Title:
WATERPROOF PLUNGER ACTUATED SWITCH ASSEMBLY
United States Patent 3586810
Abstract:
A plunger actuated switch assembly comprising a housing with a plunger-receiving space at the front thereof and a switch compartment at the rear thereof sealed from the rest of the housing except for a switch actuator-receiving opening at the front thereof. An imperforate open-ended sleeve extends forwardly from the opening and a switch actuator member is mounted in a passageway within the sleeve. A plunger member is provided extending through an opening at the front of the housing, the plunger member having a sleeve-receiving cavity open at the rear and defined by a longitudinally extending skirt movable around the sleeve. A first compression spring extends between the plunger member and the switch actuator member and a second weaker spring urges a switch contactor member in the switch compartment against the switch actuator member.
US Patent References:
Electrical assembly
Herterick - June 1955 - 2712047
Devices for controlling door-operable electric switches
Schultz - October 1958 - 2856477
Two circuit door switch
Hutt - September 1963 - 3104300
Door switch assembly
West - August 1965 - 3204069
Push button door switch
Long - May 1966 - 3249726
Electrical assembly
Herterick - June 1955 - 2712047
Devices for controlling door-operable electric switches
Schultz - October 1958 - 2856477
Two circuit door switch
Hutt - September 1963 - 3104300
Door switch assembly
West - August 1965 - 3204069
Push button door switch
Long - May 1966 - 3249726
Application Number:
05/009607
Publication Date:
06/22/1971
Filing Date:
02/09/1970
View Patent Images:
Export Citation:
Assignee:
Littelfuse, Inc. (Des Plaines, IL)
Primary Class:
Other Classes:
200/520, 200/306
International Classes:
H01H13/06; F25D29/00; H01H13/04; H01H9/04
Field of Search:
200/168G,172,159,61.62
US Patent References:
| 3504147 | REFRIGERATING DEVICE HAVING IMPROVED SWITCH | March 1970 | Christman et al. |
Primary Examiner:
Jones H. O.
Claims:
I claim
1. A plunger actuated switch assembly comprising: a housing having partition wall means defining a plunger-receiving space at the front thereof and a switch compartment at the rear thereof sealed from the rest of the housing except for a switch actuator-receiving opening at the front thereof, switch means in said switch compartment having a portion movable into switch opening and switch closing positions, an imperforate sleeve extending forwardly into said plunger-receiving space from a portion of said partition wall means and having an open-ended switch actuator-receiving passageway extending longitudinally therethrough and communicating with said opening at the front of said switch compartment, the sleeve passageway being the only possible entryway for water into said switch compartment from said plunger-receiving space, an opening in the front of said housing in alignment with said sleeve and a plunger member mounted for reciprocation in said front housing opening between a forwardmost position and a rear switch actuating position and resiliently urged into the former position, switch actuator means mounted for longitudinal movement in said sleeve passageway with the movement of said plunger member and coupled to said movable portion of said switch means to move the same between said switch opening and switch closing positions as it is moved in said sleeve passageway by depression of the plunger member, said plunger member having a sleeve-receiving cavity open at the rear end thereof and defined by an outer longitudinally extending imperforate skirt movable in close proximity to and around said sleeve, the front end of said sleeve extending forwardly at least to a point at the rear open end of said plunger cavity when the plunger member is in its forwardmost position so the only possible entryway for water into said sleeve from outside of the housing thru said housing opening is along an irregular path including a portion extending forwardly through a limited clearance space between the plunger member and the sleeve, said sleeve being located a progressively greater distance within said plunger cavity as the plunger member is depressed.
2. The switch assembly of claim 1 wherein said switch actuator means is separate from said plunger member, said plunger member being urged into said forwardmost position by a coil spring compressed between said switch actuator means and an abutment wall at the front end of said plunger cavity.
3. The switch assembly of claim 2 wherein said plunger member has an internal stem closely surrounded by said coil spring, said stem extending rearwardly from said abutment wall in spaced relation to said skirt to define an annular cavity in said plunger member, the outer portion of the cavity receiving said sleeve and the inner portion thereof receiving said coil spring.
4. The switch assembly of claim 3 wherein said plunger member has an outwardly extending stop flange at the rear end portion thereof which is urged against the front wall of the housing when the plunger member is permitted to be urged into said forwardmost position by said coil spring.
5. The switch assembly of claim 3 wherein there is located in said switch compartment of the housing spring means which urges said movable portion of said switch means forwardly into one of said positions thereof, said switch actuator means engaging said movable portion of said switch means, the compressibility of the coil spring being less than that of the spring means so the movement of the plunger member will effect the rearward movement of said switch actuator means to move the movable portion of said switch means into the other of said positions thereof.
