US3851130A - Polarity reversing switch for high current loads - Google Patents

Abstract

A fixed base having four contacts arranged in a generally square pattern. A movable switch frame carrying two conductor bars for spanning pairs of the fixed contacts and establishing a current path therebetween. The movable switch frame is movable away from the fixed contacts so that it can be rotated 90* and then moved back into contact with the fixed contacts to form a different circuit configuration between the fixed contacts. A slideable, spring biased mechanism for attaching the conductor bars to the switch frame so as to compensate for minor misalignment between the switch frame and the fixed contacts. The fixed contacts protrude from the base in which they are mounted and have arcuate convex faces to afford uniform contact by the conductor bars. The conductor bars and the base on which the fixed contacts are carried are made of massive conductive material through which are provided passages for a cooling fluid such as water.

Description

United States Patent [191 Paulson Nov. 26, 1974 [75] Inventor: Peter C. Paulson, Pinole, Calif.

[73] Assignee: Electro-Coatings, Inc., Moraga,

Calif.

[22] Filed: July 5, 1973 [2]] Appl. No.: 376,382

[52] US. Cl 200/153 R, 200/1 V, 200/158, 200/165, 200/289, 317/100 [51] Int. Cl HOlh 21/66, HOlh 1/62 [56] References Cited UNITED STATES PATENTS 3,233,059 2/1966 Pridham, Jr. et a1. 200/83 N 3,244,833 4/1966 Gillett et al 200/289 X 3,265,846 8/1966 Brechtel et a1. 200/158 3,315,057 4/1967 Geltner ZOO/153 R 3,445,609 5/1969 Cardenas 200/1 V 3,686,457 8/1972 Dubac et a1. 200/166 BH X 3,778,680 12/1973 Vaneerden 200/166 K X FORElGN PATENTS OR APPLlCATlONS l.l50,187 8/1957 France 200/166 K 'ver Primary Examiner-James R. Scott Attorney, Agent, or FirmRobert Charles Hill 57 ABSTRACT A fixed base having four contacts arranged in a generally square pattern. A movable switch frame carrying two conductor bars for spanning pairs of thefixed contacts and establishing a current path therebetween. The movable switch frame is movable away from the fixed contacts so that it can be rotated 90 and then moved back into contact with the fixed contacts to form a different circuit configuration between the fixed contacts. A slideable, spring biased mechanism for attaching the conductor bars to the switch frame so as to compensate for minor misalignment between the switch frame and the fixed contacts. The fixed contacts protrude from the base in which they are mounted and have arcuate convex faces to afford uniform contact by the conductor bars. The conductor bars and the base on which the fixed contacts are carried are made of massive conductive material through which are provided passages for a cooling fluid such as water.

4 Claims, 4 Drawing Figures POLARITY REVERSING swrrcrr FOR HIGH CURRENT LOADS BACKGROUND OF THE INVENTION This invention relates to a high current polarity reversing switch of the type typically employed in the direct current power supply circuit to electroplating tanks and the like. More particularly the invention relates to such polarity reversing switch of increased current carrying capacity.

Polarity reversing switches having certain characteristics common to those described in more detail hereinbelow are disclosed in US. Pat. Nos. 3,265,846 and 3,315,057. Both of the cited patents disclose polarity reversing switches that have gained significant commercial acceptance. The present invention discloses certain improvements in such prior art switches which further enhance their utility.

SUMMARY OF THE INVENTION According to the present invention the current carrying capacity of reversing switches of the type disclosed in the above cited patents is materially increased without substantially increasing the size of such prior art switches. In contrast with a current carrying capacity feasible with the prior art switches of about 12,000 amperes, the present invention increases the capacity of such switches to about 24,000 amperes without materially increasing the physical size of the switch.

