US2307374A - Radial hydraulic pump - Google Patents

Description

Jan- 5" 1943 D. JOHNSTON 2,307,374

RADIAL HYDRAULIC PUMP Y Filed J-une 20, 1940- 3 Sheets-Sheet 1 a 53 ff j @iff/'ff @WfWf/@Qf Jan. 5, 1943. D. JOHNSTON 2,307,374 l RADIAL HYDRAULIC PUMP Filed Jupe- 20, 1940 s sheets-sheet '2,

I Jan. 5, A1943. D JOHNSTON 2,307,374 A RADIAL HYDRAULIC PUMP Filed June 20, 1940 l I5 SheetsSheet 5 Patented Jan. 5, 1943 2,307,374 RADIAL mnlimcrcm Douglas Jehnston, shelbyvme. n1., or' te Tallman Manufacturing Company, She H e,

Ill., a partnership Application vJune 20, 1940, Serial No. 341,421

(Cl. 1mi-174) 4Claims.

'l'his invention relates to high pressure hydraulic pumps and more particularly to a pump of radial design employing a piston structure of new and novel mechanical characteristics.

It is recognized in the trade that radial pumps possess certain inherent advantages over any other type of pump on the market and are particularly desirable because o! their compact nayvention to provide a pump' including a piston arrangement whereby the discharge pressure against which the piston is working does'not act over the entire area of the piston, but only against a portion thereof, so that the area oi the wristpin bearing may be comparatively large with re- `yspect to the active area of the piston.

ture, silent operation, long life and freedom from mechanical diiiiculties. It is also recognized that theradial arrangement or cylinders around a single crank shaft makes possible a smoothness and absence or pulsation not ordinarily accomplished in any other type of pump. It has, however, been'heretofore regarded as impractical 'to use the radial design for high pressure pumps, as, for example, in pumps adapted to drive hydraulic presses, hydraulic oil well pumps, fluid actuated automatic machinery, or any similar application in which a large volume of liquid must be displaced under'pressures ranging upwardly from 3,000 pounds per square inch. v

This opinion arises from an inherent defect or limitation heretofore present in conventional piston design, for the reason that if a given sized piston is vemployed against 3,000 or 4,000 pounds vper square inch pressure, there is'not suicient diameter of piston to provide a wristpin bearing area that will stand up under continuous use, since good engineering practice limits wristpin pressures to about 2,000 lbs. perl square inch maximum, and even if the entire projected area A further object of' the invention is to provide 4an improved sleeve-type piston comprising a sleeve of comparatively large diameter and the comparatively thin wall section to provide ample space for a large wristpin bearing, area and suiilcient diameter in which a short connecting rod may swing through a large arc for a longfstroke and make it possible to proportion the piston, so that regardless of discharge pressure, the force against the piston, wristpin, connecting rod and th entire system` may Ahe as low as desired. v

Another object of the invention is to provide a radial hydraulic pump frame aond operating assembly-including removable cylinder heads and pistons of such design that a single pump a'ssembly may be utilized for a `y pump adapted to 4operate under a speciiied horsepower, wherein pistons and cylinder heads of different dimenv`sions may be substituted to alter the entire of the piston could be utilized for bearing area, f

which is impossible, the bearing pressure still would be excessive. From the above comments it will be appreciated that the inherent'limitations of conventionalpiston designs apply not only to their use in radial pumps, but also to their use in any other arrangement.

It has been a common expedient, however, to attempt to surmount the diiilculty thus-presented by providing some form of cross slide to carry the wristpin bearing or to attempt to drive the characteristics of the pump and provide either a pump of large piston displacement adapted to operate under comparatively low pressure or a pump of correspondingly small piston displacement adapted to operate under extremely high pressures.v A

These and other important. objects are accomplished in the present invention by providing a conventional cylinder with a cylindrical core portion secured to the cylinder head and projecting 'into the cylinder to denne an annular chamber between the outer walls of the .cylinder core and the inner walls of the' cylinder and arranging a sleeve-like piston to operate in this annular chamber.

