IL39057A - Electrical switch - Google Patents

Description

♦ own Ann j Electrical switch BUNKER RAMO CORPORATION :37062 This invention relates generally to electrical switches and more particularly to an improved clapper arm for a microwave or RF coaxial switch.

RF coaxial switches are used for transmit-receive switches to switch a single antenna between transmitter and receiver and for other RF signal transfer purposes. As the frequencies of interest have climbed ever higher, it has been increasingly difficult to maintain optimum impedance match to the active channel thus obtaining low VSWR (Voltage Standing Wave Ratio) and adequate RF voltage and RF power handling capabilities while still maintaining good isolation for the unused channel. While this problem may to some extent be overcome by the use of electronic devices such as semi-conductor diodes, ionizable electron tubes and various breakdown devices as the switching elements, mechanical switches are still preferable in many instances.

One example of a prior art radio frequency coaxial switch is described in U.S. Patent No. 3, 1 ,8 9 that issued on December 3, 1968, to W. G. Burt, Jr. In the aforemention-ed patent, the armature of a solenoid bears against and displaces a spring biased rocker arm. Means are provided for pivotally mounting the rocker arm so that the underside thereof bears against a pair of laterally displaced pins which are also spring mounted. The pins carry plates or blades that are arranged to contact terminal means mounted in the support base of the device. While the structure of the prior art switches is effective, it will be readily appreciated that the rocker arm represents a substantial mass, so that the solenoid must exert a larger than necessary force in order to pivot the rocker arm. This results in the need for a larger more expensive solenoid. The solenoid itself is larger, heavier and more expensive than a coil, primarily because of the existence of the armature. A design which does not require the use of a solenoid would thus be preferable. The prior art switches also pivot the rocker arm at one end thereof. This results in the force being applied to one of the pins being greater than the force applied to the other pin and presents other mechanical problems. With a solid, one-piece rocker arm, it is also difficult or impossible to make small adjustments to compensate for manufacturing and assembly tolerances.

The present invention represents an improvement over the prior art switches discussed briefly hereinabove. The improvement resides primarily in the construction of the clapper arm, together with the support frame therefor and results in the elimination of the rocker arm as well as the spring for biasing the rocker arm. In the present invention, one leg of an L-shaped support frame is mounted on one end of the solenoid. The clapper arm is pivotally mounted on the other leg of the support frame and is provided with two elongated, centrally located and tandemly arranged fingers that are arranged to bear against pins which carry the switch contaot blades. The opposite end of the improved clapper arm is in closely spaced opposition to a coil so as to be angularly displaced when the coil is energized. The two fingers of the improved clapper arm that are displaced by the armature of the solenoid may be adjusted to compensate for manufacturing and assembly tolerances merely by bending, as required after assembly .

Accordingly, it is an object of the present invention to provide an improved electrical switch, and in particular, an^ v improved radio frequency coaxial switch.

It is another object of the present invention to provide improved construction for the clapper arm used in a radio frequency coaxial switch.

A further object of the invention is to provide a construction for a RF coaxial switch which permits the use of a coil in place of a solenoid.

A feature of the present invention is that the rocker arm and the spring biasing means therefor, such as have been used in the prior art, have been eliminated.

An advantage of the present invention is the relatively simple adjustment of the clapper arm as regards the pins that support the switch contact blades.

These and other objects, features and advantages of the invention will, in part, be pointed out with particularity, and will, in part, become obvious from the following more detailed description of the invention taken in conjunction with the accompanying drawing, which forms an integral part there-of .

In the various figures of the drawing, like reference characters designate like parts.

FIG. 1 is a fragmentary side elevational view, partially in section, illustrating the components comprising the present invention.

FIG. 2 is an exploded perspective view of the improved clapper arm comprising the present invention together with the coil mounted frame that supports the clapper arm.

FIG. 3 is a plain view of the support frame and clapper arm shown in FIG. 2.

PIG. 4 is a transverse, elevational sectional view taken along line 4-4 of FIG. 3..

