US2092829A - Switch - Google Patents

Description

Sept. 14, 1937.

, I nnnnnnn. uuuuum A. J. BOWIE swucn File d Dec. 26, 1933 F'Is.5.

2 Sheets-Sheet 2 IN V EN TOR.

Patented Sept. 14, 1937 UNITED STATES PATENT O'FFICE' SWITCH Augustus Jesse Bowie, San Francisco, Calif.

Application December 26, 1933, Serial No. 703,875

10 Claims.

This invention applies to the use of high-pressure contacts for switches, with reference not only to single-pole switches but also to gang D- erated' switches. When contacts have to be engaged and disengaged as in switch work the advantages of applying high pressure to the contact surfaces are now well recognized, as the heating of the contact is greatly reduced thereby.

The customary form of switch construction consists of a clip and a blade which is moved into and out of engagement with this clip, and reference is made particularly to this construction, altho other corresponding equivalents of course may be substituted.

To obtain the best type of contact, the contact surfaces should preferably be made of conductors of high conductivity, such as copper or silver. The use of a silver contact is very desirable since, altho many metallic oxides are insulators, silver oxide is a conductor. Hence the materials best adapted for contacts are of high been built heretofore in general involved for each pole of the switch a link'or other mechanism generally directly connected with the blade for bringing the blade into contact with the clip.. After 49 the contacts are engaged a release means frees the blade from control of this mechanism, and further motion of the device which actuates the switch is employed to operate another mechanism for bringing high pressure onto the contacts. This is quite objectionable in many cases for obvious reasons, particularly with an inverted switch where as soon as the blade is disengaged it may fall partially apart from full contact while the high pressure is being applied. Another 50 class of mechanism already in use involves a hinged switch blade which co-operates with a clip. This blade is driven by a link which is permanently connected to the blade. The construction is such that in the closure of the switch the ..3 High-pressure contacts in switches which have tion directly opposing the clip without frictional contact therewith, and when the blade has bottomed on the clip cap further motion of the actuating means for operating ,the switch will twist the blade or the clip cap so that the twisting will then cause the contacts to engage. In the reverse operation, the first motion will cause the rotation of one of the contacts and their consequent disengagement, and further motion will cause the switch blade to open. A switch of this type is open to two objections: first, that there is no positive definite control of the position of the blade by the actuating device, and if for any reason there should be any resistance to the blade entering the clip, such as ice packed on the clip, this would cause a premature rotation of the blade or clip before proper position was reached for making contacts; moreover, a switch of this type would not work in the inverted position with the blade opening downward, as is obvious. The second objection is that the high pressure between the blade and clip is accompanied by a relative motion of the contact surfaces which, if the pressure be material, will cause scarring of the surfaces. With this general construction, with verylong blades (unless the motion is extremely slow, which is objectionable) there is apt to be also a considerable blow from impact when the blade bottoms on the clip cap.

It is obviously an important advantage to have a definite positive control of the position of the moving contact at all times and not to have any loosely connected mechanism of the type just cited where any slight unexpected interference will cause premature operation of the means which will effect the high pressure. Also, the relative motion of the contacts under high pressure is most undesirable. It is one of the objects of this invention to keep the means of definite blade operation in substantially continuous engagement thruout the entire stroke. To accomplish this result I keep the means of engagement of the switch in substantially continuous operation thruout not only the opening or closing of the switch but also during the time the high-pressure contact is being applied. J

Normal action of the switch and the highpressure application for each -pole are generally efiected thru an insulator which operates each pole of the switch, but'the high-pressure means I apply at such a time as the motion of the switch blade is substantially nil, due to the passing ofoperating toggles over dead center. There will be, it is true, a very slight strain set up in the blade after engagement from this cause, but this strain is substantially negligible and at the same time it allows full benefits to be obtained without the disengaging of the switch blade and without allowing it to drop back or otherwise to move while the high pressure is being applied.

Where high voltages are employed with consequent long blades it is very essential that the control of the blade motion be definite, and that the blade in the closed position be brought to rest gently and positively.

To accomplish this a very desirable method is to move the blade thru a mechanism involving a crank and connecting rod which shall be on dead center when the blade is closed, thus not only giving definite control but also taking out any'jar in action, since the blade comes to rest like an engine piston at the end of the stroke.

Types of mechanism commonly used for high pressure would release the blade when it reached bottom in its clip and before its velocity of motion ceased, and then apply high pressure, causing consequent objectionable jar and uncertainty in operation of closing the switch-avoided by my method of operation.

