US1927395A - Gear pump - Google Patents

Description

Sept. 19, 1933. L, EDWARDS 1,927,395

GEAR PUMP Filed Nov. 13, 1931 3 Sheets-Shea?l 1 zz INVENTOR Cttorneg Sept. 19, 1933. l l EDWARDS 1,927,395

GEAR PUMP Filed Nov. 13, 1931 3 Sheets-Sheet 2 nventor L. L Edwards' Sept 191 L. EDWARDS 1,927,395

GEAR lPUMP 'v Filed Nov. 15, '1931 5 vSheets-Shea?, 5

rwentor L' L Erdwa/rd APatented Sept. 19, 1933 PATENT OFFICE 1,927,395 GEAR PUMP Leonard L. Edwards, Longview, Wash.

Application November 13, 1931 Serial No. 574,890

8 Claims.

This invention is directed to an improvement in gear pumps with a view to providing certain details of construction tending to increase the life of the pump as a Whole and simplify the renewal or adjustment of parts necessarily subjected to wear in the operation of the pump.

The primary object of the present invention is the provision of liners for the pump chambers, with the liners in separable meeting sections, such liners being arranged to completely cover the inside of the pump chambers and protect the housing from Wear of any kind incident to the use of the pump.

A further object of the invention is the correlation of the liners of each pump chamber, so that it may be readily reduced in axial dimension in the event of wear, together With the provision of means for automatically maintaining the liners in proper relation to the pump rotor.

A' further object of the invention is the provision of means by which the means for automatically maintaining the liners in proper relation to the pump rotor is utilized to provide in effect arrelief valve for the pump when the pump has reached a given pressure.

A further object of the invention is the provision of a packing nut which is held in perfect alignment with the shaft when the nut has been hacked oli' for the insertion of new packing, thereby avoiding the loose position of the nut in ordinary structures when backed oli for the addition of packing, and materially simplifying the reapplication of the nut in shaft packing relation.

The invention is illustrated in the accompanying drawings, in which:

Figure 1 is a view in elevation of the pump.

Figure 2 is a section longitudinally of the pump, the line of section passing through one of the pump rotors.

' Figure 2a is a section on the line 2a-2a, Fig. 2.

Figure 3 is a perspective View of one of the half liners.

Figure 4 is a perspective view of the pump housing.

Figure 5 is a perspective view of one of the packing nuts.

Figure 6 is a broken vertical sectional View, showing one means for holding the reconstructed liner sections against axial movement.

Figure 7 is a similar View showing a modified means for holding the reconstructed liner sections against axial movement.

Figure 8 is a similar view showing a further modied means for holding the reconstructed liner sections against axial movement.

The pump is made up of a pump housing 1 having upper and lower intersecting circular rotor chambers 2 and 3, these chambers intersecting in the central plane of the housing to form the usual opening through which the pump rotors may cooperate. inlet 4 and an outlet 5 in line with the intersection of the pump rotors, these details being the usual conventional construction.

Each end of the pump housing is provided with a removable end housing at 6 and 7, these housings being of identical construction and each including a cover plate 8 designed to directly bear against the end of the pump housing and close the latter except for the shaft openings 9 in such plates. Each end housing includes a roller bearing carrier plate 10 secured in spaced relation to the cover plate by webs 11.

A gear housing 12 is removably secured to the carrier plate 10 of one end housing, as 6, this gear housing being formed with an opening 13 for the extension of one of the pump rotor shafts for driving provisions, a suitable bushing or bronze bearing 14 being employed. The opposite end housing 7 is provided With a cover plate 15 conforming to the general outline shape of the pump housing.

The end housings 6 and 7 are secured to the pump housing by bolts 16 passing through the respective housings, having heads at one end and nuts at the opposite end to maintain a iuidtight connection, while the gear housing 12 and cover plate l5 are secured to the bearing carrier plates 10 by suitable bolts and nuts 17.

The pump rotor gears 18 and 19 are arranged in the respective rotor chambers 2 and 3 and scoured upon shafts 20 and 21 to provide for the necessary pumping cooperation of the gears. These shafts pass through the openings 9 in the cover plates 8 and openings 22 in the roller bearing carrying plates 10, the shafts being provided with cooperating driving gears 23 in the gear housing 12, with one' of the shafts extending through the opening 13 for driving purposes, the opposite ends of the shafts extending into the cover plate 15.