High current switches of the type contemplated by the present invention typically employ bus bars of copper having a cross-sectional dimension of 1 inch X 12 inches. Because the surface area of such bus bars is relatively small compared to the cross-sectional area of the bus bars an adequate surface area for heat dissipation is not available in certain environments. According to the present invention, such bus bars are bored or milled to define a plurality of fluid passages through the bus bar and a cooling fluid such as water is supplied to the passages in order to avoid excessive temperature rises within the bus bars. I

A factor contributing to temperature rise in the bus bars and other elements of polarity reversing switches is high contact resistance which arises from low contact pressure. According to the present invention the bus bars that form part of the structure are mounted to afford a slight degree of movement so that the bus bars can compensate for minor misalignment of the other parts of the structure. The bus bars are spring loaded so that even when slightly misalined they will make adequate and uniform contact with the stationary parts of the switch whereby adequate contact pressure and consequent low heat energy generation is achieved.

Accordingly, it is an object of the present invention to provide a contact reversing switch of high current carrying capability. This object is achieved according to the present invention by providing fluid passages for cooling fluid within the bus bars and stationary terminals that constitute a part of the invention. Accordingly, excessive heat is carried away by the cooling fluid and high current flow is afforded.

Also contributing to achievement of the above stated object is a mount for the bus bars that affords a limited degree of movement of the'bus bars so that it exerts adequate contact pressure notwithstanding minor misalinements between the parts of the device. The fixed contacts are somewhat raised above the surface so that contact between the fixed contact and the bus bars is assured, notwithstanding minor misalinements. Moreover, the bus bar is spring biased toward the fixed contacts in order to provide good contact pressure.

The foregoing together with other objects, features and advantages of the present invention will be more apparent after referring to the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a high capacity polarity reversing switch according to the present invention.

FIG. 2 is a front elevation view of the switch with portions broken away to reveal certain details.

FIG. 3 is a fragmentary crosssectional view taken along line 3-3 of FIG. 2.

FIG. 4 is an enlarged detailed view of the region of FIG. 3 delineated by line 4-4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawing reference numeral 12 indicates a fixed base insulated structure on which are mounted four fixed bus bars l4, l6, l8 and 20. The fixed bus bars, in one structure designed according to the present invention, are solid copper members having a thickness of 1 inch and a width of 12 inches. Centrally of base 12 and of the bus bars is a shaft 22 on which is supported a movable switch frame designated generally at 24. The movable switch frame includes a dish-shaped spring 26, an insulative support board 28 and two bus bars 30 and 32. The movable switch frame is moved toward and away from base 12 along shaft 22 and is rotated relative said shaft by means of accouterments as described in US. Pat. No. 3,315,057, the disclosure of which is incorporated insofar as the same is essential. Suffice it to say when movable switch frame 24 is in the position shown in FIG. 1 bus bar 30 bridges fixed bus bars 14 and 16 to establish a circuit connection therebetween and bus bar 32 bridges fixed bus bars 18 and 20 to establish a circuit there between. When switch frame 24 is rotated in a counterclockwise direction as viewed in FIG. 1, bus bar 30 bridges fixed bus bars 14 and 18 to establish a circuit therebetween and bus bar 32 bridges fixed bus bars 16 and 20 to establish a circuit therebetween. As described in the patents cited hereinabove, the fixed bus bars 14, l6, l8 and 20 are connected to the DC power supply and to the electroplating bath in order that the polarity of the current supplied to the bath is reversed on rotating movable switch frame 24 as described next above.

The bus bars although they are of solid copper have insufficient cooling surface relative to their crosssectional area to dissipate heat generated during high current operation. In order to maintain the temperature of the bus bars the present invention provides passages forrned in the bus bars through which passages a cooling fluid, such as water, is conveyed. Exemplifying the fixed bus bars is bus bar 14 which, as seen in FIG. 2, includes three parallel vertically extending passages 34, 36 and 38. Joining the upper ends of passages 34 and 36 is a milled slot 40 which is closed by an impervious cover 42, braised in place within bus bar 14. The opposite end of passage 36 is joined to the lower end of passage 38 by the milled slot 44 which is closed by a cover 46 braised in place as is cover 42. There is thus provided a continuous passage through the inner part of bus bar 14 which terminates at end fittings 48 and 50. Bus bar 18 has a corresponding opening 50' (see FIG. 3) and bus bar 20 has a corresponding opening 50". Thus cooling fluid such as water supplied to the passages maintains the temperatures of the bus bars at a rated value.