1. A plunger actuated switch assembly comprising: a housing having partition wall means defining a plunger-receiving space at the front thereof and a switch compartment at the rear thereof sealed from the rest of the housing except for a switch actuator-receiving opening at the front thereof, switch means in said switch compartment having a portion movable into switch opening and switch closing positions, an imperforate sleeve extending forwardly into said plunger-receiving space from a portion of said partition wall means and having an open-ended switch actuator-receiving passageway extending longitudinally therethrough and communicating with said opening at the front of said switch compartment, the sleeve passageway being the only possible entryway for water into said switch compartment from said plunger-receiving space, an opening in the front of said housing in alignment with said sleeve and a plunger member mounted for reciprocation in said front housing opening between a forwardmost position and a rear switch actuating position and resiliently urged into the former position, switch actuator means mounted for longitudinal movement in said sleeve passageway with the movement of said plunger member and coupled to said movable portion of said switch means to move the same between said switch opening and switch closing positions as it is moved in said sleeve passageway by depression of the plunger member, said plunger member having a sleeve-receiving cavity open at the rear end thereof and defined by an outer longitudinally extending imperforate skirt movable in close proximity to and around said sleeve, the front end of said sleeve extending forwardly at least to a point at the rear open end of said plunger cavity when the plunger member is in its forwardmost position so the only possible entryway for water into said sleeve from outside of the housing thru said housing opening is along an irregular path including a portion extending forwardly through a limited clearance space between the plunger member and the sleeve, said sleeve being located a progressively greater distance within said plunger cavity as the plunger member is depressed.
2. The switch assembly of claim 1 wherein said switch actuator means is separate from said plunger member, said plunger member being urged into said forwardmost position by a coil spring compressed between said switch actuator means and an abutment wall at the front end of said plunger cavity.
3. The switch assembly of claim 2 wherein said plunger member has an internal stem closely surrounded by said coil spring, said stem extending rearwardly from said abutment wall in spaced relation to said skirt to define an annular cavity in said plunger member, the outer portion of the cavity receiving said sleeve and the inner portion thereof receiving said coil spring.
4. The switch assembly of claim 3 wherein said plunger member has an outwardly extending stop flange at the rear end portion thereof which is urged against the front wall of the housing when the plunger member is permitted to be urged into said forwardmost position by said coil spring.
5. The switch assembly of claim 3 wherein there is located in said switch compartment of the housing spring means which urges said movable portion of said switch means forwardly into one of said positions thereof, said switch actuator means engaging said movable portion of said switch means, the compressibility of the coil spring being less than that of the spring means so the movement of the plunger member will effect the rearward movement of said switch actuator means to move the movable portion of said switch means into the other of said positions thereof.
Description:
This invention relates to plunger operated switches and has one of its most important application in refrigerator and freezer door operated switches.
A substantial hazard of electric shock exists in various electrical appliances like refrigerators, freezers, and the like which utilize plunger actuated switches which are operated by the door of the refrigerator or freezer to operate a light upon opening the door or to operate an air circulating fan upon closure of the door. The electric shock hazard is particularly acute when a housewife moves a wet sponge over the area of the refrigerator or freezer including the plunger actuated switch. When the sponge is drawn over the plunger of such a switch, a substantial amount of water may be squirted into the switch. One of the contacts of such a switch is permanently connected through the device to be energized to a source of relatively high voltage, such as 110 volts AC, and if a continuous body or layer of water extends between this contact and the wet sponge, the high voltage is applied to the person holding the wet sponge which could harm or kill the person involved.
Accordingly, an object of the invention is to provide a plunger actuated switch assembly usable as a door-operated switch in refrigerators, freezers and the like wherein the hazards of electrical shock under the circumstances described above are substantially eliminated. More specifically, an object of the invention is to provide a plunger actuated switch-assembly which minimizes the possibility of water or moisture entering the front portion of the switch assembly from gaining access to the terminals or contacts in the switch housing. A related object of the invention is to provide a plunger actuated switch assembly as described which occupies a minimum of space. A still further related object of the invention is to provide a plunger actuated switch assembly as described which has a very simple, economical and reliable construction.
In accordance with one of the features of the present invention, the plunger actuated switch assembly includes a housing having a plunger-receiving space at the front thereof and a switch compartment at the rear thereof sealed from the rest of the housing except for a switch actuator-receiving opening at the front of the sealed compartment. An imperforate sleeve extends forwardly from the opening at the front of the switch compartment and switch actuator means is mounted within the sleeve for longitudinal movement therein, the switch actuator means being in engagement with a movable portion of a switch contact assembly within the switch compartment. A plunger member is movably mounted within said plunger-receiving space at the front of the switch housing, the plunger extending through an opening in the front of the switch housing and being resiliently urged into a forwardmost or fully extended of a refrigerator or freezer door or the like, the plunger member moves the switch actuator means within the sleeve to operate the switch contact assembly in the switch compartment. The switch housing is provided with one or more drain holes in the bottom portion thereof communicating with the plunger-receiving space, so water entering the opening in the front of the switch housing around the plunger cannot accumulate in the switch housing as it drains through the one or more drain openings referred to. Also, the sleeve referred to is located within the confines of the plunger member so water entering the plunger-receiving space from around the plunger member cannot splash within the sleeve.