Each opening 9 in each cover plate 8 is formed on the side next the bearing carrier plate 10 to provide a packing seat 24, the cover plate on the side next the plate 10 having an integral annular extension or Wall 25 concentric With the shaft opening 9 but of greater diameter than the diameter of such opening to provide for the reception of the packing about the shaft for guiding the The housing is formed with an A packing nut for the proper compression of such packing.

The openings 22 in the roller bearing carrier plates are, at the end next the housing 12 and cover plate 15, of sufficient diameter to receive and support ball bearings 26 through which the shafts and 21 pass, the plates 10 being thickened concentric with the opening to pro'- vide for the ball bearing reception and to fur,- ther provide for receiving and support packin nuts 27.

These packing nuts, as shown more particularly in Figure 5, are centrally formed with an opening to more or less accurately permit the passage of the shafts 2O and 21 and include a packing section 28 having a diameter to accurately fit within the wall 25, with such section 28 formed with openings 29 by which the packing nut may be adjusted.

Each packing nut 'also includes a circumferentially enlarged section 30, integral, of course, with the section 28, which section 30 is exteriorly threaded at 31 to cooperate with threads 32 formed in the enlargement 33 supporting the ball bearing, the surface formed of the threads 32 being of somewhat less diameter than the opening receiving the ball bearing and thus providing for the complete removal or insertion of the packing nut when necessary and also forming a shoulder 33' against which the ball bearing race outer ring bears to position the ball bearing. This packing nut arrangement provides an important detail of the present invention which will be more specifically referred to hereinafter.

The important detail of the invention is the provision of liners arranged to substantially encircle the pump gears on rotors and providing a removable and readily replaceable element which will take up wear incident to the use of the pump and also provide an automatic relief for the pump when the pump pressure has reached a given point. These liners, as shown more particularly in Figure 3, are made up of duplicate sections, each including an end wall 34, the periphery of which is accurately machined to rit a corresponding rotor chamber, and side wall extending inwardly from the end wall at the periphery thereof and concentric with the rotor chamber.

Each liner is made up of two such sections assembled with the free edges of their side walls 35 in contact, with their end walls 34 closely cooperating With the sides of the pump gears and the side walls concentric with such gears to define the uid space necessary in the pumping operation. The end walls 34 are interrupted at the meeting line of the rotor chambers, so that when the liners are assembled in the respective chambers. these interrupted or plain portions 36 of the end walls of respectively similar liners are in contact.

The side walls 35 of each liner are cut away adjacent the plain portions 36, as at 36', so that when the sections of the upper and lower liners are in proper position in the rotor chambers, an opening is provided by the interruptions of the side walls of the liners substantially corresponding to the inlet and outlet openings, obviously providing for the now of uid.

It will thus be plain that each pump gear or' rotor is. except throughout their meshing area and in correspondence with the inlet and outlet openings of the housing, completely enclosed by the liners and that the liner of each pump rotor is made up of two sections, movable relatively in opposite directions either for separation or application. The liners obviously provide a wear element for the pump rotors and thus, under such wearas will interfere with proper pump operation,.the liners may be removed and the Wear compensated for, as will later appear, or following the limit of such compensation, the liners may be readily replaced by new liners. In any event, the pump housing which, as compared with the liners, is the expensive and material element, is'protected from wear by the liners and thus the life of the housing so far as pump Wear is concerned is indefinite.

If the end walls 34, which is the detail subjected materially to wear, become worn to an extent to interfere with pump operation, the liner sections are simply removed and the free edges ofthe side walls 35 filed away to the desired extent, so that when the liner sections are replaced, the end walls 34 of the sections of a particular liner will be permitted to approach each other more closely to compensate for the previously worn condition and serving in this manner to restore the pump to normal operation so far as the wear of the pump rotors is concerned.