" It will be appreciated, of course, that an annu- Y lar chamber of this design is of comparatively pump by cam means instead of a connecting rod and crank shaft, but these make-shift arrangements have beeniound to be highly unsatisfactory in the art. It is believed. fundamental that a connecting rod and wristpin represents the iinest engineering practice. while any camarrange ment or additional parts, such as cross-slides, are not inherently good in a mechanical design and are particularly objectionable whenever they are called upon to operate in oil containing even 'a very small amount of foreign abrasive matter. v`

It is, therefore, the principalobject or this ingreat diameter with respect to its cross-sectional area, with the result that the entire diameter of the cylinder may be used forproviding suitably large wristpin bearing surfaces and yet the .annular displacement of the piston or active pres- Sure area will be equal to only a fraction of the area of the full diameterof the cylinder. 4

Referring now more particularly to the drawings: Fig.. 1 is a fragmental front elevational view, partly in section, of a radial pump constructed in u accordance with the teachings of this disclosure;

Fig. 2 is a detail sectional view taken substantially on the plane of the line 2-2 in Fig. 1;

Fig. 3 is a detail sectional view taken substantially on the plane of the line 3-3 in Fig: l.

The main frame of the pump chosen as illustrative of the principles of this invention cornprises a circular frame casting II secured to a cast crank shaft housing I2 by a multiplicity of bolts I4. A crank case cover plate to the circular casting II by the bolts I6.

The crank shaft 2I is rotatably mounted within the crank shaft llollsing 22, carried by the crank shaft housing I2 by the bolts 24 and a second anti-friction bearing (not shown) is provided adjacent the outer end of the crank shaft. In certain instances, as, for example, in installations of oil well pumps that are air balanced, the intake manifold and crank case of a hydraulic pump may be under pressures in the vicinity of 1,200 pounds per square inch, and since thesepressures tend to force the crank shaft of the pump out of the crank shaft housing. a thrust bearing 25 is provided to bear against the shoulder 26 of the crankshaft housing I2 and to maintain the crank shaft in proper position by means of the spacer 26, which extends between the raceway of the bearingj25 and the inside raceway of the bearing 22 to act against the shoulder 21 of the crank shaft. Suitable oil sealing devices 30 are provided to prevent the escape of oil around the crankshaft bearings.

The eccentric crank pin 28 is provided at the /inner end of the crank shaft 2I, and a bearing containing flange 29 is secured thereon by a bolt 3I threaded on a reduced portion 32 of the crank pin to secure a master connecting rod 33 in position on the crank pin 28. The master connecting rod 33 is provided with an anti-friction bearing 34 and includes a connecting rod arm 35 extending to the wristpin of one of `the pistons and a pair of opposed flanges or cheeks 36 and 31 to provide a suitable mounting for a'plurality of articulated connecting rods 38 extending to the other pistons of the pump. In the present disclosure a nine-cylinder pump has been illustrated, but it is to be understood "that the principles of this invention may be practiced equally well in pumps having fewer or more cylinders.

Each of the articulated connecting rods 38 is movable with respect to the master connecting rod 33 and is connected with the flanges 36 and 31 of the master rod by a wristpin 4I locked to the connecting rod 38 by set screw 42 and extending on either side of the connecting rod 3B into suitable wristpin bushings 43 and 44 mounted in the flanges 36 and 31, respectively.

The cylinders 45 of the pump are formed in the outer circular frame casting II and each cylinder is provided with a piston 46 secured to one of the connecting rods 35 or 38 by a wristpin 41 locked to the connecting rod by\a set screw 48 and journaled in suitable bushings 49 in the base portion of the piston 46. Preferably, the wristpins 41 and 4I are of case-hardened steel, and the bushings 43, 44, and 49 are also of hardenedAtool-steel to provide ample strength to resist the pressures developed in the pump.

The cylinders 45 are each closed at their outer end by an individual cylinder head 52 bolted in position on the main casting II by a' plurality of bolts 53 and sealed around the; cylinder by anv annular gasket 54 clamped between opposite 75 a flanged I2 on an inner bearing {he bearing retainer 23, `toned m I is bolted compression surfaces on the cylinder head and the Acasting I I, respectively.

The cylinder head 52 includes a cylindrical pilot portion 55 of the same diameter as the bore of the cylinder extending downwardly into the cylinder a considerable distance, as shown in Figs. l and 2. At the lower end of the pilot portion 55, the cylinder head is further reduced to provide a cylindrical core 56 of a diameter somewhat less than the diameter of the cylinder and extending downwardly in the center of the cylinder throughout a considerable portion of the cylinder length. This arrangement provides an annular space or chamber 51 outside of the core 56 and inside of the cylinder 45, and it is this annular chamber 51 that comprises the actual active portion or displacement area of the pump.