In the most preferred form of the invention, the switch actuator means makes a close slide fit with the sleeve so in the unlikely event water appears in the sleeve by condensation or the other means, it cannot readily pass into the switch compartment by flowing through the small clearance between the switch actuator means the sleeve.
In accordance with another aspect of the invention, a long irregular path of small cross section is provided for the possible passage of water between the plunger-receiving space and the switch compartment by providing a plunger construction including a sleeve-receiving cavity defined by a longitudinally extending skirt which fits around the outside of the sleeve. When the plunger member is in its forwardmost position, the rear end of the skirt preferably overlaps the front end of the sleeve so water cannot gain entrance to the sleeve unless it flows first forwardly in the limited clearance between the plunger member skirt and the sleeve and then rearwardly into the sleeve. Upon depression of the plunger member, the sleeve will move further along the outside of the sleeve to increase the length of the path necessary for water in the plunger-receiving space to reach the front end of the sleeve.
In accordance with still another aspect of the invention, the plunger member and switch actuator means are separate members with the motion of the plunger member transmitted to the switch actuator member by a coil spring compressed between the plunger member and the switch actuator member. The coil spring is preferably positioned around a stem in the plunger member extending rearwardly from the front portion thereof. The stem is spaced from the longitudinally extending skirt of the plunger to form an annular cavity therein within which the coil spring is located and within which the aforesaid sleeve can fit within the plunger cavity between the skirt thereof and the spring. The coil spring transmits the motion of the plunger member to the switch actuator member within the sleeve passageway.
Other features of the invention to be described deal with the manner in which the switch actuator member and switch contact assembly are interconnected.
The above and other objects, advantages and features of the invention will become apparent upon making reference to the specification to follow, the claims and the drawings wherein:
FIG. 1 is a side elevational view of a switch assembly of the invention;
FIG. 2 is a bottom view of the switch assembly of FIG. 1;
FIG. 3 is an enlarged horizontal sectional view through the switch assembly of FIGS. 1 and 2, taken along section line 3-3 in FIG. 1;
FIG. 4 is a transverse vertical sectional view through the switch assembly shown in FIG. 3 taken along section line 4-4 therein;
FIG. 5 is a transverse vertical sectional view of the switch assembly shown in FIG. 3 taken along section line 5-5 therein;
FIG. 6 is an enlarged vertical longitudinal sectional view of the switch assembly of FIGS. 1--5 mounted on the front of a refrigerator cabinet, the plunger thereof being depressed by a refrigerator door; and
FIG. 7 is a fragmentary sectional view of a modified switch assembly where the contacts therein are open when the plunger is in its extended position .
Referring now more particularly to FIGS. 1--3 and 6, the switch assembly there shown and identified by reference numeral 2 includes a switch housing 4 having a pair of vertically extending terminals 6-6' exposed at the rear of the housing assembly. A depressible plunger member 8 projects forwardly from the front of the housing 4. In FIG. 6, the switch assembly is shown mounted in an opening 9 of a refrigerator or freezer housing 11 so that closure of door 10 thereof will depress the plunger member 8. As illustrated, the switch assembly 2 most advantageously has a pair of flexible fingers 13-13 extending forwardly from opposite sides of the housing 4. Each of the fingers 13-13 has a rearwardly and outwardly extending front surface 13a which joins a rearwardly and inwardly extending rear surface 13b. These surfaces 13a and 13b meet at an apex 13c, the spacing between the apexes 13c -13c of the fingers 13-13 being greater than the diameter of the opening 9 in which the switch assembly is mounted. When the switch assembly is pushed rearwardly through the opening 9 the fingers flex inwardly and then outwardly when the apexes expand outwardly behind the frame 11, as best shown in FIG. 6. A bezel flange 14 of the housing then engages the front surface of the frame.
Switch means to be described is provided within the housing 4 either to provide electrical continuity or discontinuity between the terminal 6-6' when the plunger member 8 is in its fully extended position, depending upon the function to be served by the switch assembly. Where there is electrical continuity provided between the terminals 6-6' when the plunger member 8 is in its fully extended position, the switch assembly may be utilized to energize a light within the refrigerator, freezer or the like, and where there is a lack of such electrical continuity between the terminals 6-6' when the plunger member 8 is in its fully extended position the switch assembly may be used to energize a circulating fan. The switch contact arrangement illustrated in FIG. 3 provides electrical continuity between the terminals when the plunger is fully extended. (FIG. 7 illustrates a switch assembly 2' which provides a discontinuity under these conditions.)