Normally, the liners including the thickness of the end wall 34 and the axial length of the side wall 35, are such that when the liners are in place, the relatively outer surface of the end wall 34 is in line with the ends of the pump casing, so that the cover plates 8, when in applied position, serve to hold the liner sections xedly against axial movement. By cutting away the free edges of the side wall 35 to compensate for wear, it will of course be apparent that when such reconstructed liner sections are replaced, the outer sections of the end walls will be inwardly of the normal holding surfaces of the cover plates 8 and in order to hold the liners in proper position against relative axial movement, several means are.pro posed.

Disregarding for the moment an additionally material function of one of such ways as will later more specifically appear, it is apparent that conventional shims 37 may be placed between the cover plates 8 and the end walls of ythe liner sections to provide the necessary contact bearing, such, for example, as illustrated in Figure 6. Another means for accomplishing this result is through the medium of set-screws 38 threaded through the cover plates 8 and bearing on the end walls 34 of the liner sections to hold the reconstructed liner sections against axial movement.

The preferred method of accomplishing this result, however, is shown more particularly in Figure 2 and in a slightly modified form in Figure 8. This preferred means, as shown in Figure 2, consists in a coil spring 39 arranged to encircle the shafts 20 and 21, of course in spaced relation thereto, and seating at their respective ends in appropriate recesses 40 formed in the outer surfaces of the end walls of the liner sections, and, if desired, similar recesses formed in the end plates 8, though the latter are not essential.

In Figure 8, a slight modification of this arrangement is shown, wherein the compensating member is formed by a series of small springs 41 interposed between the end wall 34 of the liner section and the cover plate, the ends of the springs being preferably seated in recesses 42 in both the liner section end walls and the cover plate.

The preferred method proposed for compensating for the relatively reduced axial length of the liner incident to cutting laway the side walls to take up wear is, of course, automatic in its action, as the springs act normally to maintain the free edges of the liner sections in contact, but as the holding means is thus resilient, an important function in connection with the pump proper is provided for. These springs, either in the form shown in Figure 2 or in the form shown in Figure 8, will yield to permit relatively opposite axial movement of the liner sections making up a liner or an axial movement of one of said sections relative to the pump rotor. As the strength of these springs can, of course, be predetermined, it naturally follows that the pressure on the inner surface of the end wall of the liner section at which the spring will yield may be set.

As the liner sections, or one of them, will yield axially under pump pressure unless prevented and as the preventing means is incident to the springs, the 'force of which may be determined, it follows that at a predetermined pump pressure, as regulated by the strength of the springs, the liner sections, or one of them, will yield axially to relieve this pressure or to prevent an excess pressure within the pump. Therefore, the spring means for compensating for the reconstructed liner sections as described also permit the liner sections to serve as an automatic relief valve, as will be apparent. This is particularly advantageous when pumping heavy oils, for example, due to the fact that the-section of the pump is affected in proportion to the discharge that is being returned and with proper regulation of the predetermined effective pressure of the pump, it is apparent that it is not necessary for the pump to draw its full capacity and suction and overow that which is not being used from the discharge side.

The liner sections, therefore, provide a means for completely protecting the pump housing against wear. The liner sections are further arranged in such correlation that by the simple operation of cutting away the free edges of their side walls, they can be made to compensate, for a considerable period, for the wear incident to the operation of the pump and ordinarily affecting the end walls of such sections. Furthermore, the liners are held in position preferably through the medium of means which will permit the liner sections to act as `automatic relief valves, with the relief function set at any predetermined pressure within the limits of the pump.

Of course, it is to be understood that, while the use of the springs has been described primarilyas a'means for holding the liner sections in place when such sections Yhave been adjusted to compensate for wear, the function of the automatic relief feature is'not to be understood as applicable only to the liner sections following their reconstruction to compensate for wear.

The liner sections as originally applied may have their end walls 34 of such relative thickness that they will not be held through direct contact with the cover plates 8 and under these conditions the springs 39 or 41 may be employed from the very inception of the construction. Thus, the automatic relief function provided by the liners will be effective whether the liners are in their original condition or in their reconstructed condition to compensate for wear. Thus, it will be understood that a salient feature of the invention is the utilization of liners made up in sectional form which not only protect the pump housing from wear but in themselves provide automatic at all times in threaded cooperation with the wall 25 and that when it is desired to apply new packing, the nut is simply threaded into the enlargement 33 so that the free end of the packing section 28 is suflciently removed from the end of the wall 25 to permit the introduction of new packing. After the packing has been inserted, the packing nut is simply advanced to compress the packing, remaining at all times in cooperation with the enlargement 33 through the threads 30 and 31. The nut is thus held in perfect alignment with the shaft, the usual diculty of applying the conventional wholly separated packing nut is entirely avoided, and the mere turning of the nut through the use of a` suitable tool cooperating with the openings 29 provides for either relieving the packing or completing the packing compression in a simple and expeditious manner.

