US 3548804 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
O United States Patent [1113548304  Inventors Francis I Faehling,  References Cited wit New, Wisconsin Rapids, UNITED STATES PATENTS [211 App. No 831,080 icon 126/273 1 1gelbach.... 126/ 197x [221 Ned 3 313 91s 4/1967 Barber l26/l97X  Patented Dec. 22,1970
 Assignee Preway Inc. Primary Examiner-Charles J. Myhre a corporation of Wisconsin Attorney- Hofgren, Wegner, Allen, Stellman & McCord ABSTRACT: A self-cleaning oven for a range having a movable top panel mounting surface heating units and with an oven SELF-CLEANING OVEN door which is locked during a self-cleaning cycle with a 6cllilllsi3m'fl'lllfl 8 manually operated handle for operating a latch to lock the 5 s c 2 7 oven door. A limit switch responsive to a predetermined tem- 126/42, 126/197, 126/273 perature in the oven prevents movement of the handle to unlock the oven door. The handle is positioned beneath the top [5| 1 m F24: 3/12, panel so that access thereto can only be had by raising the top F24: 15/02 panel and a second switch operable by the top panel is pro-  Field oiSearch 126/37, vided to maintain the limit switch ineffective unless the top 37A, 39, 39C, 42, 197, 273 panel has been raised to provide access to the handle.
PATENTED 05122 I976 iwenza/"ax SELF-CLEANING OVEN I BACKGROUND OF THE INVENTION This invention pertains to a range having a self-cleaning oven and, more particularly, to such a range having a manually operable member for locking the oven door during a self-cleaning cycle and with the manually operable member only accessible by moving a cover panel.
Self-cleaning ovens are well known and have provision for locking of the oven door before the self-cleaning cycle can commence. Such ovens also include a limit switch responsive to the temperature existing within the oven whereby the door cannot be unlocked when a high temperature exists in the oven. These systems include a solenoid which is in circuit with the limit switch and as the critical temperature for operating this limit switch is approached there is inherently a resulting chattering operation of the solenoid which results in an annoying noise and renders the present systems unsatisfactory.
SUMMARY 1 An object of this invention is to provide a new and improved locking system for the oven door of a self-cleaning oven and particularly for such an oven as part of a range.
Another object of the invention is to provide a self-cleaning oven having a latch for locking the oven door and a manually engageable member for causing operation of the latch with the manually engageable member being positioned behind a movable cover, control means for the latch including a limit switch responsive to a certain temperature within the oven for preventing unlocking of the oven door, and means for rendering said limit switch ineffective to provide control of oven door locking so long as said cover panel is closed to prevent access to said manually engageable member.
Still another object of the invention is to provide a range having a self-cleaning oven and a movable top panel with surface heating units wherein a manually operated handle is located within the confines of the range and only accessible by lifting said top panel, control means for preventing movement of the handle when the oven is in a self-cleaning cycle including a limit switch responsive to a certain temperature in the oven, and means for causing said limit switch to be effective only when the top panel is raised providing access to the handle, including a switch operated by the top panel and which is normally open but which closes when the top panel is raised to place said limit switch effectively in the control circuit.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front perspective view of the range with selfcleaning oven;
FIG. 2 is a view similar to FIG. 1 with the range top panel in elevated position; and
FIG. 3 is a plan view of the door lock mechanism and control means associated therewith.
DESCRIPTION OF THE PREFERRED EMBODIMENT The invention is shown embodied in a range having a casing indicated generally at with an oven having a front opening closed by an oven door 11 which is hinged along its lower edge for opening movement. The top of the range has a top panel 12 which is hinged along its rear edge 13 to the cabinet of the range for raising movement pivotally about the rear edge. The top panel mounts a series of surface heating units 14. The top panel 12 is shown closed in FIG. 1 and is shown in raised position in FIG. 2.
The oven has suitable circuitry providing for a self-cleaning cycle which at this time is well known in the art. Basically, this cycle provides for a prolonged period of heating of the oven to place the oven interior at a sufficiently high temperature to dispose of food particles and other material deposited on the interior oven surfaces. It is also well known to provide for locking of the oven door to prevent opening thereof during the self-cleaning cycle and to provide asuitable interlock switch which indicates that the oven door has been locked before the self-cleaning cycle commences. Such handles have been positioned at the front of the oven and normally protrude into the room when positioned to lock the oven door.
As shown in FIG. 3, the oven door locking handle 20 is positioned within the confines of the range and beneath the top panel 12 whereby the top panel must be raised to permit access to the handle. The oven door locking mechanism including the handle 20 is of conventional construction wherein a mounting unit 21 attaches to an interior plate 22 positioned beneath a cover plate 22a underlying the top panel 12 and has a latch 23 movable to engage a catch 24 formed in the oven door 11 to lock the door. The handle 20 is pivoted on unit 21 by a pivot pin 25 and has an upwardly offset part to extend out over cover plate 22a. Movable with the handle 21) and catch 23 is an arm 31) which coacts with a stop member 31 pivoted to the base of unit 21 at 32. The stop member 31 is spring urged by a spring 33 in a counterclockwise direction. A pin and slot connection 34 limits the movement of stop member 31. With the stop member 31 positioned as shown in FIG. 3, it can engage the arm 30 and prevent movement of the handle 20 all the way to oven door locking position. After the oven door has been locked, the arm 30 has moved to a position beyond the stop member 31 wherein the stop member can be shifted by the spring 33 to a position to block the arm 30 from return movement and thus block the movement of the handle 211 to unlock the oven door.
