US 3437773 A
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April 8, 1969 m. KOERT GE 3,437773 CONVERTIBLE ELECTRIC SWIQTCH MODULE Sheet of 2 Filed Aug. 24, 1967 April 8, 1969 N. H. KOERTGE 3,
I CONVERTIBLE ELECTRIC SWITCH MODULE Filed Aug.- 24, 1967 Sheet 2 of 2 mm 2%. 34m
United States Patent 0 3,437,773 CONVERTIBLE ELECTRIC SWITCH MODULE Nobel H. Koertge, Elm Grove, Wis., assignor to Cutler- Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Filed Aug. 24, 1967, Ser. No. 663,160 Int. Cl. H01h 3/00 US. Cl. 200-166 6 Claims ABSTRACT OF THE DISCLOSURE Cross-reference to related applications While the switch of this application may be used in various push-type operator control devices, it is particularly well suited to be used in electromagnetic control relays or the like such as described and claimed in my copending application Ser. No. 663,067 filed Aug. 24, 19-67 and assigned to the assignee of the immediate application.
Summary of the invention The switch of this invention is designed to be a completely self-contained convertible switch unit to be mounted to a control device housing structure and is convertible by inverting the switch within the housing structure. The module case is formed of a transparent electrical insulating material to provide a ready visual indication of both the contact-condition and the position thereof. Contact pressure and return springs are contained within the module in a novel arrangement wherein one of the springs which is unnecessary to contact actuation in one contact mode is maintained in its original condition during operation and does not add unwanted spring pressure to the device.
It is, therefore, a primary object of this invention to provide a self-contained convertible switch module wherein a spring member unnecessary to one contact actuation mode thereof is maintained in an inactive state.
It is a further object of this invention to provide a convertible switch module which may be readily converted from normally closed to normally open contact actuation modes, or vice versa, by a simple inversion procedure.
It is still a further object of this invention to provide a convertible switch module wherein the condition of the contacts therein and their relative positions may be readily visualized by providing the module with a transparent, insulating case. 4
' These and other objects will become more apparent in the following specification and claims when read in conjunction with the accompanying drawings.
Description of the drawings FIGURE 1 is an isometric view of a switch constructed in accordance with this invention;
3,437,773 Patented Apr. 8, 1969 See FIG. 2 is a side elevational view of the switch of FIG. 1 shown mounted in one contact actuation mode;
FIG. 3 is a view like FIG. 2, but showing the switch in an inverted position for another contact actuation mode;
FIG. 4 is a sectional view of the switch taken along line 4-4 of FIG. 2;
FIG. 5 is a top plan view of one of the elements of the switch;
FIG. 6 is a fragmentary view of the underside of a typical housing member for a control device in which the switch of this invention is to be utilized;
FIG. 7 is a sectional view of the switch as shown in FIG. 2, but in an operated condition thereof;
FIG. 8 is a sectional view of the switch of FIG. 3, but in an operated condition thereof; and
FIG. 9 is a view illustrating how the switch of this invention may be utilized in a tandem manner in a control device.
Description of the preferred embodiments The switch module of this invention is pictorially illustrated in FIG. 1. The switch has a two-piece insulating case 2 molded of a natural transparent polycarbonate material such as that sold under the trade name LeXan. The two pieces are joined together by some conventional method, preferably sonic welding, to establish an enclosed central switch cavity 2a therein. The upper and lower walls of case 2 are provided with rectangular openings 2b which communicate With the cavity 2a. The end walls of case 2 have slots 2c formed therein which also communicate with the cavity 2a. Slots 2c are stepped to be wider at the exterior surface than at the cavity surface to aid in anchoring the switch terminals which extend therethrough.
The switch terminals 4 are identical stamped metal members having contact tips 4a secured to one end and threaded openings formed in the other end. While the contact tips 4a are shown herein as being secured upon one surface of the terminals 4, it is to be understood that the tips 4a may also be inlayed to have the contact surface thereof fiush with the surface of the terminal. The terminals have their opposite ends olfset from each other to be in different planes. A pair of opposed notches 4b are formed in the ends of the terminals having the tips 4a thereon, the notches 4b fitting within the narrower portion of the slots 20 of case 2. The transverse edges of the notches 4b abut the step portions of the slots 20 and the inner cavity wall of the case, respectively, to firmly anchor the terminals 4 within the case 2 upon joining the two 1 pieces thereof together.
