US2667124A - Pump - Google Patents

Description

Jan. 26, 1954 c. c. s. LE CLAIR PUMP 2 Sheets-Sheet 1 Filed May 10, 1947 JanQZfi, 1954 c. c. 5. LE CLAIR PUMP 2 Sheets-Sheet 2 Filed May 10. 1947 midi Patented Jan. 26, 1954 PUMP Camille Clare Sprankling Le Clair, London, England, assignor to Tecalemit Limited, Brentford, England, acorporation of Great Britain Application May 10, 1947, Serial No. 747,294

tllaims priority, application Great Britain May 28, 1946 12 Claims.

l This invention relates to reciprocating pumps for liquids and particularly to pumps of the type comprising a plunger reciprocable in a cylinderprovided with an outlet port which is adapted to be opened and closed by a non-return discharge-valve.

The invention is particularly adapted to application to pumps of the type referred to for pumping lubricants such as oil and for brevity liquids and lubricants will all be referred to hereinafter as oil.

In the prior art pumps, the inlet port is uncovered toward the end of the plungers suction stroke, and a quantity of oil is drawn into the pump cylinder through that port. At a point comparatively early in its discharge stroke the plunger closes the inlet port, and during the remainder of the discharge stroke the oil entrapped in the cylinder is discharged therefrom past the discharge valve, which is of the check or nonreturn type so that there will be no reverse flow during the ensuing suction stroke. These pumps usually incorporate means for varying the pump delivery by adjusting the position of the plunger relative to the inlet port, thus varying the length of stroke of the plunger after the inlet port has closed. Since the cylinder Volume between the closing edge of the inlet port and the discharge valve is constant the adjustment of the plunger is such that whatever volume is deducted from the maximum single stroke delivery (for the purpose of reducing the pump delivery) is added to the clearance space.

The clearance space or volume referred to above is the space or volume contained in the pump cylinder-fil1ed with oil-between the underside of the valve head of the discharge valve member and the end of the plunger at the moment when, at the completion of the discharge stroke, or during the ensuing suction stroke, of the plunger, the discharge valve reseats itself.

It follows that in the prior art pumps the clearance space will be at a minimumalmost zer volume-when the pump is set for maximum delivery. When these pumps are set for smaller deliveries the clearance space increases, with a corresponding increase of oil retained in the cylinder at the end of the discharge stroke. It has been found that as this clearance space increases, the pump has a great tendency to become air locked.

it is one of the principal objects of the present invention to provide a novel pump of the reciproeating plunger type in which the above mentioned disadvantage is overcome.

Another object is to provide an improved reciprocating plunger pump incorporating means for varying the volume of oil delivered on each discharge stroke without varying the plunger stroke and without varying the clearance space.

A further object is to provide an improved reciprocating plunger pump wherein the clearance space is at all times of very small dimensions and is so formed that any air bubbles which may form in it are broken up and are ejected with the discharged liquid.

Still another object is to provide an improved reciprocating plunger pump wherein the clearance space is of capillary dimensions and is formed by a stem projecting into the cylinder and which is so constructed that the clearance space is formed between the stem and the cylinder wall or which is hollow or porous so that capillary passages are formed therethrough.

And a further object is to provide an improved reciprocating plunger pump wherein the volume or" oil delivered on the discharge stroke of the plunger may be varied by adjusting the position of the discharge valve seat relative to the cylinder inlet port in such a manner that the total volume of oil enclosed in the cylinder at the closing or" the inlet port is. varied. I

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a sectional illustration of an oil pump of the type referred to above in which the said clearance space consists of a fine annular space left between a piston part of the discharge valve and the wall of the pump cylinder;

Figure 2 is a section through a multiple pumping unit which comprises a number of individual oil pumps, all constructed substantially as described with reference to Figure l; and

Figures 3 to 9A show in section diiferent methods of constructing the piston part of the discharge valve so as to provide a pump cylinder clearance space of substantially capillary dimensions.

In the ensuing description the pump is assumed to be disposed so that its axis is vertical, the plunger being at the bottom and the discharge valve at the top.