The pivoted stop member 31 is pinned at 38 to a link 39 which is pinned at 40 to the armature of a solenoid 41. With the solenoid 41 deenergized, the spring 33 is effective to urge the stop member 31 to a forward position in blocking relation with the arm 30. When the solenoid is energized, the armature is drawn in to move the link 39 and the stop member 31 toward the rear of the range and permit free movement of handle 20.
The control means for the operation of the handle 20 includes in addition to the solenoid 41 and pivoted stop member 31, a limit switch 45 which is connected in circuit with the solenoid 41. The circuit includes lines 50 and 51 connected to the limit switch 45 and solenoid 41, respectively, and with interconnecting wires 52 and 53. The limit switch 45 is normally closed and is responsive to the temperature within the oven to open when the oven reaches a high temperature and this conventionally is approximately 580 F. In conventional systems, as the self-cleaning cycle starts and the oven door has been locked, the limit switch 45 is closed which results in the solenoid 41 being energized to permit movement of the oven locking handle. As the oven approaches the preset temperature, such as 580 F., there is an interval of time when the limit switch is approaching the fully open condition when the sole noid 41 will chatter.
As part of the invention disclosed herein, provision is made for avoiding this chattering condition and this is accomplished by adding a second switch 60 in series with the limit switch 45 and as shown connected between wires 52 and 53. This normally closed limit switch is positioned to be held in an open position by the top panel 12 when the top panel is closed. The opening of switch 60 renders the limit switch 45 ineffective to control the solenoid 41. This providessatisfactory operation since the switch 60, by being open, signals that the top panel 12 is down and therefore access to the handle 20 is prevented. So long as access to the handle 20 is prevented, there cannot be any inadvertent opening of the oven door 11.
In the event the top panel 12 is raised during the self-cleaning cycle, this shifts the switch 60 from an open condition to the normally closed condition which then permits the limit switch 45 to effectively control the solenoid 41. If the oven temperature is still below the preset value for operation of the limit switch, the solenoid 41 is energized to permit movement of the handle. This condition must occur as a preliminary to the self-cleaning cycle since the stop 31 must be withdrawn in order to permit the handle 20 and the arm 30 to move to lock the oven door. If the top panel 12 is raised when the oven temperature is above some figure such as 580 F. which indicates that the oven is well into the self-cleaning cycle, then the limit switch 45 will have been opened and even though the switch 60 is closed, this will result in the solenoid not being energized and the pivoted stop 31 maintained in position to block the arm 30 and handle 20. From the foregoing, it will be seen that a self-cleaning oven has been provided wherein a manually engageable member for either locking or unlocking the oven door can only be engaged when a cover panel is moved and interlock means are provided to detect when the cover panel is opened and, if the panel is opened, then a limit switch responsive to the oven temperature is placed in circuit to prevent operation of the accessible member if the oven temperature is above a preset figure.
1. A self-cleaning oven having an oven door which is locked during the self-cleaning cycle, a latch for locking the door, means for operating said latch including a manually actuated member, a movable pane covering said manually actuated member, means to prevent operation of said latch operating means when the oven temperature exceeds a preset figure including a thermally operated switch, and means to render said switch ineffective when said panel covers said manually actuated member and prevents access thereto.
2. An oven as defined in claim 1 wherein said operation preventing means includes a solenoid in circuit with said thermally operated switch, said solenoid preventing operation when deenergized, and the means rendering the switch ineffective includes a second switch in series with said solenoid and thermally operated switch, said second switch being open when said panel is closed and closed when said panel is open.
3. A self-cleaning oven having an oven door, a manually operated latch for locking the oven door, a handle for operating said latch, a movable panel covering said handle and movable to permit access thereto, control means to preclude movement of the handle when said oven temperature exceeds a certain figure including a thermally controlled switch, and means to render said switch ineffective when said movable panel covers said handle and thus prevents access thereto.
4. A range with a self-cleaning oven having an oven door and a raisable top panel for the range mounting the surface heating units, a manually operated latch for locking the oven door, a handle for operating said latch located entirely within the confines of the range and accessible only by raising said top panel, control means including a limit switch to prevent operation of said handle when said oven temperature exceeds a certain figure, and interlock means to render said limit switch effective only when said top panel is raised and the handle is accessible.
5. A range as defined in claim 4 wherein said control means includes a movable detent which in one position blocks the handle, a solenoid which, when energized, moves the detent from said one position to permit the handle to be moved, and a circuit including said solenoid and said limit switch with said switch being normally closed and opening when said oven temperature is reached to open the circuit, and said interlock means including a second switch operated by the top panel and in series with said limit switch switch and which opens the circuit when the top panel is closed to render the limit switch ineffective, said second switch closing when the top panel is raised to permit movement of the handle unless said limit switch has opened.
6. A range with a self-cleaning oven having an oven door and a raisable top panel for the range mounting the surface heating units, a manually operated latch for locking the oven door, and a handle for operating said latch located entirely within the confines of the range and accessible only by raising said top panel.