US2596673A - Pressure rheostat - Google Patents

Description

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UNITED STATES PATENT GFFICE PRESSURE RHEOSTAT Richard Garey, Brooklyn, N. Y.

Application July 23, 1949, Serial No. 106,399

9 Claims. 1

This invention relates to rheostats such as are commonly employed in controlling operation of an electric sewing machine and similar apparatus. More particularly, the invention deals with a foot actuated device of the type and kind employing carbon disc resistors and a foot actuated element for controlling operation of the rheostat.

The novel features of the invention will be best understood from the following description, when taken together with the accompanying drawing, in which certain embodiments of the invention are disclosed and, in which, the separate parts are designated by suitable reference characters in each of the views and, in which:

Fig. 1 is a longitudinal section through a rheostat made according to my invention.

Fig. 2 is a view similar to Fig. 1 showing one end portion only of the device with part of the construction in elevation and showing a section through a different part of the device.

Fig. 3 is a perspective plan view of the device.

Fig. 4 is a bottom plan view of the device, as seen in Fig. 1, with the cover and supporting ring removed.

Fig. 5 is a diagrammatic view of the circuit as shown in Figs. 1 4, inclusive, and;

Fig. 6 is a view similar to Fig. 5 showing a modification.

AIn practice, I employ an elongated shallow casing Ill which can be formed from moulded plastics or the like, the casing having an inclined top wall portion I at one end thereof, apertured, as seen at I2, and adjacent and at one side of the aperture I2, the wall II has a roughed tread portion I3 forming a foot-rest.

The deep end wall I4 of the casing is apertured, as seen at I5, for the reception of the circuit wires and all of thewalls of the casing terminate in an outwardly extending peripheral flange I6.

Mounted upon the inner surface of the top wall I1 of the casing are two porcelain or other blocks I8 and I9, these blocks being held together and on the wall I1 by screws 20 and 2|. The blocks |8 and |9 are further held in an assembled relationship to each other by the center bolt 22. At each side of the blocks I8 and I9 and formed on adjacent surfaces thereof are elongated bores 23 and 24, in which are disposed carbon disc resistors 25 and 26. have carbon ends or caps 21 and 28 which protrude through one end of the blocks I8 and I9, as clearly seen in Figs. 2 and 4 of the drawing. The outer or lower surface of the block I9 has a longitudinal recess 29. in which is slidably These resistors mounted an elongated bar 30, which may be termed a switch or contact bar, this bar having elongated apertures 3| and 32 for reception of the screws 20, 2|, respectively. The heads of the screws retain the bar 30 in position. One end of the bar has an offset contact portion 33 with a protruding contact element 34. The other end of the bar has an offset wide plate portion 35, at each side of which are L-shaped bearing portions 36, note Figs. 2 and 4.

The wide plate portion has secured to the center thereof a spring contact plate 31, the yieldable ends of which are adapted to engage the ends 21 and 28 in completing the circuit through the carbon disc resistors.

Also arranged between the plate 35 and the ends of the blocks I8 and I9 is a spring 38, which normally supports the switch bar 3Uv in the inoperative position shown in Figs. 1 and 4 of the drawing. The inner surface of the inclined wall portion II of the casing has a transverse V-trough 39, note Fig. 2. This trough forms a pivotal support for contracted pivot ends of a foot actuated switch lever or element 4|. The element 4| is preferably in the form of a plastic casting having, at one end, a raised hollow footpiece 42, the central portion of the element having, at one side of the footpiece, an elongated passage 43 for the reception of a sleevelike member 44 fixed to the casing I0 or the wall I thereof, the sleeve being adapted to receive a screw 45 having a large head 46.

At either side of the aperture 43, the lower surface of the element 4| has curved bearing surfaces 41, against which the inner surface of the screw head 46 or a bearing ring 48 thereon is adapted to operate in supporting the element 4| in the casing and in guiding swinging movement of said element. In other words, the surfaces 41 are on a radius swung from the pivotal axis of saidv element. The sides of the element 4I, beyond the surfaces 41, have downwardly extending lugs 49 reinforced by web portions 50. The lugs 49 are adapted to engage the L-shaped bearing portions 36 in actuation of the rheostat.

The blocks I9 and I9 have, at the other ends of the carbon disc resistors, screws 5I and 52. The screw 52 has an offset terminal portion 53, with which one circuit wire is adapted to be connected, as seen at 54, Fig. 5; whereas the other circuit wire 55 is connected with the screw 2| completing the circuit to the bar 30. The screw ends 5|, 52 support a bridging contact plate 56, thus placing these ends of the carbon disc resistors in circuit with the wire 54.