There are several different mountings commonly used in switch construction for high tension switches, namely, the horizontal mounting with the insulators upright and the blades and clips mounted on top; inverted mounting with the insulators upright, but with the blades mounted underneath. There are also inclined mountings used. The first mentioned type of mounting, where the blade and clip are brought into cooperation, if the means for driving the clip into this position is released and the high pressure then applied, the blade will not move during the application of this high pressure, but if the inverted mounting is employed, and the means which drives the blade closed is then released, and the blade will drop partially open during the time high pressure is applied, and it is one of the objects of my invention to prevent anything of this kind happening, and for that reason I keep a positive control of the blade at all times, including the time when the high pressure is applied. Where the switch is horizontally mounted with upright insulators with blades and clips mounted on top, if the means for driw'ng the contacts together is released while the high pressure is being applied, there will necessarily be a period of time during which the blade will be free from any positive control, and if a short circuit were to come on the line at this instant, it would move the blade'upward, and might throw it out of the clip entirely before the high pressure was applied. If high pressure is'applied to a switch when the contacts are fully engaged, it will prevent abrasion of the contacts which would occur if the switch is closed under high pressure. The strains of switch operation which would occur if the blade were closed against a high sliding pressure, will be avoided if the pressure is applied after full contact engagement. It is hence, my primary object to avoid any appreciable friction with consequent abrasion of the blade in closure outside of a gentle wiping action. Consequently there is a decided element of hazard in allowing a lapse of time between any release of the blade control and the full application of high pressure, since either the weight of the .blade if downward opening, or the effect of a possible short circuit with any mounting would cause the blade to open partially. This would be very detrimental to proper action causing premature action of high pressure with the blade in the wrong place in the contact or entirely disengaged.

Figurel shows the side elevation of the singlepole switch which is in closed position.

Figure 2 shows the plan of same.

Figure 3 shows a partial plan corresponding to Figure 2 when the contacts are not engaged and the switch is partially open.

Figure 4 shows a cross-sectional view of the high-pressure contact with the switch closed.

Figure 5 shows a side elevation of Figure 4.

Figure 6 shows the cross-section corresponding to Figure 4 with the pressure released.

Figure 7 shows an arrangement alternative to Figure 4 in the closed position for the highpressure blade end.

I is a base. 2, 3' are stationary insulators. 4 is a rotating insulator. 5, 6 are bearings. -1 is a rotating insulator cap. 8 is a pin in 1. 9 is a roller freely movable on 8. I is a pivoted cam mounted on pivot. I l which is mounted on bridge 4|. I2 is a rotating crank fast on rotating shaft 40 which is secured to cap 1. I3 is a ball end of the same. I4 is a connecting rod end engaging the ball end. I is a connecting rod for operat ing the blade. I6 is the other connecting rod end. I1 is a blade lever arm for connecting rod attachment. I8, l9 are connecting rod universal pins. 20 is a blade. 2| is a hinge cap on which the blade is pivoted on pivots 22, 22. 23, 23 are blade ends. 24, 24 are yoke sides which surround the blade. 25, 25, are toggle link rods with dumb-bell-shaped ends. 26, 26 are the seats for the same. 21, 21 are bolts for the yoke sides. 28 is a yoke center. 29, 29 are slots in the blades. 30 is a rod end for the high-pressure thrust rod 3| which moves in bearing 32. 33 is a connecting rod pivot. 34, 34 are rod ends for cam connecting rod 35. 36 is a cam rod pivot. ,31 is a cam rod bearing. 38 is a tongue type clip contact. 39 is a bottom insulator shaft. 40 is a top rotating insulator shaft fast in cap 1. a bridge connecting rigidly the upper bearing 5 of the rotating insulator 4 to the hinge cap 2|. 42, 42 are springs separated from the blade ends 23, 23 by spacers 43, 43. 44, 44 are blade shoes attached to the blade ends. 45, 45 are seats for sliding of these blade shoes in which the toggle rods 25, 25 play. 46 is a spring mounted at the blade end on pin 41 with distance collar 48, adapted to give the blades a gentle wiping pressure when engaging the clips.

Referring to Figure 7, this shows an alternative arrangement wherein 49 is a coiled spring pressing against a plunger 50 which slides in blade yoke 5|. 52 is the other side of the yoke. 53 is a cap for yoke 5|.

The blade 20, which is pivoted on the hinge cap 2| by blade pivots 22, 22, is operated thru the rotating crank |2 with its connecting rod l5 which operates the blade 20 thru the blade lever |1. When the switch is in fully closed position the rotating crank I2 is on dead center. This is a well known form of switch mechanism the desirability of which increases as the length of the blade increases. The fact that'the blade is on dead centerwhen the switch is closed means that .the moving blade must be brought gently to rest like the piston of an engine when crank |2 passes over dead center. This means not only absence of jar but certainty of blade and clip 7 positions when closed. For a few degrees motion of crank |2 either side ,of dead center there is substantially no change in the blade position, and

His-

I take advantage of this important feature to utilize these few degrees of travel to apply the high pressure to the switch.

