary antenna 40 serves to set up a basic TE 1 31 mode which excites complementary TE122 modes in the mode stirrer or parasitic exciter 42. There would be a metal rack (not shown) suspended between the side walls of the oven liner for supporting food to be cooked within the oven cooking cavity 13.

The door latch mechanism of the present invention is indicated by the numeral in FIG. 1, and it is preferably located within the oven cabinet or range body above the door opening and above the top layer of thermal insulation 23. As mentioned previously, the use of a door latch mechanism of some kind has been found of primary importance in the operation of a hightemperature, pyrolytic self-cleaning oven. In such an oven theremay be provided, in addition to the lower bake element 18 and the upper broil element 19, a third heating element or mullion heater 52 as seen in FIG. 1 that is located near the door opening of the oven liner 21 to encircle the oven liner, or at least part of it, the compensate for the loss of heat through and around the oven door 14 for obtaining uniform temperature distribution.

Referring particularly to FIGS. 2, 3 and 4, the latch mechanism 50 is shown as comprising a mounting bracket or base plate 54 whichis generally of flat sheet metal configuration with an upturned vertical front flange 55 which is adapted to be fastened against the inner surface of the front door frame 56 of the oven body. The base plate 54 has a second upturned vertical flange 58 along the right side edge thereof which is adapted to support a first door interlock switch 60 for use in the microwave power supply circuits. Another upstanding vertical flange 61 is located along the left side of the base plate 54 and it serves as a mounting means for a second door interlock switch 63 for use in the oven' thermostat circuit in the self-cleaning oven mode. There is another upstanding vertical flange 65 adjacent the right side of the base plate, near the front thereof, and this serves as an anchoring means for one end of a tension spring 66 that is connected at its other end 67 to a pivoted cam follower 68. There ,is a latching bolt 70 with a front hook portion 71. This latching bolt is pivotally as well as slidably connected to the base plate 54 by a pivot pin 72. Positioned on top of the latching bolt 70 is a door sensor bar 74. The presence of this door sensor bar overlying the latching-bolt 70 tends to complicate an understanding of the drawings. This door sensor bar 74 is not pivoted on the pin 72 on which the latching bolt 70 is pivoted. There is a fixed pin 76 that is carried by the innermost end of the door sensor bar 74. This pin 76 extends down through they latching bolt and is captured in a cam-shaped guide slot 78 formed in the base plate 54. The top of the pin 76 is confined in a second cam-shaped slot 80 that is formed in a latch lever 82 that in turn is pivotally mounted to the base plate 54 by means of a central pivot bolt 84.

Next there is the latch handle 86 that is an elongated bar that is pivoted to the base plate 54 by a sliding bolt 88 that is confined in an elongated slot 89 in the base plate. This slot 89 extends in a direction from front to back of the front mounting flange S5 of the base plate. In addition, the latch handle 86'is connected to the latch leverby a pivot pin 90 such that movement of the latch handle 86 from right to left in FIG. 2 causes the latch lever 82 to move in a counterclockwise direction such that the cam slot 80 exerts a pressure on the pin 76 that extends through both the door sensor bar 74 and the latching bolt 70 causing the sensor bar and the latching bolt as a unit to move in a clockwise direction generally about the pivot pin 72.

The interrelation between the latching bolt 70 and the door sensor bar 74 is the same as is taught in U.S. Pat. No. 3,367,697 of Joseph S. Fox, Sr., which is assignedto the same assignee as is the present invention. A bent-up tab 92 extends upwardly from the left side of the latching bolt 70 to extend above the door sensor bar 74. An opposing tab 94 is folded up from the right side of the door sensor bar so that a small tension spring 96 may be connected between the two

tabs

92 and 94 so as to normally retain the door sensor bar 74 in a position where it overlies the front hook portion 71 of the latching bolt 70, but is capable ofa small amount of relative movement therefrom, as is best seen in FIG. 3. This door sensor bar 74 also has a hook portion 98 which acts in the event the oven door 14 is not in its fully closed position to engage with the side edge 100 of a slot 101 formed in the front flange 55 of the base plate 54. This interengagement would prevent any further movement of the latch mechanism into the second or third positions. In the event the oven door 14 is in its closed positionflas best seen in FIG. 3, then the edge the locking bolt 70, this bolt will be pulled rearwardly thereby putting a tension force on the oven door 14 causing itto be compressed against its door gasket (not shown.) and form a tight seal.