PIG. 5 is a longitudinal, sectional view taken along line 5-5 of PIG. 3, with the clapper arm also shown in phantom outline in an alternate position.

Referring to PIG. 1 of the drawing, there is shown a single pole, double-throw coaxial switch 10 comprising the present invention. The switch 10 includes a support base 12 and three, coaxial connectors 14, 16 and 18, which are se-cured to the base 12 such as by a threaded connection, for example. The central terminals 20, 22 and 24 of the connectors 14, 16 and 18, respectively, extend through openings 26, 28 and 30, respectively. An elongated cavity 32 is formed in the upper surface of the support base 12 with the free end of each of the terminals 20, 22 and 24 being located in the cavity 32. The dimensions of the chamber 32 are such that it forms a wave guide below cut-off with a principal wave guide mode in the operating frequency range of switch 10.

A cover plate 34, that is suitably secured to the top surface of the support base 12, is provided with an elongated recess 36 that is in opposition to the cavity 32. A pair of counterbored holes 38 are formed in tandem along the longitudinal axis of the cover plate 34. Pins 40a and 40b extend slidably through the counterbored holes 38 with the heads of the pins 40a and 40b being positioned above the cover plate 34. Compression springs 42a and 42b are positioned in the counterbored holes 38 about the shanks of the pins 40a and 40b and beneath the heads thereof so as to normally bias the pins 40a and 40b in an upward direction. The inner end of the pins 40a and 40b or the ends opposite the heads thereof have switch contact blades 44a and 44b respectively, secured" thereto In any suitable manner. One switch contact blade 44a spans the terminals 20 and 22 while the adjacent switch contact blade 44b spans the terminals 22 and 24. Connector 16 is a common connector which is connected alternatively to either connectors 14 and 18, by the switch 10.

The cover plate 34 is also formed with integral support pads 46 and 48 to which is mounted one leg of an L-shaped support frame 50. A coil 5 is secured to the other leg of the L-shaped support frame 50 by means of a screw 56. The coil 52 is comprised of a bobbin 58 about which is wound an insulated wire coil generally designated by the reference character 60.

For purposes to be described hereinafter, a leaf spring 62 is captured between one end flange of the bobbin 58 and the leg of the L-shaped support frame 50 through which the screw 56 extends.

Reference may now be had to FIGS. 2, 3, 4 and 5 for a more complete description of the L-shaped support frame 50 and the clapper arm that is pivotally mounted thereon. The L-shaped support frame 0 includes a first leg 64 having a counter-sunk hole 66 through which the screw 56 extends. The second leg 68 of the support frame 50 includes several holes 70 that accommodate screws (not shown) by which the support frame 50 is mounted to the support pads 46 and 48. The free end of the leg 68 is provided with a pair of opposed, laterally extending tabs 72 that are bent downwardly to the position shown in phantom outline in FIG. 2 and in solid outline in FIGS. 3, 4 and 5 during the assembly procedure. Holes 74 are formed during the stamping operation in each of the tabs A clapper arm generally designated by the reference character 76 is mounted on the L-shaped frame, utilizing the downwardly bent tabs 72. The clapper member 76 comprises a plate 78 which is normally in spaced opposition to the coil 50 .

A leg 80 extends outwardly from the plate 78 and terminates in a transverse shaft 82. At assembly, the tabs 72 are bent downwardly so that the outward ends of the shaft 82 are journaled therein utilizing the holes 74 for this purpose. A first finger 84 extends outwardly from the plate 78 and a second finger 86 extends outwardly from the transverse shaft 82 in tandem, co-linear relationship with the finger 84. As shown in FIG. 1, the first finger 84 is positioned over the top of the pin 40b while the second finger 86 is positioned over the top of the pin 40a. The free end of the leaf spring 62 bears downwardly against the upper surface of the first finger 84 to bias clapper arm 76 in the position shown in FIG. 1. It is apparent that, the spring could also bear against arm 80 in addition to or instead of finger 84, that a coil spring could be substituted for the leaf spring 62, or that some other suitable biasing means could be provided for the clapper arm.

