US325276A

US325276A - Rotary pump

Info

Publication number: US325276A
Authority: US
Publication date: 1885-09-01
Anticipated expiration: 1902-09-01

Description

gNo Model.)

1?. M. ROOTS.

ROTARY PUMP.

No. 325,276. Patented Sept. 1, 1885.

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FRANCIS M. ROOTS, OF CONNERSVILLE, INDIANA.

ROTARY PUMP.

SPECIFICATION forming part of Letters Patent NO. 325,276, dated September 1, 1885.

(X0 model.)

To aZZ whom it may concern.-

Be it known that I, FRANCIS M. Roo'rs, a citizen of the United States, and a resident of Oonnersville, in the county of Fayette and State of Indiana, have invented certain new and useful Improvements in Rotary Pumps, of which the following is a specification.

The object of the invention is an improved rotary abutment that can be constructed with less labor and with greater accuracy than those now in use, and that will occupy less of the air-space within the shell, and thus increase the capacity of the machine.

Vith these objects in view my invention consists in a piston the opposite major and minor convex curves of which are composed of arcs of circles of different radii, cut from common centers, whereby the labor of handling the abutments in finishing them for use is reduced one-half, and accuracy in dressing to the proper shape attained.

In my Patent No. 264,962, dated September 26, 1882, the compound convex curves or contact-surfaces were all described from different centers, and the abutments, when mounted between templets for dressing, were made to turn around these centers as axes, as described in my Patent No. 247,691, dated September 27, 1881. This required a great deal of handling, and as it is difficult to have so many holes on the templets (eight in each one) and get each hole perfectly concentric with the points from which the major and minor curves of the pistons are described, the slightest inaccuracy in centering the piston in the dressing-tool would of course affect the accuracy of the abutment, and perfect contact of the pistons during their entire revolution in the pump was not always attained, especially in the larger machines.

By my present invention I have overcome all these difficulties, and am able to produce a perfect machine having much greater capacity by reason of the diminished ends of the abutments, and greater strength by reason of the shortened waist between the pistons. I will here remark that when I speak of abutment I mean the two pistons, one at each end, with the waist formed by the two recesses which connects the two pistons; and when I speak of pistons I mean the convex parts of the abutments which keep up contact with each other and the case when the pistons are revolving.

In order to distinctly point out the difference between my present invention and that shown in my previous patent, No. 264,962, upon which this invention is an improvement, I have shown in the drawings at Figure 2 a diagram illustrating the form of pistons of my said former patent and the method by which they were produced; and Fig. 1 is a diagram illustrating my newly-invented piston and my new method or system for obtaining the points from which, as centers, the compound curves forming the contact-surfaces of the pistons are described.

I will first describe my present invention, and then by reference to Fig. 2 point out how it is distinguished from my former inventions.

Referring now to Fig. 1, the shafts A A upon which the abutments are mounted are placed the proper distance apart, depending upon the size of the machine to be constructed. Two equal circles, P, are described around the shaft-centers by a radius equal to half the dis tance between said centers. These are the pitch circles. \Vithin the pitch circles P and from the same centers I describe two smaller circles, I, by a radius equal to three-fourths of the radius of the pitch circles. This I term the inscribed circle. Both of these circles are divided into four equal parts by the radial lines X Y. Vithin the pitch circle I inscribe a square by the lines O,which intersect the pitch circle at the same points where the lines X and Y cut the same. \Vhere the lines 0 cut the inscribed circle upon each side of the lines X and Y at j, are the centers from which the compound curves of the pistons are described. I now divide the inscribed square into four equal parts by the radial lines Z, and through the centers j, I draw the lines L, extending them beyond the pitch circle for the purpose of obtaining the radius by which the minor curves of the pistons are described.

To obtain the radius of the major curve I place one foot of the dividers in one of the pointsj, and extend the other across the line X or Y to the point a,where the diagonal line Z cuts the pitch circle. Vith this radius all the outer or major curves of the pistons are described. The major curve is continued through the pitch line P to the point 7:,whcre it meets the line L. Now,with one foot of the dividers in pointy, I extend the other to the point It. This gives me the radius by which all the minor curves are described from the centers j. These curves meet the major curves at points 70, and extend a short distance within the inscribed circle and lines 0. The major curves extend from points it a short distance across the lines 0, at the outer ends of the pistons.

The ends of the pistons, instead of being left sharp at the apex or ends of the pistons, as is shown by dotted lines, may be turned off, as shown by the curved linesp 12, so as to give more bearing-surface against the cylindrical part of the case; or grooves may be planed in I the ends of the pistons, as shown, to be fitted with adjustable or spring packing, as most desirable for the duty required; or the ends may be packed, as shown in Fig. 2. The spaces from the points in the major curve, (marked 9a,) to where the ends of the pistons come in contact with the case, not being necessary to keep up contact, are cut back, as shown at 0. These need not be dressed, and are left in the rough.

The recesses of the abut-ments are described from the points ten the minor axes of the abutments, so as to give the piston ends ainple clearance. The recesses have no part to perform in keeping up contact between the pistons. They therefore require no dressing, but may be left in the rough, as their only of fice is to clear the ends of the pistons to permit them to revolve.

The construction of the case, its supports, the driving mechanism, and bearings are the same as described in my former patents above referred to, are well known to those skilled in the art, and therefore need not be illustrated or described herein.

The circles surrounding the points j j, Fig. 1, and 2" and 4, Fig. 2, represent the holes bored in the templets (the templets are the exact size and shape of the ends of the abutments) to receive the centers which support the abutments in the dressing-tool while the pistons are being finished.

It is evident from an examination of the two diagrams, Figs. 1 and 2, that the number of centers is reduced from eight in the latter to four in the former: consequently the labor of centering and handling is reduced one-half,

as when the abutment, Fig. 1, islnounted up on one of the centers the major curve is first dressed, and then the abutment turned halfway around and the minor curve upon the opposite side dressed. This operation is re peated until all the contact-surfaces are dressed down to the templets.

I have drawn in dotted line at Fig. 2 the form of my improved piston to clearly show the difference in working capacity between the new and the old form of piston. The metal of the pistons outside of the dotted lines being removed in the new pistons leaves, of course, just so much additional air-space within the shell or case. As this increased volume of air is taken in and forced out at each revolution of the abutments,it will be readily understood that the capacity ofthe machine is greatly in creased.

It is evident that a good and effective pump may be made by slightly varying the centers from the pointj; but these centers are, it is believed, in the exact position to giv the best results.

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

Pistons for rotary pumps, constructed substantially as hereinbefore set f0rththat is, having the convex abutting surfaces composed of arcs of circles at different radii, the centers from which said several arcs are described being the pointsj, which are common centers to the major and minor curves on opposite sides of the major axis X Y.

FRANCIS M. ROOTS.

Witnesses:

Gno. J. lVIURRAY, ALFRED BENEDICT.