In comparing the first (unlocked) position of the door latch of FIG. 2, with the second (locked) position ofFlG. 3, it will be seen that in the second.(locked) position a side extensionor spur 107 at the rearmost end of the door handle 86 serves to engage a button or switch actuator 109 of the door interlock switch 60 so as to close certain microwave circuits in which this interlock switch is interposed.

This latch mechanism has also been designed to provide a third (locked) position as is illustrated in FIG. 4. When moving through the second (locked) position to v the third (locked) position, the latching bolt 70 remains substantially stationary. The latch handle 86 is moved from an intermediate position of FIG. 3 to the extreme left position of FIG. 4. This feat is accomplished mainly by extending the cam slot 80 to the left sition, and a second detent 121 for use in the third (locked) position. This cam surface 114 cooperates with a pivoted cam follower 68, that was mentioned previously. The cam follower is generally in the shape of a bell-crank lever of spaced double thickness that is pivoted to the base plate at its center by a pivot'bolt.

tween the first (unlocked) position and the second (locked) position is about 65 degrees. The included angle between the second (locked) position and the third (locked) position is about degrees, or a total of about 85 degrees from the first (unlocked) position to the third (locked) positiomLooking back to FIG. 3,

there is at the left side of the latch mechanism a reciprocable lockingbar 127 which is of elongated shape that during the final moments of the lockingactionof at a constant radius thereby allowing the latch lever 82 to pivot around its pivot bolt 84 for 20. Looking at the pin 76in FIG. 3, the cam slot is shown with about 215 dwell to the right thereof which allows the latch handle 86 to be moved to the right toward the first (unlocked) position without relieving the tension on the locking bolt 70 and hence the door gasket to prevent the ovendoor 14 from opening until the microwave interlock switch 60 is deenergized to shut off the microwave power to the magnetron generator 29 before the door sealing gasket relaxes. I

Attention is drawn to the right side edge of the latch lever 82 that is formed with a cam surface 114 having a stop formation 115 for use in the first (unlocked) position, a long sweeping slowing rising cam surface 117 and a first detent 1 19 for use inthe second (locked) pothat is pivotally. connected at one end to the latch lever 82 by means of a pivotpin 129; 1

Turning to the cross sectional elevational view of FIG. 5, there is shown an upstanding bracket member 131 having a small horizontal slotted opening 132 receiving' and supporting the locking bar 127 therethrough in a close fitting relationshipfor guiding the movement-of the locking bar as the .latchlever' 82 turns when the latch handle 86 is shifted from one of the three positions. This bracket member has a lower horizontal base portion 134 which is fastened beneath the base plate 54 by means of fastening screws 135. This bracketmember 131 has its vertical side edges'folded forwardly intoside walls 137 for supporting adjacent the bottom an elongated pivot pin 139 therebetween. Carried by this pivot pin 139 is a verticallypivoted lock lever 141 as is best seen in FIG. 5. This lock lever 141 has the shape of a bell-crank lever with a-gen'erallyhorizontal arm 142 and a generally vertical arm 143. The vertical arm 143 of the lock lever 141 is pivotally connected to an armature 145 of a solenoid 147 by a cotter pin. This solenoid is shown supported beneath a horizontally disposed top flange 149 of the bracket member 131 by means of fastening screws 151. There is a spiral spring 153 slipped over the armature 145 for normally biasing the armature outwardly of the solenoid housing such that the energization of the solenoid 147 causes the armature to be pulled in for pivoting the lock lever 141 in a clockwise direction about its pivot pin 139, as bestvseen in FIG. 5. 1