When the coil 52 is energized, the clapper arm 76 is pulled in a direction towards the coil and thus overcomes the force of the leaf spring 62. The clapper arm 76 pivots in a counter-clockwise direction about the shaft 82. The finger 86 thereby depresses the pin 40a working against the force of the spring 42a and thereby brings switch contact blade 44a into electrical contact with the terminals 20 and 22 of con- nectors 14 and 16, respectively. When the clapper arm 76 pivots in the counter-clockwise direction, as just described, it will move away from the pin 40b so that the spring 42b will urge the pin 40b in an upward direction, thus moving the switch contact blade 44b from the terminals .22 and 24 of the connectors 16 and 18, respectively. When the coil 52 is de-energized, the leaf spring 62 will urge the clapper arm 76 in a clockwise direction and thus return it to the position shown in FIG. 1.

While the switch 10 has been referred to as a coaxial switch and the inputs as coaxial connectors, in the discussion heretofore, the inputs could, in fact, be in the form of coaxial lines and cables, parallel plate lines, strip lines, microstrip, wave guide or any other acceptable transmission line for microwave energy. The term "coaxial" is thus being used as a generic term for the type of switch involved. The improved clapper arm configuration of this invention might also find application in electrical switches utilized for D.C. and selected A.C. applications..

It will be appreciated that an improved clapper arrangement has been provided for a radio frequency coaxial or other electrical switch. The rocker arm and the compression spring used in the prior art are replaced by a simpler, lighter and less expensive support frame and clapper arm that may be fabricated by a stamping operation and assembled by a simple bending operation. The solenoid has been replaced by a coil. By pivoting the actuating arm between the two fingers, balanced forces on the pins and generally superior mechanical movement are obtained. Minor adjustments to compensate for manufacturing and assembly tolerances may be made independ- - - ently to the two fingers of the clapper arm merely by bending them after assembly, as required.

There has been disclosed heretofore the best embodiment of the invention presently contemplated. However, it is to be understood that various changes and modifications may be made thereto without departing from the spirit of the invention.

Claims (6)

WHAT WE. CLAIM IS:

1. An electrical switch having a coil and two contact-controlling pins, both of which are normally biased to a first position, one of said pins being moved to a second position when said coil is energized, and the other of said pins being moved to said second position when said coil is de-energized, characterized by: a clapper, arm having a first leg with two independently canti-levered fingers positioned in tandem collinearily with the pins, each of which is adapted to bear against a corresponding one of said pins to move the pin to its second position, and a pivot shaft positioned between said fingers and at substantially right angle thereto; and a second leg' substantially perpendicular to said first leg, said second leg being positioned to be acted upon by said coil when said coil is energized to rotate said arm about said pivot;

2. The switch as claimed in Claim 1 including a leaf spring for biasing said arm to move the other of said pins to said second position when said coil is de-energized.

3. The switch as claimed in Claim 1 including a frame fixed at one end to said switch and including means at the other end for pi otally supporting the pivot shaft of said clapper arm.

4. The switch as claimed in Claim 3, wherein said pivotally supporting means is a pair of laterally spaced tabs having coaxially aligned openings therein, the ends of said pivot shaft being journaled in the aligned openings of said tabs.

5. The switch as claimed in Claim 1, wherein said fingers are adapted to be i dependently bent to finely adjust the second position of the corresponding pin.

6. The switch as claimed in Claim 1, wherein said switch is a coaxial switch including: a base; three terminals mounted in tandem in the base; conductive contact blade means positioned in opposition to each two adjacent terminals, each of said blade means being movable between a first position interconnecting the terminals and a second position spaced from the terminals, a separate pin means being slidably mounted in the base for supporting each of the contact blade means during movement thereof, the movement of said pins being operative to control moving the contact blade means between said first and second positions of said blade means.