The piston 46 is arranged to include a sleevelike upper portion 58 adapted to closely fit in the annular chamber 51 and is provided with a plurality of piston rings 6I on this outer cylindrical surface to establish a seal between the outer surface of the piston and the inner surface of the main cylinder wall, while a pair of piston rings 62 are mounted in grooves on the lower extremity of the cylinder core 56 to establish a seal between the outer bearing surface of the core 56 and the inner surface of the sleeve portion 58 of the piston.

It will be appreciated that this arrangement provides a comparatively great area for the wristpin bearings, since the diameter of the main cylinder 45 1s comparatively large, but at the same time provides an arrangement whereby the active pressures on the wristpin bearings will not rise to great extremes even when the pump is developing up to 4,000 pounds of pressure per square inch, since the completek area of the cylinder 45 is not used as a displacement area and the actual active displacement area, namely, the` area of the annular chamber 51 is comparatively smallwith respect to the total area of the cylinder. y

All of the pistons of the pump are provided with a common circular intake manifold 1I and a common discharge manifold 12 cast in a circular formation on opposite sides on the main cylinder casting II.

The valving arrangement of the pump is best illustrated in Figs. 1 and 3, where it will be seen that each cylinder is provided with an intake valve 13 and a discharge valve 14, each threaded in shoulder portions 15 and 16, respectively, in a transverse cored opening 11 extending completely through the casting II and closed at the intake side by a threaded plug 18 and at the discharge side by a threaded plug 19. Each cylinder of the pump has an identical valve structure including the valves 13 and 14 and the plugs 18 and 19, so that any one of the plugs 18 may be removed to provide a threaded connection for an inlet pipe while -any of the plugs 18 may be removed to provide a similar threaded connection adapted to receive an outlet pipe constituting the discharge line of the pump.

The valves 13 and 14 are of similar design, each including a threaded valve body portion 8| formed to provide a conical valve seat .82, and a valve rod bearing 83 mounted on a spider 84. The movable member of the valve includes a conical valve head 85 provided with a rod or shank 86' extending through thebearing 83 and provided with a coiled compression spring 81 between the spider 84 and end tting 88 threaded to the valve rod the crank case.

88 in order to 'draw the valve head 85 into rm of the pump may be ycorrespondingly altered.

pressure engagement with the valve seat 82. By-

pressure of the oil, thus permitting thefluid to flow into the discharge manifold 12..

It has vbeen pm out that-the pistpn 4s is divided by the inner. circular bearing surface of tlie core 56, so that only the outer area 51 functions as a displacement area for the pump. Itis, however, essential to provide some vent arrangement to prevent the remaining central area of the central portionof the piston from developing any f pressure that would resist the operation of the pump. To 'accomplishthia each cylinder is provided with a vent extending from the circular intake manifold 1I to the crank case. This vent includes av cored opening 9| extending from .the manifold 'H to the outer surface` of the cylinder and connecting with a return passage 492 cored in the cylinder head and extending downwardly through the central core portion of the cylinder to To insure a perfectly sealedconnection between the passages 9 I and 92, a washer 93 is provided at the sealing surface between the casting Il and the cylinder head 52, and a pair of sealing gaskets 94 are positioned on either surface of this washer in pressure engagement between the annular sealingsurfacesof the castings. The passages 9| and 92 provide a complete vent between the manifolds 1I and the'crank case, inasmuch as the base portion I of the piston 46 is open and unobstructed around either side of the connecting vrod 35 (see Fig. l). This venting arrangement through the pistons allows sumcient flow of oil between the crankcase and manifold largeyolumes of oil through the comparatively small spaces or vents through the base ofthe piston, and/thus prevents any appreciable frictional .or heat losses.