The switch housing 4 as illustrated is made of an assembly of three synthetic plastic molded parts 4a, 4b, and 4c. The part 4a forms the main central portion of the housing and has a generally hollow horizontally flattened cylindrical body 4a' open at the front and rear, with the mounting fingers 13-13 projecting therefrom. The housing part 4a has a transversely extending partition wall 15 (FIG. 3) which separates a rear switch compartment 17 from a plunger-receiving space 18 at the front of the housing part 4a. The part 4b includes a front wall 19 forming the bezel flange 14 and a reduced portion 4b' which fits into the open front end of the main housing part 4a where the rear face of the front wall 19 thereof is welded to the front face 21 of an enlarged front end portion 4a" of the housing part 4a. The front wall 19 has a centered opening 20 through which the plunger member 8 passes. The forward extent of the plunger member 8 is limited by the engagement of a stop flange 8a extending outwardly from the rear of the plunger member 8 with the rear face of the front wall 19 of the part 4b. The open rear end of the main housing part 4a is closed by the housing part 4c which forms a cover which is welded to the rear edges of the housing part 4a completely to seal the rear of the switch compartment 17. To this end, the cover part 4c has projecting portions 4c" (FIG. 5) fitting and welded into corresponding depressions 4a '" in the housing part 4a. Before the cover-forming part 4c is applied to the rear of the main housing part 4a, various switch-forming parts to be described are mounted in place within the compartment 17.
The plunger member 8 has a longitudinally extending outer skirt 8b which terminates in the aforementioned stop flange 8a. The skirt 8b defines the outer extremities of an annular sleeve and spring-receiving cavity 22 which is open at the rear thereof. The inner extremity of the annular cavity 22 is defined by a stem 8c extending rearwardly from a front abutment wall 27 at the front end portion of the plunger member 8.
The partition-forming wall 15 in the main housing part 4a has a centrally disposed opening 29 communicating with the switch compartment 17. A sleeve 31 extends forwardly from the partition wall 15, the sleeve 31 having a passageway 31a which communicates with the opening 29 at the rear end and opens onto the annular cavity 22 of the plunger member 8. The forward end of the sleeve 31 is located within the confines of the plunger member (that is, it is located within a region radially inwardly of a cylinder touching the outer extremities of the plunger member). Additionally, the forward end of the sleeve most advantageously projects at least slightly into the annular plunger member cavity 22 when the plunger member is in its fully extended position. A switch actuator member 33 is mounted within the slide passageway 31a preferably with a close slide fit so as to hinder the passage of water in the very small clearance space between the switch actuator member 33 and the defining wall of the sleeve passageway 31a. The switch actuator member 33 has a stem-receiving opening 33a therein which opens onto the front end of the switch actuator member 33. The switch actuator member 33 has at the rear thereof a reduced portion 33b which extends into the switch compartment 17. The reduced portion 33b of the switch actuator member 33 receives thereover a switch contactor member 40 having a transverse end wall 40a provided with an opening 40a' through which extends the reduced portion 33b of the switch actuator member 33. The transverse end wall 40a terminates in rearwardly extending wall portions 40b-40 b in turn terminating in rearwardly and outwardly inclining contact-forming portions 40c-40c. The forwardly facing surfaces of the contact-forming portions 40c-40c of the switch contactor member 40 are adapted to make sliding contact with the rearwardly facing surfaces of a pair of stationary contact-forming portions 42a-42a' of spaced stationary contact member 42-42' anchored in any suitable way within the forward end portion of the switch compartment 17. The aforementioned terminals 6-6' are extensions respectively of the stationary contact members 42-42' passing through suitable openings in the main housing part 4a.
The contactor member 40 is normally urged into a forward position to make good contact with the stationary contact members 42-42' to electrically interconnect the same by a coil spring 44 compressed between the rear face of the cover-forming part of the housing 4 and the transverse end wall 40a of the contactor member 40. The cover-forming part 4c is provided with a forwardly extending cylindrical wall 4c' for positioning the coil spring 44 in the switch compartment 17. The reduced end portion 33b of the switch actuator member 33 passes within the opening 45 defined by the cylindrical wall 4c'.