Movable bus bars 30 and 32 have similar cooling fluid passages. More specifically, bus bar 32, see FIG. 2, has a horizontally extending passage 52 and avertically extending passage 54 which communicate with one another at their inner ends and are provided with fittings 56 and 58 at the outer edges of bus bar 32. The opposite end of bus bar 32 hasa horizontal passage 60 corresponding to passage 52, a vertical passage 62 corresponding to passage 54, which passages intersect interiorly of bus bar 32. Passage 60 has an external fitting 64 and passage 62 has an external fitting 66 for effecting connection of water supplied to the passage. Bus bar 30 has cooling passages similar to those described in connection with bus bar 32.

The cooling passages of bus bars 30 and 32 are fed from hoses 68 which are connected to a water supply system (not shown) which includes pumping and cooling apparatus. The specific details of such apparatus form no part of the present invention and therefore require no detailed explanation.

Conduits for cooling fluid to fixed bus bars 14, 16, 18 and 20 feed through the rear of such bus bars and therefore do not appear in FIG. 1. Suffice it to say there are conduits or hoses corresponding to hoses 68 connected to inlet fittings exemplified at 48 and S with respect to fixed bus bar 14.

Because movable switch frame 24 is relatively massive, alinement problems between movable bus bars 30 and 32 and fixed bus bars 14, 16, 18 and 20 would be likely to occur but for the features of the present invention. Movable bus bars 30 and 32 are supported for movement relative to rigid plate 28. For so supporting the movable bus bars there are installed adjacent the .comers of the movable bus bars in a generally rectangular pattern four stub shafts 70. Because the installation of the stub shafts is identical, only one will be described in detail in reference to FIGS. 3 and 4. Referring to FIG. 4, stub shaft 70 is seen embodied in a bolt having a threaded shaft 72 which is threaded into an appropriate opening in bus bar 32. Plate 28 is apertured to receive an insulative bushing 74 which is centrally bored to receive shaft 72 and has an outer circular flange 76 for inhibiting the bushing against inward movement. Bushing 74 is slidable within the opening in plate 28 and has on the interior extension thereof intermediate plate 28 and the movable bus bar a compression spring member, exemplified by a Belleville spring washer 78 which is installed between two flat washers '80. Thus it will be seen from FIG. 4 that the force of spring 78 urges movable bus bar 32 toward fixed bus bar 20; because spring 78 is resilient however a certain degree of upward movement of the movable bus bar 32 is afforded. The movable switch frame is so arranged that when force is applied to plate 28 and bus bars 30 and 32 by dish-shaped spring 26, compression springs 78 are at least partially compressed so that adequate pressure is exerted by the movable bus bars ontofixed bus bars 14, 16, 18 and 20.

For further improving the contact between the movable bus bars and the fixed bus bars, each fixed bus bar is provided with a cylindric conductive member 82 (see FIG. 3) which is preferably formed of copper and braised in a complementary depression in the fixed bus bars. Cylindric member 82 extends outward of the surface of the fixed bus bars and has an arcuate convex surface 84 adapted to contact the inner surface of movable bus bars 30 and 32. In one switch designed according to the present invention cylindric members 82 have a diameter of about 2 /2 inches, a thickness of about 13/16 inch and a radius of curvature on surface 84 of about 7 inches.

It will be noted in FIG. 2 that cylindric contact members 82 lie within the rectangular pattern defined by stub shafts when the movable bus bars are inbridging relation to the fixed bus bars. This affords optimum movement of the movable bus bars to bring the bus bars into conformity and contact with cylindric contact members 82 notwithstanding a degree of misalinement of movable switch frame 24- with respect to base 12.