As hereinbefore pointed out, it is often desirable for a manufacturing company tobe able to standardize o n one type of pump, and at the same time it is absolutely essential to be able to provide Dumps of different inherent characteristics and adapted to different uses; for example, some applications will require a tremendously highpressure Thus, if it is desired to provide a pump adapted to displace a larger volume of oil at a lower pressure, itis only necessary to install pistons having a greater wall thickness than the sleeve portions 58 and cylinder heads having a correspondingly smalldiam'eter to the core portion 56. If upon the other hand it is desired to provide a pump to develop greater pressures than those developed by the pump illustrated, it is only necessary to provide a piston having thinnerwall portions and cylinder heads having a correspondingly large! diameter core. l

From the foregoing description, it will be appreciated that by practicing the principles of this v invention it is not only possible to provide a pump well adapted to manufacturing practice and p ossessing inherent advantages by virtue-of the ease with which the pump may be altered, but it is also possible to obtain'results not heretofore ac-V complished in the art by the use of the particular piston' design here disclosed.

It has been pointed out that the discharge pressure against which the piston is working does not act over the entire area of the piston, but only against a portion thereof, so that the areas of the wristpin arings may be comparatively large with respect hefactive area of the piston and vwill thus be well adapted to continuous hard service and abuse, even under adverse conditions.

It should again be stressed that it is well recognized in engineering circles that a connecting rod and wristpin arrangement isfar superior to any cam actuated mechanism from a standpoint of cost, smooth operation and long life and has heretofore been used in every application Where the wristpin pressures could be held within reasonable limits. By the practice of the principles of this invention, the problem of dealing with excessive wris solved and it is now entirely fea ible to extend the use of the connecting rod and wristpin arby reversing the core arrangement to provide a core on the piston extending into the \cylinder head and/or venting the annular chamber of the cylinderto provide a` central displacement area, and I therefore do not wishto be limited except as by the scope of the appendedclaims;

I claim:

l. In a. radial hydraulic pump; a circular l frame casting,'including a. central ,circular crank case, radial cylinders extending from the crank case, a circular intake manifold around one side of the cylinders, radial vent means in the intake manifolds opposite each cylinder and having a passage extending through said cylinder for constant free communication `with said crank case,

` a circular discharge manifold around `the other and in other uses it may be more desirable to have a somewhat lower pressure and a correspondingly greater volume of voil.v In apumpof the present design, the characteristics of the unit may be changed by replacing the pistons and cylinder heads only without in any way altering the crank rods, manifolds or valves, since by changing the' side of the cylinders,l s'aid intake and discharge manifolds providing a web connection between the cylinders; intake and discharge valves for each cylinder mounted .in said web, in-line inlet and discharge openingsthru the intake and dis- .charge manifolds\for yinserting said valves, a

. shaft bearings, oil seals, crank case,4 connecting crank shaft mounted in a housing supported on' one side of the crank case, a connecting rod and piston assembly mounted on said crank shaft,

in pressures is and means to close the cylinders and crank case.

2. In a radial hydraulic pump; a circular frame casting, including a circular crank case, radial cylinders extending from the' crank case, a circular intake manifold around one side of the cylinders, radial vent means in the intake manifolds opposite each cylinder and having a passage extending through said cylinder for constant free communication with said crank case, a circular discharge manifold around the other side of the cylinders, .said intake and discharge manifolds providing a web connection between the cylinders; intake and discharge valves for each cylinder mounted in sad web; in-line inlet and discharge openings through the intake and discharge manifolds for inserting said valves; a crank shaft mounted in a housing supported on one side of the crank case; a connecting rod and piston assembly mounted on said crank shaft, said pistons being in the form of cylin drical sleeves; cylinder heads including male cylindrical extensions to iit the bore of the cylinders; and a vent through the extensions and head connecting the intake manifold and the crank case.

3. In a hydraulic pump, a crank case, a plurality of cylinders, intake and discharge manifolds operatively connecting said cylinders, a piston for each cylinder, a head for each cylinder, smaller auxiliary pistons supported from each head coacting within the pistons, and vent passages throughthe auxiliary pistons and the heads connecting the intake manifold and the crank case to permit oscillation of idle uid between the several cylinders of the pump.

4. In a hydraulic pump, a crank case, a plurality of cylinders, intake and discharge manifolds operatively connecting said cylinders, inlet and discharge valvs within said manifolds connecting the cylinders, a piston for each cylinder, a head for each cylinder, smaller auxiliary pistons supported from each head co-acting within the pistons, and vent passages thru the auxiliary 'pistons and the head connecting the intake manifold and the crank case to permit oscillation of idle fluid between the several cylinders of the pump.

DOUGLAS JOHNSTON.

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