US2302865A - Pump - Google Patents

Description

INQV. 24, 1942. s, QX' I I 2,302,865

PUMP

. Filed Jan. 16, 1942 (Ittornegs Ritenteci Nov. 24, 1942 UNITED STATES PUMP ' Harry s. Wilcox, Chicago, ni., mimito Hydraulic Controls, Inc., a corporation of Illinois Application January 16, 1942, Serial No. 427,053

Claims.

This invention relates to high pressure displacement pumps and particularly to pumps in which the cylinders are radially arranged. Y

The invention relates particularly to pumps of the type disclosed in the application of Harvey 5 S. Pardee, which since the filing of the present;- application issued as Patent No. 2,271,570 on February 3, 1942, under which applicant's assignee is operating. In the Pardee pump, an

even number of single acting cylinders (usually four or eight) are used, and these cylinders are oiiset from true radial lines in a direction opposite to the direction of rotation of the drive shaft. The drive shaft carries an eccentric on which a sleeve is rotatably mounted by means 16 of a'needle bearing. Between the sleeve andeach pump plunger is a crescent shaped slipper which offers a concave cylindrical bearing contacting the sleeve and a convex cylindrical Journal which is received in a concave cylindrical :0

bearing machined across the inner end of the plunger. Flanges at the ends of the journal on the slipper limit motion of the slippers in the direction of the axis of the sleeve.

A plurality of bow or arcuate wire springs con- 20 nect opposed plungers in pairs, and flex slightly as the pump runs, to accommodate slight differences in the instantaneous velocities of the two opposed plungers, such diflerences being entailed by the geometry of the crank and connecting rod couples comprising the eccentric and each slipper.

In the Pardee pump the slipper is not positively connected either to the sleeve or to the plunger.

' On the contrary, the assembled relation is maintained by the springs which are mounted under suiiicient initial tension to ensure that the parts will be held in close engagement at all times. This implies suiilcient tension to pull the plunger through its suction stroke and maintainunder 40 all conditions a thrust engagement with the slipper.

In commercial pumps having plunger strokes and cylinder bores each of the order of inch,

this action is consistently secured, as evidenced by oscillograph studies, at speeds up-to at least 3500 R. P. M. though the usual operating speed is 1750 R. P. M. At such speeds the pump has good operating characteristics delivering against discharge pressures from 2500 to 3000 per square inch.

Obviously precise manufacture, the elimination of excess weight in the plungers, and the use of excellent heat treated material are essential to sustained performance because inertia eflects 55 pounds are substantial and unit pressures are high. The

bearing area between slipper and plunger cannot be increased, being coextensive with the end of the plunger. Use 01' a simple cylindrical plunger is dictated by the requirements of precise manufacture at reasonable cost. Indeed, many features'of the design are critical to an extent not obvious at first glance.

Failure 0! .a spring, which has proved to be a rare occurrence, releases two slippers. Contrary to what might be expected, this does not necessarily wreck the pump, but it does involve serious risk.

Connection of the slipper with the pump.

' January 16, 1942, and assigned to applicant's asj signee, involves the use of a slender wire stirrup which embraces the slipper and engages the plunger. Because such a stirrup cannot be located so as to operate accurately as a swinging link, it is maderesilient and is mounted under stress so that it urges the slipper toward the plunger.

The object oi the present invention which was conceived as an improvement on the Huber invention is to provide a more rugged sheet metal clip which engasrs an arcuate groove in the slipper, the are being concentric with the plunger ens s ns journal in the slipper. Thus, the clip is simply a retainer and has no spring action. It has no active function in the normal operation of the pump, but prevents the escape of a slipper if its plunger tends to stick slightly during the suction stroke. Also it retains the slipper in the event of breakage of a cross-connecting spring and thus minimizes the danger of wreck:

ing the pump.

.Critical factors in the design of pumps of this type impose the use of very small clearances, a fact which greatly complicates the problem of developing asmall and rugged attachment. Two somewhat similar embodiments which meet practical requirements will now be described by reference to the accompanying drawing, in which:

Fig. 1 shows a commercial eight cylinderpump with the front cover plate removed to show the invention applied. The pump is shown approximately full size in the Patent Office drawing as filed.