Referring first to Figure 1:

In this constructional example, the oil pump comprises a hollow cylindrical liner 5 which is provided with a parallel bore exttending substantially from end to end to form the pump cylinder. The liner is fitted in a housing 2 which is bored to three different diameters, viz., a small diameter 3 at its lower end, a middle portion 4 of intermediate diameter extending to substantially half the height of the housing, and a larger diameter extending from the intermediate diameter to the top face of the housing. Two shoulders 6 and 1 are thus formed in the housing. The largest diameter bore 5 is internally threaded for a portion of its length. The liner is machined externally to three different diameters 8, 9 and ill corresponding to the three different diameter bores 3, 4 and 5 of the housing, so that the liner can be inserted within the housing, in which it is a sliding fit. Sealing washers H and I2 are fitted between the two shoulders 6 and l in the housing and the two corresponding shoulders on the liner.

If desired, the liner may be formed with an external thread adapted to cooperate with the internal thread in the housing, so that the liner may be screwed into the housing.

A solid plunger I3 is slidable in the lower end of the pump cylinder, the lower extremity of the plunger, which projects out of the liner, being formed with a head M with which a cam or other actuating device is adapted to cooperate to reciprocate the plunger. A spring l5 reacts between the head M of the plunger and a shoulder E6 on the liner and urges the plunger downwardly out of the pump cylinder and holds it in contact with the said cam or other actuating device.

An inlet port I! is formed in the central portion 9 of the liner, at a position where it will be uncovered by the upper end of the plunger l3 when, as shown in Figure 1, the latter is in its lowest position at the end of the suction stroke, the inlet port connecting the pump cylinder with an annular groove [8 cut in the outer cylindrical surface of the liner.

The annular groove 18 communicates with a port is which is formed in the wall of the housing 2 and is connected to the oil inlet branch 28, which latter is connected to a source of supply of oil not shown in the drawing.

The upper end part IU of the liner is counterbored for a short distance from its upper face to a diameter larger than that of the pump cylinder in order to provide an annular recess 2] in which is located a number of superimposed, centrally-apertured annular sealing washers 22. Each of the washers is a good sliding fit in the recess 2! and the central hole in the washer is equal to, or slightly larger than, the parallel bore of the pump cylinder.

A threaded part of a hollow plug 23 is screwed into the upper threaded portion of the bore 5 of the housing 2, the lower end of the plug being reduced in diameter so as to form a spigot 24 which is adapted to fit in the annular recess 2| in the liner. The hollow plug serves to hold the annular washers 22 in place in the recess 2|, so that there is liquid-tight engagement between the washers, to secure the liner in position in the housing 2 and to ensure liquid-tight seals between the liner and its housing by exerting pressure upon the sealing washers II and I2 arranged between the shoulders on the liner and the corresponding shoulders 6 and 1' in the housing. The hollow plug also forms a closure for the upper end of the pump cylinder. The plug also houses a discharge valve member 25 and its coil spring 25 and preferably carries a union nut and cone 2'! or other coupling means whereby the interior of the plug may be connected to an 4 oil discharge pipe leading to the point to which oil is to be delivered.

The discharge valve member comprises a flat valve head 25, which is arranged within the hollow plug and is thrust into contact with the uppermost of the annular seating washers by the spring 26 which is registered upon the head of the spigot 25A. The discharge valve member also comprises a cylindrical stem or piston 21 which projects through the coaxial central holes in the annular washers 22 into the upper end of the pump cylinder to form a piston. The piston is of such diameter that there is a small clearance, of capillary dimensions, between the piston and the cylinder wall and the coaxial holes in the washers 22.

When the plunger i3 has just completed its downward or suction stroke, being then in the position shown in Figure 1, a quantity of oil is drawn into the pump cylinder through the inlet port IS, the annular groove IS and the inlet port I! to fill the void in the cylinder between the plunger and piston 21, and in the clearance surrounding the latter. As the plunger is raised on its discharge stroke by the rotating cam or other actuating means it first closes the inlet port ll, thus entrapping a quantity of oil between itself and the piston. The continued upward movement of the plunger causes the entrapped oil to force the discharge valve 25 off its seat (which is constituted by the uppermost of the annular washers 22) against the pressure of its spring 23. Further upward movement of the plunger drives some of the entrapped oil past the discharge valve 25 by way of the above mentioned narrow clearance space between the piston and the cylinder, into the interior of the hollow plug 23 and thence via the said oil discharge pipe to the place of use.

Since the said clearance space is very fine, the oil displaced by the plunger may not be able to pass through it as quickly as the plunger delivers. In this case, the discharge valve and its piston part will be forced to move upwardly away from the plunger. During the plunger discharge stroke, however, some of the oil passes through the clearance space and out past the discharge valve so that the volume of entrapped oil diminishes and the piston gradually moves downwardly until ultimately its bottom end contacts the upper end of the plunger.

