US3367697A

US3367697A - Door latch mechanism

Info

Publication number: US3367697A
Application number: US533344A
Authority: US
Inventors: Sr Joseph S Fox
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1966-03-10
Filing date: 1966-03-10
Publication date: 1968-02-06
Anticipated expiration: 1985-02-06

Description

J. S. FOX, SR

DOOR LATCH MECHANISM Feb. 6, 1968 2Sheets-Sheet 1 Filed March 10, 1966 F'IGZ H s ATTORNEY Feb. 6, 1968 J 5. FOX, SR 3,367,697

I DOOR LATCH MECHANISM Filed March 10, 1966 2 Sheets-Sheet 2 6 FIGS I v 4. INVENTOR.

TOSEPH 3. Fox, 5'2.

ms- ATTORNEY United States Patent ()flice 3,367,697 DOOR LATCH MECHANISM Joseph S. Fox, Sr., Louisville, Ky., assignor to General Electric Company, a corporation of New York Filed Mar. 10, 1966, Ser. No. 533,344 6 Claims. (Cl. 292-413) ABSTRACT OF THE DISCLOSURE A door latch mechnism as for use with a kitchen appliance such as a self-cleaning baking oven or an automatic dishwasher where the mechanism includes a supporting bracket having a pivoted latching bolt and a pivoted handle lever connected thereto by means of a cam follower arrangement to give the latching bolt both a swinging and a lineal movement to pull the door in tight. Also pivoted to the bracket and generally coinciding and moving with the latching bolt is a door sensor bar that serves to interrupt the closing action of the latch mechanism if the door is not present in its closed position. The door sensor bar is adapted to be deflected aside by the presence of the door so that the latching bolt may complete its travel to the fully closed position.

The present invention relates to a door latch mechanism for holding a door in a tightly locked position. Such doors are sometimes referred to as a self-sealing type; i.e., doors having latches which are so designed that during the final stages of their closing movement they cause compression of a door gasket.

This invention is an improvement over the door latch mechanism of Letters Patent 3,189,375 issued to Clarence Getman on June 15, 1965, and assigned to the General Electric Company, the assignee of the present invention. Both of these door latch mechanisms were developed for use with a high temperature oven for domestic use where the oven has provision for an automatic heat cleaning cycle during which the temperature is raised to between about 750 F. and about 950 F. so as to decompose all food soil from the oven liner Walls. With such high operating temperatures it is imperative to latch the oven door before the cleaning cycle is set in motion so that the door can not be opened during the heat cleaning cycle. It is likewise important to seal the door so as to preclude the escape of smoke, odor and heat from around the door while the food soil is being removed from the oven liner walls by a process of pyrolysis. If it were possible to open the door while the oven was operating at these elevated heat cleaning temperatures, there would be a sudden inrush of oxygen into the oven cavity to combine with the hot gases and this might cause a sudden high flame which could be harmful. Accordingly, door latches and oven controls have been devised which prevent the initiation of the heat cleaning cycle until the door latch mechanism has clamped the door into a sealed position, and they prevent the door from being re-opened until the temperature within the oven drops to a level below the maximum normal cooking temperature of about 550 F.

The primary object of the present invention is to provide a simplified door latch mechanism having an improved door sensing means to insure that the door latch mechanism cannot be closed it the door is not first present in its closed position.

Another object of the present invention is to provide such a door latch mechanism which is constructed from a minimum number of parts that are easy to assemble and reliable in operation.

The present invention, in accordance with one form thereof, is embodied in a door latch mechanism including 3,361,697 Patented Feb. 6, 1968 a bracket mounted within a door frame adjacent the distal edge of the door. The bracket includes a flange portion disposed adjacent an opening in the door frame. A latching bolt is pivotally mounted on the bracket and adapted to engage and disengage the door to be locked. A handle lever is also pivotally mounted to the bracket and connected to the latching bolt by a cam follower arrangement so that swinging movement of the handle causes first a comparable swinging movement of the latching bolt to engage the door and then a substantially lineal movement toward the door frame by the latching bolt to compress the door gasket. The flange portion has an opening therein through which the latching bar is moved by the handle lever. A door sensor bar is pivotally supported on the latching bolt for movement therewith and includes a hook portion which will engage the flange so that the handle cannot be moved to its fully closed position unless the door sensor bar has first been deflected by the presence of the door. If the door is moved to and retained in its closed position prior to the closing movement of the handle lever, the door sensor bar will be deflected by the door so that its hook portion will not engage the bracket flange and the latching bolt will be free to fully close and lock the door.

