US2742924A - Piston for divisional feeder - Google Patents

Description

April 24, 1956 R. L. HARTER 2,742,924

PISTON FOR DIVISIONAL FEEDER Filed Aug. 8, 1950 We E5 INVENTOR. ROBERT L. HARTER K? v M115 PISTON FOR DIV ISIONAL FEEDER Robert L. Hatter, Shaker Heights, Ohio, assignor to Trabon Enginee g Corporation, Cleveland, Ohio, a corporation of Ohio Application August 8, 1950, Serial No. 178,271 1 Claim. c1. 137-42542 This invention relates to divisional feeders for centralized lubricating systems and has for its object the provision of improved feeder assemblies and pistons therefor.

Known types of divisional feeders, such as is described in Reissue Patent No. 21,236, issued October 17, 1939, to D. R. Hillis, utilize a multiple stage valve for sequential switching of the fluid circuits. The valve includes a piston incorporating a body portion and a series of lands which bear upon the inner surface of the cylinder wall, the various lands forming the various stages of the valve. Each piston also forms a unitary operational assembly in which the entire piston is moved to accomplish the various valving actions simultaneously.

In the development and practical use of divisional feeders incorporating such pistons, it has been found that the use of a piston formed from a single piece of metal imposes very strict tolerance requirements in the formation of the cylinder bore in order to avoid excessive operational wear and reduction in the life of the feeder. It was accordingly proposed to form the piston in three pieces, a center piece including two or three of the valve lands and separate end land pieces to form the drive stages of the valve. Such a composite piston showed great advantages over a single piece piston, although after a considerable period of operation there was a tendency for the valve to become clogged with metal chips due to cock- I ing of the end pieces in the cylinder. in production assembly of the feeders, to take care to obtain proper insertion of the piston parts in the cylinders by the workers in order to avoid faulty units.

In carrying out the invention in-its preferred form, a novel piston is employed whereby further improvements are obtained in ease and accuracy of assembly, durability of the apparatus, and reliability and uniformity tion over long periods of time. The piston is formed in two parts, each part carrying two lands. One end of each part is formed with an annular protuberance from the body portion, the pieces then being connected by a sleeve whose ends are rolled inward to engage the shoulders formed by the protuberances. This simple construction leads to many advantageous results. First, as to production, the piston sections are identical and only one class of production operation is necessaiy; the spacing between the lands permits a land finishing operation by centerless grinding with an adequate alignment and concentricity of the land surfaces; and, since the finished piston is a single symmetric piece, there can be no error in assembly. Secondly, as to operation, the spacing between the lands of a single part or section prevents the broaching action of the piston in the cylinder thus elimimating the undue wear which resulted from the earlier form of construction. Finally, servicing operations in the field are simplified and it is impossible for a serviceman to reassemble a feeder so that it will not operate.

An object of the invention is the reduction of operational wear in divisional feeders and increase in the reliability of operation and length of accurate performance.

It was necessary of opera- 2 An object of the invention is the simplification of the production assembly of divisional feeders.

An object of the invention is the simplification of the field servicing of divisional feeders.

An object of the invention is the reduction of the cost of producing pistons for divisional feeders.

These and other objects and features of the invention willbe more readily apparent from a consideration of the following detailed specification and appended claim, taken in connection with the accompanying drawing, in which:

Fig. 1 is aside viewof the piston of the invention;

Fig. 2 is a section view of the piston point prior to the rolling operation; v v

i Fig. 3 is a sectional view of the completed joint; and" Fig. 4 is a side view of a piston incorporating an alternative form of joint, shown in section. 7

Figs. 5, 6 and 7 are views of a divisional feeder section incorporating the novel piston.

Referring now to Fig. 1, the piston 10 of the invention includes twosimilar sections 11 and 12; Each section comprises a body 13 of cylindrical cross section and having a drive land 14 and a valve land 15 formed as a part of the body. in accordance with the invention, the lands are spaced at a distance greater than the width of a single land, the primary object being to obtain bearing points sufficiently separated to stabilize the motion of the piston. The diameter ratios of the body and the lands is determined with reference to the lubricating capacity of the feeder and the lubricant pressure.