It is advantageous to arrange for the plunger discharge stroke to be carried out quickly, after which its suction stroke may preferably be delayed and/or made very slowly.

The delayed or retarded suction stroke gives time for the oil entrapped between the faces of the plunger and the piston to escape and permit the descending piston to contact the plunger before the head of the discharge valve member 25 has been reseated upon the washers 22. Thereafter, when the piston descends the plunger will descend in unison with it until the head of the discharge valve member reseats itself, whereupon continued downward movement of the plunger causes a void to form in the pump cylinder between the plunger and piston into which a fresh supply of oil will enter as soon as the inlet port I! is again opened by the plunger. With the commencement of the subsequent discharge stroke the cycle of operations is repeated.

It will be appreciated from the foregoing description that the amount of oil entrapped in the pump cylinder at the closing of the inlet port l1 during the discharge stroke of the plunger [3 is seamstequal to the volume contained between the plunger end face and the underside of" the head of the discharge valve member less the-volume of the valve stem or piston 2i, that is; between the plunger end face and the opposed piston end face, plus the clearance between the cylindrical surface or" the valve piston part 2? and the cylindrical bore or" the liner. Further, since the plunger and piston faces are incontactwhen the discharge valve 2?; is reseated, there will be no oil entrapped between them and the only oil remaining in the pump cylinder will be that whichfills the clearance space, and hence the amount of oil discharged will be the difference between these amounts, that is, the amount entrapped between the plunger and piston faces-at the closing of the inlet port during the discharge stroke. Hence, if this amount is varied the pump discharge can be varied. This may be accomplished by removing one or more of the washers 2" housed in the recess 21 in the top end part H! of the liner. Thus, by removing one washer, the discharge valve seat, and hence the valve with its stem is lowered by an amount equal to the thickness of the washer, and the volume of oil entrapped between the plunger and piston faces is reduced by this amount.

By discharging the oil through the narrow clearanc between the piston 2'. and the pump cylinder wall any large air bubbles existing in the oil are broken up into a dispersion of very small bubbles or films which are more easily expelled with the oil. Hence, the pump is less liable to stoppage through air locks.

When a number of pumps according to the invention is embodied in a multiple pump lubrication unit the individual pumps are preferably driven from a common driving shait carrying a cam, or cams, which is, or are, adapted, either directly or indirectly, to cause the operation of the plungers of the individual pumps. The individual pumps of the multiple unit may be disposed in various ways. For instance, as shown in Figure 2, they may be disposed in one plane parallel to the common driving shaft 28 upon which are mounted cams 29, each of which is adapted to operate the plunger 38 of one of the individual pumps. On the other hand, the pumps may be arranged in two or more planes or they may be disposed radially about the common driving shaft.

Preferably, the casing 35 containing the driv ing mechanism of the pumps is filled with the oil to be pumped and serves as a reservoir from which the pumps are supplied through inlet ports 32 formed in the liners 32A within the reservoir.

In a modified pump as shown in Figures 3 and 3A the piston part 33 of the discharge valve 3'1 is hollow and is formed with a core 35 of porous material such as, for instance, sintered or granular metal.

In this construction, the piston 33 is a normal close fit in the pump cylinder such that the clearance space between the piston and the cylinder wall does not constitute a discharge passage and on the plunger discharge stroke the oil passes through the interstices in the core 35 which form capillary passages wherein large air bubbles are broken up as previously explained. In this construction, least one fine port 31 is drilled through the hollow piston wall close up to the head of the discharge valve member 34 for the purpose of permitting oil which has passedthrough the porous core to reach the space between the discharge valve and its seat.-

further modification which is shown in- Figures 4* and 4A, the piston part 38 of the dis charge valve member 39 comprises a solid core ts having an outer coating 4| of porous material, e: g., sintered metal.

Alternatively, see Figure 5, the solid piston part of the discharge valve member 42 may be disp'ensed with altogether and replaced by a cylindrical plug 32' of porous material, e. g., sintered metal, embodied in or attached to the underside or seating face of the valve, so that the discharged oil is forced through the narrow interstices of the material of the porous plug. 'The plug could be keyed to the valve member by being fitted a recess in the underside thereof or, alternatively, a spigot on the underside of the valve member could be fitted in a recess in the plug.

If'desired, any other means may be employed, in lieu of those described, whereby the discharge passage of the pump comprises or includes a capillary passage or passages, or a series of narrow interstices, through which the discharged oil must be forced. Thus, an assembly of rods or tubes, a series of spaced laminae, perforated diaphragms or the like, or any other suitable type of labyrinth, may be disposed in the clearance space or associated with the discharge valve seat so as to produce the same effect as the means already described.