What is claimed as new is:

l. A gear pump including a pump housing having gear chambers, a liner for each chamber substantially enclosing the gear therein, said liner being made up of independent wholly disconnected sections, a cover plate for closing the ends of the gear chambers, and springs intermediate the cover plate and each liner section to maintain pressure on the sections toward each other in an axial direction, said springs permitting axial yielding of the sections at predetermined pumping pressure to cause the liner sections to function as a relief valve.

2. A gear pump including a pump housing formed with gear chambers, pump gears operating in the chambers, a sectional liner substantially enclosing each pump gear, the liner of one chamber having bearing contact relation with the liner of the other chamber to prevent rotative movement of the liners, each liner being made up of two wholly disconnected sections each comprising an end wall and a side wall, the side walls of the sections having edge contact and being interrupted to provide for the inlet and outlet of the fiuid, a cover plate closing the ends of the gear chambers, and springsintermediate each cover plate and each liner section.

3. A gear pump including a pump housing formed with gear chambers, pump gears operating in the chambers, a sectional liner substantially enclosing each pump gear, the liner of one chamber having bearing contact relation with the liner of the other chamber to prevent rotative movement of the liners, each liner being made up of two wholly disconnected sections each comprising an end wall and a side wall, the side walls of the sections having edge contact and being interrupted to provide for the inlet and outlet of the fluid, a cover plate closing the ends of the gear chambers, and springs intermediate each cover plate and each liner section, said springs maintaining the free edges of the sections of the liner in contact and permitting separation of such edges under predetermined pump pressure to function as an automatic relief valve.

4. A gear pump including a pump housing, cooperating pump gears operative therein, a liner substantially enclosing each pump gear and made up of two wholly disconnected sections having a median line substantially at the circumferential median line of the gear, and means for permitting axial movement of at least one section of each liner to provide for automatic relief of the pump pressure.

5. A gear pump including a pump housing, cooperating pump gears operative therein, a liner substantially enclosing each pump gear and made up of two wholly disconnected sections having a median line substantially at the circumferential median line of the gear, and means for permitting axial movement of at least one section of each liner to provide for automatic relief of the pump pressure, said means being variable to predetermine the pump pressure at which the liner section acts as the relief valve.

6. A gear pump of the type including a housing and cooperating gears operative within the housing, said pump including a two-part liner for each gear, the respective parts of the liner for each gear being free of connection with each other and with the housing or with the parts of the liner of the other gear, the respective parts of the liner of each gear having relatively straight edges for cooperation with similar edges of the liner of the other gear when -the liners are in applied position to prevent independent rotative movement of the liners, a portion of each liner part of each gear being cut away to provide,

when the liners are assembled, an uninterrupted passage through the liners coincident with the cooperating plane of the gears.

7. A liner to be arranged between the gears and housing of gear pumps, each liner being made of two parts including a wall to overlie the side of the gear and a flange to partly overlie the periphery of the gear, the Wall terminating in a straight edge and the ange being cut away adjacent such straight edge, the liners for one gear together enclosing such gear except through' the area dened by the cut away portions of the flanges.

8. A two-part liner for the gear of a gear pump, each liner part including a side wall to overlie the side wall of the gear, and a lateral flange to overlie approximately one-half of the width of the periphery of the gear, the free edges of the flanges abutting when the liner parts are in position, the side walls terminating in a straight edge and being formed with an opening for the passage therethrough of the shaft of the gear, the lateral ange of each liner being cut away adjacent. the straight edge of the side Wall to present, when the liner parts are assembled in relation to the gear, an opening in the line of the operative plane of the gear.

LEONARD L. EDWARDS. [L.S.]

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