During this few degrees therefore, appreciable sliding or abrading motion of one contact surface on the other has ceased, and the contacts may be forced laterally together under high pressure without danger of abrading the contact surfaces; The high pressure is applied thru the motion of the cam III which engages the roller 9 a few degrees before crank I2 comes on dead center and exerts pressure on rods 3|; 35 and yoke center 28.- After engagement it is entirely permissible to have an appreciable angular motion of the rotating crankeither side of deadcenter without appreciable motion of the blade end, and I utilize this feature for applying the high pressure to the switch and allowing variation in the control mechanism. The high pressure is applied thru the motion of the cam, the cam being held in substantially uniform position after engaging its roller for a few degrees either side of dead center. The high pressure is applied thru motion of the two ,connecting rods 3| and 35,

which give longitudinal motion to the yoke center- 28. This yoke center 28, which is fastened thru bolts 21, 21 to the yoke sides 24, 24, causes the pressure to be applied to the contacts. The yoke combination is guided in the slots' 29, 29 in the blade ends. These two yokes farry the toggle rods 25, 25 which play in the yoke seats. The inner ends of these toggle rods are mounted in seats 45, which are freely movable perpendicularly to the blade in the spring shoes 44, 44 mounted on the blade ends. The seats45, 45 rest on the disc springs 42 42 which are in turn set on spring spacers 43, 43. In the position shown in Figure 5 where the high pressure is disengaged the inclined position of the rods- 25, 25 allows the blade ends 23, 23 to separate slightly wider than the width of the clip 38 with which they engage.

- The spring 46, however, which is comparatively light exerts a slight pressure on the blade ends to give a gently wiping action when the clips and blade ends come into engagement. After the blade has reached the end of its stroke and has come into full engagement with the clip the high pressure is brought into engagement by thrusting forward the yoke center with its yoke sides until it assumes the position shown in Figure 4 where the toggle rods, instead of being inclined, are perpendicular to the blade ends. The difference between the lengths of the toggle rods when straight out and their projected length perpendicular to the blade when inclined is utilized to compress the springs 42, 42 and to exert a very high pressure on the blade. Inasmuch as the initial engagement of the surfaces is made under the light wiping pressure of the springs 46 and the resiliency of this portion of the blade, the contact surfaces are already together. The application of pressure is therefore accomplished without any appreciable relative motion of the contact members. In fact the only motion is the extremely slight deformation of the contacts under this pressure in overcoming the microscopic irregularities of the contact surfaces.

The opening operation is the reverse ofclosing,

first the yoke being drawn back and then the blade being opened, but at no position of the stroke' is the blade freed from the direct control thru the rotating crank l2 and its connecting rod l5.

The arrangement shown in Figures 4, 5, and 6 indicates a disc type of spring, but Figure '1 may be used alternatively. This shows a single coiled spring 49 on one side playing in a yoke 5land provided with a cap 53. This spring presses against the plunger 50 which slides in the yoke 5|, and when the high pressure is set as in Figure 6 this plunger is pushed upward from the seat 54. The high pressure is released when the yokes are moved backward so that the plunger 50 rests against the seat 54. In this arrangement the spring is already loaded when an initial pressure sure. -This means that during the entire opening stroke there is no motion of the yoke or of the high-pressure rods. Inasmuch as the axis of connecting rod passes through the axis of the hinge and if extended, through the approximate center of the engaged contacts, the operating stresses in this rod in applying pressure have no component tending to move the blade about the hinge, and thus to cause relative motion of the contact surfaces.

I differentiate, as explained, from prior practice in keeping the blade motion or contact motion at all times under substantially thorough control and in maintaining the contact surfaces relatively immovable by means of the operating mechanism itself during the application of pressure. No latches, trips, or similar devices are necessary to maintain the pressure applying mechanism of my switch inoperative. during motion of the contact members. Due to the fact that switches are often continually exposed to corrosive action of the atmosphere, dust, dirt andfumes, together with-normal wear, the operation of such devices, necessarily somewhat delicate in adjustment, is frequently unreliable. The operation of my switch is positive and high pressure can only be applied when the contact surfaces are fully engaged.