It will also be noted in FIG. 2 that the passages for cooling fluid are arranged to be adjacent to and at least partially surround the point of contact between cylindric contact members 82 and movable bus bars 30 and 32. More specifically the cylindric contact member mounted in fixed bus bar 14 is intermediate fluid passages 36, 44 and 38 which surround the cylindric member on three sides. The cooling passages in movable bus bars 30 and 32 are arranged to surround the point of contact with cylindric member 82 on two adjacent sides. The proximity of the cooling passages to the point of contact between the cylindric contact members 82 and the movable bus bars assures that the switch will operate at rated temperatures for virtually all magnitudes of current flow therethrough. 1 The switch of the present invention operates as follows: in the normal condition, depicted in FIG. 1, it can be assumed that the positive side of the DC power supply is connected to fixed bus bar 14 and the negative side is connected to fixed bus bar 20. It can be further assumed that the anode of the plating tank is connected to fixed bus bar 18 and the cathode is connected to fixed bus bar 16. In this condition dish-shaped spring 26 urges movable switch frame 24 inward and the force of the dish-shaped spring plus that in compression springs 78 assures uniform contact between movable bus bars 30 and 32 and the respective cylindric contact members 82. When polarity reversal is desired mechanism associated with shaft 22 and more fully described in the above cited US. Pat. No. 3,315,057, is operated to release the force supplied by dish-shaped spring 26 so that the movable bus bars move outward on shaft 22 and out of contact with fixed cylindric contact members 82. After the switch frame is manually rotated such mechanism again applies pressure through dishshaped spring 26 so as to urge movable bus bars 30 and 32 into contact with fixed cylindric members 82. The resilient mount of the fixed bus bars afforded by stub shafts 70 and springs 78 permit the movable bus bars to move to a degree sufficient to compensate for any misalinement of switch frame 24 with the fixed bus bars. In addition the supply of cooling fluid through hoses 68 and the passages in the fixed and movable bus bars assures that rated operating temperature is not exceeded.

By employing the present invention a reversing switch in which the fixed and movable bus bars are formed by copper bars having a 1 inch by 12 inch crosssectional area can safely carry 12,000 amperes and remain within the rated temperature rise. The present invention makes possible a reversing switch having a capacity of up to 24,000 amperes without materially increasing the physical size thereof.

Thus it will be seen that the present invention provides a polarity reversing switch that has higher capacity within a given temperature range without increasing the overall dimensions of the switch. Moreover the capacity of the contacting parts to be at least partially self alining reduces the importance of strict manufacturing tolerances to achieve proper operation. Finally, the present invention lends itself to manufacture of polarity reversing switches having current ratings far exceeding that which has heretofore been feasible.

Although one embodiment of the invention has been shown and described, it will be obvious that other adaptations and modifications can be made without departing from the true spirit and scope of the invention.

What is claimed is:

1. In a high capacity polarity reversing switch of the type including a stationary base member having two pairs of stationary terminals, a movable member having internal terminal engaging conductors and being operable in a first position to form a circuit between pairs of said stationary terminals and in a second position to form a circuit between different pairs of said stationary terminals, and means axially alined relative to said base for selectively engaging and disengaging said members in circuit forming positions, the improvement comprising rigid conductor bars constituting said terminal engaging conductors, means for supporting said rigid conductor bars for movement relative said movable member toward and away therefrom and toward and away from said stationary terminals, means for resiliently biasing said rigid conductor bars away from said movable member and toward said stationary terminals, said stationary terminals formed by cylindric conductive members having one end mounted to said base member and the other end protruding therefrom toward said conductor bars, said protruding end being arcuately convex so as to make contact with said conductor bars irrespective of misalinement of said movable member relative said base member, said conductor bar supporting means comprising first and second stub shafts attached to said conductor bars and extending therefrom, means for guiding said stub shafts for sliding movement in said movable member, said guiding means being disposed so that said stub shafts lie on opposite sides of said cylindric conductive members when the respective conductive bar is in contact with the convex surface of said cylindric conductive member, and wherein said resilient biasing means comprises first and second compression springs circumscribing respective said shafts intermediate said movable member and said conductor bar, said conductor bars and stationary terminals defining a plurality of fluid passages therethrough, and means for supplying a cooling fluid to said passages.

2. A switch according to claim l wherein said fluid passages extend adjacent at least three sides of said cylindric conductive member.