The contactor member 40 is thus floatingly mounted and forwardly spring urged within the switch compartment 17 and is guided by the reduced end portion 33b of the switch actuator member 33. This construction insures good electrical contact between the contact-forming portions 40c-40c of the contactor member 40 and the contact-forming portions 42a-42a' of the stationary contact members 42-42' despite loose tolerances which may be utilized. The camber of the contact-forming portions 40c-40c effect a sliding or rubbing action against the contact-forming portions 42a -42a ' of the stationary contact members 42-42' keeping the contact areas clean.
The plunger member 8 is urged to its fully extended position by a coil spring 46 positioned around the plunger member stem 8c and extending in a compressed condition between the abutment wall 27 at the front end portion of the plunger-member 8 and the front end of the switch actuator member 33. The coil spring 46 is a stiffer spring than the coil spring 44 in the switch compartment 17, so that depression of the plunger member 8 will cause the switch actuator member 33 to move rearwardly within the sleeve passageway 31a. The reduced end portion 33b of the switch actuator member provides an abutment shoulder 33c which engages the transversely extending end wall 40a of the contactor member 40, so that the movement of the switch actuator member 33 by the depression of the plunger member 8 will move the contactor member 40 rearwardly, thereby separating the contact-forming portions 40c-40c of the contactor member 40 from the contact-forming portions 42a -42a' of the stationary contact members 42-42'. It can be seen that the depression of the plunger member 8 will cause the skirt 8b of the plunger member 8 to move rearwardly along the outer surface of the sleeve 31 and the plunger member stem 8c to move within the center portion of the sleeve passageway 31a. When the plunger member 8 is fully depressed, the rear end portion of the stem 8c passes within the opening 33a of the switch actuator member 33.
As previously indicated, the primary advantage of the switch construction of the present invention is its freedom from shock hazards under such extreme circumstances as when a person moves a wet sponge or the like over the plunger member 8. In such case, the plunger member 8 will obviously be depressed to a smaller or greater extent depending upon the force with which the sponge or other cleaning means is moved over the plunger member and water will be squirted or forced into the plunger-receiving space 18. Most of this water is removed from the switch housing by a large drain opening 50 formed within the portion of the main switch housing part 4aincluding the plunger-receiving space 18. Water or moisture which does not immediately drain through the opening 50 cannot gain access to the switch compartment 17 at the rear of the switch housing without going through a very small irregular path which first extends forwardly between the plunger member skirt 8b and the sleeve 31 and then rearwardly through the sleeve. The clearance space between the plunger member skirt and sleeve may very widely, as for example, 0.030 to 0.040 inches or smaller. The clearance space between the switch actuator member and the sleeve passageway is, for example, preferably as small as about 0.010 inches. Thus, with such an irregular limited path between the plunger-receiving space 19 and the switch compartment 17, it is practically impossible for any water to ultimately reach the switch compartment. In other respects, the switch housing is a very simple, reliable and economical construction and represents a substantial improvement over the switch assemblies of the prior art.
Refer now to FIG. 7 which shows a modified switch assembly 2' similar in most respects to the switch assembly 2 of FIGS. 1--6, The switch assembly 2' has a normally open contact arrangement in the rear switch compartment 17', so that the switch assembly is open when the plunger member is in its extended position. Thus, the switch assembly 2' has stationary contact members 43 and 43' positioned in the switch compartment 17' at a point rearward of a contactor member 40' . A coil spring 44' contacts the transversely extending end wall 40a' of the contactor member 40' and urges the same against the abutment shoulder 33c' of the switch actuator member 33' . The contact-forming portions 40c'-40c' of the contactor member 40' are then in spaced relation to the contact-forming portions 43a-43a' of the stationary contact members 43-43'. When the associated plunger member is depressed and the switch actuator member 33' is moved rearwardly, the contact-forming portions 40c -40c' of the contactor member 40' make contact with the contact-forming members 43-43'.
It should be understood that numerous modifications may be made in the most preferred forms of the invention described without deviating from the broader aspects of the invention.
A substantial hazard of electric shock exists in various electrical appliances like refrigerators, freezers, and the like which utilize plunger actuated switches which are operated by the door of the refrigerator or freezer to operate a light upon opening the door or to operate an air circulating fan upon closure of the door. The electric shock hazard is particularly acute when a housewife moves a wet sponge over the area of the refrigerator or freezer including the plunger actuated switch. When the sponge is drawn over the plunger of such a switch, a substantial amount of water may be squirted into the switch. One of the contacts of such a switch is permanently connected through the device to be energized to a source of relatively high voltage, such as 110 volts AC, and if a continuous body or layer of water extends between this contact and the wet sponge, the high voltage is applied to the person holding the wet sponge which could harm or kill the person involved.
