US3525957A - High voltage relay - Google Patents

Description

Aug. 25, 1970 R. H. LONERGAN I 3,525,957

HIGH VOLTAGE RELAY Filed May 17, 1968 I y l 63 I ZZZT L 69 2 e9 L 54 38 I 52 i L Q FIG. 2

INVENTOR. RICHARD H. LONERGAN ATTORNEYS United States Patent 3,525,957 HIGH VOLTAGE RELAY Richard H Lonergan, Brockton, Mass., assignor to Joseph Pollak Corporation, Boston, Mass., a corporation of Massachusetts Filed May 17, 1968, Ser. No. 730,014 Int. Cl. H01h 67/06 US. Cl. 335125 1 Claim ABSTRACT OF THE DISCLOSURE Some rather elaborate devices have been designed for the switching of high voltages. Even the best of these devices sometimes give rise to difficulties. Most commonly, arcing which inevitably accompanies the switching of high voltage causes pitting of contact surfaces and that pitting is very soon followed by welding. The situation is frequently aggravated by contact bounce which can be so severe as to destroy relay operation.

The switching of high voltage is necessary in a multitude of applications. Frequently, the high voltage which is being switched is in the form of pulses. This situation exists in such apparatus as radio and radar transmitters, X-ray generators, welding apparatus and, more recently, medical electronic apparatus. Although the present invention is a uniquely valuable contribution to the lastmentioned application, it also finds use in a variety of fields in addition to those mentioned.

Specifically, the present invention serves a vital purpose in defibrillating equipment which is used to shock the heart back into normal beating when fibrillation sets in. The efiicacy of such techniques for restoring a normal heart beat have been known for some time to the medical profession. However, equipment for such purposes has been relatively crude and hazards to the patients life have inhibited'more extensive use of shock difibrillators.

The principal object of the present invention is the improvement of high voltage relays.

Another object of the present invention is the elimination of contact bounce and welding in high voltage relays.

Still another object of the present invention is the lengthening of the operating life and the improvement of the efiiciency of high voltage relays.

A still further object of the present invention is to render practical and more widespread medical use of high voltage relays.

Generally, the present invention is based upon the concept of continuing motion of a movable contact or contacts after their initial closure with a fixed contact or contacts during the closing cycle and the gaining of momentum by the moving member before its final break with the stationary member during movement in the opposite direction. Implementation of these concepts is preferably by the use of opposed moving contacts which are normally urged together but wedged apart by tapered fixed contacts after an initial closure. This action provides a high and increasing contact pressure and prevents contact bounce. In the break cycle of the relay the moving contacts are permitted to gain momentum before they encounter the particular area of the fixed contact at which initial closure is made and where damage may exist. A shorting bar operating in conjunction with the travel of the moving contacts eliminates any need for a synchronizing circuit or the like and prevents undesired output from the relay. For a better understanding of the present invention together with other and further objects, features and advantages, reference should be made to the following specification which should be read in conjunction with the attached drawing in which:

FIG. 1 is an elevation of a preferred embodiment of the high voltage relay of the present invention,

FIG. 2 is a side view, partly in section, of the embodiment of FIG. 1,

FIG. 3 is a top sectional view taken along the lines 33 of FIG. 1,

FIG. 4 is a top sectional view taken along the lines 4--4 of FIG. 1,

FIG. 5 is a fragmentary sectional view taken along the lines 5-5 of FIG. 4, and

FIG. 6 is a simplified schematic circuit diagram of the invention as it may be applied to a defibrillator.

Referring to FIGS. 1, 2, and 3, the relay shown in the drawing is normally enclosed in a container from which it may be spaced as by internally threaded hexagonal spacers 12, 14, 16 and 1 8. These spacers form the bottom members of support post arrangements at the corners of a mounting plate 20 through which holes are drilled to pass threaded studs such as that shown at 22. The threaded studs are screwed into the spacers and also into internally threaded cyclindrical ceramic insulators, the insulators 24 and 26 being typical.