Figures 6 and 6A show the hollow piston part is of the discharge valve member [l5 filled internally with a number of longitudinal, parallel wires s6 and provided with a port ii just below the head of the discharge valve member.

In the construction .shown in Figures 7 and 7A, the piston part of the discharge valve membar 43 comprises a cylindrical central core it around which is wound a spiral lamina 58 having etched or otherwise roughened surfaces.

An alternative construction is shown in Figures 8' and 8A, in which a number of perforated laminae or washers 55 (which could also be etched or roughened) are fitted upon the cylindrical central core 52 of the piston part of the discharge valve member 53.

Figures 9 and 9A show yet another construction in which the piston part of the discharge valve member 54 is constituted by parallel laminae 55-having etched or otherwise roughened surfaces arranged in cruciform fashion.

I claim:

1. A reciprocating plunger type pump comprising in combination means forming a cylinder, a plunger slidable in said cylinder, an inlet port for said cylinder adapted to be opened and closed by said plunger, an outlet port from said cylinder, a discharge valve seat formed with said outlet port, a non-return discharg valve having a valve head associated with said valve seat and adapted to open and close said outlet port, said discharge valve having a stem slidable in said cylinder and forming in said cylinder a discharge passage of small dimensions connected to said outlet port so that the clearance volume in said cylinder may be kept at a minimum, and means associated with said valve seat adapted to adjust the volume of fluid delivered by the pump per discharge stroke of said plunger, without adjusting the position of said plunger relative to said inlet port, without varying the stroke of said plunger and without varying said clearness volume, by adjusting the position of said discharge valveseat relative to said inlet port so that the total volume of fluid enclosed within said cylinder at the closing of said inlet port is varied.

2. A reciprocating plunger type pump comprisin in combination means forming a cylinder, a plunger slidable in said cylinder, an inlet port for said cylinder adapted to be opened and closed by said plunger, an outlet port from said cylinder, a discharge valve seat formed with said outlet port, a non-return discharge valve having a valve head associated with said valve seat and adapted to open and close said outlet port, said discharge valve having a stem slidable in said cylinder and forming in said cylinder a discharge passage of capillary dimensions connected to said outlet port so that the clearance volume in said cylinder may be kept at a minimum and so that any air bubbles which may form in the clearance volume space are broken up and ejected with th fluid discharge, and i leans associated with said valve seat adapted to adjust the volume of fluid delivered by the pump per discharge stroke of said plunger, without adjusting the position of said plunger relative to said inlet port, without varying the stroke of said plunger and without varying said clearance volume, by adjusting the position of said discharge valve seat relative to said inlet port so that the total volume of fluid enclosed within said cylinder at the closing of said inlet port is varied.

3. A reciprocating plunger type pump comprising in combination means forming a cylinder, a plunger slidable in said cylinder, an inlet port for said cylinder adapted to be opened and closed by said plunger, an outlet port from said cylinder, a discharge valve seat formed with said outlet port, a non-return discharge valve having a valve head associated with said valve seat and adapted to open and close said outlet port, said discharge valve having a stem slidable in said cylinder and forming in said cylinder a discharge passage of small dimensions connected to said outlet port so that the clearance volume in said cylinder may be kept at a minimum, and a plurality of washers associated with said valve seat so that the position of said valve seat relative to said inlet port may be adjusted by varying the number of washers thereby to vary the total volume of fluid enclosed within said cylinder at the closing or" said inlet port whereby the volume of fluid del vered by the pump per discharge stroke of said plunger may be varied without adjusting the position of said plunger relative to said inlet port, without varying the stroke of the plunger and without varying said clearance volume.

4. A reciprocating plunger type pump comprising in combination means forming a cylinder, a plunger slidable in said cylinder, an inlet port for said cylinder adapted to be opened and closed by said plunger, an outlet port from said cylinder, at discharge valve seat formed with said outlet port, a non-return discharge valve having a valve head associated with said valve seat and adapted to open and close said outlet port, said discharge valve having a stem projecting into and slidable in said cylinder in opposed relation to said plunger, said stem having a narrow annular clearance with said cylinder and forming a clearance space of very small volume in said cylinder between said discharge valve seat and said plunger when the latter has completed its discharge stroke, and means associated with said valve seat adapted to adjust the volume of fluid delivered by the pump per discharge stroke of said plunger, without adjusting the position of said plunger relative to said inlet port, without varying the 8. stroke of said plunger and without varying said clearance space volume, by adjusting the position of said discharge valve seat relative to said inlet port so that the total volume of fluid enclosed within said cylinder at the closing of said inlet port is varied.

