US1726225A - Gravity friction switch - Google Patents

Description

Aug. 27, 1929. J. B. HOFF 1,726,225

GRAVITY FRI CTION SWITCH Filed Aug. 17. 1927 2 Sheets-Sheet 1 IN'TE'NTOR @www Aug. 27, 1929. J, B -HOFF 1,726,225

GRAVITY FRICTION SWITCH Filed Aug. 17. 1927 2 Sheets-Sheet 2 Patented Aug. 27, 1929.

UNITED STATESA JOSEPH B. HOFF, F PHILADELPHIA, PENNSYLVANIA.

v(.TrIEMLVI'FY FRICTION SWITCH.

.Application led August 17, 1927. Serial No. 213,491.

My invention relates to newand useful improvements in a gravity-frictlon swltch,

and has for its primary `object to provide an exceedingly simple and effective device of this character, whereby a mercury switch or switches may be actuated through the medium of a helical thermostat, the connection between said thermostat andthe mercury switch or switches is such as to permit actuation of the thermostat after the switch 4or switches have been operated without further affecting the latter.

A further object of my invention is to provide means for operating mercury switches from a thermostat without the use of the usual springs, clutches and the like.

A still further object ofthe invention is to provide a casing to be mounted at a place where changes in temperature take place, a drum provided with a shaft or axle for rotatably mounting said drum in the casing, a thermostat to rotate the 'drum through the medium of its shaft due to changes 1n the temperature in the locality of the thermostat, a mercury switch holder located within the drum and having itsends maintained by gravity in frictional engagement with the curved wall of the drum so as to rotate with said drum, nd yet free so as the. drum may rotate independently of the holder, means to limit the movement of the holder intwo directions, 'and a mercury switch carried by the holder for makingand breaking electrical circuits.

With'these ends in view, this invention consists in the details of construction and combination of elements hereinafter set forth and then specifically designated by the.`

claims. l In order that those skilled in the art to,I whichv this invention appertains mayunderstand how to makeand use the same, I will describe its construction in detail, referring by numerals to the accompanying drawin s forming a part of this application, in whic Fig. 1, is a vertical sectional view of a gravity-friction switch constructed in accordance with my invention showing its application to the smoke stack of a heating desv vice, a portion of which is illustrated and parts of the apparatus left in elevation. i Fig. 2, is an outer end view of the switch. Fig. 3, is a horizontal sectional view of the drum with the mercury switch holder in lace.

ig. 4, is a sectionof the bearing formed TFvit-h the casing taken on the line 4 4 of ig. 5, is an edge view of the mercury switch holder per se.

Fig. 6, is an end view of Fig. 5.

Fig. 7, is a side elevation of another form of mercury switch.

Fig. 8, is a similar view showin switch tilted for completing one circult.

In carrying out my invention as herein embodied, 10 represents a smoke stack on the enclosure of another compartment or chamber, the temperature of which is used to control the same or other temperatures. The smoke stack is merely used to illustrate an application of the invention.

A casing 11 is suitably supported in any convenient location and it preferably has a hub or bearing 12 provided with bracket said lugs or ears 13 byl which the device may be mounted in lace as on the smoke stack, in which case t e bearing projects through an opening in the stack. Within the casing is mounted a drum 14 including a rear wall 15, a curved or circular side wall 16, and a front flange 17, detachably connected with the drum and preferably with the side wall thereof, thus the front of the drum is open. Projecting from the rear wall of the drum is a shaft or axle 18 which yis journalled in .the bearing or .hub 12 of the casing and hasV as one end projecting beyond said bearin into the smoke stack 10. On the pro]ect ing end of the'shaft is mounted a thermostat 19 preferably of helical form 'and enerally termed a helix with 'one end xed to the shaft or axle as at 20 and the other end through the bearing 12 as shown at 21.

The temperature changes which take place within the smoke stack cause the thermostat 19 to expand or contract, thus imparting a rotary motion to the drum 14.