My invention will be better understod from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.

FIGURE 1 is a right side elevational view of a freestanding range having a door latch mechanism embodying the present invention;

FIGURE 2 is a fragmentary plan view, partly in cross section on an enlarged scale, taken along line 2-2 of FIGURE 1 and shows the latch mechanism in its open position disengaged from the oven door, which would be the position of the latch mechanism during normal cooking operations;

FIGURE 3 is a fragmentary plan view similar to FIG- URE 2 showing the oven door in its closed position and the latch mechanism moved to its fully closed position;

FIGURE 4 is a fragmentary plan view similar to that of FIGURE 2 illustrating the situation when the door has been left open and the handle lever has been moved toward its closed position until the hook portion of the door sensor bar has engaged the flange of the latch mechanism bracket; and

FIGURE 5 is a fragmentary elevational view taken along the line 5-5 of FIGURE 3.

Turning now to a consideration of the drawings and particularly to FIGURE 1, there is shown for illustrative purposes a freestanding electric range 10 having a top cooking surface 11 with a plurality of surface heating elements 12, and oven cavity 13, a front-opening oven door 14, and a backsplasher 15 arranged along the back edge of the cooking surface 11 and containing a control panel (not shown) having control components which govern the energization of the various heating elements of the range. The oven cavity 13 includes two standard electric heating elements; namely, a lower bake unit 16 arranged just above the bottom of the oven cavity and an upper broil unit 17 which is located just under the top wall of the oven cavity.

The latch mechanism of the present invention is indicated by the numeral 20 and is located within the oven cabinet or range body above the door opening. As mentioned previously, this invention of a new and improved latch mechanism 20 has been found of primary importance when used with a high temperature heat cleaning oven. In such an oven there is a third heating element or mullion heater 21, as seen in FIGURE 5, that is located near the front of the door opening of the oven cavity to encircle the oven liner and compensate for the loss of heat through and around the door. It is a type of heating element that has a helical resistance wire encased in a high temperature insulating material such as magnesium oxide, and which in turn is covered with a metal sheath or jacket, as is standard heating element construction in this art.

In designing oven door arrangements for ranges there is a decided advantage in placing the door latch mechanism in the range body or door frame rather than in the door structure. When the latch mechanism is in the range body it can be mounted above the oven insulation 22 so that is somewhat protected from the high temperature of the oven liner 23 which forms, with the oven door 14, the oven cavity 13. The oven door is of a relatively thin construction and would provide little heat protection for the latch as compared with the available insulated space under the top cooking surface 11. It is recognized that in other applications, such as drop-door automatic dishwashers, the parts could be reversed so as to locate the latch mechanism in the door without departing from the spirit of the present invention.

Referring now particularly to FIGURES 2-5, the latch mechanism is shown as comprising a mounting bracket 25 which is a generally fiat sheet metal member with an upturned flange 26 along its front edge so that it may be screwed to the rear surface of the front wall of the range body. A pin 28 extends from bracket 25 and is received in an elongated slot 29 formed in a latching bolt 30. Thus, the latching bolt 30 may pivot about pin 28 for a swinging type motion as Well as slide around pin 28 for a substantially lineal type motion. The forward end of the latching bolt 30 has a hook portion 31 which is adapted to engage a keeper 32 on the oven door 14. The front wall of the range body has an elongated slot or opening 33 and a portion of the flange 26 overlies the slot or opening. The flange 26 is formed with an opening or slot 34 in communication with the slot 33 and arranged for receiving the latching bolt 30 therethrough. The oven door 14 has a similar slot 35 formed in its inner door liner and is hollow in the vicinity of this slot 35 to permit the hook portion 31 of the latching bolt to extend into the interior of the door and engage around the side edge of keeper 32. A modified door design could use a cantilever spring within the door for engagement by the book 31 so as to compensate for manufacturing tolerances and allow the use of a more rigid gasket construction.

A handle lever 36 is pivotally mounted on the rearward portion of mounting bracket 25 by means of a pivot pin 37. The outer end of handle lever 36 extends outwardly between the top of door 14 and the lower side of cooking surface 11 and is formed with a knob or handle 38. This handle may be grasped by the user to manually move the handle lever in a swinging motion about pivot pin 37 between its fully open position, shown in FIGURE 2, and its fully closed position, shown in FIGURE 3. For this purpose, a slot 39 is formed between the front wall of the range body and the top cooking surface 11 and the handle lever 36 extends through this slot for manual manipulation.

