US3746382A

US3746382A - Latch arrangement for appliance

Info

Publication number: US3746382A
Authority: US
Inventors: C Hancock
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1971-06-16
Filing date: 1971-06-16
Publication date: 1973-07-17
Anticipated expiration: 1990-07-17
Also published as: CA949610A

Abstract

A latch arrangement for a dishwasher door in which the engaging faces of the pivotal bolt mounted on the door, and the strike mounted on the tub, have arcs which are related in a fashion that during that portion of the latching in which significant resistance to compression of the door gasket occurs, the gasket compressing force has a generally front-to-rear direction to prevent undue shifting of the door in a misaligning direction as the gasket is compressed.

Description

United States Patent 1191 Hancock LATCH ARRANGEMENT FOR APPLIANCE [75] Inventor: Charlie L. Hancock, Grove City,

Ohio 4 [73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: June 16, 1971 211 Appl. No.: 153,498

[52] US. Cl. 292/241, 292/DlG. 69 [51] Int. Cl. E05c 3/04 [58] Field of Search 292/240, 241, 242,

[56] f 1 References Cited UNlTED STATES PATENTS 10/1961 Jellies 292/DIG. 69 6/1926 Csiga' 292/241 X 3/1899 Brachhausen n 292/241 11/1958 Bennett 292/240 [451 July 17, 1973 FOREIGN PATENTS OR APPLICATIONS 519,411 3/1940 Great Britain 292/241 Primary Examiner-Richard E. Moore Attorney- F. H. Henson and E. C. Arenz [57] 7 ABSTRACT A latch arrangement for a dishwasher door in which the engaging faces .of the pivotal bolt mounted on the door, and the strike mounted on the tub, have arcs which are related in a fashion that during that portion of the latching in which significant resistance to compression of the door gasket occurs, the gasket compressing force has a generally front-to-rear direction to prevent undue shifting of the door in a misaligning direction as the gasket is compressed. v

7 Claims, 5 Drawing Figures 1 LATCH ARRANGEMENT FOR APPLIANCE CROSS REFERENCE TO RELATED APPLICATION My U.S. Pat. application Ser. No. 140,529, new U.S. Pat. No. 3,684,343 is related.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to the art of latching arrangements for appliance doors, and particularly to those arrangements in which a gasket is compressed during a latching operation.

2. Description of the Prior Art:

Since my invention is particularly applicable for use in latching swing down type doors on front loading dishwashers, it will be considered primarily in that connection. With such doors, the hinge axis is adjacent the lower edge of the door. A sealing gasket is interposed between tub structure framing the access opening of the tub and a facing part of the door. In a latching arrangement in which the latch bolt is pivoted about a vertical axis (i.e., swung from one side to another) during the period when the significant compression of the gasket occurs and while the latch bolt is being pulled to the side, there is a tendency to shift the door sideways dueto the resistance to compression of the gasket coupled with the lines of force between the contacting faces of the latch bolt and the latch strike, taken with the sideways force applied by the operator of the latch. Accordingly, arrangements have been provided to avoid this problem such as mechanisms having compound rotational and linear movement so. that in a given point in the latch operation, the latching force is in. a substantially front-to-rear direction to pull the door up tightly. One example of such an arrangement is found in U.S. Pat. No. 3,005,065.

Anotherproblem which must be solved in such dishwashers is to provide an arrangement in which a latch operated switch cannot be moved to its closed position while the dishwasher door is open. This is accomplished in the noted patent, as well as in U.S. Pat. No. 3,377,093, by a lock-out arrangement in which the latch bolt cannot be operated unless the door has been moved into a sufficiently closed position that the lock out is disengaged.

With both of the noted arrangements, the latching mechanism is relatively complex and expensive ascontrasted to a latching arrangement according to my invention.