The slight olfset provided on the terminals 4 is disposed exteriorly of the case 2 to position the outer ends of the terminals in a central plane of the switch. As will be brought out in more detail later, the switch is designed to be convertible between normally open and normally closed contact modes by inversion of the module and it is therefore desirable to have the wiring terminals occupy substantially the same plane in either position. The terminals are further provided with conventional wire securing means such as a wiring clip 6 and a terminal screw 8 for connecting the module in a circuit.
The movable parts of the switch are assembled and placed within the cavity 2a as a single subassembly prior to joining the two pieces of the case together. The movable subassembly comprises a contact carrier 10, a bifurcated bridging contact 12, a pair of helical compression springs 14 and 16, and a pair of identical spring retainers 18.
The contact carrier 10 is a sintered metal part formed from a high density iron. This particular choice of material provides superb wear characteristics for both the carrier and its companion parts. The metal carrier is not prone to cause powdering of these parts due to movement and therefor effectively reduces the dielectric dust that may collect within a switch cavity to foul the contact faces.
As is best seen in the cross-sectional views of FIGS. 4, 7 and 8, the contact carrier 10 is a long, flat member having cross-head portion 10a formed at each end. Portions 10b of reduced cross-section are formed on the body of carrier 10 an equal distance in from each end. Carrier 10 is further provided with a transverse flange 10c formed on the body thereof at a point offset from its longitudinal center.
The bridge member 12 comprises a blanked spring metal member having a rectangular central opening. Bridge member 12 is disposed around the body portion of carrier 10 and rests upon one side of the transverse flange 100. The outwardly extending arms of the bridge member have contact tips secured at their outer ends to be alined wtih contact tips 4a. The arms and contact tips of the bridge member 12 have been shown herein as being bifurcated, although it is to be understood that such configuration is merely a preferred choice of design and the invention is not limited thereto.
A first helical compression spring 14 is disposed over the carrier 10 to rest upon the bridge member 12. A second helical compression spring 16 is disposed over the opposite end of carrier 10. Spring 16 is formed with a reduced diameter at one end to abut the transverse flange 10c of carrier 10.
A pair of identical Spring retainers 18 are next attached to the contact carrier 10. As will become more apparent in later description, spring retainers 18 also serve as hearing members for the reciprocal movement of carrier 10 and are therefor molded of a suitable self-lubricating material such as a combination nylon and Teflon material or the like.
Spring retainers 18 have a rectangular, box-like outer configuration with a cylindrical inner cavity open to a first side thereof. A peripheral flange 18a is formed on the members 18 at the first side. A second side of the members 18, opposite the first side thereof, has a pair of intersecting rectangular openings formed therethrough to communicate with the cylindrical cavity. A first rectangular opening 18b (FIG. is formed of length and width sutficient to allow the cross-head a to pass therethrough. A second rectangular opening 180 is formed at right angles to and bisecting the opening 18b and is of sufficient length and width to provide clearance for the body portion of carrier 10. The corners formed by the junction of the two openings 18b and 18c have been cut away to define an imaginary circular central opening therein. The inner end of the cylindrical cavity has a peripheral groove molded therein to position the ends of the respective springs 14 and 16 in assembly. A pair of upstanding shrouds 18d are formed around the opposite ends of the first rectangular opening 18b for reasons that will become more apparent in the later description.
The retainer members 18 are attached to the carrier 10 by inserting the cross-head 10a of the carrier through the cylindrical cavity of the respective retainer member and through the first rectangular opening 18b to protrude from the second side of the retainer. The latter is then forced further onto the carrier 10 against the bias of the respective spring 14 or 16 until the reduced portion 10b of carrier 10 is alined with the imaginary circular opening at the junction of the two rectangular openings 18b and 18c. Carrier 10 is then rotated one-quarter turn with respect to the retainers 18 to cause the body portion thereof to be alined with the rectangular opening 18c and withdrawn under the bias of the spring 14 or 16 until the cross-head 10a abuts the outer surface of the retainer.
As mentioned earlier, the entire movable assembly is placed into the portion of cavity 2a of one of the pieces of the case 2. The retainer members 18 are positioned within the rectangular openings 2b of the case and the bridging contact is alined with the stationary contacts. The flanges 18a of the retainers are wider than the openings 2b of the case and serve to limit the outward movement of the retainers 18 within the openings after the two pieces of the case are joined together.
