Range oven door latching device

Aug. 19,1969 w. r. guy 3,462,584

RANGE OVEN DOOR LATCHING DEVICE Filed Aug. 9, 1967 2 Sheets-Sheet 1

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Aug. 19,1969 . w. r. guy 3,462,584

RANGE OVEN DOOR LATCHING DEVICE

Filed Aug. 9, 1967 2 Sheets-Sheet 2

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4TT0RNWS

3,462,584

Patented Aug. 19, 1969

United States Patent Office

3,462,584

RANGE OVEN DOOR LATCHING DEVICE

William R. Guy, Detroit, Mich., assignor, by mesne assignments, to Kelvinator, Inc., Cleveland, Ohio, a corporation of Delaware

Filed Aug. 9, 1967, Ser. No. 659,348

Int. Cl. F27d 11/02

U.S. Cl. 219—412 8 Claims

ABSTRACT OF THE DISCLOSURE ¹⁰

A latching device for a range oven door operated by an electric motor which also actuates circuit control switches of which one controls the motor and another the circuit to the oven heating elements for elevating the tern- 15 perature in the range oven to effect a self cleaning thereof by the principle of pyrolysis.

The present invention relates to door latching arrange- 20 ments for range cooking ovens and more particularly to a latching device being operative for use only during noncooking periods when it is desired to elevate the temperature within the cooking oven to above normal cooking values so as to effect a degrading of food soils adhering 25 to the walls of the oven chamber by utilizing the principle of pyrolysis.

An object of the present invention is to provide a latching device for range oven doors which is fully automatic in operation requiring no manually moved lever, or 30 manual prelatching or unlatching, to effect a locking or unlocking of the oven door.

Another object of the present invention is to provide a latching arrangement whereby the door is automatically latched upon the presetting of the heat control to effect 35 a self cleaning operation to degrade the food particles from the oven walls to automatically unlatch the door upon the heat controls being set for normal cooking needs.

A further object of the present invention is to provide ⁴⁰in circuit with a motor operating a latching and unlatching mechanism for range oven doors a switch thermostatically controlled in response to the temperature within the oven chamber to prevent unlatching during periods the temperature is being elevated above normal cooking ⁴³needs.

A still further object of the present invention is to arrange a motor to operate a latching device for a range oven door together with circuit control switches of which one controls the motor and another a heating circuit. ⁵⁰These and other objects and advantages to be gained in the practice of this invention will be better understood and further appreciated upon the reading of the following specification having reference to the accompanying _g_ drawings.

In the drawings:

FIG. 1 is a side elevational view of an electric range with parts broken away and parts shown in section and embodying my door latching device;

FIG. 2 is a fragmentary sectional view taken along ^{b J}line 2—2 of FIG. 1 illustrating the door latching device;

FIG. 3 is a sectional view taken along line 3—3 of FIG. 2;

FIG. 4 is an elevational view of the motor drive and switch arrangement viewed along line 4—4 of FIG. 2; ⁰and

FIG. 5 is a wiring diagram illustrating the control circuit for the present invention and as incorporated in a range circuit for controlling the high heat self cleaning oven operation.

Referring to the drawings, the number 20 designates in general a cooking range having a cook top 22 and an oven chamber 24.

Arranged on the cook top are a plurality of surface heating element 26.

The oven chamber 24 is formed by a box like oven liner 30 and is supported in spaced apart relation from the sides, top and bottom walls of outer casing 32 for packing suitable heat insulation 33 therebetween.

Access to the chamber 24 is through an opening 34 formed in front wall 36 of the range and which is closed by a door 40. The door 40 is hinged on a horizontal axis, as at 41, adjacent the bottom edge of the door to swing downwardly to a horizontal position when opened. The hinge arrangement may be one that incorporates a spring to hold it in closed position. It is not here described or shown for the reason that any well known arrangement may be used as the hinge arrangement forms no particular part of the present invention.

The oven chamber is heated by a lower heating element 42 and an upper heating element 44 between which are shelves (not shown) suitably positioned and supported for the placement of food that is to be cooked in the oven chamber.

No latching of the door is required when the oven chamber is in cooking use. The door is held sufficiently shut by the tension of springs incorporated in the hinge arrangement, explained above. Such an arrangement holds the door with sufficient tension to provide a slight compression on a gasket 46 between the door and the front wall 36. The gasket is carried by the door and extends perimetrically about the door opening 34. The gasket 36 may be interrupted in its continuity along the bottom edge of the door to form gaps through which a restricted amount of air may enter the oven chamber.