SUMMARY OF THE INVENTION In accordance with my invention, a relatively simple, inexpensive latchingarrange'ment is provided in which the latch bolt face adapted to engage the strike face is formed of an are having a center offset generally to the side of the pivotal axis of the latch bolt, and the strike face is formed of a plurality of arcs having different radii, and different centers located such, that as the door is pulled through that portion of its travel in which significant resistance to compression of the gasket occurs, the sliding movement of the bolt face along the strike face creates a gasket compressing force having a generally front-to-rear direction to prevent undue shifting of the door in a sideways direction as the gasket is compressed.

Since with my arrangement, the door switch is tub mounted so that it is impossible to operate the switch by operating the latch bolt when the door is open, no lockout arrangement is required. Accordingly, the initial movement of a door toward its tightly closed position during initiallatch operation may beaccomplished by operation of the latch, as distinguished from manually pushing the door to a minimum closed position, since the latch operation accomplishes this initial movement. During this initial movement, since no significant compression of the gasket occurs the sideways shifting force on the door is minimal. Also in accordance with my invention, a Bellville washer is used to provide adequate friction at the pivoted latch bolt to prevent the latch from moving toward an open position due to dishwasher vibration.

DRAWING DESCRIPTION FIG. 1 is a generally schematic side view of a front opening undercounter dishwasher as installed, and with the door in its open position;

FIG. 2 is a plan view of the latch arrangement with the latch handle and bolt as shown in full lines corresponding to an unlatched position, and the same as shown in dash lines corresponding to a fully latched position;

FIG. 3 is a plan view of the latch handle, bolt'and its supporting bracket;

FIG. 4 is an edge view of the latch handle, bolt and supporting bracket; and i FIG. 5 is a plan view of the portion of the strike including the cam face, and including details relating to the location of the centers of the different arcs forming the strike cam face and the movement of the door dur ing latch operation.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the somewhat schematic illustration shows a front opening, undercounter dishwasher 10 in its installed position and with the door 12 in an open position. The door is adapted to be swung upwardly to a closed position about a horizontal hinge axis adjacent the lower edge of the door. Details of the hinging arrangement and counterbalance arrangement are found in my copending U.S. Pat. application Ser. No. l 42,307, now U.S. Pat. No. 3,704,550. The latch '14 carried by the door at the center of its edge remote from its hinged edge operates to latch the door shut in cooperation with the switch assembly 16 mounted on the upper front center portion of the top wall 18 of the tub. It will be noted from FIG. 1 that the forward open face of the tub includes a collar portion 20 which extends along opposite sides and the top of the tub and into which the thickness of the door 12 is received when the door is shut. On the inner face of the door, adjacent the two side edges and the topedgc, a gasket 22 is provided. I

Referring to FIG. 2, the assembly l6 includes a strike plate secured in a fixed position to the collar 20 of the tub, a door switch 26 carried by the strike plate and a switch cover 28 which holds the switch to the strike plate. The cam face portion of the strike plate 24 is generally designated 30 and will be considered in some detail inconnection with FIG. 5.

The form that the latch bolt takes is best seen in FIGS. 3 and 4. The latch bolt is formed as a single piece which may be provided with an operating knob 34 at the outer end of the lever portion 36. The strike engaging hook portion is designated 38 and is turned up gensqueeze down on a Bellville washer 46 located between the head of the pin and the upper surface of the latch bolt 14.

The leading end of the hook portion 38 of the latch is provided with an angled tongue 48 disposed to engage the operating lever 50 (FIG. 2) of the door switch as the latch approaches its fully closed position. The strike engaging face 52 of the hook portion 38 is generally curved in an are having a center 54 located generally to the side of the pivotal axis of the latch bolt. With this center, it will be apparent that successive points along the arc of the hook portion from the leading to the trailing edge thereof are progressively closer to the pivotal axis for the extent of the hook portion.