Within the drum is mounted or located a mercury switch 22 consistin of two tubes 23, each having two electrical conductors leading therefrom as shown in Figs, 1 and 2,

. or said switch may consist merely of a single mercury tube 24 having two pairs of conductors'leading therefrom as shown in Figs. 7 and 8. l These mercury tubes are the well known mercury switches used for making and breaking an electrical circuit or circuits when oscillated. I

Thel mercury switch itself frictionally engages the curved side Wall 16 of the drum or is provided with means to so frictionally engage the side wall of the drum. The latter method is preferable, and for convenience of illustration, I have shown a metal plate 25 providedswith clips 26 so arranged as to hold the tubes 23 at suitable angles opposite to each other. The plate 25 being in frictional engagement with the side wall'of the drum when the latter is rotated, the plate will move with it, until said plate strikes against one of the stops 27 or 28 at which time movement of the plate 25 will be arrested, although the drum may -continue to revolve.

Where a single mercury tube is used, the plate 25 has the clips 26 arranged to hold the tube 24 parallel with the plate, but the action and ultimo result are the same.

The stops 27 and 28 are preferably carried by the casing 11 and are so fashioned as to project into the drum for disposition in the path of travel ofthe ends of the plate.

Within the casing may also be mounted a panel 29 carrying binding posts 30 to which are connected the ends of wires 31 leading to electrical instruments or appliances and said wires may be in cable form as at 32 if desired. Other wires 33-are connected to the binding posts 30 and to the terminals of the mercury switch.

From the foregoing description, it will be obviousA that when a temperature change takes place within the smoke stack, which will effect the thermostat' 19 and cause it to rotate thedrum 14 clockwise with reference to Fig. 2, the mercury switch and its plate will move with said drum because of the frictional engagement between the walls of said drum -and the plate until the oneend of said plate contacts with the stop 28, thus arresting further movement of the mercury switch, although one circuit is closed. After the mercury switch has stopped, should the change in temperature be such -as to cause the thermostat to continue rotating the drum, this may occur without in any Way alfecting the mercury switch. As soon as another change 'in' the temperature takes place which causes the-thermostat to rotate the drum counter clockwise, then the switch will be moved in this direction until the opposite end of its plate contacts with the stop 27. In this condition, the previously closed circuit will be opened and the other electrical circuit closed, but after this condition has'taken place, the drum may continueto rotate in the same direction without in any lway affecting the mercury switch.

It is to be particularly noted that in a switch lconstructed in this manner, the switch element or the circuit making and breaking means may continue to move without affecting the operation of the switch element, and this is accomplished without the use of spring, clutches or the like, and said switch element cannot be broken or damaged, no matter how far the operating elelment may move.

Of course'I donot wish to be limited to the exact details of` constructions as herein shown, as these may be varied within the limits of the appended claims without departing from the spirit of my invention.

Having thus fully described my invention, what I claim as new and useful is:

1. A switch of the class described including a casing, a drum rotatably mounted in the casing, a plate projecting across the interior of the drum and resting on the walls thereof, a switch element,l carried by the plate, temperature controlled means for rotating the drum, and means in the path of travel of the ends of the plate to stop the plate after it has moved a predetermined distance with the drum, after which said drum may continue to rotate.

2. In a device of the character stated, a

drum adapted to-be mounted for rotation, a switch plate within said drum, and means to hold the switch plate against movement, while lthe drum rotates.

3. A switch comprising a casing, a drum, a shaft on said drum for rotatably mounting the latter in the casing, a temperature controlled element connected with the casing and the shaft of the drum for rotating the latter, a switch plate mounted within the drum and frictionally engaging the walls thereof, a flange detachably mounted on the drum to prevent accidental displacement of the switch plate, means projecting from the casing into the drum in the path of travel of the ends of the switch plate to arrest movement of the latter while permitting the drum to rotate, an electrical circuit making 4and breaking means carried by the plate.

4. In a device of the character stated, a casing, a drum having a circular wall rotatably mounted in the casing, means controlled by temperature changes to rotate said drum, a Switch plate within the drum and having its ends resting on the circular wall thereof, whereby it may be rotated with the drum, and means in the path of travel of the ends of the plateto arrest its movement and permit rotation of the drum without moving the plate.

5. A device of the kind described comprising a hollow circular rotatable member, and a free switch element resting on the inside circular walls of said member and movable with the latter until arrested by an outside agency.

In testimony whereof, I have hereunto `affixed my signature.

JOSEPH B. HOFF.

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