US2447744A - Pumping unit - Google Patents

Description

Aug.24, 1948. v. E. DUEMLER 2,447,744

rimrme unn- Filed April 1, 1944 4 sheets-sheet 2 INVENTOR,

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ATTORNEY.

Aug. 2 9 8- v. E. DUEM'LER 2,447,744

PUMPING UNIT Filed April 1, 1944 4 Sheets-Sheet 3 INVENT OR,

ATTORNEY.

Aug. 24, 1948. v. E. DUEMLER 4 PUMPING u'nn' Filed April 1, 1944 ;4 Sheets-Sheet 4 v SA INVENTOR,"

Zi'rya'llf lllefille I V IO: 5.9'

valve of an oil burner.

Patented Aug. 24, 1948 PUMPING UNIT Virgil E. Duemler, West Springfield, Masa, as-

signor to Gilbert & Barker Manufacturing Company, West Springfield, Mass a corporation of Massachusetts Application April 1, 1944, Serial No; 529,048 12 Claims. (01. ins-42 l This invention relates to an improved pumping unit which is particularly suitable for use with oil burners.

The invention affords a single unitary structure which includes the pump, its driving motor and a pressure regulating valve and may also, and preferably does, include a burner cut-off valve and a filter.

The invention has for general objects the provision of a fuel pumping unit which is economical to manufacture, quiet and eflicient in operation, and easily serviced.

A particularobject of the invention is to provide a compact arrangement of the parts, above described, within a substantially cylindrical housing of substantially uniform diameter from end to end and having a smooth, unbroken exterior surface without any substantial projections and of streamlined form.

Another object of the invention is to provide a compact unit having a rotary pump and a pressure-responsive valve, mounted in a single substantially cylindrical casing with the pumping elements and valve grouped in' a circular series about the pump drive shaft, which is coaxial with the casing, and with the axes of the elements, valve and shaft in parallel relation. I

According to another object of the invention, the pressure-responsive valve may be either the pressure-regulating valve or the nozzle cut-off Also, both such valves may be, and preferably are, housed in the one pump casing.

Another object of the invention is to provide a fuel pumping unit, having its casing made up of a stack of plates, fastened together face to face, an intermediate plate containing interengaging pump e1ements,'such as gears, located between other plates, one on each side of the first-named plates. the pump casing having a chamber formed therein parallel with the axes of the pumping elements to house one or more control valves, such as the pressure-regulating valve and the nozzle cut-off valve. i

Another object of the invention is to provide in connection with either or ,both the valves described, a valve-actuating bellows, movable in one direction by a spring and in the other by pressure of the pumped oil, said bellows being carried by a disc clamped between one pair of plates of the pump casing.

. 2 such element being carried by a bellows, mounted on a disc, clamped between the pump casing and said body member.

A further object of the invention is to provide, as a safety feature, a means for venting the interior of the bellows of the pressure-regulating or of the cut-off valve to the fuel supply chamber, whereby any leak through the bellows will establish a by-pass around the pump and reduce the pressure in the pumping unit, thus allowing the cut-off valve to close and prevent flow to the nozzle. l

A further object of the invention is to provide in connection with both the pressure-regulating and the cut-off valves, vents to interconnect the interior and spring-housing parts of the two bellows, whereby the fluid pressure inside each bellows will be equalized to avoid any une ual influence by fluid pressure on the valve-closing spring-pressure.

Another object of the invention is to provide a fuel supply unit, which easily primes itself and which includes an outer housing affording within it a fuel supply chamber, a pump casing inside said chamber, and a filter of absorbent material within the chamber and surrounding the pump, characterizedin that the suction passage of the pump has its intake end at substantially the lowest point of its casing and adjacent the inner periphery of the filter whereby if pumping ceases because of exhaustion of fuel and said intake end becomes uncovered, oil will subsequently seep from said filter and raise the liquid level in the chamber far enough to cover said intake end and prime the pump.

