US2194896A

US2194896A - Balance wheel structure

Info

Publication number: US2194896A
Application number: US149530A
Authority: US
Inventors: Francis C Gromann
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-06-21
Filing date: 1937-06-21
Publication date: 1940-03-26
Anticipated expiration: 1957-03-26

Description

March 26, 1940. GRQMANN 2,194,896

BALANCE WHEEL STRUCTURE Filed June 21, 1937 Patented Mar. 26, 1940 UNITED STATES PATENT orrlcs 4 Claims.

This invention relates to improved balance wheel structure more particularly intended for use with time pieces.

One object of the invention is to provide improved balance wheel structure wherein the pivot sections or members employed Will be of such constructionthat danger of breakage due to severe shocks will be reduced to a minimum.

Another object of the invention is to provide improved balance wheel structure, the use of which will eliminate a pivot point, one hole jewel; and two cap jewels without the loss of precision.

A further object of the invention is to provide structure of this character which, in the event of breakage of any part thereof, may be readily disassembled so that replacement of the part may be easily made.

The invention seeks, as a still further object, to provide improved balance wheel structure which will be simple in construction and easy to manufacture and which, due to the fact that the parts may be removed without difficulty, may be cleaned with the greatest facility.

Other and incidental objects of the invention not mentioned in the foregoing, will become apparent during the course of the following descrlption.

My invention is illustrated in the accompanying drawing, wherein:

Figure 1 is a longitudinal sectional view of my improved balance wheel as it would appear properly mounted between the plates of the mounting bracket.

Flgure2 is a horizontal sectional view on the line 2-2 of Figure 1, looking in the direction indicated by the arrows.

Referring now more particularly to the accompanying drawing, wherein like numerals of reference will be seen to designate similar parts throughout the various views, the numeral l indicates, in general, a mounting bracket of conventional design, including upper and lower sections or plates 2 and 3. It should be understood that any conventional type of mounting bracket or means may be employed.

My improved balance wheel structure includes a balance wheel which is indicated in general by the numeral 4 and which includes a relatively large hub 5 having formed integrally thereon diametrically disposed radial spokes 6 and I. The spokes are of equal length and are disposed in a plane of 180 through the. axis of the wheel. Formed integrally on the outer end portions of the radial spokes are circumferentially disposed balance arms 8 and 9.

As will be seen, the balance armsB and 9 are adapted to have screwed therein timing screws H]. The timing screws, as best seen in Figure 2, are arrangedon each of the balance arms, in groups, and said groups are disposed diametrically opposite each other on the arms 8 and 9 and are preferably arranged in groups of two and three; although at opposite ends of the legs 6 and I there is disposed a single timing screw, these timing screws being indicated by the numerals II and I2. As seen in Figure 1 of the drawing, the hub 5 is formed with an integral sleeve I3 adapted to have carried thereabout a hair spring ll of conventional construction. The hair spring isadapted to be mounted by a mounting member l5 carried on an overhanging bracket IS. The overhanging bracket I6, as will be observed, overlies the upper surface of the section 2 of the mounting bracket I. It will be seen that the hair spring is simply and effectively mounted and is so mounted that itwill not [disturb the balance of my improved balance wheel.

In order to mount the balance wheel, I employ an upper pivot section or member I! which is threaded through the upper plate 2 and is of uniform diameter throughout its length. The upper pivot member has a concave lower end surface l8 and said upper pivot member is counterbored axially to define a recess l9 which extends upwardly substantially one-third its length. The upper pivot member is formed with a screw driver slot 20 to permit adjustment. As will be observed, said upper pivot section member extends freely through the hub 5 and the sleeve 13 thereof so that said hub and sleeve will not come into contact with the upper pivot memher at any point.

Carried in the lower section or plate 3, in the same axis as the upper pivot member I, is a lower pivot member 2| which is of the same diameter as the pivot member I! and is adapted to be screwed into the plate 3. The lower pivot member has a screw driver slot 22 for permitting adjustment thereof and is provided with an upper end portion 23 which fits snugly within the recess IS in the upper pivot member. The re duced upper end portion defines a concave or inwardly inclined shoulder 24 on the pivot member.

A single jewel 25 is mounted between the concave lower end surface I8 and the shoulder 24. The jewel is held in proper position by means of a jewel holder 26-which is held in place on the hub 5 of the wheel 4 by means of screws 21. The jewel holder includes a flat circular member 28 which cooperates with the hub 5 for holding the jewel in proper operative position. A protecting collar 28a surrounds the jewel. The jewel holder has fixed thereon the conventional double or single roller piece 29 so that said holder will, in efiect, be a combined jewel holder and roller piece.

Adjustment of the balance of said balance wheel may, of course, be effected by tightening or loosening the timing screws ID in the conventional manner. In view of the fact that the upper and lower pivot sections i1 and 2| are threaded through the plates 2 and 3, respectively, as shown in Fig. l of the drawing, the amount of end shake may be adjusted to suit the thickness of the jewel 25. It is also desired to emphasize that inasmuch as the hub 5 is provided with the sleeve i3, a collar will be defined, which collar will support the hair spring M at its inner end.

Although I have described my improved balance wheel as being primarily intended for use with time pieces, it should. be understood that the device may be used in any instrument where a balance wheel of ordinary type is employed.

Having thus described the invention, what I claim is:

1. In balance wheel structure, in combination with upper and lower plates a balance wheel having a hub, a pivot member carried by the lower plate, a guide member carried by the upper plate and engaging said pivot member, a jewel rotatably mounted between the confronting ends of the members, and a jewel holder carried by the hub for securing said jewel to the balance wheel, said jewel providing a single rotatable mounting for said balance wheel on the pivot member and guide member between the plates.

2. In balance wheel structure as recited in claim 1, wherein the jewel provides a single rotatable mounting for the balance wheel medially between the plates.

3. In balance wheel structure, upper and lower plates, a pivot member carried by the lower plate and having a reduced upper end portion, a guide member carried by the upper plate and having a recess at its lower end to receive the reduced upper end portion of the pivot member, a jewel rotatably mounted on the reduced upper end portion between the pivot member and the guide member, and a balance wheel having a jewel holder for connecting the jewel to said balance wheel, said jewel providing a single rotatable mounting for the balance wheel.

4. In balance wheel structure, upper and lower plates, a pivot member carried by the lower plate and having a reduced upper end portion defining a concave shoulder, a guide member carried by the upper plate and having an axial recess at its lower end receiving the reduced upper end portion of the pivot member, said guide member having a concave lower end surface, a jewel mounted on the reduced upper end portion between the circumferential edges defined by the concave surface and concave shoulder, a balance wheel having a hub surrounding the members, and a jewel holder carried by the hub and cooperating therewith for clamping the jewel to the balance wheel, said jewel providing a single r0- tatable mounting for said balance wheel on the pivot member and guide member, said edges defined by the concave surface and concave shoulder providing minimum uniform bearing surfaces at each side of the jewel.

FRANCIS C. GROMANN.