Referring to FIG. 5, the cam face 30 of the strike plate is formed by an edge of a molded plastic material 56 (preferred to avoid metal-to-metal sliding contact) which encases a portion of the strike plate. The cam is comprised of a plurality of arcs including a portion 30A which has a radius indicated by line 30A with a center at 30A"; an are 308 with a radius indicated by line 308 greater than 30A, and'a center at 303"; and an arc 30C with a radius indicated by line 30C and a center at 30C". While it may be seen in FIG. that the

arcs

30A and 30B merge smoothly, the arc 30C is offset from are 308 so that an interruption 30D is formed between the

arcs

30B and 30C. This interrupted portion serves both to prevent the latch bolt from moving from a closed toward an open position, and also provides a sense of feel to the user of the latch when the bolt portion moves intoits fully closed position. It is noted that the nominal center line of the tub and door is indicated by the line 58 which is generally aligned with the interruption 30D.

For the purpose of explaining the manner in which the latching operation occurs, additional lines in FIG. 5 will also be identified.

Lines

60, 62,64, 66, and 68 indicate successive positions of the axis of the latch handle as it is moved from a fully open to fully latched position. Point 70 indicates the location of the axis of the latch handle pivot when the first contact is made between the engaging faces of the latch bolt and strike cam face. Point 72 indicates the location of t e same axis after the latch has been turned so the is aligned with line 64. Point 74 indicates the location of this same axis when the lever has been turned to a fully latched position. It is noted that it is only during the period that the door moves the distance between

points

72 and 74 that any significant part of gasket compression occurs.

The following examples of radius dimensions for a dishwasher to be commercially produced are given. 30A'0.7l0 inches; 30B'0.735 inches; 30C'-0.7l0 inches; and the radius of the hook portion of the latch bolt is 0.849 inches. The distance of door travel between point 70 and point 72 without compression of the gasket is 0.28 inches, and between

points

72 and 74 with significant gasket compression is 0.10 inches.

The line 60 indicates the center line axis of the latch handle at its fully open stop position. Line 62 indicates the axis when the first part of the hook portion contacts the strike cam face A. Line 64 indicates the axis when the door has been moved 0.28 inches toward closed without gasket compression. Line 66 indicates the location of the lever axis when the door has been moved its full 0.38 inches of travel to a fully closed position. Line 68 indicates the final position of the axis of the lever with the hook portion of the latch having moved past the 30D offset.

With the arcs as illustrated and described, during most of the gasket compression the points of tangency between the hook portion and the strike cam face are closely adjacent the center line 58 of the tub and door. This results in the force for compressing the gasket being generally aligned with a front and rear direction so that the tendency for the door to shift sideways is prevented. While during the 0.28 inches of door travel, prior to significant gasket compression occurring, the points of tangency are in the arc areas 30A and then the adjacent areas of the are 303, the lack of resistance to gasket compression permits the door to simply move toward the closed position without the tendency for sideways shifting. Then during the period of significant gasket compression, the point of tangency between the hook portion and the cam face of the strike moves I close to and resides on the high point of the cam registering with the center line 58 of the tub and door.

It will also be appreciated that since there is no lockout built into the portion of the latch arrangement carried by the door, there is no need to manually push the door to a minimum closed position to disengage such a lookout before the latch can be operated.

I claim as my invention:

1. In an appliance having a cabinet with an access opening, a door for closing said opening, and gasket means interposed between said door and cabinet, a latch arrangement comprising:

a latch bolt carried by said door and havinga pivotal axis fixed relative to said door, said latch bolt including a strike engaging face formed of an are having a center offset generally to the side of the said pivotal axis in a location such that successive points along said are from the leading to the trailing edge thereof are progressively closer to said pivotal axis; and 1 strike mounted on said cabinet and including a camming face against which said bolt face engages as said bolt face slides therealong to pull said door to a tightly closed position, said camming face being formed of a plurality of arcs having different radii, and centers located such that as said door is pulled through that portion of its travel in which significant resistance to compression of said gasket occurs, the sliding movement of said bolt face along said camming face creates a gasket compressing force having a generally front-to-rear direction to prevent undue shifting of said door in a sideways direction as said gasket is compressed. 2. In an appliance according to claim I: said strike engaging face of said bolt that contacts said camming face comprises a smooth curve.

3. In an applicane according to claim 1: said camming face comprises a first are having a radius less than a successive second are, and a third successive arc having a radius less than said second successive arc.

