US2272862A - Plunger packing - Google Patents

Description

Feb. 10, 1942.

R. A. YOHPE PLUNGER PACKING Filed June 30, 1941 A TTORNEYS.

Patented Feb. 10, 1942 TATS PATT FFICE 2,272,862 PLUNGER PACKING Reinhard A. Yohpe, Battle Creek, Mich., assignor to Union Steam Pump Company, Battle Creek,

Mich.

3 Claims.

This invention relates to improvements in plunger packings.

The main objects of this invention are:

First, to provide an annular, liquid tight packing for a reciprocating plunger such as is employed in homogenizing apparatuses.

Second, to provide a packing of the type described preventing the leakage of liquid axially of the plunger, in which the packing material is restrained in a particular manner in engagement with a reciprocable plunger so as to increase the effectiveness of the sealing action as well as the life of the packing.

Third, to provide a packing of the type described wherein eifectiveness of the sealing of the plunger is dependent primarily upon the characteristics of the packing itself rather than upon the hydraulic action thereon of the liquid which it is desired to confine.

Further objects relating to details and economies of my invention will appear from the description to follow. The invention is defined in the claims.

A structure embodying the features of my invention is illustrated in the accompanying drawing, wherein:

Fig. 1 is a fragmentary view in side elevation partially broken away and in vertical section illustrating the pumping chamber of a homogenizing machine employed for homogenizing fatty emulsions such as milk, including the pumping plunger with the sealing arrangement of my invention in operative association therewith.

Fig. 2 is a perspective view illustrating th special stuffing box employed in the seal of my invention.

Fig. 3 is a perspective view illustrating the special packing designed for coaction with the stuffing box of Fig. 2.

Fig. 4 is a perspective view illustrating the special sealing cap serving the function of a compressor head and gland in association with the stufiing box and packing of Figs. 2 and 3.

This invention relates to a packing or liquid seal for the plunger of a homogenizing machine such as is commonly employed. in th homogenization of fatty emulsions by breaking up the fatty particles thereof. These machines operate at high pressure and it is necessary to provide some effective means for preventing leakage of the fatty liquid axially of the pump or plunger at the pumping state of the process. More particularly, the invention relates to a packing or sealing arrangement for the foregoing purposes which is characterized by the effectiveness of the seal provided thereby which, in this case, functions in accordance with a different principle than has been heretofore employed in machines of this type and by the fact that the life of the packing is greatly increased.

Referring to the drawing, the reference numeral I in general designates the pump head of a homogenizing apparatus including a casting 2 defining an elongated, cylindrical, pumping chamber 3 which is closed at one end by a heavy closure plate or head 30 bolted thereto, a suitable sealing gasket 4 beinginterposed.

The liquid or fatty emulsion, such as milk, is introduced into chamber 3 through an inlet valve 5 coacting with a valve seat 6 at the lower diametral side of the chamber and is discharged therefrom past a discharge valv I coacting with a seat 8 which communicates with the cylindrical chamber 3 on the opposite or upper diametral side thereof.

The pumping operation is performed by an elongated, cylindrical plunger 9 which is reciprocated in the cylinder or chamber by any suitable actuating means coupled to the plunger externally Of the pumping chamber at 3..

The sealing assembly of my invention includes a stufiing box member I l in the form of an elongated, annular, sleeve-like member having a shoulder ll telescoped into a counterbore I2 of the cylindrical chamber 3 with a sealing gasket 13 interposed. Member I! is concentric of the plunger and has an end extension 14 of reduced diameter projecting internally of the cylinder at least as far as the inlet and discharge valves 5, l and the inlet valve is provided with a radially projecting tappet or lug l5 which engages extension I4 when the inlet valve is elevated, thereby limiting the throw of the valve and at the same time preventing the same from striking the plunger at the end of said throw. Valves 5, 1 are provided with integral, cross-shaped guide arms is guiding the same in their radial seating and unseating movements.

Externally of the pump chamber housing, the stuffing box member H is provided with an annular surface I! of V-shaped outline, the apex of the V pointing outwardly of the pumping cylinder or chamber, and coacting with this surface I provide the resilient leather compressible packing I6 which is held against the surface I! by a cap l9 acting as a closure and pressure head. Bolts 20 extending through the opposite closure caps or heads 3, i9 serve to maintain the parts axially compressed for purposes to be described. It will be noted by reference to Figs. 1, 3 and 4, that the resilient leather packing I8 is of annular outline surrounding the plunger and is formed in a V-shaped or cupped section complemental to the outline of the stuffing box surface H, the inner plunger engaging portion of the packing being inclined in the axial direction of the plunger; likewise that the pressure head I9 is provided on its inner sid with an annular groove adjacent its radial inner periphery, the said groove having a V-shaped surface 2| at its bottom corresponding to the V-shaped outline of surface I! and the packing l8.