These and other objects will best be understood as the detailed description proceeds and -22 of Fig. 1 and showing the body or supporting member of the unit;

Another object of the invention is to provide in a pumping unit. a pump casing fastened to a body member having therein a pump driving shaft, together with seal ring elements for said shaft, one

Fig. 3 is a fragmentary sectional plan view taken on the line 3-3 of Fig. 2;

Figs. 4 and 5 are cross sectional views taken on the lines 4-4 and 5-5, respectively, of Fig. 3 and showing one face of one of the end plates for the pump and the pump plate, respectively;

Figs. 6, 7 and 8 are cross sectional views taken on the lines 6-6, 1-1, and H, respectively of Fig. 1 and showing the inner face of the other end plate 101 the pump; the outer face of the lastnamed end plate; and the cover plate for the pumping unit;

. Fig. 9 is a fragmentary sectional view taken on the line 9-8 of Fig. 2;

Fig. 10 is an enlarged fragmentary cross sectional view showing the relationship of the intermes'hed gear teeth with the inlet and outlet ports.

Fig. 11 is a fragmentary view of the same end plate as is shown in Fig. 6 and illustrates a modification in detail;

Fig. 12 is a fragmentary sectional view taken on the line l2l2 of Fig. 11; and

Fig. 13 is a fragmentary section-a1 view taken similarly to Fig. 9 and showing a modification.

Referring to these drawings, the pumping unit (Fig. 1) includes a housing having a body member II and a cover member l2. These members II and I2 have mating and confronting circular flanges l3 and I4, respectively, which are suitably held together, as by cap screws it (see also Figs. 2 and 3). These two housing members afford between them an inlet chamber it for the pump. They also support between them a suit-. able filter ll of annular form. as by means of the annnuar rings l8 (Figs. 1, 2, and 3) of triangular section which engage one in each end face of the filter. This filter is preferably made of absorbent material for a purpose which will later be explained. It may, for example, consist of cotton thread wound upon a coarse mesh wire screen I'I'.

Within the inner chamber, which is formed within the filter i1, is located the pumping unit proper. This unit (Fig. 1) comprises an inner end plate iii, a pump plate 20, an outer end plate 2|, 9, thin bellows-bearing disc 22 and a cover plate 22. These several plates and disc 22 are held together by a pair of cap screws 24, which are indicated in Figs. 4 to 8 and which pass loosely through plates 23, disc .22 and plates 2i and and thread into plate I9. These screws 24 serve to hold the component parts of the unit in proper assembled relation while it is being mounted in place on the body or supporting member l I. The assembled unit is held to one finished face of member II, with a seal-ring bearing disc 25 and suitable gaskets clamped therebetween, by a plurality of cap screws 26, which are best shown in Fig. 3 and also indicated in Fig. 2 and Figs. 4 to 8 inclusive. These screws 26 pass loosely through all the plates and both discs and are threaded into member H. A pair of dowels 21, fixed in member ll extend through and closely fit, registering holes in the several plates and both discs and gaskets and serve accurately to hold all these plates and discs in proper angular relation with each other and with member II.

The housing member ll may be, and desirably is as shown, an end plate for a pump driving member, such as an electric motor. This motor has a smooth, cylindrical exterior, indicated in part at 28 and of the same diameter as the smooth cylindical exterior of the parts l3 and I4. The motor serves to drive the shaft 29, which has a bearing 30 in the member Ii. The latter has a circumferential flange 3! to fit the motor casing and is suitably held thereto, as by screws i5. Flange ll is of smooth cylindrical form and of the same diameter as parts 28, i3 and It. An outer casing of smooth, unbroken,- streamlined form is thus provided.

All pipe connections are made to the body member ll, whereby the cover l2, filter i1 and the pump unit may be removed without disturbing oany pipe connections. Referring to Fig. 2. there are ports 32. II and 34 for connection. respectively, to a suction pipe leading from the fuel oil supply tank; to a pipe leading to the burner nozzle; and to a return pipe leading back to said tank. There are also ports 25 and It for connection to vacuum and pressure gauges, respectively'. The inlet port 22 opens directly into chamber Ii through the peripheral wall l-I thereof. The burner port 33 is connected by a'passage 21 (see also Fig. 9) which leads upwardly to and connects with a short passage 38, leading outwardly to and opening into a well 39 formed in the outer face of the member I I. The by-pass port 34 (Figs. 2 and 3) is connected by a horizontal passage 40 to each of two short passages ti and 42 which open outwardly to said face of member H. The ports 36 and 26 are connected by passages 43 and 44 to short passages 45 and 46, respectively, which lead outwardly to said face of member ii. The passages '38, H, 42 and 48 open in said face at points within the area covered by the end plate IQ of the pumping unit, while the passage 45 opens into a recess 45' which lies outside said area and inside the filter IT.