Fig. 2 is a fragmentary section on the line 2-2 of Fig. l, the scale being twice that of Fig. 1.

Fig. 3 is a further enlarged view .of a part of the plunger and slipper as viewed in Fig. 1.

Figs. 4 and 5 are an elevation and plan of the clip before application to the plunger.

Fig. 6 shows a blank for forming a modified type of clip.

Fig. '7 is a perspective view of the clip formed from the blank shown in Fig. 6.

Referring first to Fig. 1, 6 represents the body of the pump which is provided with an inlet connection 'l and a discharge connection 8 and a plurality of radial bosses 9 which house the cylinder bushings ll. Eight such bosses are shown in Fig. 1, the pump being of the eight cylinder type. The bosses 9 are bored to receive cy'inder bushings H which are pressed to place and seat against shoulders l2. The housing 6 is provided with passages l3 which communicate with the inlet passage 1 and with inlet ports I which are drilled in the bushings II and which are exposed by the plunger l5 when the plunger l6 moves radially inward to its limit of motion.

The discharge chambers I6 all communicate with the discharge connection 8. Cup-shaped discharge valves ll of generally cylindrical contour are urged inward, that is, in a closing direction by coil compression springs i8, whose inner ends are housed within the cup-shaped valves H and whose outer ends are received in sockets in the screw plugs I9, one of which is screwed into each of the bosses 9. Each valve 11 seats against the outer end of the corresponding bushing II and the parts are so dimensionedthat at the extreme outer limit of motion of each plunger IS, the plunger engages the valve l1 and holds it off its seat. This position is shown in Fig. 2.

The pump shaft appears at 2! and carries keyed to it an eccentric 22. In the example illustrated, it is understood that the shaft 2| turns counterclockwise, and it will be observed that the axis of each of the cylinder bushings H is offset clockwise slightly from a line radial to the center of shaft 2|.

The shaft 2| is mounted in bearings of the ball type, one of which appears at 23. These bearings are mounted in the main housing 24 of the pump, only a fragment of which appears in Fig. 2.

In an eight cylinder pump there are four such springs and the lengths of the hooked ends 3'! are differentiated so that the springs may overlap without interference, as clearly indicated in Fig. 1. Because of the bowed configuration of the springs they are out of the orbit of the sleeve 25.

So far, the pump conforms to the Pardee design and no novelty for the pump is here claimed.

The present invention provides means for retaining each slipper in operative relation with its plunger. The length of the bushings ll, necessary to ensure adequate guiding of its plunger [6, is such that the minimum clearance between the end of the bushing and the slipper is small. Furthermore, since these pumps operate at high speeds and against high discharge pressures, the unit pressure between the plunger I6 and the slipper 22 is high and it is desirable 'to maintain a thrust engagement between these two parts across the entire transverse area of the plunger.

According to the preferred form of the invention which is illustrated in Figs. 1 to 5 inclusive, use is made of a clip whose form is best shown in Figs. 2 to 5. The clip takes the form of an octagonal disc or plate 36, and this disc as initially formed, has a central aperture 36 having a serrated margin producing a series of inwardly extending fingers ll. Before the application of the disc to the plunger, these fingers 4| are curled upward, as best shown in Figs. 4 and 5. The disc carries two opposed pendant arms 42 with inturned lugs 43 (see Fig. 4). A short distance above the bearing 29 the plunger i6 is provided with a circumferential groove 44 of moderate depth and the clip is applied to the plunger by slipping it over the plunger until the fingers 4| can enter the groove 44 after which the fingers are bent back into the plane of the disc 28, as shown, for example, in Figs. 2 and 3. This fixes the disc on the plunger so that the two move as a unit in the direction of the axis of the plunger.

Mountedon the eccentric 22 is the sleeve 26 and interposed between the sleeve and the eccentric are a series of bearing rollers 26 which because of their small diameter relatively to their length, form what is commonly known as a needle hearing. The needles are confined by the discs 21 and 26. Each of the plungers I6 is formed at its inner end with an arcuate seat 28 which is machined across the entire inner end of the plunger and seats on a convex cylindrical journal 3l which is formed on the slipper, generally indicated by the reference numeral 32.

