US2327787A - Variable displacement pump - Google Patents

Description

` Aug. m, i943.

R. M. HEINTZ VARIABLE DISPLACMENT PUMB Filed Jan. 5, 1942 2 Sheets-Sheet 1 RALPH M. HEM/TZ.

Patented Aug. 24, 19.43

mph M. ueintz, cleveland, ohio, assigner to Jack & Heintz, Inc., Cleveland, Ohio Application' January 5, 1942, senat No. 425,595-

(ci. 10s-37)' Claims.

, My invention relates to variable displacement pumps, and more particularly to a pump whose output can be varied while it is operating.

Among the .objects of my invention are: To provide a simple and elcint variable displacement pump; to provide a pump whose displace- .ment may be varied from zero to maximum output; toprovide means for varying the displacement oi' a pump while operating, and to provide a means for changing the timing of one piston with relation to anotherin a variable displacement pump.

Referring to the drawings: l Figure 1 is a longitudinal view partly in section and partly in elevation taken through a vvariable displacement pump utilizing my inven-f tion;

Figure 2 is a view similar to Figure 1, indicating a change in timing of the pistons of the pump of Figure 1;

Figure 3 is a view partly in elevation and partly in section taken as indicated by the line 3--3 in Figure 2;

Figure 4 is adiagrammatic view of a radial -cylinder variable displacement pump;

Figure 5 is a diagrammatic view of a 4-cylinder v-tvpe pump:

Figure 6 is a diagrammatic view of the drive shaft and eccentrics of a 6cylinder radial pump as shown in Figure 4.

Figure 7 is a fragmentary view partly in section and partly in elevation of a modication of my device using external gear teeth on the eccentrics. y.

Figure 8 is a fragmentary view, partly in section and partly in elevation, of another modification of my device. n

My invention comprises a variable displacement pump, using two eccentrics and two pisl tons, driven bythe same shaft, together with means whereby both of the eccentrics may be rotated inopposite directions with respect to the shaft, S0 that the pistons may be timed to reciprocate either iii-phase or 180 out-of-phase.

All degrees of phase diilerence between these limits may be obtained, and if the cylinders in A which the pistons operate are interconnected, the

device, when used as a pump, will have a complete range of output from zero to the maximum' cylindrical pistons directly' driven by cams as well as pistons which may be driven from eccentrics o r cranks by means of connecting rods. The diaphragm type of piston is also included in the term.

, I My invention may be more fully understood by describing it in connection withthe drawings:

In Fig. 1, a cylinder casting iI is provided with side-by-side cylindrical bores I2 and 3 in which pistons 4 and 5 are mounted for reciprocation.

ton as broadly used herein is deemed to include 'Ihe central division 6 between the two cylinders is providedwith an aperture l above the `top of the strokes of the pistons, interconnecting thecylinder head spaces 9 and i0. Aperture 'I is of such an area that the entire displacement oi one piston may be passed through the aperture to the head space of the othergpiston without substantial ow resistance. 'Ille top of the cylinder block is closed by cylinder head II in which an inlet valve I2 and an outlet valve I4 is mounted,

Vthe inlet valve I2 being enclosed by inlet pipe I5 and the outlet valve I4 being enclosed by an outlet pipe I6. These valves may be of any conventional design, spring controlled or positively driven. The capacity of the pump comprising both cylinders is dependent upon the stroke relation of the two pistons 4 and 5. In the device Y. and 23 are provided with eccentric apertures,

these apertures being helically slotted to form an internal helical gear. .Drive shaft 24 has spacedI helical gears 25 and 26 cut thereon, the gearing being in an opposite direction as between the two gears 25 and 26. 'I'he eccentrics 22 and 23 are mounted on gears 25 and 26, respectively.

Thus shaft 24 may move axially along the gearI teeth with respect to eccentrics 22 and 23 but' the` latter are at all times coupled with shaft 24 for rotation thereby by the intermeshing of the helical gear teeth on shaft and eccentric. Shaft 24 is supported centrally by'a central web bearing 2l carrying a sleeve bearing 28. I prefer to mount web-bearing 21 on a crank case 29 which is fastened to cylinder block I along the horizontal plane intersecting the axis of shaft 24 assuming the pump is verticallypositioned. JThus all the shaft bearings become split bearings and the shaft may be easllyassembled in the pump.

3J bearing against the inner surface -of each ecbearing 21.