Centrally beneath the mounting plate there is mounted a rotary solenoid 30. The solenoid 30 is conventional in nature and of a type which is commercially available. In its normal position, a rotating drive shaft 32 is held against a stop by a spiral spring 33 (visible in FIG. 3). Electrical actuation of the solenoid through the leads 34 causes rotation of the shaft 32 against the biasof the spiral spring. Keyed or otherwise fixed to rotate with the shaft 32 is a cylindrical insulating shaft 36 which may be made of nylon or other suitable material, Mounted at the top of the shaft 36 and firmly fixed thereto is a crossmember preferably formed of a number of laminations 38. The exact manner of mounting the laminations 38 upon the shaft 36 is unimportant to the present invention provided only that the mounting be secure. Riveted to the laminations are four contact blades terminating in movable opposed contact members 42 and 4.4 at one end and 46 and 48 at the other end. The contacts 42 and 44 are normally biased strongly toward each other as are the contacts 46 and 48 by virtue of method of support of the contact blades from the laminations.

A pair of fixed tapered contacts 50 and 52 are mounted upon the insulators 24 and 28, respectively for engagement by the contact pairs 42, 44 and 46, 48, respectively. As will be best seen in FIG. 2, the insulator 28 is diagonally across from the insulator 24. In FIG. 1, the contact 3 52 is actually hidden behind a similar contact 54 which is mounted above the insulator 26.

In FIG. 1 detail may be seen on the assembly of parts and mounting plates, the stacking of elements at each corner of the device being identical. Between the tapered contact 50 and the insulator 24 is an electrical connecting terminal 51 and above the terminal 51 supported by a flange is a center mounting plate 53 made of insulating material. Next above the plate 53 is another insulator 55 joined to the insulator 24 by a threaded stud which passes through the terminal 51, the contact 50 and the mounting plate 53.

Atop the insulator 55 is another terminal 56 for electrical connection, another tapered contact 58 and a top mounting plate 60 through which a stud threaded into the insulator 55 passes. This portion of the corner post is held in place by a cap nut 61.

Reverting now to the solenoid drive shaft as it is seen in FIG. 1, a second shaft member 62 is aligned with the first shaft member 36 and firmly secured to the crossmember 38. A clearance hole is provided in the center mounting plate 53 to pass the drive shaft and atop the shaft member 62 is a second cross-member made up of laminations 63. The second cross-member 63 is identical and parallel to the cross-member 38 and is similarly firmly mounted upon the solenoid drive shaft. It also carries pairs of opposed contact members at its extremities, the individual contacts of each pair being biased toward each other. One pair of contacts engages the fixed tapered contact 58 and the other engages another diagonally opposite fixed tapered contact 65, hidden behind a similar contact 71 in FIG. 1, but visible in FIG. 2.

Finally, a rotary bearing assembly 67 for the solenoid drive shaft is carried in a suitable opening formed centrally in the top mounting plate 60.

Another important element of the present invention is a shorting bar 69 which is clearly visible in FIGS. 1 and 2. The shorting bar 69 is normally in contact with the tapered contact 54 and the similar tapered contact 71 located directly above the contact 54. The shorting bar 69 is mounted preferably by rivets upon a front slide member 72 of insulating material. A track member 74 is provided to permit the slide member 72 to move from right to left as shown in FIGS. 1, 3 and 4. The track member 74 is preferably made of insulating material and is mounted by means of screws or other suitable fasteners to the mounting plate 53.

A relatively large rectangular opening 76 is cut in the track member 74. A slot 78 somewhat wider than the opening 76 is milled in the member 74 with sides parallel to the long sides of the opening to form a shoulder which accommodates a back slide member 80 which is connected to the front slide member 69 by means of the rivets which pass through the opening 76 in the track member 74. Detail on this structure is most easily seen in FIG. 5. The inside slide member 80 is provided with a relatively small central opening in which a round-headed pin 82 is disposed. The pin 82 is threaded or otherwise firmly inserted radially in the solenoid drive shaft section 62.

Electrical operation of one embodiment of the invention can best be understood by referring to the schematic diagram of FIG. 6. A power supply, capable of providing as much as 25 kilovolts, DC, is connected to the fixed contacts 52 and 65 by way of the terminals 51 and 56, respectively. Current flowing from the power supply charges a condenser C which may have a value of 16 mfd. or more. The solenoid 30 may be triggered by a manual switch or it may be actuated in accordance with the output of a circuit synchronized to the heart beat of a patient. In either case, the first action is that of the shorting bar 69 which moves out of contact with the output fixed contacts 54 and 71. Immediately thereafter, as is indicated by the dotted showing of switch members in FIG. 3, the output of the condenser C is applied to the 4 output contacts 54 and 71. The condenser discharges through the Output electrodes applied to the patient and through a resistance R which may be of the order of 500 ohms in parallel with the patient.

