US1640046A - Alleviator for hydraulic apparatus - Google Patents

Description

. 1,640,046 ug- 7' 7 F McFARLAND AL EVIATORJ'OR HYDRAULIC APPARATUS "Filed Oct. 1a. 1926 Patented Aug. 23, 1927.

UNITED STATES PATENT OFFICE.

FRANK MCFARLAND, OF MEXICO, MISSOURI.

ALLEVIATOR FOR HYDRAULIC APPARATUS.

Application filed October 18, 1926. Serial No. 142,458.

main object to provide an alleviator of novel construction, which. is of such design that it is impossible for the medium confined between the upper end of the plunger and the upper end of the cylinder of the alleviator to leak downward through the plunger and escape from the cylinder when the pump or other apparatus with which the alleviator is used is idle or not operating.

Figure 1 of the drawings isa top plan view of an hydraulic pump equipped with an alleviator embodying my present invention; and v Figure 2 is an enlarged vertical sectional view of said alleviator.

In Figure 1 of the drawings A designates a conventional hydraulic pump whose discharge pipe 1 is provided with an alleviator of the general type disclosed in my United States patent previously referred to. Said alleviator comprises a cylinder formed preferably from a base portion 2 and a top portion 3 detachably connected together by fas tening devices 4, and a plunger 5 reciprocatingly mounted in said cylinder. The cylinder is provided at its lower end-with an opening 6 that establishes communication between the interior of the cylinder and the discharge pipe 1 of the pump, and the plunger 5 is preferably hollow and provided at its lower end with a reduced extension 7 that constitutes a dash pot element which enters the opening 6 in the lower end of the cylinder as the plunger 5.nears the end of its downward stroke. A medium is confined between the upper end of the plunger and the top wall of the cylinder of the alleviator so as to exert downward pressure on the plunger in opposition to the upward pressure exerted on the plunger by the hquid being pumped, which medium will usually consist of oil at and air that is trapped between the upper end of the cylinder and the surface of said body of oil.

In order to prevent said medium from leaking from the cylinder a packing 8 is arranged between the exterior of the plunger 5 and the bottom portion 2 of the cylinder,

and a separate packing 9 arranged at the upper end of the bottom portion of the cylinder so as to surround the top portion 3 {17 of the cylinder.

As previously stated, the main object of 1y present invention is to provide an alle- Viator which is of such construction that it impossible for the oil or air in the upper portion of the cylinder to leak downwardly around the plunger 5 when the pump or other apparatus with which the alleviator is used is standing idle.

I To this end I provide the lower end of the cylinder with an imperforate seat 10 that surrounds the'opening 6 therein, and pro vide the lower end of the plunger 5 with a gasket 11 that bears tightly against said seat 10 when the plunger is at theend of its 5' downward stroke, thereby effectively sealing the lower end of the cylinder of the allevia-tor. lVhen the plunger 5 moves downwardly' any liquid from the: discharge pipe of the pump that may be in the space between the seat 10 on the end wall of the cylinder and the opposed lower end of the plunger 5 is expelled from said space and forced back into the discharge pipe through the joint between the reduced extension 7 on the plunger and the side wall of the hole 6 in the end wall of the cylinder which receives said extension, the extension 7 having a loose fit in the hole 6.

It is immaterial, so far as my broad idea is concerned, how the extension or dash pot element 7 is combined with the plunger 5, but in order to simplify the construction and reduce the cost of manufacture of the alleviator, I prefer to form said extension from a member separate and distinct from the plunger and provide said member with a reduced externally-screw-threaded portion 7 that is screwed into the lower end of the plunger 5. The gasket 11, previously referred to, is preferably formed of fibre and is so proportioned that the inner portion of same will be clamped between the end of the plunger 5 and the dash pot element 7 on the plunger, as such aconstruction insures the gasket 11 being held securely in operative position on the plunger and permits said gasket to be replaced easily.

Having thus described my invention, whatI claim as new and desire to secure by Letters Patent is:

1. In an alleviator of the kind that comprises a cylinder provided with a plunger that is acted upon by a medium confined between the upper end of the cylinder and the upper end of the plunger, an opening in the lower end of the cylinder, a reduced extension at the lower end of the plunger constructed so as to constitute adash pot element that enters said opening when the olun 'er' is at the end of its downward stroke, and means for producing a tight joint-between the lower end of the cylinder and thelower end of the plunger that surrounds the dash potelement on the plunger.

2. In an alleviator of the kind that comprises a cylinder provided with a plunger that is acted upon by a medium confined between the upper end of the cylinder and the upper'end of the plunger, an opening in the lower end of the cylinder, a reduced extension at the lower end of the plunger constructed so as to constitute a dash pot element that enters said opening when the plunger is at the end of its downward stroke, a fiat seat on thelower end wall of the cylinder which surrounds the opening in said wall, and a gasket at the lower end of the plunger surrounding the dash pot element thereon and adapted to press a ainst said seat when the plunger is at the end or" its downward stroke.

8. Inan'alleviator of the kind that comprises a cylinder provided with a plunger that is acted upon-by a medium confined between the upper end of the cylinder and the upper end of the plunger, an opening in the lower end of the cylinder, a reduced extension at the lower end of the plunger constructed so as to constitute a dash pot element that enters said opening when the plunger is at the endof its downward stroke, a fiat seat on the lower end wall of the cylinder which surrounds the opening in said wall, and a gasket at the lower end of the plunger surrounding the dash pot element thereon and adapted to press against'said seat when the plunger is at the end of its downward stroke, said dash pot element having a loose fit in the opening in the end wall of the cylinder so as to provide for the escape of the liquid from the space between said end wall and the opposed end of the plunger when the plunger approaches the end of its downward stroke.

l. An'alleviator of the kind referred to, comprising a cylinder provided at its lower end with an opening that establishes communication between the interior oi the cylinder and the apparatus'on which the alleviatoris'mo-unted, a reciprocating plunger in said cylinder whose upward movement increases the pressure of a medium confined between the upper end'o'f the plunger and the top wall oi said cylinder, a dash pot ele mentat the lower-end of the plunger iormcd froma member provided with a reduced portion that is screwed into the plunger, a flat seat surrounding the opening in the lower end of the cylinder, and a gasket on the plunger confined in position by said dash pot element and adapted to bear against the seat at the lower end of the cylinder.

FRANK MOFARLAND.

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