What I claim is:

1. In a high-pressure switch a pair of co-operating contacts adapted to be moved into and out of engagement, one of said contacts consisting of a blade pivotally mounted on an insulating support, means for applying high pressure between said contacts after substantially complete engagement said means comprising a linkage with a pivoted Joint located substantially on the center line of the pivot of said blade when said high pressure is not in engagement, the arrangement being so adapted that rotational'motion of the blade has no effect on the motion of the highpressure parts due to the blade pivot and rod pivot being substantially in line.

2. An electric switch including a pair of contact members provided with mutually engageable contact surfaces, operating mechanism including a rotatable member'and positive'means continuously connecting said rotatable member with one of said contact members for effecting relative movement of said contact member to engage said. contact surfaces, separate mechanism for applying pressure between the contact surfaces, and an independent connection between said operating mechanism'and said pressure applying mechanism for operation of the latter by the former, said operating mechanism being adapted to maintain said contact surfaces substantially relatively stationary at a predetermined position during the operation of said pressure applying mechanism.

3. An electric switch including a first contact member, a second movable contact member, operating mechanism for effecting engagement of said members and connected to said movable contact member for continuous positive control thereof, said operating mechanismjncluding a rotatable member and a connecting rod, a separate mechanism for applying pressure between said contact members operable by said operating mechanism independently of motion of said contact members and at a predetermined position thereof when said rotatable member and con-' necting rod are substantially in dead center relation.

4. An electric switch including a frame, a contact member pivotally mounted thereon, a second contact member engageable with said first named contact member, an operating member journalled in said frame, a rod connecting said operating member with said first named contact vmember whereby engagement of said contact members is effected, means for applying pressure between said contact members associated with one contact member, a lever pivotally mounted on said frame and adapted for operation by said operating member, and a rod connecting said lever withthe pressure applying means, said rod, during application of pressure, being stressed substantially on a line passing through the pivotal axis of said pivoted contact members whereby operation of the pressure applying mechanism thereby is not productive of forces tending to produce motion of said first named contact about its pivot.

5. An electric switch including a pair of contact members provided with mutually engageable contact surfaces, an operating member for effecting relative motion of the contact members to engage said contact surfaces, pressure applying,

mechanism adapted to move the contact surface of one of said contact members substantially normally toward the coengaging surface of the other contact member, independent connections between said operating member and one of said contact members and between said operating member and said pressure applying mechanism, said pressure applying mechanism and associated connection comprising cooperative members having a positively predetermined amount of movement, and resilient means interposed between said pressure applying mechanism and the contact surface adapted for movement thereby whereby the pressure between the contact surfaces is predetermined.

6. An electric switch including mutually engageable contact members, a support upon which one of said members is mounted, an operating member pivotally mounted on said 'support, means connecting said operating member with one of said contact members for effecting positive engagement of said contactmembers in definite relation upon actuation of said operating member, separate mechanism for applying pressure between the contacting portions of said contact members, an actuating member therefor, also mounted upon said support, independent means continuously connecting said actuating member with said pressure applying mechanism, said actuating member being mounted in definite relation to said operating member for operation at a predetermined position of said contact members.

'7. A switch as described in claim 6 and including meansfor retaining said actuating member in predetermined operative relation to said operating member.

8. An electric switch including mutually engageable contact members, an operating member, positive means connecting said operating member with one of said contact members for continuous control thereof, separate mechanism carried by one of said contact members for applying pressure between the engaging portions of said contact member and an independent connection between saidoperating member and said pressure applying mechanism for positive operation of the latter by the former at a predetermined position of the contact members, said independent connection being positioned in operative relation with said pressure applying mechanism at all positions of the contact member carrying said mechanism.

9. An electric switch including mutually engageable contact members, an operating member,

positive means connecting said operating member with one of said contact members for continuous control thereof, separate mechanism for applying pressure between the engaging portions of said contact members; said pressure applying mechanism including a link normally inclined to the plane of, contact of said members in engaged position, means for restricting one portion of said link to motion substantially parallel to such contact plane, means for restricting another portion of said link to motion substantially perpendicular to such plane and means for transmitting the force of such perpendicular motion to produce pressure between the contact surfaces; and independent means for effecting operation of said pressure applying mechanism by said operating member.

10. An electric switch including apair of mutually engageable contact members, an operating member, means connecting said operating member with one of said contact members for effecting such engagement, separate mechanism'for applying pressure between the engaging surfaces of said contact members, independent means connecting said operating member with said pressure applying mechanism, said pressure applying -mechanism including a resilient member adapted to predetermine the pressure applied thereby, said resilient member serving to retain said pressure applying'mechanism in non-operative position and said independent connection in I fixed relation to the path of travel of the operating member.

AUGUSTUS JESSE BOWIE.

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