The location of the radial pin 82 and its camming effect upon the slide members 72 and is straightforward. With rotation of the solenoid drive shaft, the pin 82 drives the slide members to the left, as seen in FIG. 1, the shorting bar 69 breaking from the tapered contacts 54 and 71. Simultaneously, the cross-members 38 and 63 begin their rotary movement. As may be seen in FIG. 3, the cross-member 63 carries its associated opposed contacts first over the thicker central portions of the tapered contacts 58 and 65 and then over the thin edge portions of those contacts. The shorting bar 69 has now been removed from the tapered contacts 54 and 71 and as the cross-members 38 and 63 continue their excursion they encounter first the thin edge portion of the tapered contacts 54 and 71 and continue their travel over the surfaces of those tapered contacts until they reach the thicker central area as indicated by the dotted representation of the cross-member 63 in FIG. 3.

The discharge of the condenser C continues for approximately 2 /2 to 3 milliseconds after the original contact is made and the motion of the cross-members continues for approximately 16 milliseconds as the opposed moving contacts continue their wiping action over the increasingly thicker body of the fixed tapered contacts. This same action is reversed when current no longer flows in the solenoid 30. That is, the opposed moving contacts press on opposite surfaces of the fixed contacts passing from the thicker central portions and then over the thinner edge portions before swinging clear to begin their excursion toward the thin edges of another pair of tapered fixed contacts.

The importance of the overtravel of the moving contacts as they reach the fixed contact lies in the fact that with high current in-rush arcing may occur at the point of original meeting of the moving and fixed contacts. The continued movement beyond the original meeting point eliminates the possibility of welding at the point where welding is most likely to occur, namely, the point of original meeting which may be pitted or otherwise damaged by arcing.

Conversely in moving apart the moving contacts have an opportunity to gain momentum before passing over the point where pitting may exist and are carried beyond, again avoiding possible welding that might be a danger in some applications, as, for example, where an inductive load is being switched.

In effect, the taper of the fixed contact which in the embodiment described is about 16 provides a wedging and climbing action of the opposed contacts upon the tapered fixed contact. This angle is not critical and may be varied as may be the 45 angle of travel. Moreover, a structure in which the moving contact is tapered and the fixed contacts are opposed contacts through which the moving contact overtravels may be utilized.

The shorting bar is also of significance in several applications, particularly in the defibrillator. The output is shorted at all times other than during the discharge, and no undesired output can reach the patient. Also, the fact that it is synchronized with the switching in its operation from the same drive shaft eliminates need for a synchronizing circuit.

Finally, of course, the principles of the invention are adaptable to numerous circuit configurations. By way of example, a switch can be double pole-double throw, shorted output, shorted input or other combination. Moreover, the solenoid may be made responsive to a low voltage signal to achieve high voltage switching. Although pulsed voltages are what the unit is primarily designed to switch, it is also capable of limited use in steady-state applications.

What is claimed is:

1. In a high voltage relay of the type wherein pairs of rotary moving contacts and single fixed contacts are closed or opened by the operation of a solenoid, the combination of a shaft connected to and rotatable by said solenoid, a cross-member carried by said shaft for supporting said moving contacts at points radially displaced from said shaft, said cross-member normally urging each of a pair of said movable contacts toward the other of said pair, each of said single contacts having a thin peripheral portion and an increasingly thicker central portion whereby rotary motion of a pair of said movable contacts over each of said single fixed contacts in response to energization of said solenoid causes a continuous wedging apart of each said pair during closing thereof upon each said single fixed contact, a shorting bar normally electrically connected between at least two of said References Cited UNITED STATES PATENTS 1,992,036 2/ 1935 Meier.

2,553,478 5/1951 Schleicher 335130 2,662,130 12/1953 Sealey.

3,097,278 7/1963 Alderman 335125 3,192,328 6/ 1965 Wilson.

BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner

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