Outside of one eccentric in this modification,

lthe shaft 24 terminates in a stub end 3i, which ends in an oil chamber 32. The other end of the shaft 24 terminates in a splined end 34 to which is applied an internally splined power shaft 35 to which is attached a drive pulley 36, this drive pulley being provided with a thrust bearing 31 carried on a bearing hanger 38 to absorb end thrust. It should be fully understood that while I have shown plain bearings throughout the structure, roller or ball-bearings may be utilized for absorbing both rotatable and thrust friction wherever deemed necessary. Inasmuch as power shaft 35 is larger than splined end 34 of shaft 24 an oil chamber 4I! will be formed around l splined end 34, thus exposing a pressure shoulder v4I on the left hand end of gear 24. Oil chamber 40 is supplied with oi1 through an oil pipe 42 passing through a reversible pump 44, the oil -then passing through oil line 45 to oil chamber 32 at the other end of the shaft. Eccentrics 22 and 23 are maintained as to outward movement by outer bearings 46 and 41, respectively. As thus mounted eccentrics 22 and`23 are :naintained in proper axial position to rotate their pistons 4 and 5 through connecting rods I1 and I8. However, the entire shaft 24 is capable of axial movement in accordance with the differ` ential oil pressures exerting against the opposite ends of shafts 24 by reversible pump 44, and due to the spline connection with drive shaft 35 canbe rotated in any axial position.

I prefer to rotate the structure shown in Fig. 1 in a direction which will cause eccentrics 22 and 23 to exert their thrust against sleeve bearing 28, which is free to rotate in web bearing 21. Inasmuch as, under normal circumstances, both eccentrics rotatetogether and in synchronism,

f sleeve bearings 28 will rotate with the eccentrics.

As the thrust will be' equal and opposite against sleeve bearing 28 will rotate with the eccentrics.

in any bearing. When shaft 24 is in the position shown in Fig. 1, both pistons will rise and fall together and consequently the output of the pump will be that of the additive displacements of both pistons; i. e., maximum output of the pump I If, however, by means of reversible pump 44, shaft 24 is axially moved, the eccentrics 22 and 23 will be rotated-on the helical gears with respect to ,shaft 24, and when shaft 24 has been moved to the left for example, as far as it need travel, the eccentrics 22 and 23 will be 180 out-of-phase and the pistons will also be similarly out-ofphase. Inasmuch as the opening 1 will carry the complete displacement of either piston, the contents of the cylinders will be simply transferred from one cylinder to the other, back and forth,

' and there will be no appreciable output pressure developed. This position corresponds to the zero delivery of the pump, and is shown in Fig. 2 The reversible pump 44 can be utilized to axially position shaft 24 in any intermediate stage between full 'pump output and zero output. Thus,

- the combination of the two cylinders becomes a.

pump which can be varied as to displacement, from zero delivery to maximum delivery. Furthermore, any such change in displacement may be accomplished while thepump is running`` Thus the pump I have described is ideally adapted for use, for example, in supplying hydraulic pressure which can be used to feed oil to a Diesel engine in metered amounts, to control gun turrets, astronomical telescopes or other heavy machinery where delicate adjustment of delivery is desired.

Other uses will suggest themselves to those skilled in 'the art. While I have described my device as using hydraulic control of the axial the shaft 24 has three eccentrics 22, and three eccentrics 23, mounted on helical gears 25 and 26, respectively. Each of the eccentrics 22 drives one of the pistons in each cylinder pair, with eccentrics 23 driving the other of the pistons in each pair. Each pair of cylinders is provided with inlet and outlet pipes I5 and I8 as in Fig. 1. which are then Joined to form inlet and outlet manifolds 50 and 5I. Each pair of cylinders 2-3 also includes inlet and outlet valves I2 'and I4, and the interconnecting aperture 1. The axial 'position of shaft 24 is controlled as in the device of Figs. l and 2.

Fig. 6 illustrates the relative positions of the three eccentric bearings 20, and the three eccenltric bearings 2l, on the respective helical gears 25 and 25,'this figure being lan enlarged fragmentary view taken `at right angles through Fig. 4 to correspond to Fig. l. If the shaft 24 and 'its gears 25 and 28 are shifted to the left, as in Fig. 2, the three eccentrics 22 and their eccentric bearings 20 will be shifted angularly in one direction, while the three eccentrics 23 and their eccentric bearings 2l will be shifted angularly an equal amount in the opposite direction, in the same manner as the pair of single eccentric and bearing combinations 22, 20 and 23, 2I in Fig. '2, it being understoodA that means (not shown) are provided in Fig. 6 as in Figs. 1 and 2 to prevent axial movement of the eccentrics. From the above vdescription it is obvious that more than three pairs of cylinders maybe arranged in radial fashion about the drive shaft, if desired.

Fig. 5 is a 4-cylinder arrangement similar to Fig. 4, except in this case only two eccentrics 22 and 23 need be mounted on each helical gear 25 and 26. The eccentric 22 will operate a piston in each of the two cylinders 2, and the eccentric 23 will operate a piston in each of the two cyl. inders 3. One pair of cylinders 2-3 then forms a right bank and the other pair of cylinders 2-3 forms a left bank, each pair being provided with an interconnecting aperture 1, inlet and outlet valves, and inlet and outlet pipes connected into the manifolds 50 and 5I. Other cylinder arrangements of my invention will readily suggest- '24 is then provided, rotation and axial movement being provided i'or in a fashion similar to that described in conjunction with Figs. 1 and @samer direction desired but of course the thrust fric v tion must'be taken up by suitable thrust bearings as the cranks are between the two gears II and 56. l