Accordingly, an object of the invention is to provide a plunger actuated switch assembly usable as a door-operated switch in refrigerators, freezers and the like wherein the hazards of electrical shock under the circumstances described above are substantially eliminated. More specifically, an object of the invention is to provide a plunger actuated switch-assembly which minimizes the possibility of water or moisture entering the front portion of the switch assembly from gaining access to the terminals or contacts in the switch housing. A related object of the invention is to provide a plunger actuated switch assembly as described which occupies a minimum of space. A still further related object of the invention is to provide a plunger actuated switch assembly as described which has a very simple, economical and reliable construction.
In accordance with one of the features of the present invention, the plunger actuated switch assembly includes a housing having a plunger-receiving space at the front thereof and a switch compartment at the rear thereof sealed from the rest of the housing except for a switch actuator-receiving opening at the front of the sealed compartment. An imperforate sleeve extends forwardly from the opening at the front of the switch compartment and switch actuator means is mounted within the sleeve for longitudinal movement therein, the switch actuator means being in engagement with a movable portion of a switch contact assembly within the switch compartment. A plunger member is movably mounted within said plunger-receiving space at the front of the switch housing, the plunger extending through an opening in the front of the switch housing and being resiliently urged into a forwardmost or fully extended of a refrigerator or freezer door or the like, the plunger member moves the switch actuator means within the sleeve to operate the switch contact assembly in the switch compartment. The switch housing is provided with one or more drain holes in the bottom portion thereof communicating with the plunger-receiving space, so water entering the opening in the front of the switch housing around the plunger cannot accumulate in the switch housing as it drains through the one or more drain openings referred to. Also, the sleeve referred to is located within the confines of the plunger member so water entering the plunger-receiving space from around the plunger member cannot splash within the sleeve.
In the most preferred form of the invention, the switch actuator means makes a close slide fit with the sleeve so in the unlikely event water appears in the sleeve by condensation or the other means, it cannot readily pass into the switch compartment by flowing through the small clearance between the switch actuator means the sleeve.
In accordance with another aspect of the invention, a long irregular path of small cross section is provided for the possible passage of water between the plunger-receiving space and the switch compartment by providing a plunger construction including a sleeve-receiving cavity defined by a longitudinally extending skirt which fits around the outside of the sleeve. When the plunger member is in its forwardmost position, the rear end of the skirt preferably overlaps the front end of the sleeve so water cannot gain entrance to the sleeve unless it flows first forwardly in the limited clearance between the plunger member skirt and the sleeve and then rearwardly into the sleeve. Upon depression of the plunger member, the sleeve will move further along the outside of the sleeve to increase the length of the path necessary for water in the plunger-receiving space to reach the front end of the sleeve.
In accordance with still another aspect of the invention, the plunger member and switch actuator means are separate members with the motion of the plunger member transmitted to the switch actuator member by a coil spring compressed between the plunger member and the switch actuator member. The coil spring is preferably positioned around a stem in the plunger member extending rearwardly from the front portion thereof. The stem is spaced from the longitudinally extending skirt of the plunger to form an annular cavity therein within which the coil spring is located and within which the aforesaid sleeve can fit within the plunger cavity between the skirt thereof and the spring. The coil spring transmits the motion of the plunger member to the switch actuator member within the sleeve passageway.
Other features of the invention to be described deal with the manner in which the switch actuator member and switch contact assembly are interconnected.
The above and other objects, advantages and features of the invention will become apparent upon making reference to the specification to follow, the claims and the drawings wherein:
FIG. 1 is a side elevational view of a switch assembly of the invention;
FIG. 2 is a bottom view of the switch assembly of FIG. 1;
FIG. 3 is an enlarged horizontal sectional view through the switch assembly of FIGS. 1 and 2, taken along section line 3-3 in FIG. 1;
FIG. 4 is a transverse vertical sectional view through the switch assembly shown in FIG. 3 taken along section line 4-4 therein;
FIG. 5 is a transverse vertical sectional view of the switch assembly shown in FIG. 3 taken along section line 5-5 therein;
FIG. 6 is an enlarged vertical longitudinal sectional view of the switch assembly of FIGS. 1--5 mounted on the front of a refrigerator cabinet, the plunger thereof being depressed by a refrigerator door; and
FIG. 7 is a fragmentary sectional view of a modified switch assembly where the contacts therein are open when the plunger is in its extended position .
Referring now more particularly to FIGS. 1--3 and 6, the switch assembly there shown and identified by reference numeral 2 includes a switch housing 4 having a pair of vertically extending terminals 6-6' exposed at the rear of the housing assembly. A depressible plunger member 8 projects forwardly from the front of the housing 4. In FIG. 6, the switch assembly is shown mounted in an opening 9 of a refrigerator or freezer housing 11 so that closure of door 10 thereof will depress the plunger member 8. As illustrated, the switch assembly 2 most advantageously has a pair of flexible fingers 13-13 extending forwardly from opposite sides of the housing 4. Each of the fingers 13-13 has a rearwardly and outwardly extending front surface 13a which joins a rearwardly and inwardly extending rear surface 13b. These surfaces 13a and 13b meet at an apex 13c, the spacing between the apexes 13c -13c of the fingers 13-13 being greater than the diameter of the opening 9 in which the switch assembly is mounted. When the switch assembly is pushed rearwardly through the opening 9 the fingers flex inwardly and then outwardly when the apexes expand outwardly behind the frame 11, as best shown in FIG. 6. A bezel flange 14 of the housing then engages the front surface of the frame.