The handle lever 36 is connected to the latching bolt 30 and both of these elements are further connected to the mounting bracket 25 by a compound pin and slot or cam follower connection which may best be understood by reference to FIGURE 3 in conjunction with FIGURE 5. A pin 46 is provided to extend through a suitable opening in latching bolt 30 so that the latching bolt may pivot with respect to the pin and may move linearly with the pin. The lower end of pin 40 is captured within a cam-shaped slot 41 formed in mounting bracket 25 and the upper end of the pin is captured in a complementary cam-shaped slot 41a formed in handle lever 36. This arrangement forms a cam follower connection between the handle lever 36 and the latching bolt 30. Cam-

shaped slots

41 and 41a are so shaped that pivotal or swinging movement of the handle lever 36 in a counterclockwise direction from the position shown in FIGURE 2 toward the position shown in FIGURE 3 will cause a clockwise pivotal or swinging movement of the latching bolt from the position shown in FIGURE 2 toward the position shown in FIGURE 3. By the same token, a reverse movement of the handle lever will cause a reverse movement of the latching bolt. Moreover, cam-

shaped slots

41 and 41a serve to pull the latching bolt 36 into the range cabinet in a lineal manner once the latching bolt 36 has engaged the keeper 32 of the door. This lineal movement serves to tightly clamp the door gasket 42 between the door 14 and the door frame.

Firm seating of the handle lever and thus the remainder of the latching mechanism in the open and closed positions is assisted by means of an overcenter spring 43 which is connected between a tab 44 formed on the rearward portion of handle lever 36 and a second flange 45 formed along one lateral edge of mounting bracket 25. Once the handle lever has been moved from either of its extreme positions past the center position of the spring 43, the spring tends to pull the handle lever to its other extreme position. The positioning of the spring is such that it goes over-center as it passes beyond pivot pin 37.

As an important feature of this invention there is incorporated a door sensor bar 46. The rearward end of the door sensor bar is pivotally mounted about pin 40 and is spaced from latching bolt 30 by an expanded center portion 47 of the pivot pin 40. A torsion spring 48 is connected between a tab 49 formed on the latching bolt 30 and a tab 50 formed in the door sensor bar. The torsion spring 48 functions to normally retain the door sensor bar in a position where it overlies the hook portion 31 of latching bolt 30 while leaving the door sensor bar 46 free to pivot away from the hook portion 31. The door sensor bar is formed with a hook portion 51 which will engage the flange 26 adjacent one edge of the slot 34 (as shown in FIGURE 4) to provide a stop means for preventing complete closure of the latch mechanism unless the door has first been moved to its closed position.

Combined with the latch mechanism 20, but not shown, is an electric control circuit which is activated only when the latch mechanism is in its fully locked position. This electric control circuit controls the heat cleaning circuit for the oven so that it is not possible to raise the oven temperature into the heat cleaning temperature range of between about 750 F. and about 950 F. unless the latch mechanism 20 is fully closed. One modification would utilize an electric switch that would be actuated by the door sensor bar 46 once the bar has been deflected by the door keeper 33. With such a switch, a person could not energize the heat cleaning cycle by manually moving the sensor bar, because once the hand is removed the sensor bar would disengage the switch.

Now for an explanation of the operation of the latch mechanism, attention is invited to FIGURE 4. It should be recognized that the oven door 14 is not present in its closed position. The handle lever 36 has been moved in a swinging or pivotal movement from the position shown in FIGURE 2 to an intermediate position between the unlocked and locked positions of FIGURES 2 and 3 respectively, but this is as far as the latch mechanism will move. The swinging motion has brought hook portion 51 of the door sensor bar 46 into engagement with flange 26 adjacent the upper edge of slot 34 (as seen in FIGURE 4). Continued swinging movement of the handle lever 36 would cause a lineal movement of the latching bolt 30 and door sensor bar 46 into the oven cabinet. This is due to the cam follower arrangement between the pin 40 and the cam-shaped

slots

41 and 41a. However, the engagement of hook portion 51 with flange 26 prevents movement of door sensor bar 46 and thus prevents movement of the entire latching mechanism. It will be noted that over-center spring 43 has not moved completely ovcr pin 37 so that the tension of the over-center spring tends to move the handle lever to the mechanism open position shown in FIGURE 2. Thus, if the user releases the handle lever the latch mechanism will be moved back to the unlocked position of FIGURE 2.