The foregoing description represents the completed module, the movable assembly thereof being relatively free for reciprocal movement as a unit with respect to the case 2. When the switch is oriented in a manner in which the contact bridge 12 is above the stationary contact tips 4a as is shown in FIG. 1, the bridge 12 rests upon the contacts under gravitational force. Conversely, when the switch is inverted so that the bridge member 12 is below the stationary contacts, the gravitational influence moves the assembly to a point wherein the flange 18a of the then lower spring retainer abuts the inner cavity wall adjacent the respective case opening 21) and the bridge 12 is separated from the contacts 4a.
The switch disclosed herein is designed to be used in conjunction with a control device which may have a mechanical or electromechanical operator for actuating the switch. The switch is suitably attached to the housing of the control device, a preferred method of attachment being more fully disclosed in the earlier mentioned copending application. This method, insofar as may be necessary to the understanding of the switch, is briefly described in the following.
The switch is supported within a pocked formed in the control device housing represented by the cross-hatched fragments 20 in FIGS. 2, 3, 7 and 8. The housing has an opening in the bottom of the pocket to expose the control device operator to the lower end of the switch contact carrier 10. The pocket supports the switch at the lower corners of the case 2 against horizontal and downward movement. A second housing member, such as a cover shown fragmentarily at 22 in FIGS. 2, 3, 6, 7 and 8, is secured to the first housing member to overlie the case 2 and hold the switch within the pocket.
The underside of cover member 22 is shown in FIG. 6. While the particular configuration of the cover is relatively unimportant to this application, it is important that it provide means not only to hold the switch within the pocket, but also that it provide means to hold the outer, or second, surface of the upper spring retainer 18 flush with the upper surface of the case 2. Additionally, the cover must also provide a space for the switch contact carrier 10 to move upward upon switch operation. The fragmentary cover shown in FIG. 6 has provisions for overlying two switches mounted side-by-side on a control device housing. A rectangular groove 22a is formed in the cover 22 to provide the clearance for movement of the carrier 10. The inner and outer portions of the cover surrounding the groove 22a are on the same plane and bear directly on the switch case in assembly. Additionally, the portions marked with an X each extend over a corner of the upper spring retainer 18 to limit the upper surface thereof to a plane flush with that of the switch case. The cover 22 is further provided with pairs of recesses 22!) for each switch module in which are disposed the upwardly extending shrouds 18d of the upper retainer 18. Shrouds 18d and recesses 22b effectively increase the creepage distance between two adjacent contact carriers 10 should any arcing occur. A rounded rib 220 is also formed on the cover to extend between adjacent switch modules to additionally increase the creepage path.
When the switch is assembled to a control device housing in the aforedescribed manner and oriented as shown FIG. 2, the bridge member 12 rests across the stationary contacts 4a to complete a circuit through the switch. The contacts are maintained in this normally closed contact mode under the bias of spring 14 bearing between the upper spring retainer 18 which is fixed relative to the case 2 'by the cover 22 and the bridge member 12, thus providing contact pressure for the switch. In this particular position the contact carrier is under the influence of gravity, the upper cross-head 10a resting upon the outer surface of upper retainer 18'.
FIG. 7 illustrates the actuated condition of the normally closed switch of FIG. 2, the control device operator exerting an upward force represented by arrow 24 on the lower cross-head 10a of carrier 10. The latter moves upward in response to the operator force against the bias of spring 14, the upper portion of the carrier 10 occupying the groove 22a. The transverse flange 10c abuts the underside of bridge 12 during the upward travel to positively carry the bridge out of engagement with the contacts 4a. Upon removal of the force 24 of the operator, the spring 14 biases the bridge back to its normally closed position. It is important to note that in this version the spring 16 extending between the lower spring retainer 18 and the flange 100 is not flexed and does not add unwanted spring pressure to the switch.
To change the contact mode to a normally open condition the cover 22 is removed from the housing, the switch is removed from the pocket and inverted. Terminal screws 8 and clips 6 are changed to be on the opposite side of the terminals 4 and the switch is reinserted into the pocket and the cover 22 replaced. The normally open position is illustrated in FIG. 3, the cover 22 again overlying the upper retainer 18 to maintain it flush with the upper surface of case 2. The carrier 10 is under a gravitational influence and assumes a position limited by the engagement of the flange 18a of the lower retainer 18 with the inner wall of the cavity 2a surrounding the lower opening 2b. Spring 14 biases the bridge member against the flange 100.