Notice in FIG. 5 that the locking bar 127 has two

elongated slots

155 and 157 formed therein. The front slot 155 is provided with a short, downwardly inclined ramp 159 adjacent the front edge thereof. Moreover, there is a cross bar 161 separating the'front slot 155 from the rear slot 157. The horizontal arm 142 of the lock lever 141 has a downwardly inclined-hook forma-, tion 163. Comparing FIGS. 2 and 5, which is the first (unlocked) position of the latch mechanism, the-hook formation 163 of the locklever 141 is shown resting on top of the locking bar 127. When the latch handle 86 is moved to the second (locked) position as seen in FIGS. 3 and 6, the locking bar 127 is pulled forward by the latch lever 82, thereby allowing the lock lever 141 to drop down into the slot 155 a's'is seen in FIG. 6, thus preventing further movement of the latch handle in the forward direction toward the third (locked) position. It should be understood that the action of the lock lever 141 in making locking engagement with the cross bar 161 in the'second (locked) position, does not preclude the normal return action of the latch handle 86 from the second position back to its first (unlocked) posi- 111011.

In order to disconnect the lock lever 141 from the cross bar 161 of the locking bar 127, so as to be able to shift the latch handle 86 from the second (locked) position to the third (locked) position, it is first necessary to energize the solenoid 147, thereby causing the armature 145 to be activated and drawn into the solenoid, thereby pulling back on the vertical arm 143 of the lock lever 141 and lifting the hook end 163 out of the slot 155. Then the latch handle 86 may be shifted to its third position at which time the solenoid 147 would be de-energized and the lock lever 141 would assume the position shown in H0. 7 due to the action of the spiral spring 153, thereby causing the switch 148 to close so as to short out the oven temperature control 182 in the self-cleaning mode. Then it can be seen that the hook portion 163 of the lock lever 141 has been allowed to fall behind the cross bar 161 of the locking bar 127, and this temporarily prevents manipulation of the latch mechanism in rearward directions. This condition can only be altered when the solenoid 147 is again energized, thereby lifting the lock lever out of engagement with the locking bar 127 and enabling the latch handle to be moved to either, the second or first positions.

Looking at FIGS. 3 and 4, it should be noted that there is a second interlock switch 63 mounted on a side extension 172 of the base plate 54. This switch has a pivoted spring biased toggle actuator 174 which overlies a portion of the locking bar 127., An upstanding finger 176 is carried at the side of the locking bar for engaging the toggle actuator 174 during the movement of the latch handle 86 from the second to the third position of the latch mechanism to thereby close the switch 63 for setting up the self-cleaning oven circuit. This toggle actuator 174 has an internal spring mechanism (not shown) which returns the toggle to its normal open position shown in FIG. 2.

7 Now turning to the schematic circuit diagram of FIG. 8, the oven is shown furnished with an electrical service of three-wire Edison source of power, nominally of 230 volts, single phase, 60 Hz, A.C., which is usually available in the average residence having adequate wiring. This voltage source is fed to the oven through a threewire cable having a pair ofline wires L and L with a voltage of 240 volts therebetween, and a grounded neutral conductor N with half voltage or 120 volts measured across any line wire L or L, with the neutral conductor N for supplying power to the electrical load of the oven. The conventional electrical load is characterized by three heating elements: a baking element 18, a broiling element 19, and a mullionheater 52. These

heating elements

18, 19 and 52, are arranged in varying circuits by virtue of an oven selector switch 180 for setting up different combinations of heating elements at different voltages to obtain a variety of heating rates. A manually settable oven thermostat 182 is also available for controlling the temperature within the oven at preselected temperatures during baking operations, and at a separate maximum temperature during broiling and oven cleaning operations. Such an oven thermostat 182 controls a hot-wire relay 184 that is in series with the

heating elements

18', 19 and 52 for opening and closing the power circuit to the heating elements as a function of the oven temperature with relation to the temperature predetermined or preset by the thermostat 182. g

The oven selector switch 180 is provided with a series of line terminals L N, L, and L as well as a series of three load terminals K, J and P. This oven switch 180 is provided with a plurality of switch contacts 192-200. These switch contacts are labeled with the particular cooking or cleaning operation that is involved when such contacts are closed. For example, during a Baking" or a Time-Baking operation,

contacts

192, 193, 198 and 199 are closed. During a Broiling operation,

contacts

196 and 197 are closed. During a Cleaning Cycle,"

contacts

193, 194, 195, 196, 199 and 200 are closed.