Switch means to be described is provided within the housing 4 either to provide electrical continuity or discontinuity between the terminal 6-6' when the plunger member 8 is in its fully extended position, depending upon the function to be served by the switch assembly. Where there is electrical continuity provided between the terminals 6-6' when the plunger member 8 is in its fully extended position, the switch assembly may be utilized to energize a light within the refrigerator, freezer or the like, and where there is a lack of such electrical continuity between the terminals 6-6' when the plunger member 8 is in its fully extended position the switch assembly may be used to energize a circulating fan. The switch contact arrangement illustrated in FIG. 3 provides electrical continuity between the terminals when the plunger is fully extended. (FIG. 7 illustrates a switch assembly 2' which provides a discontinuity under these conditions.)
The switch housing 4 as illustrated is made of an assembly of three synthetic plastic molded parts 4a, 4b, and 4c. The part 4a forms the main central portion of the housing and has a generally hollow horizontally flattened cylindrical body 4a' open at the front and rear, with the mounting fingers 13-13 projecting therefrom. The housing part 4a has a transversely extending partition wall 15 (FIG. 3) which separates a rear switch compartment 17 from a plunger-receiving space 18 at the front of the housing part 4a. The part 4b includes a front wall 19 forming the bezel flange 14 and a reduced portion 4b' which fits into the open front end of the main housing part 4a where the rear face of the front wall 19 thereof is welded to the front face 21 of an enlarged front end portion 4a" of the housing part 4a. The front wall 19 has a centered opening 20 through which the plunger member 8 passes. The forward extent of the plunger member 8 is limited by the engagement of a stop flange 8a extending outwardly from the rear of the plunger member 8 with the rear face of the front wall 19 of the part 4b. The open rear end of the main housing part 4a is closed by the housing part 4c which forms a cover which is welded to the rear edges of the housing part 4a completely to seal the rear of the switch compartment 17. To this end, the cover part 4c has projecting portions 4c" (FIG. 5) fitting and welded into corresponding depressions 4a '" in the housing part 4a. Before the cover-forming part 4c is applied to the rear of the main housing part 4a, various switch-forming parts to be described are mounted in place within the compartment 17.
The plunger member 8 has a longitudinally extending outer skirt 8b which terminates in the aforementioned stop flange 8a. The skirt 8b defines the outer extremities of an annular sleeve and spring-receiving cavity 22 which is open at the rear thereof. The inner extremity of the annular cavity 22 is defined by a stem 8c extending rearwardly from a front abutment wall 27 at the front end portion of the plunger member 8.
The partition-forming wall 15 in the main housing part 4a has a centrally disposed opening 29 communicating with the switch compartment 17. A sleeve 31 extends forwardly from the partition wall 15, the sleeve 31 having a passageway 31a which communicates with the opening 29 at the rear end and opens onto the annular cavity 22 of the plunger member 8. The forward end of the sleeve 31 is located within the confines of the plunger member (that is, it is located within a region radially inwardly of a cylinder touching the outer extremities of the plunger member). Additionally, the forward end of the sleeve most advantageously projects at least slightly into the annular plunger member cavity 22 when the plunger member is in its fully extended position. A switch actuator member 33 is mounted within the slide passageway 31a preferably with a close slide fit so as to hinder the passage of water in the very small clearance space between the switch actuator member 33 and the defining wall of the sleeve passageway 31a. The switch actuator member 33 has a stem-receiving opening 33a therein which opens onto the front end of the switch actuator member 33. The switch actuator member 33 has at the rear thereof a reduced portion 33b which extends into the switch compartment 17. The reduced portion 33b of the switch actuator member 33 receives thereover a switch contactor member 40 having a transverse end wall 40a provided with an opening 40a' through which extends the reduced portion 33b of the switch actuator member 33. The transverse end wall 40a terminates in rearwardly extending wall portions 40b-40 b in turn terminating in rearwardly and outwardly inclining contact-forming portions 40c-40c. The forwardly facing surfaces of the contact-forming portions 40c-40c of the switch contactor member 40 are adapted to make sliding contact with the rearwardly facing surfaces of a pair of stationary contact-forming portions 42a-42a' of spaced stationary contact member 42-42' anchored in any suitable way within the forward end portion of the switch compartment 17. The aforementioned terminals 6-6' are extensions respectively of the stationary contact members 42-42' passing through suitable openings in the main housing part 4a.