By comparing FIGURE 4 with FIGURE 3, wherein the latch mechanism is shown in its fully closed position, you will notice that the outer end of door sensor bar 46 has been engaged by the edge of keeper 32 of oven door 14, which has prevented the hook portion 51 from swinging into alignment with the edge of flange 26 of the mounting bracket 25. Because of this clearance between hook portion 51 and flange 26, the door sensor bar 46 was free to move linealy as movement of the handle lever was continued past the position shown in FIGURE 4 so that the handle lever and thus the entire latch mechanism was moved to its fully locked position.

Although I have described my invention of an improved door latch mechanism for an appliance such as an oven of a domestic range, it will readily be apparent to those skilled in this art that such a latch mechanism would have general utility in other arts such as in a drop-door dishwasher and for the door of a microwave oven.

Modifications of this invention will occur to those skilled in the 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.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A latch mechanism for locking a door, a door and a door frame where the door is hingedly mounted to the door frame along one edge thereof, said latch mechanism having a bracket which is supported in a position adjacent one edge of said frame removed from the pivoted edge of the door, a latching bolt pivotally mounted on said bracket and including a portion on the free end thereof for mating engagement with the door, a handle lever pivotally mounted on said bracket and pivotally connected to said latching bolt so that swinging movement of said handle lever causes swinging movement of said latching bolt, a door sensor bar pivotally supported on said bracket generally overlying the same, biasing means acting on said door sensor bar to cause swinging movement of said sensor bar .in response to swinging movement of said handle lever, and means defining an opening in the door frame through which said latching bolt and door sensor bar move during swinging movement thereof, the movement of the handle lever from the open position toward the closed position being interrupted if the door is not present in its closed position, the door sensor bar being positioned for lockingly engaging a portion of the said opening defining means to cause said interruption and preventing further movement of either the latching bolt or the sensor bar, while the presence of the door in its closed position would deflect the position of the door sensor bar with relation to the latching bolt thereby disabling the door sensor bar and permitting the latch mechanism to complete its travel to the fully closed position.

2. A latch mechanism adapted for locking a door, a door and a door frame where the door is hingedly mounted to the door frame along one edge thereof, said latch mechanism having a bracket which is supported in a position adjacent an edge of said frame removed from the pivoted edge of the door, a latching bolt pivotally mounted on said bracket and including a portion on the free end thereof for mating engagement with the door, a handle lever pivotally mounted on said bracket and pivotally connected to said latching bolt so that swinging movement of said handle lever causes swinging movement of said latching bolt, a door sensor bar pivotally supported on said bracket, biasing means acting on said door sensor bar to cause a portion of it to overlie said free end of said latching bolt, and means in the door frame defining an opening through which said latching bolt and said door sensor bar move during swinging movement thereof, the movement of the handle lever from the open position to the closed position being interrupted if the door is not present in its closed position, the door sensor bar being positioned for lockingly engaging a portion of the said opening defining means to cause said interruption and preventing further closing movement of the handle lever, while the presence of the door in its closed position would deflect the door sensor bar from such locking engagement and permit the handle lever to complete its travel to the fully closed position.

3. A latch mechanism adapted-for locking a door, a door and a door frame where the door is hingedly mounted to the door frame along one edge thereof, said latch mechanism having a bracket which is supported in a position adjacent an edge of said frame removed from the pivoted edge of the door, a latching bolt mounted on said bracket for combined swinging and lineal movement and including a portion on the free end thereof for mating engagement with the door, a handle lever pivotally mounted on said bracket, a cam follower arrangement connecting said latching bolt and said handle lever so that swinging movement of said handle lever from an open to a closed position causes first a swinging movement of said latching bolt and then a substantially lineal movement toward the door frame, a door sensor bar pivotally supported on said bracket, a spring acting on said door sensor bar to cause a portion of it to overlie said free end of said latching bolt, said door sensor bar including a hook portion, and means in the door frame defining an opening through which said latching bolt and said door sensor bar move in response to swinging movement of said handle lever, the movement of the handle lever from the open position to the closed position being interrupted if the door is not present in its closed position, the hook portion of the door sensor bar being positioned for engaging the said opening defining means to cause said interruption and preventing the said lineal movement of the latching bolt, while the presence of the door in its closed position would deflect the door sensor bar so that the bar clears the opening defining means and permits the handle lever to complete its travel to the fully closed position.