The actuated position of the normally open contact mode is depicted in FIG. 8 wherein the operator force is again represented by the arrow 24. The operator acting against the lower cross-head 10a of carrier 10 moves the carrier upward into the groove 22a against the downward bias of spring 16. Bridge member 12 engages the stationary contacts 4a during the travel and compresses the spring 14 somewhat to provide contact pressure. Upon the removal of the operator force 24, spring 14 couples with spring 16 to urge the carrier downward in the early travel, prior to contact separation. Thereafter the spring 16 urges the carrier downward until the upper cross-head 10a engages the surface of the upper retainer member 18. Gravitational force then causes the movable assembly to assume its original position wherein the flange 18a of lower retainer 18 abuts the cavity wall surrounding the lower opening 2b.
The reciprocal movement of contact carrier 10 is guided in each of the foregoing orientations by the spring retainers 18. The upper retainer in each instance remains stationary with respect to the case 2 and the carrier body is guided for movement within the rectangular opening 18c. The lower retainer in each instance moves directly with the carrier, the retainer being guided by the opening 2b of the case 2 and the carrier being positioned within the opening 18c.
Due to the straight through movement of contact carrier 10, which extends through both top and bottom surfaces of the case 2, the control device housing may also be modified to accommodate tandemly arranged switch modules as shown in FIG. 9. To provide better access to the wiring screws 6 when the switch is used tandemly, the lower switch is provided with longer terminals 26. Since the contact carriers 10 are of electrical conducting material and are conductive when the bridging members engage the stationary contacts, an insulating member 28 is disposed between the switches. Member 28 is slidably secured in the control device housing to be movable in response to movement of the carriers 10.
While the foregoing description has primarily contemplated a switch utilized in a control device housing wherein operation occurs from the bottom, it is to be understood that the switch is susceptible to various other applications without departing from the scope of the appended claims. One such modification exemplary of this would be a push-button operator wherein the operator housing may be mounted to a panel and have a depending support strap or the like to encompass the case 2 and fix the lower retainer 18. The operator would therefor bear upon the upper end of carrier 10 to move the latter downwardly for switch actuation.
1. A convertible electric switch module comprising, in combination:
an insulating case having an enclosed central cavity therein, alined openings in the upper and lower walls thereof communicating with said cavity, and spaced stationary contact means alined within said cavity and having portions thereof extending exteriorly of said case through opposite side walls thereof;
a movable contact assembly mounted for reciprocal movement within said case, said assembly comprisa contact carrier extending through said alined openings in said case, said carrier having transversely extending cross-head portions formed on each end thereof and a transverse flange formed on the body portion thereof to be disposed within said cavity;
a bridging contact member slidably disposed on said contact carrier and having the ends thereof cooperably alined with said stationary contact means for engagement therewith;
a pair of spring retainer members slidably mounted on said contact carrier at the ends thereof and slidably disposed within said alined openings of said case;
a first spring member disposed around said contact carrier and extending between said transverse flange and one of said retainer members to bias that member against the respective transversely extending cross-head portion; and
a second spring member disposed around said contact carrier and extending between said bridging contact member and the other of said retainer members to bias that member against the respective transversely extending cross-head portion and to bias said bridging contact member towards said transverse flange.
2. The combination according to claim 1 wherein said alined openings in said case and said spring retainer members are formed to have a complementary configuration having at least one straight side to prevent rotary movement of said retainer members within said openings and to provide guided reciprocal movement therein.
3. The combination according to claim 2 together with outwardly extending flange portions formed on the inner ends of said spring retainer members to interfere with the cavity wall adjacent said alined openings in said case to provide a limit for outward movement of said retainer members with respect to said case.
4. The combination according to claim 1 together with means overlying portions of the spring retainer member at one end of said contact carrier to maintain said retainer at a fixed limit of outward travel with respect to said case, and operating means engaging the opposite end of said contact carrier to move said carrier slidably through said fixed retainer against the bias of a respective one of said spring members to cause contact actuation of said switch module.
5. The combination according to claim 4 wherein said contact carrier member is constructed of an electrically conductive material and the portion of said operating 7 8 means which engages said carrier is constructed of an 3,251,964 5/1966 Lawrence et al 335198 electrical insulating material. 3,253,092 5/1966 Landow.
6. The combination according to claim 1 wherein said 3,272,949 9/ 1966 Lawrence. case is formed of a transparent electrical insulating ma- 3,339,161 8/1967 Conner et a1. terial.
References Cited 5 ROBERT K. SCHAEFER, Primary Examiner. UNITED STATES PATENTS H. O. JONES, Assistant Examiner.
2,897,311 7/1959 Schleicher 335198 3,188,405 6/1965 Scheib 335 132 335 132 CL 3,238,341 3/1966 Haydn.