US533270A

US533270A - Electrical measuring-instrument

Info

Publication number: US533270A
Authority: US
Publication date: 1895-01-29
Anticipated expiration: 1912-01-29

Description

(No Mbdel.)

W. H. BRISTOL.

ELECTRICAL MEASURING INSTRUMENT.

No. 533,270. Patented Jan 29, 1895.

. (R in INVENTORI William H. Br'wc o\ ATTOR N EY WITNESSES:

Ag @Wa UNITED STATES PATENT OFFICE.

WVILLIAM H. BRISTOL, OF HOBOKEN, NEXV JERSEY.

ELECTRICAL MEASURING-INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 533,270, dated January 29, 1895.

Application filed September 24, 1894. Serial No. 523,874- (No model.)

To all whom, it may concern.-

Be it known that 1, WILLIAM H. BRISTOL, a citizen of the United States of America, and a resident of Hoboken, in the county of Hudson and State of New Jersey, have invented certain new and useful Improvements in Electric Measuring-Instruments, of which the following is a specification.

My invention has reference to electrical de vices of that character especially adapted for use in galvanometers, ampere -meters, and similarinstruments for indicating and recording an electric current, or the Work done thereby.

It has forits objects to provideasensitiveinstrument, such as an ampere-meter, in which the divisions of the scale are quite uniform and in which the vibrations of the moving armature, due to inertia, are reduced to a minimum,whereby the instrument is rendered practically dead beat,and an accurate and easily read record produced. With theseobjects in view,I construct the metallic armature in the form of a thin disk, making it as light as possible in all respects, so as to reduce the momentum acquired to a minimum, and provide a damping device offering a resistance to the movement of the armature toward and from the attracting coil, which prevents the indicating or recording arm from being carried to any appreciable extent beyond the position corresponding to the current in case of sudden fluctuations in the strength of the same, and in general prevents undue vibration of the armature. I also provide the armature With a core entering the coil or solenoid and so arranged that it offers increased magnetic resistance to the motion of the armature as it approaches the coil or solenoid and permits the scale to be made quite uniform.

The nature of my said invention will best be understood when described in connection with the accompanying drawings, in which Figure 1 represents a Vertical section in the plane l1, Fig. 2, of an ampere-meter embodying my invention. Fig. 2 is a vertical cross-section in the plane 2-2, Fig. 1. Fig.

3 is a sectional front elevation, part being broken away. Fig. 4 is a perspective detail Fig. 5 is a of the armature and its shaft.

cross-section of a bi-metallic armature drawn to a larger scale than the preceding figures.

Similar letters of reference designate corresponding parts throughout the several views.

Referring to the drawings, the letter E designates a coil or solenoid secured to the back of the casing, and A is a movable armature arranged in line with the coil E.

The armature A is secured to a horizontal non-magnetic shaft Ct passing through the coil or solenoid E and having at opposite ends V- shaped notches b b. The notches rest on knife edges formed in flexible supports J J secured to a suitable bracket 0 affixed to the back of the casing. The coil or solenoid E has its terminals 6 6, connected to binding posts F F secured to the casing.

To an extension of the flexible support J is secured a pointer, recording arm, or like deviceI arranged adjacent to a scale or chart S in the usual manner. In this instance I have shown a recording arm attached to the support J and having a style bearing on a chart S, to which latter a rotary motion is imparted by a suitable clock movement 0.

It will be readily seen that when the armature A moves toward the coil or solenoid E, the flexible support J is deflected about its point of attachment and consequently the recording arm I, which practically forms a prolongation of said support, participates in said movement about the point of attachment of the support as acenter, and moves through a greatly increased arc, thereby permitting levers and similar multiplying devices to be dispensed with.

As before stated the main objects of my present invention are, first, to reduce to a minimum the vibrations due to the inertia of the armature and, secondly, to obtain a uniform scale.

Relative to the vibrations I attain the end sought by making the armature quite thin and light, preferably in the form of a disk about two and one half inches in diameter and 0.005 inches thick. The disk is preferably made bimetallic, say, of iron and brass, the iron being, as stated, very thin to reduce the error due to magnetic lag to a minimum, while the brass or other non-magnetic metal imparts strength and rigidity to the disk.