3. A high current capacity polarity reversing switch comprising a base, four fixed contacts supported on said base in a generally square planar pattern, a switch frame, means for supporting said switch frame for rotative movement on an axis centrally of said square pattern and normal to the plane thereof, means for moving said switch frame along said axis toward and away from said fixed contacts, first and second conductor bars for spanning said fixed contacts, and means for mounting said conductor bars on said switch frame in parallelly spaced apart relation so that said conductor bars effect a first circuit configuration between pairs of said fixed contacts in a first position of said switch frame and effect a second circuit configuration between different pairs of said fixed contacts in a second position of said switch frame from said first position, said mounting means including means for supporting said conductor bars for movement toward and away from said switch frame and means for resiliently biasing said conductor bars away from said switch frame and toward said fixed contacts, said conductor bar supporting means including a stub shaft attached adjacent each comer of said conductor bar and extending therefrom, said stub shafts being in a substantially rectangular pattern, and means for guiding said stub shafts for sliding movement in said switch frame, and wherein said conductor bar biasing means includes a compression spring circumscribing each said stub shaft intermediate said switch frame and said conductor bar, said fixed contacts protruding from said base and being positioned to reside within the rectangular pattern of said stub shafts so that said conductor bar is urged into uniform contact with said fixed contacts when said switch frame is moved toward said fixed contactsin said first and second positions.

4. A switch according to claim 3 wherein said conductor bars define a plurality of fluid passages therethrough, and means for supplying a cooling fluid to said passages.

Claims (4)

1. In a high capacity polarity reversing switch of the type including a stationary base member having two pairs of stationary terminals, a movable member having internal terminal engaging conductors and being operable in a first position to form a circuit between pairs of said stationary terminals and in a second position to form a circuit between different pairs of said stationary terminals, and means axially alined relative to said base for selectively engaging and disengaging said members in circuit forming positions, the improvement comprising rigid conductor bars constituting said terminal engaging conductors, means for supporting said rigid conductor bars for movement relative said movable member toward and away therefrom and toward and away from said stationary terminals, means for resiliently biasing said rigid conductor bars away from said movable member and toward said stationary terminals, said stationary terminals formed by cylindric conductive members having one end mounted to said base member and the other end protruding therefrom toward said conductor bars, said protruding end being arcuately convex so as to make contact with said conductor bars irrespective of misalinement of said movable member relative said base member, said conductor bar supporting means comprising first and second stub shafts attached to said conductor bars and extending therefrom, means for guiding said stub shafts for sliding movement in said movable member, said guiding means being disposed so that said stub shafts lie on opposite sides of said cylindric conductive members when the respective conductive bar is in contact with the convex surface of said cylindric conductive member, and wherein said resilient biasing means comprises first and second compression springs circumscribing respective said shafts intermediate said movable member and said conductor bar, said conductor bars and stationary terminals defining a plurality of fluid passages therethrough, and means for supplying a cooling fluid to said passages.

2. A switch according to claim 1 wherein said fluid passages extend adjacent at least three sides of said cylindric conductive member.

3. A high current capacity polarity reversing switch comprising a base, four fixed contacts supported on said base in a generally square planar pattern, a switch frame, means for supporting said switch frame for rotative movement on an axis centrally of said square pattern and normal to the plane thereof, means for moving said switch frame along said axis toward and away from said fixed contacts, first and second conductor bars for spanning said fixed contacts, and means for mounting said conductor bars on said switch frame in parallelly spaced apart relation so that said conductor bars effect a first circuit configuration between pairs of said fixed contacts in a first position of said switch frame and effect a second circuit configuration between different pairs of said fixed contacts in a second position of said switch frame 90* from said first position, said mounting means including means for supporting said conductor bars for movement toward and away from said switch frame and means for resiliently biasing said conductor bars away from said switch frame and toward said fixed contacts, said conductor bar supporting means including a stub shaft attached adjacent each corner of said conductor bar and extending therefrom, said stub shafts beIng in a substantially rectangular pattern, and means for guiding said stub shafts for sliding movement in said switch frame, and wherein said conductor bar biasing means includes a compression spring circumscribing each said stub shaft intermediate said switch frame and said conductor bar, said fixed contacts protruding from said base and being positioned to reside within the rectangular pattern of said stub shafts so that said conductor bar is urged into uniform contact with said fixed contacts when said switch frame is moved toward said fixed contacts in said first and second positions.

4. A switch according to claim 3 wherein said conductor bars define a plurality of fluid passages therethrough, and means for supplying a cooling fluid to said passages.

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