In Fig. 8, however, I have shown a crank operated device wherein the sleeve bearing 28 is utilized. Here the sleeve bearing 28 maybe split longitudinally and centrally provided with an annular channel 02 ,to receive'ilanges Il onl the end of stub shafts Il and I9.- If shaft 2l in this modification is then rotated in a. direction to force the helical gears l5 and 58 together, the thrust will be taken by sleeve bearing 28 as in the modification shown in Figs. l and 2. In the modification of Fig. il, the flanges ,83 position the helical gears during relativemovement, and absorb thrust in case the pump rotation is reversed. e

My invention is capable of still further modil fications. Changes, therefore, in the construction and arrangement may be made which do not depart from the spirit and scope of the invention as defined in the appended claims.r

I claim: 1. A- variable displacement pump comprising a pair of adjacent cylinders. a pistonin each cylinder. the space above said. pistons being interconeccentric means driven by vsaid drive shaft for operating said pistons, and adjustable means for a shifting the relative angular positions of said eccentric means so as to simultaneously vary the phase positions of the pistons in eachpair of cylinders to vary the displacement of the pump,

n said adjustable means comprising a pair of helically threaded members rotated by said shaft, the

threads on said members being oppositely pitched, l helical threads on saideccentric means meshing with said members. -external means' for axially inQYinS said to said eccentrics, and means for rotating said hydraulic control shaft/comprising a coaxial power shaft fixed as to axial movement and spltned to one end of said drive shaft, said axial moving means including a pressure shoulder on said drive shaft, an oil chamber surrounding a portion of said drive shaft between said pressure shoulder and an end of said power shaft, an oil chamber containing the opposite endl of said drive shaft, and means for supplying controlled hydraulic pressures to said foil chambers selectively.

ff. A variable displacement pump comprising a pair of adjacent cylinders, a piston in each I cylinder, the space above said pistons being innected to form a pump chamber, inlet and outv let valves in the walls of said pump chamber, an eccentric connected to operate each piston, a drive shaft, a pair of helically threaded members rotated by said shaft, the threads on said members being oppositely pitched, helical threads'on each of said' eccentrics meshing with one of said members, means for axially moving said shaft with respect to said eccentrics, and means for rotating said shaft, said axially moving means comprising external hydraulic control means `ar ranged to apply hydraulic pressures selectively on opposed cross sectional 'areas of said shaft.

2. A variable-displacement pump comprising a pair of adjacent cylinders. a piston in each cylinder, the space above said pistons being inv terconnected to forma pump chamber, inlet and A outlet valves in the walls of said pumpchamber, an eccentric connected to operate each "piston, a

movement and splined to one end of said drive shaft, saidi axiallymoving means including a sealed space between a cross-sectionafarea oi' said drive shaft and a cross-sectional area of sadi power shaft. the opposite end of said drive shaft enteringa second sealed space, together with means for supplying controlled hydraulic pressures to said spaces.

3. A variable. displacementv pump comprising a plurality of pairsl of adjacent cylinders 'arranged radially about a drive shaft. pistons in said cylinders. inlet and outlet valves incommunication with each pair of cylinders, a free A communicating passageway connecting the cylinders of each pair, inlet and outlet manifolds connected with each pair of cylinders, a plurality of i terconnected to form a pump chamber, inlet and outlet valves in the wallsof said pump chamber,

,an leccentric connected to operate each piston.

a drive shaft. a pair of helically threaded meglbers rotated by said shaft. the threads on said members'being oppositely pitched, helical threads on each of said4 eccentrics meshing with one of said members, external hydraulic control means for axially moving said shaft with respect to said eccentrics, a web between said cylinders, a web bearing in said web, and a sleeve bearing freely rotatable in said web bearing and having end portions .abutting said eccentrics to receive and tend to neutralize opposing thrusts therefrom to vreduce thrust friction lin the operation of the pump.

, 5. A variable displacement pump comprising a pair of adjacent cylinders, a piston in each cylin der.. the space above said pistons being interconnect'edto form a pump chamber, inlet and outlet valves in the walls of said pumpchamber,

an eccentric connected to operate each piston,' a drive shaft, a pair of helically threaded membersrotated by said shaft, the threads onsaid members being oppositely pitched. helical threads on each of said eccentrics meshing with one of said members, external hydraulic control means for vaxially moving said shaft with respect to said eccentrics, a web between said cylinders, a web bearing in said web, a sleeve bearing freely rotatable in said web bearing vand having end portions abutting said eccentrics to receive and tend to neutralize opposing thrusts' therefrom to reduce thrust friction in the operation of the pump and means for\ rotating said shaft comprising a coaxial power shaft fixed as to axial movement and .splined to one end of said drive shaft. said axially moving means including a pressure shoulder on said drive shaft, an oil chamber surrounding a portion of said drive shaft between said pressure shoulder and an end of said power shaft, an oil chamber containing the opposite end of said drive shaft, and means for supplying controlled hydraulic pressures'tosaid oil-chambers selectively.

. RALPH M. HEINTZ.

shaft with respect l

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