The body member II also contains a central recess 41 coaxial with shaft 29 and a passage ll for venting and draining said recess. Another passage 49 serves to conduct lubricant to hearing 30.

Referring now to the pumping unit proper, this includes a pair of intermeshing gears 50 (Fig. 5 housed one in each of a pair of cylindrical holes 5! formed in, and passing entirely through, the

' pump plate 20. One of these gears is driven by a small pinion 52 formed on the outer end of shaft 29 (Fig. 1). The pinion is housed in a cylindrical hole 53 (Fig. 5) formed in and passing entirely through plate 20. The outer extremities of the teeth of gears 50 and those of pinion 52 closely fit the peripheral wall of their respective holes 5| and 53. The teeth of the gears and those of the pinion are preferably relatively pointed as shown. The gears 50, as shown, are of equal size. The pinion 52 is much smaller so as to efiect a reduction of the speed of the gears to approximately one third of the speed of shaft 29. Each gear 50 is rotatably mounted on a stud 54. Each such stud is fixed at one end by being pressed into plate l9 (Fig. 1) and has its other end extending into a hole in plate 2|. The faces of the gears 50 closely fit the adjacent faces of said end plates. as shown in Fig. 1.

The inlet and outlet ports for the gear pump are shown at 55 and 58. respectively. They are formed in those faces of plates l9 and 2| which engage the pump plate 20. One set of these ports is shown in Fig. 4 and the other in Fig. 6. Both inlet ports are alike and both outlet ports are alike. Fuel oil is drawn from the chamber it through a passage M (Fig. 4) leading from substantially the lowest point in the periphery of plate i9 upwardly to about the lever of the shaft 29 but at a point laterally offset there-. from where it communicates with a hole 58 which opens into the inlet port 56 in plate i9. The two inlet ports 55 are interconnected by a through passage 69 in pump plate 20 (Fig. 5). The two outlet ports 58 are similarly interconnected by a through passage 6.0 in plate 20. The outlet port 56 in plate 2| is connected by a passage 6| (Fig. 6) to a circular groove '2 in the outer face of the plate (see also Fig. '7). This groove serves to conduct the pumped oil into two cylindrical chambers 33 and 54. The chamber 83 is formed by registering holes 33 in plates 2|, 23 and I3.

These. links extend entirely through plates 2| and'23 but only partly through plate It. The chamber 34 is formed by registering ho es 33 formed in and extending entirely throughthe plates 2| and 23. These chambers '33 and 34 respectively receive part of thecut-oil valve mechanism (controlling the flow of oil to the burner) and part of the by-pass valve (controlling the fiow of oil back to the suctionside'oi the pump or to the supply tank, whichever is de sired).

Thedisc 22, above referred to, carries a bellows 31 which extends into the chamber 33 and forms a movable partition therefor. Within thebellows and acting between the closed end wall 33. thereof and an adjustable 'seat 33 on cover plate 23 is a spring 13. The cut-oil valve is shown at II. It is slidably mounted in a sleeve 12. Sleeve vl2 fits in a bushing 13 and has a longitudinal groove 12' (Figs. 4 and 9) in'its exterior enabling oil to flow from chamber 33 to the valve. Instead of the groove 12'. a spiral groove may be formed in valve II as shown in Fig. 13 for the same purpose. The oil fiowing through this spiral groove serves to lubricate the valve stem and prevent it from sticking in its guides. The bushing 13 carries the seat for valve 1|. This bushing is threaded into plate i3 and has an end extending into the well 33, above described. The

outer end ofthe stem of valve it rests against the wall 33 of the bellows. A small spring 14 tends to open valve 1|, when permitted by an outward movement of wall 33 under the pressure of oil in chamber 33. Oil will then flow into hole 33 and thence by passage 31 to the burner port 33. .The valve II will open when the oil attains the desired pressure for atomization, say for example 85 pounds per square inch.

