US2039339A - Thermostat for scales - Google Patents

Description

J. S. @GSBURY THERMOSTAT FOR SCALES Filed Feb. 5, 1932 ATTORN EY- Patented May 5, 1936 UNITED STATES PATENT OFFICE THERMO STAT FOR SCALES Application February 3, 1932, Serial No. 590,605

10 Claims. (Cl. 26569) This case relates to spring scales and particularly to a thermostat device therefor.

In spring scales, expansion and contraction of the spring resistant in accordance with temperature aiTects the indication and accordingly, it is customary to provide thermostatic means for compensating the effect of temperature changes in the spring resistant.

The object of this invention is to provide several forms of a novel thermostatic device for compensating effect of temperature changes on a spring resistant.

Various other objects and advantages of my invention will be obvious from the following particular description of one form of mechanism embodying the invention or from an inspection of the accompanying drawing and the invention also constitutes certain new and novel features of the construction and combination of parts hereinafter set forth and claimed.

In the drawing: Fig. 1 is a plan view of a lever provided with the novel thermostatic device,

Fig. 2 is a side View of the lever partly in section, and

Fig. 3 is a detail of a modification. Referring to the drawing and particularly Figs. 1 and 2, in detail, It represents a base lever of 2. Dayton spring scale such as shown, for example, in Patent No. 1,355,499. The intermediate portion of the lever is bifurcated, the furcations being joined by a cross brace or web I I. The inner end I2 of the lever extends centrally of the furcations, being on the longitudinal axis of the lever and has a guideway therethrough to guide a rod I3 for movement.

The rod is provided at the forward or nose end with nose iron I4 having a V-shaped bearing groove resting on a knife edge I5 of a stirrup I6 connected by tape II to the automatic counterbalancing and indicating means (not shown). At the rear, the rod I3 passes through and is loosely uided in a hole I8 in the web I I. The rear end of the rod is formed with a threaded portion I9 0 passing through a hole in a circular band or ring 20 and is held in adjusted position by nuts 2|,

one on each side of the band. Diametrically opposite the connection of the rod I3 thereto, the band 20 is secured to a bracket 22 fastened by screws 23 to the lever. Coil springs 25 are each fastened at one end to the lever and at the other end to the band, their points of connection with the band being at diametrically opposite points and the springs extending oppositely in line with with the band. This diameter is at right angles to the line extending between the point of connection of the band to the plate 22 and its connection to the rod I3.

The band is of flexible metal such as steel or 5 composition material such as bakelite and is formed as a true circle. When the two coil springs 25 are hooked to the band, at 70 Fahrenheit, normal temperature, the band is distorted to an appreciable extent out of true circular l0 shape, shortening it in the direction of the rod B. This is the normal position of the band and the rod I3 is adjusted at this setting of the band to correctly set the nose iron I I, the setting of the nose iron obviously determining the effective 15 length of the lever which in turn affects the operation of the counterbalancing and indicating means.

When the temperature increases, the springs 25 expand, thus permitting band 20 to spring 20 back towards true circular shape, the band thus expanding in the direction of the rod I3 and moving the rod forwardly to increase the effective moment arm of the spring resistants. The expansion of the band is proportional to the in- 25 .crease in temperature, the band never quite reaching its true circular form. The increase in the moment arm of the spring resistance acting on the lever compensates for the lower counterbalancing values of the spring resistants with 30 increase in temperature.

When the temperature falls below 70, the springs 25 contract and shorten the band in the direction of the rod I3, moving the latter rearwardly and decreasing the effective moment arm 35 of the spring resistants which compensates for the increase in resistant strength of the springs as the temperature decreases.

In Fig. 3 is shown a modification in which a single coil spring 3!! is used to distort the band 20' in accordance with temperature for adjusting the position of the rod I3 carrying the nose iron. Spring 30 extends diametrically of the band in the same direction as the rod I3 and is hooked at the forward end to the free side of the band while at the rear end, the spring is hooked to a fixed point of the band.

At normal temperature, the spring is of such length as to distort the ring and shorten it in the direction of the rod. When the temperature in creases, the spring expands and permits the band to move towards true circular form thus moving rod I3 forwardly. When the temperature decreases, the spring contracts and shortens the band further in the direction of the rod I3 moving the latter rearwardly.

While there has been shown and described and pointed out the fundamental novel features of the invention, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. I therefore intend to be limited only as indicated by the scope of the following claims:

I claim:

1. In a scale, a scale lever, a pivot, and a thermostatic device carried by the lever and comprising an element movably mounted on the lever for carrying the pivot, an endless flexible member connected to the element, and temperature responsive means for distorting said member to move the element and pivot according to temperature variations.

2. In a scale, a load responsive lever, a pivot, an element movably carried by the lever and coacting with the pivot, and a thermostatic device comprising a flexible member connected to the element, and a spring separately connected to the member to distort the latter according to temperature variations and thereby move the element accordingly to shift the pivot longitudinally of the length of said lever.

3. In a scale, a load responsive lever, a nose iron, an element movably mounted on the lever and carrying the nose iron, and a thermostatic device comprising a flexible member connected to the element, and a plurality of springs connected to opposite sides of the member to distort it according to temperature changes and move the element accordingly.

4. In a scale including a load responsive element; at thermostatic device comprising a ring of flexible material connected to said element, and temperature responsive means for distorting said ring to move the element.

5. In a scale as defined in claim 4, said means comprising a spring effectively connected to said ring.

6. In a scale as defined in claim 4, said means comprising a plurality of springs connected to the ring at diametrically opposite points.

'7. In a scale as defined in claim 4, said means comprising a coil spring connected to the ring.

8. In a scale including a lever and a pivot carrying member movable longitudinally of the lever; a thermostatic device comprising a ring connected at diametrically opposite points to the lever and said member, and temperature responsive means for distorting the ring to move the member.

9. In a scale including a lever and a pivot carrying member movable longitudinally thereof, a thermostatic device comprising a closed ring connected at diametrically opposite points to the lever and the member and a coil spring connected to the ring to distort it for moving the member.

10. The scale as defined in claim 9, there being two such coil springs connected at diametrically opposite points to the ring.

JAMES S. QGSBURY.

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