The Baking" circuit has the bake element 18 operating at full wattage acrosslines L, and L at 240 volts through a temperature switch 202 which connects the selectorswitch 180 with line L while the other end of the bake element 18 is connected to the hot-wire relay 184 and through a smoke eliminator 204 to the other line L During, the Baking" cycle, the other two

heating elements

19 and 52 are also energized. They are in a series circuit connected back through the temperature switch 202 to line L,, and also connected through the hot-wire relay 184 and smoke eliminator 204 to the line L2. 1

In the Broiling circuit, only the broil element 19 is energized, and it is connected across lines L, and L through the temperature switch 202 as well as through the hot-wire relay 184 and smoke eliminator 204 to line L If a component failure should occur during a cooking operationof either Baking, Time-Baking or Broiling, and the oven temperature were to rise above the preset temperature of the oven thermostat 182 and reach an oven temperature of say 580 F., then the temperature switch 202 would be operating to open the circuits therethrough, thereby deenergizing the

heating elements

18, 19 and 52 and preventing a runaway temperature condition. Thus, this temperature switch 202 serves as an overtemperature limit control when the oven is in any normal cooking operation. Thus, in the event ofa malfunction of the primary temperature control, any hazard due to overheating of the oven during the Baking, Broiling and Time-Baking mode of operation is eliminated. This particular temperature switch is described in U.S. Pat. No. 3,656,182 of Paul R. Staples,

entitled Hydraulic Thermostat With Double Throw Switch Mechanism," which is assigned to the same assignee as is the present invention.

During a self-cleaning mode of operation, the oven selector switch is not connected through the temperature switch 202 to line L but instead is connected to neutralconductor N by means of lead 208. However, the temperature switch 202 does connect 2 fan motor 210 to line L by means of lead 211. During the selfcleaning operation, the three

heating elements

18, 19 and 52 are connected in parallel at half voltage across line L; and neutral conductor N in order to obtain a heating rate somewhat lower than the heating rate during normal baking operations. This temperature switch 202 is a single-point thermostat set at about 580 F. At

temperatures below about 580 F., this switch is closed to connect a lead 213 to the selector switch 180 for normal cooking operations. At temperatures about 580 F., the temperature switch 202 opensthe circuit to the lead 213 and closes it to the lead 211. As mentioned previously,'there is a solenoid 147 for cooperation with the lock lever 141 in its cooperation with the locking bar 127. This solenoid is connected at one side to line L, through

leads

213, 215 and 216. in this lead 216 is'a momentary latch-release switch 218 which might be mounted in the backsplash 16. The other side ofthe solenoid is connected by lead 220 through

switch contacts

221 and 222 of the oven selector'switch 180, and then back to neutral conductor N by way of lead 224. Thus, at temperatures above 580 F., the temperature switch 202 opens a circuit to lead 213, thereby deenergizing the circuit for the solenoid 147 and rendering the door latch mechanism inoperable until the temperature of the oven returns to below the critical temperature of about 580-F. During such a high temperature operation, the temperature switch 202 is closed for establishing a circuit to lead 211 and the cooling fan 210 and by means of lead 226 through a thermal fan I switch 228, and then through the second interlock switch 63 and back to neutral conductor N by means of lead 232 and lead 224.

In order to set up the self-cleaning oven circuit, there are several preliminary operations that must be performed first. As mentioned previously, it is imperative that the oven door 14 first be closed'and then locked by moving the latch handle 86 to the third (locked) position. Also, it isimperative that the oven door remain closed and incapable of being opened while the oven temperatures are above normal cooking temperatures of about 580F. The door latch mechanism 50 is shown schematically in the circuit diagram of FIG. 8 by merely showing the reciprocating locking bar 127 with its two

slots

155 and 157 in cooperation with the autofunctioning of the microwave generator29, as seen in FIG. 1, it should suffice to say that these microwave circuits are connected by the first interlock switch 60 across lines L, and L This microwave interlock switch 60 is closed by positioning the latch handle 86 in the second (locked) position of FIG. 3.

Modifications of this invention will occur to those skilled in this art, therefore, it is to be .understood that this invention is not limited to the particular embodiments disclosed, but that it is intended to cover all modifications which are within the true spirit and scope of this invention as claimed.