4. lnan appliance according to claim 3:

said camming face includes an offset formed at the juncture of said second and thing arcs; and

said strike engaging face of said latch bolt is dimensioned so that said trailing edge traverses said offset in moving to a fully latched position of said latch bolt.

5. In an appliance according to claim I:

switch means carried on said cabinet and adapted to be engaged by the leading end portion of said latch bolt strike engaging face.

6. In an appliance according to claim 1:

said latch bolt is carried by said door through a mounting bracket having a headed pivot pin attaching said bolt to said bracket; and

said pivot pin carries a compressed friction washer located between the head of said pivot pin and said bolt.

7. In a front-opening dishwasher having a swingdown door for closing the front opening of the dishwasher tub, and having compressible gasket means for sealing between the door and tub, a latch arrangement comprising:

a latch bolt carried by the upper edge of said door for side-to-side pivotal movement, said latch bolt having a strike engaging face in the form of a curve in which successive points therealong from the lead ing to the trailing edge thereof are successively closer to the pivotal axis of said latch bolt;

a strike mounted on said cabinet and including a camming face against which said bolt face engages as said bolt face slides therealong to pull said door to a tightly closed position, said camming face being sufficiently extensive in its total. length and most rearward point of said camming face.

Claims

1. In an appliance having a cabinet with an access opening, a door for closing said opening, and gasket means interposed between said door and cabinet, a latch arrangement comprising: a latch bolt carried by said door and having a pivotal axis fixed relative to said door, said latch bolt including a strike engaging face formed of an arc having a center offset generally to the side of the said pivotal axis in a location such that successive points along said arc from the leading to the trailing edge thereof are progressively closer to said pivotal axis; and a strike mounted on said cabinet and including a camming face against which said bolt face engages as said bolt face slides therealong to pull said door to a tightly closed position, said camming face being formed of a plurality of arcs having different radii, and centers located such that as said door is pulled through that portion of its travel in which significant resistance to compression of said gasket occurs, the sliding movement of said bolt face along said camming face creates a gasket compressing force having a generally front-to-rear direction to prevent undue shifting of said door in a sideways direction as said gasket is compressed.

2. In an appliance according to claim 1: said strike engaging face of said bolt that contacts said camming face comprises a smooth curve.

3. In an applicane according to claim 1: said camming face comprises a first arc having a radius less than a successive second arc, and a third successive arc having a radius less than said second successive arc.

4. In an appliance according to claim 3: said camming face includes an offset formed at the juncture of said second and thing arcs; and said strike engaging face of said latch bolt is dimensioned so that said trailing edge traverses said offset in moving to a fully latched position of said latch bolt.

5. In an appliance according to claim 1: switch means carried on said cabinet and adapted to be engaged by the leading end portion of said latch bolt strike engaging face.

6. In an appliance according to claim 1: said latch bolt is carried by said door through a mounting bracket having a headed pivot pin attaching said bolt to said bracket; and said pivot pin carries a compressed friction washer located between the head of said pivot pin and said bolt.

7. In a front-opening dishwasher having a swing-down door for closing the front opening of the dishwasher tub, and having compressible gasket means for sealing between the door and tub, a latch arrangement comprising: a latch bolt carried by the upper edge of said door for side-to-side pivotal movement, said latch bolt having a strike engaging face in the form of a curve in which successive points therealong from the leading to the trailing edge thereof are successively closer to the pivotal axis of said latch bolt; a strike mounted on said cabinet and including a camming face against which said bolt face engages as said bolt face slides therealong to pull said door to a tightly closed position, said camming face being sufficiently extensive in its total length and spannIng a sufficient front-to-rear distance that with said door in its unlatched at rest position the leading edge of said bolt face will move into engagement with a portion of said camming face without closely approaching a gasket compressing condition, said camming face further having a contour including a plurality of arcs of different radii and related to the curve of said bolt face that throughout significant compression of said gasket, the points of tangency between said camming face and said bolt face are located closely adjacent the most rearward point of said camming face.