The disc 22 also carries a second bellows 13 (Fig. 1) which extends into chamber 34 and forms a movable partition therefor. Its inner and closed end 11 bears the pressure-regulating valve "which engages with a seat formed ina bushing' 13 fixed in plate 13. The stem of this valve is of modified square section (Fig. 4) and slidably fits in the round hole of bushing 13 (Fig. 1) to'guide the valve. spaces being left between the wall of the hole and the flat sides of the square section of the stemior oil to flow from chamber 64 to reach the valve. A spring 33 acts between 23 to hold valve 13 closed. When, howeventhe pressure of the pumped oil reaches a predetermined figure, the wall 11 will be moved outwardiy (to the right as viewed in Fig. 1) and open the valve 13, allowing oil to escape into passage 42 and thence into passage 43. The valve 13 is intended to open at a somewhat higher pressure than the cut-oil valve, say from 90 to 125 pounds per square inch.

The cut-off valve I is-preferably made of very I when valve 13 is on its seat.

The oil escaping into passage 43 may be returned to the fuel supply tank by means of a of a passage 32 (Fig. 3) made up of a series of registering holes formed in plates I3, 23, 2i and 23, indisc 22 and in disc 23 and the gaskets therefor, which holes are coaxial and communi cate with the hole 4i above described. When a separate return pipe connected to port 34 is used. then theouter end of passage 32 will be closed. as by a plug 33, threaded'lnto cover 23. When an internal by-pass is used, the port 34 is closed by a plug and 'the plug 33 is removed.

' Access to plug 33 may be had by removing cover l4. Access may also be had in the same manner for adjusting the tension of the cut-oi! valve ,wall 11 and an adjustable seat 3| in cover plate spring I3 by turning the threaded spring seat 33. The adjustment of spring 33 of the pressureregulating valve may be varied without removing cover 14. A plug 34 is provided in cover I! and by removing this plus. access may be had for turning the adjustable nut 3| which varies the tension of spring 33. It is seldom necessary to adiust the tension of the spring of the. cut-oi! valve. Hence, the adjustment therefor need not be accessible from outside cover [4.

The bellows 31 is vented to the inlet chamber l3 by means of a hole 33 (Fig. 9) formed in plug 33. The bellows I3 is also vented to this chamber by a hole 33 (Fig. 1) formed in cover plate 23. By these vents the force which is due to liquid pressure and which acts internally on these bellows and the valves is exactly equalized. Also,

because of the vents, pressure cannot build up.

in the pump and cause an unsafe condition. In the event, that a bellows breaks. the leak is to the suction side of the pump. This leak establishes a. by-pass for the pump. If the leak is large enough. the pressure in chambers 33 and 34 will be reduced to such an extent that both valves will close. The pump will then idle and cannot build up any substantial and dangerous pressure.

In the end plate I! (Fig, 3) and in the disc 25 are registering holes 43' which align with the passage 43 leading to the pressure gauge. The hole 43' in plate I! opensinto the pressure 0 amber 34 which houses the bellows for the sure-regulating valve and thus to-the pressure side of the pump.

The bearings and faces of the gears 33 may be lubricated by the pumped oil, as by means of a pair of passages 31 (Fig. 6) in plate 2 I. Each passage 31 leads. from an inlet port 33 radially to the stud receiving recess in plate 21 of the gear it is intended to lubricate. One such passa e 31 is shown in section in Fig. 1.

The disc 23 (Fig. 1) carries a bellows 33 located coaxiaiiy thereof and extending into the recess 41 in housing member II. This bellows carries a seal ring element 33 which engages a rotary seal ring element 33 threaded and sealed on shaft 23. A spring 3! acts between disc 25 and "element 33 to urge the latter against element 33.

'-This passage is sealed off from the rest of the inlet chamber so that no fluid can enter or leave the chamber when plug 34 is removed to adjust turned directly to the inlet chamber 16 by means the spring seat 3|. In the ease of a gravity feed (one-pipe) system. oilwould fiow out from chamber 13 on removal of plug 34,- except for seal 33.

res-

In the case of a suction feed from a low-level tank in a two-pipe system, the removal of plug 84 would break the vacuum and cause the pump to lose its prime, if the seal 93 were not provided.