What is claimed as new and desired to be secured by Letters Patent of the United States is: b

l. A multiple position, sliding latch mechanism comprising a base, a latch handle pivotally connected to said base adjacent the rear thereof, a latch lever pivotally connected to the base and to the latch handle, a latching bolt pivotally connected to the base and joined to both the said latchlever and the base by a lost 'rnotion connection whereby movement ofthe latch handle from a first (unlocked) position causes a turning action of the latch lever and hence a turning action of the latching bolt, and indexing means associated with the latch lever to temporarilyhold thelatchmechanism in each of its multiple positions, and a locking bar pivotally connected tothe latch lever and'ex tending rearwardly thereof, an-automatic lock'lever'associated with the locking bar for locking the latch mechanism against further movement in the forward direction, and electroresponsive means for deactivating the lock lever to enable the movement of the latch mechanism to-aft'hird position at which point the automatic lock lever actsto lock the latch mechanism from further "movement, the said electroresponsive means again being operable to deactivate the said lock lever whereby the latch mechanism may be shifted to any position.

2. A multiple position, sliding latch mechanism cornprising a base plate, a latch handle pivotally connected to said base plate adjacent the rear of the base plate, a latch lever pivotally connected to the base plate and "to the latch handle, a latching bolt pivotallyconnected to the base plate and pivotally and s'lidably connected'to the latch lever, whereby movement of the latch handle in one direction from a first (unlockedlposi'tion to a second (locked) position'causes a turning action ofthe latch lever in the opposite direction and also a turning action of the latching bolt in the first direction u'n t'il it reaches the second (locked) position, the latch handle having a third (locked) position which results in niovement of the latch lever without altering the locked" position of the locking bolt, and separate interlocking switch means cooperating with the latch 'mechanis'r'n in each the second and third positions to set upinde'pehdent control circuits.

3. A multiple position, sliding latchm'ech'anism asr'ecited in claim 2 with indexing means associated with the latch lever to locate the second and third locked positions of the latch handle.

4. A multiple position, sliding latch mechanism as recited in claim 3 wherein the indexing means includes a cam surface formed on one side edge of thelatch lever and a spring biased cam follower supported from the base plate for cooperation with the cam surface.

5. A multiple position, sliding latch mechanism-as recited in claim 4 with a locking bar pivotallyconnec ted to the latch lever and extending rearwardly thereof, an automatic lock lever associated with the locking bar for locking the latch mechanism in the second (locked) position against further movement in the forward direction, and an electroresponsivemeans for deactivating the lock lever to enable the movement of the latch mechanism to the third (locked) position at which point the automatic lock lever acts to hold the locking bar from further movement, the said electrorespon' si've means being operable to deactivate the said lock lever so that the latch mechanism may be shifted backto either its second or first positions.

6. A multiple position, sliding latch mechanism corn prising a base plate, a latch lever pivotally connected I to the base plate, a latching bolt pivotally connected to the base plate adjacent the front thereof, and a lost motion connection between the latching bolt and the latch lever, and an elongated latch handle having a lost motion connection with the base plate adjacent the rear thereof and overlying the latch mechanism and extend- 11 ing forwardly beyond the latching bolt in its fully extended position, and a pivotal connection between the latch handle and the latch lever whereby movement of the latch handle causes a related movement of the latch lever and latching bolt for effecting a locking action, whereby the distal end ofthe latch handle moves in a relatively flat arc of a circle.

7. A multiple position, sliding latch mechanism as recited in claim 6 wherein the said lost motion connection between the latching bolt and thelatch lever is extended whereby the latch handle has a first (unlocked) position, a second (locked) position and a third (locked) position, and indexing means associated with the said latch lever to establish three distinct positions of the latch mechanism.