Supported on the screw 52 is an offset spring contact element 51, disposed in such position as to be engaged by the contact 34 of the bar 39 in snorting-out the carbon disc resistors.

Turning now to Fig. 6 of the drawing, here is shown a slight modification, wherein terminal wires 54', 55 are directly connected with screws or posts 5l and 52', both of which are substantially similar to the post 5I, 52 and include 53 in- A two spring contact fingers, as at 51 an stead of the single nger 51. With this construction, the screws 5I', 52 are not electrically ccnnected as by the contact or wire 56. Otherwise the structure of Fig. 6 is the same as that shown in Figs. 1-5, inclusive. 30' in Fig. 6 represents the bar element which includes a spring contac 31 similar to 31.

With the structure shown in Fig. 6, resistance takes place through the two carbon disc units in series, whereas in Fig. 5, the circuit is in multiple.

Turning now to the casing le, corner portions of the casing have seats or platforms, as at 59, 59', and 60, 6U', upon which a lower cover plate or bottom wall 6| is adapted to seat. The plate 6l nts within the lower open end of the casing and can be held in place by the inwardly extending flange portion 62 of a rubber ring 63 or, if desired, the screws can be passed through the plate and into une platiorm portions 59, 55', one of these screws being seen at 64 in Fig. 1 of the drawing. The ring B3 envelopes the outwardly extending flange I6 of the casing and has an inturned lip engagement 65 therewith. The ring 63 is preferably made of elastic material and can be extended to engage the flange portion of the casing in the manner shown. This ring also forms a cushion support for the casing on any surface.

In the use of the device and when the parts are in normal position, as seen in Figs. 1 and 4, the spring contact 31 is out-of-engagement with the ends 21, 28 of the carbon disc resistors and the element 4I, which may be regarded as a treadle, is in the raised position. However, upon applying the foot to the element or the footpiece 42 thereof, the element swings on its pivot end 40 and this operation moves the lugs 49 into engagement with the bearings 3S which, in turn, advances the bar 30 to the right, bringing the contact 31 into engagement with the ends 21 and 28, thus completing the circuit and, as the element 4l is depressed, the resistance through the carbon discs varies in providing the desired control of machine operation. Upon depressing the element 4l to the fullest extent, the circuit is closed through the contacts 34, 51 or between the contacts 51', 58, Fig. 6, which, in both instances, will short-out the resistance and provide direct current supply to the operating motor.

With my improved construction, it will be seen that the element 4| is a very simple and economical construction and is held and guided in its pivotal mounting solely by the head of the screw or the bearing washer provided thereon which operates over the arcuate surfaces 41. This swinging movement contributes to the switch bar 30, 30' the longitudinal sliding movement and a corresponding axial movement upon the carbon disc resistors.

The lugs 49 are so positioned on the element 4I and, particularly, with respect to the bearing portions 36 as to provide a more or less straight line action upon said bearings, thus minimizing frictional engagement between these parts. Suitable bushings 25', 2 I' are provided on the screws 20, 2| for operation of the bar 30 thereon to again minimize frictional engagement.

It will be understood that the two blocks I8 and I9 form a unit in which the carbon disc resistors and carbon pile resistors are arranged. The switch bar 3B may be said to comprise a carbon pile operating element which is mounted on and movable longitudinally of said unit. It will also be apparent that the footpiece or treadle element 4l has a free pivotal action in the casing and is held in the casing solely by the screw 45. These structural features give simplicity to the end device.

From the foregoing, it will appear that the entire structure of the device is simple and economical which enables the device to be produced at a very nominal cost and, still further, the question of assemblage is simplified by reason of the simplicity in the structure.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent is:

l. A rheostat device of the character described comprising a casing open at the bottom, the casing being defined by top and side walls, the top wall having an inclined end portion, an insulated block unit secured directly to the inner surface of the top wall, said unit comprising a pair of insulator plates secured together centrally thereof, two carbon pile resistors arranged and housed in the plates of said unit, an elongated bar mounted on and slidably engaging the lower surface of the blocl; of the unit, said resistors having terminal ends protruding through one end of the unit, said bar having a cross-head in alinement with said terminal ends, a spring contact supported on said cross-head for yieldably engaging said terminal ends of the resistors, a manually actuated treadle pivotally mounted on the inner surface of the inclined wall of said casing and having a footpiece protruding through and projecting above the upper surrace of said wall. and said treadle and the cross-head of the bar having cooperating members, whereby in manual operation of the treadle the bar is moved longitudinally or' said unit.