5. A reciprocating plunger type pump comprising in combination means forming a cylinder, a plunger slidable in said cylinder, an inlet port for said cylinder adapted to be opened and closed by said plunger, an outlet port from said cylinder, a discharge valve seat formed with said outlet port, a non-return discharge valve having a valve head associated with said valve seat and adapted to open and close said outlet port, said discharge valve having a piston-like stem projecting into and slidable in said cylinder in opposed relation to said plunger and fitting closely in said cylinder, said stem including a structure having minute interstices therein to form a clearance space of very small volume in said cylinder between said discharge valve seat and said plunger when the latter has completed its discharge stroke, and means associated with said valve seat adapted to adjust the volume of fluid delivered by the pump per discharge stroke of said plunger, without adjusting the position of said plunger relative to said inlet port, without varying the stroke of said plunger and without varying said clearance space volume, by adjusting the position of said discharge valve seat relative to said inlet port so that the total volume of fluid enclosed within said cylinder at the closing of said inlet port is varied.

6. A reciprocating plunger type pump as claimed in claim 5 wherein said stem structure comprises a porous material formed of sintered metal,

'7. A reciprocating plunger type pump as claimed in claim 5 wherein said stem structure comprises a porous material formed of granular metal,

8. A reciprocating plunger type pump as claimed in claim 5 wherein said stem structure consists of bundles of longitudinal rod-like members.

9. A reciprocating plunger type pump as claimed in claim 5 wherein said stem structure consists of bundles of tubes.

10. A reciprocating plunger type pump as claimed in claim 5 wherein said stem structure consists of finely perforated diaphragms.

11. A reciprocating plunger type pump comprising in combination means forming a cylinder, a plunger slidable in said cylinder, an inlet port for said cylinder adapted to be opened and closed by said plunger, an outlet port from said cylinder, a discharge valve seat formed with said outlet port, a non-return discharge valve having a valve head associated with said valve seat and adapted to open and close said outlet port, said discharge valve having a hollow piston-like stem projecting into and slidable in said cylinder in opposed relation to said plunger and fitting closely in said cylinder, a port in said stem adjacent the valve seat face of said discharge valve through which fluid is discharged from said cylinder and through said stem, said hollow stem being filled by a space filling structure having minute interstices therein to form a clearance space of very small volume in said cylinder between said discharge valve seat and said plunger when the latter has completed its discharge stroke, and means associated with said valve seat adapted to adjust the volume of fluid delivered by the pump per discharge stroke of said plunger, without adjusting the position of said plunger relative to said inlet port, without varying the stroke of said plunger and Without varying said clearance space volume, by adjusting the position of said discharge valve seat relative to said inlet port so that the total volume of fluid enclosed within said cylinder at the closing of said inlet port is varied,

12. A reciprocating plunger type pump comprising in combination means forming a cylinder, a plunger slidable in said cylinder, an inlet port for said cylinder adapted to be opened and closed by said plunger, an outlet port from said cylinder, a diaphragm valve seat formed with said outlet port, a non-return discharge valve having a valve head associated with said valve seat and adapted to open and close said outlet port, said discharge valve having a stem projecting into and slidable in said cylinder in opposed relation to said plunger, a structure arranged externally of said stem and movable therewith and having a close fit within said cylinder, said structure being formed with minute interstices to form a clearance space of very small volume in said cylinder between said discharge valve seat and said plunger when the latter has completed its discharge stroke, and means associated with said valve seat adapted to adjust the volume of fluid delivered by the pump per discharge stroke of said plunger, without adjusting the position of said plunger relative to said inlet port, without varying the stroke of said plunger and without varying said clearance space volume, by adjusting the position of said discharge valve seat relative to said inlet port so that the total volume of fluid enclosed within said cylinder at the closing of said inlet port is varied.

CAMILLE CLARE SPRANKLING LE CLAIR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,046,491 Scott July 7, 1936 2,109,785 Starr Mar. 1, 1938 2,139,894 High Dec. 13, 1938 2,188,859 Edwards Jan. 30, 1940 2,234,936 Streby Mar. 11, 1941 2,383,324 Le Claire Aug. 21, 1945 2,414,696 Miller Jan. 21, 1947

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