In utilizing the principle of pyrolysis to self clean the oven walls of adhering food and grease soils the temperature within the oven chamber is elevated to between 750 F. to 950° F. for a predetermined period. As the temperature range is considerably above the normal cooking requirements of 150° F. to 550° F. safety standards require that the door be securely latched and locked against opening during this elevated temperature period. Further, to insure that a uniform temperature is had in all areas of the oven chamber the gasketed section must be drawn up to prevent or minimize air entrance into the chamber except through such gap that may be provided for limited air movement into the oven. By tighly sealing the door the oven walls adjacent the door area cannot be cooled by inflow of cooler room air and so the area remains sufficiently heated to degrade the food soils without the need of additional heaters about the access opening 34.

The latching device of the present invention is indicated in general by the numeral 50 and is located within the range cabinet or body, being mounted on a partitional panel 52 located above the top insulation on the oven liner and being a spatial distance below the cook top 22.

The latching device comprises an electric motor 54 operatively connected to a reduction drive 56 which in turn is connected to drive a cam member 58. A link or

3,462,584 rod 59 connects the cam member 58 to a latch member 60 to pivotally swing it into and out of engagement with a keeper 62 carried by the door 42. Associated with the cam member for sequestial actuation thereby are switches 64, 66 each connected in respective circuits to a manually actuated controller 68. The switches 64, 66 are each of the double throw type. The switch 64 is in circuit with the motor 54 and a non-adjustable thermostat switch 70. The thermostat switch 70 is positioned to be responsive to the temperature within the oven chamber and with switch 64, controller 68, forms a control arrangement for the latching and unlatching of the door automatically. The switch 66 controls the circuit to the heating elements 42, 44 during the self-cleaning operation.

The motor 54 is pre-assembled with the reduction drive 56 and is mounted by a bracket 72 to the panel 52. From the reduction drive 56, extends a driven shaft 73 upon which is secured to be driven thereby the cam 58. Engaging against the cam 58 are cam followers 74, 75 arranged to actuate the switches 62, 64 respectively. The switches 62, 64 are supported on arms 72 secured to bracket 70.

Secured by a pin 76 to the body of the cam 58 for carry thereby concentric about the axis of the shaft 73 is one end of the rod 59 whose opposite end is pinned to the latch member 60. The latch member 60 is journaled on a shaft TI that is secured to a bracket 78. The bracket 78 is attached to the rear face of the front wall 36 and across an opening 79 formed in the front wall through which enters the keeper 62 upon the closing of the door 40.

The latch member 60 is formed with a hook finger 80 to engage the keeper 62 and arranged whereby the finger is slightly eccentric to the axis of the latch member so that as the latching action continues a drawing up of the door to the front wall is had to compress the gasket 46 therebetween.

The manually actuated controller 68 includes a plurality of switches 90, 91, 92 actuated by rotation of a knob 84. The knob is selectively setable in positions of Clean, Time, Bake and Manual. Other switches are found in the controller to control circuits to provide various heating needs in various cooking operations but are here omitted for clarity of the present invention. For further disclosure, reference is made to the application filed by Herbert A. Kauranen, titled “Range Oven Control Circuit for Pyrolytic Oven Cleaning,” Serial No. 659,775 which application is assigned to the same assignee as here and filed on Aug. 10, 1967.

The switch 90 is a double throw type and its contacts 94, 95 are connected to respective contacts 96, 97 of the switch 64 by conductors 98, 99 respectively. The switch blade of switch 90 is connected to a power supply line N while the switch blade of switch 64 is connected by conductor 101 to one side of the motor 54 which in turn is connected by conductor 102 to the thermostat switch 70. A conductor 103 connects the thermostat switch 70 to a contact 104 of a double throw door switch 105 whose switch blade is connected by conductor 106 to a power supply line L2. The other contact 107 of the door switch 105 connects by conductor 108 a lamp 109 to the power supply line N. When the door is opened the switch 105 is upon the contact 107 to energize and illuminate the oven chamber. Closing the door moves the switch upon the contact 104.

Signal lamps 112,114 are provided to indicate the latching of the door and that the circuit for the self cleaning oven period is closed. The signal lamp 112 is connected by a conductor 116 in a shunt circuit to the thermostat switch 70 and in series with the motor 54. The lamp 112 is also connected in shunt to the motor by a resistor 117 in shunt to the motor and in series with the switch blade of the switch 64. The signal lamp 114 is connected across from the contact 96 to the conductor 103.

Knob 84 for normal use of the oven is set on Time Bake or Manual which places the switch 90 upon the contact 95. If the door is latched this will close the circuit to unlatch the door and reset the switch upon the contact 96 for the period the door is held unlatched. The thermostat switch 70 is influenced by the temperature of the oven and is normally closed while the temperature remains below 575° F. and opens when the temperature is elevated thereabove. The thermostat switch 70, with switch 64 on contact 96, presets the latching circuit so that in setting the knob to Clean, this closes the switch 90 upon contact 94, the motor is immediately energized to effect a latching of the door. The circuit follows from power line N, switch 90 on contact 94, conductor 98, switch 64 on contact 96, motor 54, thermostat switch 70, conductor 103, door switch 105 on contact 104, conductor 106 to power supply line L2.