z. A rheostat device of the character described comprising a casing open at the bottom, the casing being defined by top and side walls, the top wall having an inclined end portion, an insulated block` unit secured directly to the inner surface of the top wall, said unit comprising a pair of insulator plates secured together centrally thereof, two carbon. pile resistors arranged and housed in the plates of said unit, an elongated bar mounted on and slidably engaging the lower surface of the block of the unit, said resistors having terminal ends protruding through one end of the unit, said bar having a cross-head in alinement with said terminal ends, a spring contact supported on said cross-head for yieldably engaging said terminal ends of the resistors, a manually actuated treadle pivotally mounted on the inner surface of the inclined wall of said casing and having a footpiece protruding through and projecting above the upper surface of said wall, said treadle and the cross-head of the bar having cooperating members, whereby in manual operation of the treadle the bar is moved longitudinally of said unit, the other end portion of said unit having terminals with which circuit wires are connected, said terminals being in circuit with the carbon resistors, and means on said bar for aseaevs snorting-out the resistors in one depressed position of said treadle.

3. A rheostat device of the character described comprising a casingopen at the bottom, the casing being dened by top and side walls, the top Wall having an inclined end portion, an insulated block unit secured directly to the inner surface of the top wall, said unit comprising a pair of insulator plates secured together centrally thereof, two carbon pile resistors arranged and housed in the plates of said unit, an elongated bar mounted on and slidably engaging the lower surface of the block of the unit, said resistors having terminal ends protruding through one end of the unit, said bar having a cross-head in alinement with said terminal ends, a spring contact supported on said cross-head for yieldablyengaging said terminal ends of the resistors, a manually actuated treadle pivotally mounted on the inner surface of the inclined wall of said casing and having a footpiece protruding through and projecting above the upper surface of said wall, said treadle and the cross-head of the bar having cooperating members, whereby in manual operation of the treadle the bar is moved longitudinally of said unit, the other end portion of said unit having terminals with which circuit wires are connected, said terminals being irl circuit with the carbon resistors, means on said bar for shorting-out the resistors in one depressed position of said treadle, and a single screw for supporting said treadle for free pivotal movement in the casing.

4. A rheostat device of the character described comprising a casing open at the bottom, the casing being defined by top and side walls, the top wall having an inclined end portion, an insulated block unit secured directly to the inner surface of the top Wall, said unit comprising a pair of insulator plates secured together centrally thereof, two carbon pile resistors arranged and housed in the plates of said unit, an elongated bar mounted on and slidably engaging the lower surface of the block of the unit, said resistors having terminal ends protruding through one end of the unit, said bar having a cross-head in alinement with said terminal ends, a spring contact supported on said cross-head for yieldably engaging said terminal ends of the resistors, a manually actuated treadle pivotally mounted on the inner surface of the inclined wall of said casing and having a footpiece protruding through and projecting above the upper surface of said wall, said treadle and the cross-head of the bar having cooperating members, whereby in manual operation of the treadle the bar is moved longitudinally of said unit, the other end portion of said unit having terminals with which circuit wires are connected, said terminals being in circuit with the carbon resistors, means on said bar for snorting-out the resistors in one depressed position of said treadle. a single screw for supporting said treadle for free pivotal movement in the casing, and said treadle having arcuate bearing surfaces operatively engaging said screw.

5. A rheostat device of the character described comprising a casing open at the bottom, the casing being defined by top and side walls, the top wall having an inclined end portion, an insulated block unit secured directly to the inner surface of the top wall, said unit comprising a pair of insulator plates secured together centrally thereof, two carbon pile resistors arranged and housed in the plates of saidunit, an elongated bar. mounted on and slidably engaging the lower surface of the block of the unit, said resistors having terminal ends protruding through one end of the unit, said bar having a cross-head in alinement with said terminal ends, a spring contact supported on said cross-head for yieldably engaging said terminal ends of the resistors, a manually actuated treadle pivotally mounted on the inner surface of the inclined wall of said casing and having a footpiece protruding through and projecting above the upper surface of said wall, said treadle and the cross-head of the bar having cooperating members, whereby in manual operation of the treadle the bar is moved longitudinally of said unit, the other end portion of said unit having terminals with which circuit wires are connected, said terminals being in circuit with the carbon resistors, means on said bar for snorting-out the resistors in one depressed position of said treadle, and said last nam-ed means operatively engaging one of said terminals.