Referring to Figs. 11 and 12, the intake for the pump may be arranged so that the gears 50 and their bearings may be lubricated by the fuel oil in the course of its travel to intake port 55. Thus, instead of the single intake passage ll in pump plate ll. two intake passages 96 may be provided in end plate 2|. These passages lead from the lowest point in the periphery of plate 2| upwardly one to eachof the wells 91 in which the gear studs 54 loosely fit. Oil from these wells flows by way of the grooves U to the intake port 85. As distinguished from the plan of lubrication above described for gears 50, the present plan maintains the oil in circulation and keeps the wells 91 sweat free from sediment.

The pumping unit is shown as adapted for connection to a low-level supply tank by a suction pipe, connected to port 32, and a return pipe connected to port 34. Operation of the motor will rotate the gears Ill and create a vacuum to draw oil up through the suction pipe and into chamber I, where the oil will rise to a level above the intake end of suction passage 51. Oil entering this passage will eventually reach the gears 50 and be carried around in the tooth spaces of these gears to outlet ports 56, whence the oil will fiow through hole I to groove 02 and thence to chambers 63 and I4. When sufllcient pressure has been built up in chamber II, the cut-oil valve II will open and allow oil to flow through passages 38 and 11 and port I! to the nozzle of the oil burner. When the oil in chamher 84 reaches a somewhat higher pressure, valve 18 will open and allow excess oil to pass by passages and ll to port 34 and thence by the return' pipe to the low-level tank.

To adapt the unit for a gravity-feed, one-pipe system, the port 34 is plugged and'the plug I3 is removed. Operation of the pump will draw in liquid from the supply chamber l6 and force it to the burner port 33, as before, but on opening of the pressure-regulating valve II, the

excess oil will be carried through passages 42, 40, II and 82 back to the inlet chamber it, these passages forming an internal by-pass for the pump.

The pump is especially quiet in operation. Contributing to this result is the relatively low speed of the gears 50 due to the reduction effected by the drive from pinion 52. Reduction in pulsations in the oil stream is also a factor in reducing noise. The oil is fed in pulses by a gear pump. A large number of small teeth in the gears 50 produce a larger number of smaller pulses per revolution than would be the case'if the gears had a smaller number of larger teeth. A better and smoother stream, more nearly approximating uniform flow, is had. A very substantial factor in reducing noise is the avoidance of trapping of the oil and the subsequent compression of the oil between the teeth of gears ill at the time when they near and pass through full mesh position. Oil thus trapped will be placed under heavy pressure, resulting in a hydraulic hammer noise and also in an undesired thrust on the studs of the gears which tend to spread them apart and produce rapid wear and higher power consumption. Reduction of the land between the port I! and BI, to the extent shown in Fig. 10, prevents any oil from being trapped between the teeth until they do reach the full mesh position. The use of relatively pointed teeth reduces the spaces available to hold 011 near full mesh positions of the gears. The oil is fed to the tooth spaces of the gears simultaneously from both ends and there is a relatively large amount of time for these spaces to fill, which helps in securing quiet operation. Oil once fed to the tooth spaces is retained therein. against the action of centrifugal force, by the closely-fitting cylindrical walls of the gear cavities ll, which extend as far around as possible toward full mesh position, where the spaces empty into the discharge ports I. The highpresure zone is concentrated in a relatively small area to avoid undue pressure on the studs of the gears. The pump operates under a high vacuum condition without producing noise. It does not become noisy when air is allowed to pass into the pump with the oil.

In the event that the fuel supply becomes exhausted and no more fuel enters the chamber It, the level of oil in the latter will drop until the intake end of the suction passage 51 becomes uncovered, whereupon fiow of fuel from the pump will oon cease. When the supply tank has been replenished,fthe pump will readily prime itself because some of the oil contained in the filter II, which is made of absorbent material, will seep out into the chamber and raise the level until the intake end of suction passage 51 is covered.

Thus. the pump will be primed and enabled to pump liquid and establish a sufllcient vacuum in the supply pipe to draw up oil from a lowlevel tank. By the use of the term "absorbent material," I mean any material that will retain oil for the purpose described whether the material is non-metallic as above described or metallic. Finely divided metal, such as steel wool or the like will retain in the interstices of the mass suillcient oil for the purpose.

The fuel unit is characterized by a very compact arrangement of parts which enables the pump, filter, pressure-regulating and cut-oil valves to be contained in a small housing no larger in diameter than the motor casing and without the protuberances or projections which have heretofore been customary. The outer housing may be substantially cylindrical and of uniform diameter from end to end, presenting a smooth, unbroken, and streamlined appearance. The motor and fuel unit combined appears hardly any diiferent than an ordinary motor itself. The unit is slightly longer than the end plate of the ordinary motor casingbut this is hardly noticeable.