8. A multiple position, sliding latch mechanism as recited in claim 7 with a locking bar pivotally connected to the latch lever and extending rearwardlythereof, an automatic lock lever'associated with the locking bar for locking the latch mechanism in the second (locked) position against further movement in the forward direction, and anelectroresponsive means for deactivating thelock lever to enable'the movementof' the latch mechanism to the third (locked) position at which position the automatic lock lever acts to hold the latch mechanism from further movement, the electroresponsive means being operable at temperatures below about 6 00F. in an associated control cavity to deactivate the automatic lock lever'so that the latch mechanism may be shifted to either its second (locked) position or the first (unlocked) position. v

9. A multipleposition, sliding latch mechanism as recited in claim 8 with separate interlocking switch means cooperating with the latch mechanism in each the second and third positions to set up independent control circuits. I

10. In a combined microwave and pyrolytic selfcleaning oven having an ovencavity formed by a boxlike oven liner and a front-opening access door, a multiple position, sliding latch mechanism mounted in the oven body adjacent the top front of the oven, said latch mechanism comprising a base ,plate, a latch lever pivotally connected to the base plate, a latching bolt pivotally connected to the. base plate adjacent the front thereof, and a lost'motion connection between the latching bolt and the latch lever, and an elongated latch handle having a lost motion connection with the base plate adjacent the rear thereof and overlying the latch mechanism and extending forwardly beyond the front surface of the oven door, and a pivotal connection between the latch handle and the latch lever whereby movement of the latch handle causes a related movement of the latch lever and latching bolt for effecting a locking action, whereby the distal end of the latch handle moves in a relatively flat arc of a curve.

11. In a combined microwave and pyrolytic selfcleaning oven construction as recited in claim 10, wherein the said lost motion connection between the latching bolt and the latch lever is extended whereby the latch handle has a first (unlocked) position, a second (locked) position and a third (locked) position, and separate interlocking switch means cooperating with the latch mechanism in each the second and third positions to set up independent control circuits for the oven.

l 12. ln a combined microwave and pyrolytic self- I vcleaning'oven construction as recited in claim 11 with sponsive means for deactivating the lock lever to enable the movement of the latch mechanism to the third (locked) position at which position the automatic lock lever acts to hold the latch mechanism from further movement, the electroresponsive means being operable at oven temperatures below about 600F. m deactivate the automatic lock lever so that the latch mechanismmay be shifted to either its second (locked) posi tion or the first (unlocked) position.

Claims

1. A multiple position, sliding latch mechanism comprising a base, a latch handle pivotally connected to said base adjacent the rear thereof, a latch lever pivotally connected to the base and to the latch handle, a latching bolt pivotally connected to the base and joined to both the said latch lever and the base by a lost motion connection whereby movement of the latch handle from a first (unlocked) position causes a turning action of the latch lever and hence a turning action of the latching bolt, and indexing means associated with the latch lever to temporarily hold the latch mechanism in each of its multiple positions, and a locking bar pivotally connected to the latch lever and extending rearwardly thereof, an automatic lock lever associated with the locking bar for locking the latch mechanism against further movement in the forward direction, and electroresponsive means for deactivating the lock lever to enable the movement of the latch mechanism to a third position at which point the automatic lock lever acts to lock the latch mechanism from further movement, the said electroresponsive means again being operable to deactivate the said lock lever whereby the latch mechanism may be shifted to any position.

2. A multiple position, sliding latch mechanism comprising a base plate, a latch handle pivotally connected to said base plate adjacent the rear of the base plate, a latch lever pivotally connected to the base plate and to the latch handle, a latching bolt pivotally connected to the base plate and pivotally and slidably connected to the latch lever, whereby movement of the latch handle in one direction from a first (unlocked) position to a second (locked) position causes a turning action of the latch lever in the opposite direction and also a turning action of the latching bolt in the first direction until it reaches the second (locked) position, the latch handle having a third (locked) position which results in movement of the latch lever without altering the locked position of the locking bolt, and separate interlocking switch means cooperating with the latch mechanism in each the second and third positions to set up independent control circuits.

3. A multiple position, sliding latch mechanism as recited in claim 2 with indexing means associated with the latch lever to locate the second and third locked positions of the latch handle.

4. A multiple position, sliding latch mechanism as recited in claim 3 wherein the indexing means includes a cam surface formed on one side edge of the latch lever and a spring biased cam follower supported from the base plate for cooperation with the cam surface.