6. A rheostat device of the character described comprising a casing open at the bottom, the casing being defined by top and side walls, the top wall having an inclined end portion, an insulated block unit secured directly to the inner surface of the top wall, said unitcomprising a pair of insulator plates secured together centrally thereof, two carbon pile resistors arranged and housed in the plates of said unit, an elongated bar mounted on and slidably engaging` the lower surface of the block of the unit, said resistors having terminal ends protruding through one end of the unit, said bar having a cross-head in alinement with said terminal ends, a spring contact supported on said cross-head for yieldably engaging said terminal ends of the resistors, a manually actuated treadle pivotally mounted on the inner surface of the inclined wall of said casing and having a footpiece protruding through and projecting above the upper surface of said wall, said treadle and the cross-head of the bar having cooperating members, whereby in manual operation of the treadle the bar is moved longitudinally of said unit, the other end portion of said unit having terminals with which circuit wires are connected, said terminals being in circuit with the carbon resistors, means on said bar for snorting-out the resistors in one depressed position of said treadle, and said last named melans operatively engaging both of said termina s.

7. A rheo'stat device of the character described comprising a casing open at the bottom, the casing being :defined by top and side walls, the top wall havingan inclined end portion, an insulated block unit mounted upon the inner surface of the top wall, two carbon pile resistors arranged and housed in said unit, an elongated bar mounted on and slidably engaging the lower surface of the block of the unit, said resistors having terminal ends protruding through one end of the unit, said bar having-a cross-head in alinement with said terminal ends, a spring contact supported on said cross-head for yieldably engaging said terminal ends of the resistors, a manually actuated treadle pivotally mounted on the inner surface oi the inclined wall of said casing and having a footpiece protruding through and projecting above the upper surface of said wall, said treadle and the cross-head of the bar having cooperating members, whereby in manual operation of the treadle the bar is moved longitudinally of said unit, the other end portion of said unit having terminals with which circuit wires are connected,

'andere said terminals being in circuit with the carbon resistors, means on said bar for snorting-out the resistors in one depressed position of said treadle, al single screw for supporting said treadle for free pivotal movement in the casing, said treadle having arcuate bearing surfaces operatively engaging said screw, the lower portion of the casing having atl corner portions thereof bearing suriac'es for a closure plate, and means arranged on the" peripheral lower edge of the casing for supporting said plate on the casing.

8. A rheostat device of the character described comprising acasing open at the bottom, the casing` being dened by top and side walls, the top wall. having an inclined end portion, an insulated block' unit mounted upon the inner surface of the top wall, two carbon pile resistors arranged and housed in said unit, an elongated bar mounted onA and slidably engaging the lower surface of the block of the unit, said resistors having terminal ends protruding through one end of the unit, said bar having a cross-head in alinement with said terminal ends, a spring contact supported on said cross-head for yieldably engaging said terminal ends of the resistors, a manually actuated treadle pivotally mounted on the innerV surface of the inclined wall of said casing and having a footpieoe protruding through and projecting above the upper surface of said wall, said treadle and the cross-head of the bar having cooperating members, whereby in manual operation of the treadle the bar is moved longitudnally of said unit, the other end portion of said unit having terminals with which circuit wires are connected, said terminals being in circuit with the carbon resistors, means on said bar for snorting-out the resistors in one depressed position of said treadle, a single screw for supportingsaid treadle for free pivotal movement in the casing, said treadle having arcuate bearing surfaces operatively engaging said screw, the lower edge portion of the casing having an outwardly extending peripheral flange, a rubber ring engaging said ange, and said ring having an inwardly extending annular portion overlying the lower edge of the casing and the open end thereof.

9. In rheostat devices of the character described employing a pair of carbon disc resistors mounted in an insulated body and a switch element controlling operation of said resistors, a. casing open at the bottom and having top and side Walls, said body being housed within the casing and secured to the top wall thereof, a treadle'y having a free pivotal mounting on the casing, the treadle having a part projecting outwardly through one wall of the casing for manual operation thereof, a single screw secured to the top wall of the casing for supporting the treadle in connection therewith, said switch element and treadle having pairs of cooperating members at opposed sides of said screw for contributing manual movement of the treadle to said switch element, said insulated body having a longitudinal groove on the lower surface thereof, the switch element being mounted in said groove, and means on said body engaging the switch element to guide the same in its movement longitudinally of said body.

RICHARD GAREY.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,777,988 Wilms Oct. 7, 1930 2,117,257 Shenk May l0, 1938 2,371,772 Naul Mar. 20, 1945

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