Each section is formed with a connecting end portion including a body portion 16 of reduced cross section and a portion 17 enlarged or protruding with respect to the portion 16. A tapered surface 18 joins the portions 16 and 17, the shoulder thus formed acting as a retainer for a sleeve 19 which joins the respective sections. The ends of the sleeve 19 are tapered or bent toward the interior thereof to form a generally frustro-conical surface which bears against the surface 18 of the shoulders and joins the sections. The end portions 17 act as abutments, the end surfaces 20 being smoothly finished and the spacing of the sections and the spacing between the end portions and the sleeve being such that the piston structure is only slightly flexible.

In an alternative form of the invention shown in Fig. 4, the end portions 17 are formed with generally conical end surfaces 21. The sections are then maintained in abutting relationship while permitting a slight fiexibility for sidewise motions. Rounded end surfaces may also be utilized to this end.

In manufacture, the sections are formed identically by turning from soft steel or other stock. The sections are carburized and case hardened and then centerless ground so that the lands are concentric with a common axis and of the desired diameter. In assembly, the connecting end portions of the sections are positioned in a cylindrical tube (Fig. 2), and the ends of the tube are then turned inward by rolling to form the joining sleeve. As an example of the practice of the invention, not to be construed as a limitation, the assembled piston may have a lateral extensibility of less than .010 inch and an angular flexibility in the order of 2 to' 4 degrees.

Referring now to Figs. 5, 6 and 7, the divisional feeder section therein comprises a body or housing 22 of suitable material such as steel. The novel piston 23 of the invention is fitted into an opening 24 extending transversely through the body 22 to form a cylinder. The ends of the cylinder are closed by cap screws 25 fitted into an enlarged opening at either end of the cylinder. Drive ports 26 communicate with the chambers so formed, the ports and chambers accommodating lubricating fluid under pressure appropriate to driving the piston through Patented Apr. 24,1956

- 3 the required switching operations. The motion of the piston serves to interconnect a fluid inlet port 27 alternately with one of a first set of valve ports 28 and the remaining first valve port with an associated second valve port '29. Outlet ports 30 are provided with suitable openings in the block for accommodating appropriate fittings for the conduction of the lubricant to the lubrication points. The feeder section is normally associated with other similar sections, the first set of valve ports of the section here shown being interconnected with the drive ports of a second section and the second set of valve ports of the section here shown being interconnected with the outlet ports of the second section. A plurality of such sections form a cyclically operative unit, as shown in detail in application Serial No. 196,921, filed November 21, 1950, by Robert L. Harter.

It is to be understood that the specific nature of the disclosure is not intended to be restrictive or confining and that various modifications of design may be resorted to without departing from the scope or spirit of the invention as herein claimed.

What is claimed is:

A piston for the cylinder of a divisional feeder comprising two similar sections, each section having a body,

two portions of greater diameter than the body spaced apart along the body and constituting lands, and a portion protruding from one end of the body having a diameter larger than that of the body but smaller than that of the land forming portions, said sections being arranged with their protruding portions approximately in end-to-end contact, and a sleeve surrounding said protruding portions and having its ends extending inwardly to engage the remote end of the surfaces of said protruding portions to hold the sections in assembled relation while permitting limited relative axial and transverse movement of said portions.

References Cited in the file of this patent UNITED STATES PATENTS 537,862 Smith Apr. 23, 1895 583,822 Shem June 1, 1897 721,483 Wells Feb. 24, 1903 l,8l6,l5l Howsam July 28, 1931 1,906,313 Clifford May 2, 1933 2,372,850 Platz Apr. 3, 1945 2,489,450 Crookston Nov. 29, 1949 FOREIGN PATENTS 9,767 Great Britain 1900 2,090 Great Britain 1908 408,691 France 1910

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