4. A latch mechanism adapted for locking a door, a door and a door frame where the door is hingedly mounted to the door frame along one edge thereof, said latch mechanism having a bracket which is supported in a posi tion adjacent an edge of said frame removed from the pivoted edge of the door, a latching bolt mounted on said bracket for combined swinging and lineal movement and including a portion on the free end thereof for mating engagement with the door, a handle lever pivotally mounted on said bracket, a cam follower arrangement connecting said latching bolt and said handle lever so that swinging movement of said handle lever from an open position to a closed position causes first a swinging movement of said latching bolt and then a substantially lineal movement of said latching bolt toward the door frame, a door sensor bar generally coinciding with the latching bolt and connected to said handle lever by said cam follower arrangement, a spring acting on said door sensor bar to bias it for combined swinging and lineal movement in response to swinging movement of said handle lever, said door sensor bar including a hook portion, the door frame defining an opening adjacent said bracket, said bracket including a flange overlying the opening in the door frame, said flange defining an opening through which said latching bolt and door sensor bar move in response to swinging movement of said handle lever, the movement of the handle lever from the open position to the closed position being interrupted substantially midway of its travel if the door is not present in its closed position, the hook portion of the door sensor bar being positioned for engaging the said bracket flange and preventing the lineal movement of the latching bolt to cause said interruption, while the presence of the door in its closed position would disable the door sensor bar so that the bar clears the bracket flange and the handle lever is permitted to complete its travel to the fully closed position.

5. A latch mechanism adapted for locking a door, a door and a door frame where the door is hingedly mounted to the door frame along one edge thereof, said latch mechanism having a bracket which is supported in a position adjacent an edge of said frame removed from the pivoted edge of the door, a latching bolt pivotally mounted on said bracket and including a portion on the free end thereof for mating engagement with the door, a handle lever pivotally mounted on said bracket and pivotally connected to said latching bolt so that swinging movement of said handle lever causes swinging movement of said latching bolt, a door sensor bar pivotally supported on said bracket, a spring acting on said door sensor bar to cause a portion of it to coincide generally with said free end of said latching bolt, the door frame defining an opening adjacent said bracket, said bracket including a flange overlying the opening in the door frame, said flange defining an opening through which said latching bolt and said door sensor bar move during movement thereof, the movement of the handle lever from the open position to the closed position being interrupted if the door is not present in its closed position, the door sensor bar being positioned for lockingly engaging the bracket flange and preventing further movement of the handle lever to cause said interruption, while the presence of the door in its closed position would cause a portion of the door to deflect the door sensor bar out of coincidence with the latching bolt thereby disabling the sensor bar and permitting the handle lever to complete its travel to the fully closed position.

6. A latch mechnaism adapted for locking a door, a door and a door frame Where the door is hingedly mounted to the door frame along one edge thereof, said latch mechanism having a bracket which is supported in a position adjacent an edge of said frame removed from the pivoted edge of the door, a latching bolt mounted on said bracket for combined swinging and lineal movement and including a portion on the free end of the bolt for mating engagement with the door, a handle lever pivotally mounted on said bracket, a cam follower arrangement connecting said latching bolt and said handle lever so that swinging movement of said handle lever from an open position to a closed position causes first a swinging movement of said latching bolt and then a substantially lineal movement of said latching bolt toward the door frame to pull the door in tight, a door sensor bar pivotally supported on said bracket, a spring acting on said door sensor bar to cause a portion of it to overlie said free end of said latching bolt, said door sensor bar including a hook portion, the door frame defining an opening adjacent said bracket, said bracket including a flange overlying the opening in the door frame, said flange defining an opening through which said latching bolt and said door sensor bar move in response to swinging movement of said handle lever, the movement of the handle lever from the open position to the closed position being interrupted if the door is not present in its closed position, the hook portion of the door sensor bar being positioned for lockingly engaging the edge of the said opening in the bracket flange and preventing further forward movement of the handle lever and hence the lineal movement of the latching bolt to cause said interruption, while the presence of the door in its closed position would cause the door sensor bar to engage a portion of the door and the bar to be deflected thereby to clear the bracket flange and permit the latching bolt to complete its lineal movement into its fully closed position.

References Cited UNITED STATES PATENTS 10/1961 Jellies ZOO-61.62 6/1965 Getman 292*111 X