The contactor member 40 is normally urged into a forward position to make good contact with the stationary contact members 42-42' to electrically interconnect the same by a coil spring 44 compressed between the rear face of the cover-forming part of the housing 4 and the transverse end wall 40a of the contactor member 40. The cover-forming part 4c is provided with a forwardly extending cylindrical wall 4c' for positioning the coil spring 44 in the switch compartment 17. The reduced end portion 33b of the switch actuator member 33 passes within the opening 45 defined by the cylindrical wall 4c'.
The contactor member 40 is thus floatingly mounted and forwardly spring urged within the switch compartment 17 and is guided by the reduced end portion 33b of the switch actuator member 33. This construction insures good electrical contact between the contact-forming portions 40c-40c of the contactor member 40 and the contact-forming portions 42a-42a' of the stationary contact members 42-42' despite loose tolerances which may be utilized. The camber of the contact-forming portions 40c-40c effect a sliding or rubbing action against the contact-forming portions 42a -42a ' of the stationary contact members 42-42' keeping the contact areas clean.
The plunger member 8 is urged to its fully extended position by a coil spring 46 positioned around the plunger member stem 8c and extending in a compressed condition between the abutment wall 27 at the front end portion of the plunger-member 8 and the front end of the switch actuator member 33. The coil spring 46 is a stiffer spring than the coil spring 44 in the switch compartment 17, so that depression of the plunger member 8 will cause the switch actuator member 33 to move rearwardly within the sleeve passageway 31a. The reduced end portion 33b of the switch actuator member provides an abutment shoulder 33c which engages the transversely extending end wall 40a of the contactor member 40, so that the movement of the switch actuator member 33 by the depression of the plunger member 8 will move the contactor member 40 rearwardly, thereby separating the contact-forming portions 40c-40c of the contactor member 40 from the contact-forming portions 42a -42a' of the stationary contact members 42-42'. It can be seen that the depression of the plunger member 8 will cause the skirt 8b of the plunger member 8 to move rearwardly along the outer surface of the sleeve 31 and the plunger member stem 8c to move within the center portion of the sleeve passageway 31a. When the plunger member 8 is fully depressed, the rear end portion of the stem 8c passes within the opening 33a of the switch actuator member 33.
As previously indicated, the primary advantage of the switch construction of the present invention is its freedom from shock hazards under such extreme circumstances as when a person moves a wet sponge or the like over the plunger member 8. In such case, the plunger member 8 will obviously be depressed to a smaller or greater extent depending upon the force with which the sponge or other cleaning means is moved over the plunger member and water will be squirted or forced into the plunger-receiving space 18. Most of this water is removed from the switch housing by a large drain opening 50 formed within the portion of the main switch housing part 4aincluding the plunger-receiving space 18. Water or moisture which does not immediately drain through the opening 50 cannot gain access to the switch compartment 17 at the rear of the switch housing without going through a very small irregular path which first extends forwardly between the plunger member skirt 8b and the sleeve 31 and then rearwardly through the sleeve. The clearance space between the plunger member skirt and sleeve may very widely, as for example, 0.030 to 0.040 inches or smaller. The clearance space between the switch actuator member and the sleeve passageway is, for example, preferably as small as about 0.010 inches. Thus, with such an irregular limited path between the plunger-receiving space 19 and the switch compartment 17, it is practically impossible for any water to ultimately reach the switch compartment. In other respects, the switch housing is a very simple, reliable and economical construction and represents a substantial improvement over the switch assemblies of the prior art.
Refer now to FIG. 7 which shows a modified switch assembly 2' similar in most respects to the switch assembly 2 of FIGS. 1--6, The switch assembly 2' has a normally open contact arrangement in the rear switch compartment 17', so that the switch assembly is open when the plunger member is in its extended position. Thus, the switch assembly 2' has stationary contact members 43 and 43' positioned in the switch compartment 17' at a point rearward of a contactor member 40' . A coil spring 44' contacts the transversely extending end wall 40a' of the contactor member 40' and urges the same against the abutment shoulder 33c' of the switch actuator member 33' . The contact-forming portions 40c'-40c' of the contactor member 40' are then in spaced relation to the contact-forming portions 43a-43a' of the stationary contact members 43-43'. When the associated plunger member is depressed and the switch actuator member 33' is moved rearwardly, the contact-forming portions 40c -40c' of the contactor member 40' make contact with the contact-forming members 43-43'.
It should be understood that numerous modifications may be made in the most preferred forms of the invention described without deviating from the broader aspects of the invention.