As a convenient means for limiting the motion of the slipper in 'a direction transverse to the plunger l5, flanges 33 are provided at the two ends of the slipper. The lower face of the slipper is formed with a concave cylindrical bearing 34 which fits the cylindrical sleeve 25 already mentioned. The inner ends of the bushings II are slotted as indicated at 35 and opposed plungers I6 are connected together by cross connecting springs 36. These have hooked ends 31 which enter sockets 40 bored in the plungers l5 and work in the slots 35. These sockets are drilled at a slight angle, as best indicated in Fig. 2, so that the springs retain themselves. The construction causes the bushing to guide the plungers close to the eccentric and slippers and the slots guide the springs 36.

clip is not a complete annui v at 46 so that it may be opened s ightly and sprung Slipper 32 is provided on its two end or plane faces with arcuate grooves 45 which receive the inturned lugs 43, already described. Obviously the slipper may be brought into engagement with the lugs 43 by a rotary motion after which the clip serves to retain the slipper in position against the bearing 28. The clip is not loaded during the normal operation of the device, butunder the conditionsabove stated, the clip retains the slipper in engagement with the end of the plunger so that it will not drop away and become jammed in other moving parts of the pump.

The modification shown in Figs. 6 and 7 is believed to be inferior, but reasonably satisfactory.

- The finished clip takes the form of a stamping having an annular section 38a with inwardly projecting fingers lla surrounding the central aperture 360. The blank from which the clip is formed is illustrated in Fig. 6. The clip carries pendantarms 2a with inturned fingers 30. Being formed from a fiat strip, as indicated, the but is separated over the end of the plunger l6 until the fingers Ila can enter the groove 44. While the type of clip shown in detail in Figs. 4 and 5 is preferred, the clip shown in Figs. 6 and 'I has sufficient strength for most purposes and when used performs the same function as the preferred form of clip.

The invention has the advantage that the clip is comparatively rugged; it can be used with clearances now standard in commercial pumps and does not reduce the bearing area between the slipper and the plunger or the bearing area between the slipper and the sleeve. Furthermore, because the clip is free to rotate on the plunger and because the arc of its engagement with the slipper groove is small, the clip leaves the slipper sufliciently free to assume proper alinement. The slipper is not subject to load in the normal operation of the pump and it is ample to retain the slippers in engagement with the pump plunger upon failure of a cross connecting spring, or in the event that a piston sticks slightly during the suction stroke.

While two embodiments of the invention have been described in considerable detail, their specific forms are prescribed by critical design factors in the particular pump chosen for illustration.

Modifications within the general scope of the invention are possible and are contemplated and may be dictated in the case of pumps of somewhat diilerent design. Consequently the description above given is intended to be exemplary engaging arcuate guiding means formed in the ends of the slipper concentrically with the axis of the journal on the slipper; and yielding means urging said plunger radially inward and serving to maintain thrust engagement between eccentric, slipper and plunger.

2. The combination defined in claim 1 in which the plunger is of simple fi lindrical configuration and the swivel connection between plunger and retainer comprises a circumferential groove on the plunger which secures and confines portions of the retainer.

3. The combination defined in claim 1, in which the plunger is formed with a circumferential groove and the retainer comprises a continuous encircling annulus formed with lugs confined in said groove.

4. The combination defined in claim 1 in which the guiding means on the ends of the slipper are arcuate grooves, which are engaged by intumed portions of arms, formed on the retainer and straddling the slipper.

5. In an eccentric-driven radial pump, the combination of a rotary eccentric; at least two substantially radial plungers -mounted in opposed relation and each having a cylindrical bearing formed across its inner end; slippers one for each plunger, each slipper having a bearing engaging the eccentric and an opposed journal engaging the bearing on a corresponding plunger; means for connecting each slipper with its plunger, said means comprising a retainer swiveled on the plunger adjacent the inner end thereof and having extensions engaging arcuate guiding means formed on the ends of the slipper concentrically with the axis of the journal on the slipper; and yielding means mounted under stress and serving to connect said opposed plungers in pairs.

- HARRY'S. WILCOX.

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