5. A multiple position, sliding latch mechanism as recited in claim 4 with a locking bar pivotally connected to the latch lever and extending rearwardly thereof, an automatic lock lever associated with the locking bar for locking the latch mechanism in the second (locked) position against further movement in the forward direction, and an electroresponsive means for deactivating the lock lever to enable the movement of the latch mechanism to the third (locked) position at which point the automatic lock lever acts to hold the locking bar from further movement, the said electroresponsive means being operable to deactivate the sAid lock lever so that the latch mechanism may be shifted back to either its second or first positions.

6. A multiple position, sliding latch mechanism comprising a base plate, a latch lever pivotally connected to the base plate, a latching bolt pivotally connected to the base plate adjacent the front thereof, and a lost motion connection between the latching bolt and the latch lever, and an elongated latch handle having a lost motion connection with the base plate adjacent the rear thereof and overlying the latch mechanism and extending forwardly beyond the latching bolt in its fully extended position, and a pivotal connection between the latch handle and the latch lever whereby movement of the latch handle causes a related movement of the latch lever and latching bolt for effecting a locking action, whereby the distal end of the latch handle moves in a relatively flat arc of a circle.

7. A multiple position, sliding latch mechanism as recited in claim 6 wherein the said lost motion connection between the latching bolt and the latch lever is extended whereby the latch handle has a first (unlocked) position, a second (locked) position and a third (locked) position, and indexing means associated with the said latch lever to establish three distinct positions of the latch mechanism.

8. A multiple position, sliding latch mechanism as recited in claim 7 with a locking bar pivotally connected to the latch lever and extending rearwardly thereof, an automatic lock lever associated with the locking bar for locking the latch mechanism in the second (locked) position against further movement in the forward direction, and an electroresponsive means for deactivating the lock lever to enable the movement of the latch mechanism to the third (locked) position at which position the automatic lock lever acts to hold the latch mechanism from further movement, the electroresponsive means being operable at temperatures below about 600*F. in an associated control cavity to deactivate the automatic lock lever so that the latch mechanism may be shifted to either its second (locked) position or the first (unlocked) position.

9. A multiple position, sliding latch mechanism as recited in claim 8 with separate interlocking switch means cooperating with the latch mechanism in each the second and third positions to set up independent control circuits.

10. In a combined microwave and pyrolytic self-cleaning oven having an oven cavity formed by a box-like oven liner and a front-opening access door, a multiple position, sliding latch mechanism mounted in the oven body adjacent the top front of the oven, said latch mechanism comprising a base plate, a latch lever pivotally connected to the base plate, a latching bolt pivotally connected to the base plate adjacent the front thereof, and a lost motion connection between the latching bolt and the latch lever, and an elongated latch handle having a lost motion connection with the base plate adjacent the rear thereof and overlying the latch mechanism and extending forwardly beyond the front surface of the oven door, and a pivotal connection between the latch handle and the latch lever whereby movement of the latch handle causes a related movement of the latch lever and latching bolt for effecting a locking action, whereby the distal end of the latch handle moves in a relatively flat arc of a curve.

11. In a combined microwave and pyrolytic self-cleaning oven construction as recited in claim 10, wherein the said lost motion connection between the latching bolt and the latch lever is extended whereby the latch handle has a first (unlocked) position, a second (locked) position and a third (locked) position, and separate interlocking switch means cooperating with the latch mechanism in each the second and third positions to set up independent control circuits for the oven.

12. In a combined microwave and pyrolytic self-cleaning oven construction as recited in claim 11 with indexing means associated with the said latch lever to establish threE distinct positions of the latch mechanism.

13. In a combined microwave and pyrolytic self-cleaning oven construction as recited in claim 12, with a locking bar pivotally connected to the latch lever and extending rearwardly thereof, an automatic lock lever associated with the locking bar for locking the latch mechanism in the second (locked) position against further movement in the forward direction, an electroresponsive means for deactivating the lock lever to enable the movement of the latch mechanism to the third (locked) position at which position the automatic lock lever acts to hold the latch mechanism from further movement, the electroresponsive means being operable at oven temperatures below about 600*F. to deactivate the automatic lock lever so that the latch mechanism may be shifted to either its second (locked) position or the first (unlocked) position.