In operation, sufficient force is applied on the pressure head 9 to substantially compress the resilient packing l8 and urge the inner annular extremity thereof into sealing engagement with the plunger, the latter being constrained at either axial side thereof by the V-shaped surfaces of the end of the stuffing box and the pressure head with which it is nestingly engaged. In this manner, the angularity of the packing section cannot b changed by hydraulic action axially of the plunger, the only hydraulic action tending to increase the effectiveness of engagement with the plunger existing at the very point of engagement of the packing with the plunger. I depend, however, primarily on the plasticity or resiliency of th material of the highly compressed packing to cause the material thereof to urge itself radially inwardly against the plunger.

I am aware that in apparatuses of this type it has been proposed to employ a packing disposed inside the bore of the plunger stuffing box on th side thereof toward the pumping chamber, depending upon the hydraulic pressure to urge the packing against the plunger. However, I have found that the hydraulic pressure has a definite tendency to change the angularity of the packing and in time decrease the efiectiveness of its sealing action. In such cases, reliance is placed on the packing spreading out to compensate for wear; however, in the present construction, compensation for wear is effected solely by the radial inward flow or creep of the material under compression. This is an entirely different and much more effective action and the structure is characterized by a longer effective life. Only the tip of the packing at its radial innermost periphery is in contact with the liquid on the plunger. Consequently, it is not subject to being coated and impregnated with the fatty sugar-bearing content of the latter. This I regard as a feature of substantial importance in the present invention as well as the fact that the angles of the packing l8 cannot be changed with age to alter the effectiveness of their plunger engagement. Being axially constrained on both sides, the angle of my V-shaped packing cannot be changed. It will likewis be noted that the compression head 3 and compression gland l9 on the cylinder block 2 are held in place by the same set of bolts extending through the cylinder block itself. This is a highly advantageous arrangement by reason of its simplicity and the ease and speed of installing which the same make possible.

An important feature of the invention is the fact that only an extremely small area of the packing is exposed to the liquid being pumped resulting in a very sanitary condition when pumping milk or other food products. The greater the area of the packing exposed to the liquid, the greater will be the bacterial action on the liquid and with the packing such as proposed this bacterial action is at a minimum. With ordinary types of packing located inside the stufiing box, a much larger area is exposed to the liquid. Also the proposed arrangement reduces the absorption of liquid by the packing to a minimum because the packing is highly compressed tending to force out liquid which normally would be absorbed by capillary action, and this is a further sanitary feature.

The terms and expressions which have been herein employed are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described. It is recognized that various modifications are possible within the scope of the invention claimed.

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

1, In a structure of the type described having a housing providing a pump chamber and having a plunger reciprocable axially thereof, a liquid-tight annular seal surrounding said plunger comprising a sleeve-like stuffing box telescoped with said plunger and extending into said chamber, said stuffing box having an outwardly convexed V-shaped surface concentric with the plunger on the outside of said housing and chamber, a cap externally telescoping said stuffing box at the outer end of the latter and provided with an annular V-shaped recess complemental in shape to said stulhng box surface, an annular resilient packing having a V-shaped cross section in nested relation to said surface, and means for drawing said cap axially toward said stuffing box to compress said packing and urge the inner peripheral surface thereof radially inwardly for sealing engagement with the plunger, the resilience of the compressed packing maintaining the same against said plunger following wear on the packing.

2. In a structure of the type described having a housing providing a pump chamber and having a plunger reciprocable axially thereof, a liquidtight annular seal surrounding said plunger comprising a sleevelike stuffing box telescoped with said plunger and extending into said chamher, said stuffing box having an outwardly convexed surface concentric with the plunger, a cap externally telescoping said stuffing box at the outer end of the latter and provided with an annular recess complemental in shape to said stuffing box surface, an annular resilient packing having a cupped cross section in nested relation to said surface, and means for drawing said cap axially toward said stuffing box to compress said packing and urge the inner peripheral surface thereof radially inwardly for sealing engagement with the plunger, the resilience of the compressed packing maintaining the same against said plunger following wear on the packing, and a sealing member between said stuffing box and said chamber to prevent passage of fluid between said stufiing box and chamber to said packing.

3. In a packing structure for a plunger and pump chamber of the typ described, a stuffing box concentric with and fitting around the plunger and provided with an outwardly angled V-shaped annular surface surrounding and concentric with the plunger, a closure cap provided with an internal annular V-shaped surface complemental to said first-named surface and likewise concentric with and fitted around said plunger, means for pressing said cap to position toward said stuffing box to compress a packing between said surfaces, and an annular resilient packing of V-section complementing said surfaces and disposed nestingly thcrebetween under substantial compression with the inner periphery of the packing in sealing engagement with said plunger.

REINHARD A. YOHPE.

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