The drive 56 reduces the motor’s rotation to rotate the cam 58 a half revolution to fully latch the door. That is, the cam need travel only 180! degrees for finger 80 to become fully interlocked with the keeper 62 whereupon the motor is then de-energized by the cam actuating the switch 64 from contact 96 to contact 97. With the door latched the switch 64 now presets an alternate circuit to unlatch the door. To unlatch the cam is continued in its rotation for a second half turn, or another 180 degree travel, and upon completion the switch 64 is actuated from the contact 97 back to contact 96 to preset the first or the latching circuit.

Should it be decided not to proceed with the self cleaning operation, or the knob is accidently reset from Clean to either of the other positions, the switch 90 moved upon the contact 95 will either complete or preset the unlatching circuit dependent upon the temperature prevailing within the oven chamber. If it has not risen above 575° F. the door is immediately unlatched as the thermostat switch 70 will still be closed. However, if the temperature has been elevated thereabove the door will not be unlatched until the chamber has cooled to and below 575° F. to effect the reclosing of the thermostat switch 70.

With the operation of the switch 64 the cam 58 also actuates the switch 66 to provide a by-pass circuit to the parallel connected heating elements 42, 44 around the thermostat 130 that normally controls the heating element for normal cooking uses. The switch 66 also disconnects the circuit to one of the surface heating elements 26 through which the oven chamber 24 is vented by a conduit 132 during the period the temperature is being elevated to approximately 750° F. to 950° F. to degrade the food soils adhering to the walls of the chamber.

The circuit energizing the heating elements 42, 44 to elevate the temperature to between 750° F. to 950° F. within the oven chamber follows: power supply line LI, conductor 134, switch 66 on the contact 121, conductor 135, closed switch 91 to closed timer switch 136, conductor 137, parallel connected heating elements 42, 44, conductor 138, a non-adjustable oven control thermostat switch 140 to power line L2. The thermostat switch 140 is normally closed and opens when the temperature within the oven chamber reaches and rises above 850° F.

As it is important to control the temperature rise within the oven chamber so as not to be too rapid, each having element 42, 44 is connected in series to a cycling switch 142, 144 respectively. Each switch is thermally responsive to a respective heating element 145 to being cyclically opened and closed and each heating element is accordingly cycled. The cycling of the switches controls the heat output from the heating elements 42, 44 to provide for a slow heat rise in the oven chamber. The heating elements 145 are connected to and placed in circuit by the switch 92 and each heating element is connected in series with the respective switch it influences to self de-energize itself upon influencing the opening of the switch.

The timer 136 terminates the operation of the heating elements 42, 44 and thereafter it is necessary that the knob 84 be manually reset from Clean to either of the other positions to open the switches 91, 92 and simultaneously reset the switch 90 upon the contact 95. The

3,462,584 reset switch 90 with switch 64 on contact 97 sets the circuit to energize the motor to unlatch the door. The unlatching may not be immediately effected as the circuit will remain open until the oven chamber temperature has sufficiently cooled to effect a closing of the thermostat switch 70. After unlatching the door, the switches 64, 66 are both actuated, the switch 64 de-energizing the circuit to motor 54 while the switch 66 resetting on contact 120 reconnects in circuit the surface heating element 26. The heating elements are returned in circuit for control by the thermostat switch 130 and the circuit to the heater elements 145 are held open.

From the foregoing it is apparent that an automatically actuated safety door latching device is provided for the oven chamber when it is to be elevated to temperatures of 750° F.-950° F., and which requires no manual operation of levers by the user. The latching and rmlatching being fully automatic requires the operator merely to preset the controller knob 84 to the use desired of the oven. To latch the door it must be fully closed otherwise the door switch 105 will maintain the circuit open and in this position either the latching device 50 will function nor will the heating elements be energized until the door has latched and the switch 66 has been actuated by the motor 54 upon the contact 121. Further the door cannot be unlatched as long as the temperature within the oven chamber is elevated above 575° F.

Though a timer 136 is shown and described as controlling the period of energization of the heating elements 42, 44 the period may be terminated by the user upon resetting the knob 84 of controller 68 from Clean to either of the other needed positions. This will open the switches 91, 92 and reset switch 90 upon 95 to set the motor circuit with switch 64 upon contact 97 to energize the motor 54 as soon as the oven chamber has cooled to below 575° F. and effected a reclosing of the thermostat switch 70.

Although a specific embodiment of this invention has been shown and disclosed, it will be appreciated that certain modifications and improvements are within the spirit and scope thereof. Accordingly such modification and improvements as are not specifically excluded by the language of the hereinafter appended claims are to be considered as inclusive thereunder.