Contributing to the compactness is the construction oi the pump casing proper. The pump gears 50 are oifset from the center of plate 20 because of the drive from pinion 29. Because the gears 60 are thus offset and because the driving pinion is small, sufficient room is left for the chambers," and 84. The four holes 5|, 5|. .3 and N are distributed over the area of the plate 20 in a circular series about the axi of the plate. A large part of the area of the plate is thus usefully employed. By locating the valves and valve chambers with their axes paralleling the axes of the pumping elements 50, the described compact arrangement within a cylindrical casing is made possible. The arrangement allows the pump casing to be located coaxially of the motor casing which is desired, Then the filter H can also be located coaxially with the motor casing and with the inner periphery thereof closeto the outer the motor casing. By arranging the valves and pump gears and filter in parallel and overlapping relation, endwlse space is saved so that the endwise extension of the motor casing, necessary to house the fuel pumping unit, is reduced to a minimum. As will be clear from an inspection of Fig. 1, the many parts have been packed into a space of relatively small volume within the end portion of an electric motor.

The fuel unit'is easily serviced. If adjustment I of the pressure-regulating valve only is required,

this may be effected by merely removing plug 84. By removing cover it, access is had to the filter which may easily be removed, cleaned and re-' placed. Also, access is had for adjustment of the- Removal of the pump unit may cut-off valve. then be effected simply by removing the four cap screws 26 and drawing the pump casing axially outward to pull it ofl the driving shaft 29. The pump parts are still held together as one unit by the two cap screws 24. A new pump unit may bequickly substituted or. if necessary or desired, the pump unit may be opened up by simply removing the two cap screws 14. d

The invention provides a fuel pumping unit which is quiet and elllcient in operation, easy'to' service, economical to manufacture and which embodies a compact arrangement of parts enabling all necessary parts of the unit to be housed within one end portion of the housing of an electric motor,

What I claim is:

1. A fuel supply unit for oil burners, including a casing made up of a pump plate having holes therethrough, first and second side plates located one on each side of the pump plate for closing said holes, rotary pump elements housed in the holes of the pump'plate and between the side plates, aligned openings extending through the first side plateand the pump plate and forming a chamber closed at one end by the second side plate, a disc carrying a bellows, the latter extending into said chamber and closing the other end thereof,'a fourth plate between which and the first side plate said disc is located, means for clamping said plates and disc together, a valve seat provided in the second side plate, a valve .cooperating with said seat and movable with the bellows, and a spring inside the bellows and between the fourth plate and the valve-engaging part of said bellows.

2. A fuel supply unit for oil burners, comprising, an outer housing made up of body and cover members aifordingbetween them an inlet chamber, an inner housing secured to one wall of the body member, a rotary pump housed .in the inner housing; the inner housing having a suction passage extending from the inlet chamber to said pump. a valve chamber, a passage connecting the outlet of the pump to the valve chamber, and an outlet from the valve chamber, a pressure regulating valve housed in the valve member and controlling said outlet, an imperforate bellows mounted in said valve chamber formovement in one direction by pressure of the pumped fluid and connected on one side to the valve to open the same when moved in said direction, and a spring acting on the other side of the bellows to move it in the other direction and close th valve,- said inner housing provided with a passage for connecting the interior of the bellows to said inlet chamber, whereby should the bellows break, a leak path to said chamber is establishedforming a.

i0 by-pass for the pump to prevent the building up of excessive pressure in the inner housing.

3. A fuel supply unit for oil burners, comprising, an outer housing made up of body and cover members aflording between them an inlet chamher, an inner housing secured to one wall of the body member, a rotary pump housed in the inner housing; the inner housing having a suction passage extending' from the inlet chamber to said pump. two valve chambers, a passage connecting the outlet of the pump to each valve chamber and an outlet from each valve chamber, a pressure regulating valve and a cut-oil valve mounted one in each valve chamber and controlling the outlet thereof, an imperforate bellows in each valve chamber and movable in one direction by the pres-A sure of the pumped fluid, the bellows in each valve chamber being connected on one side to the valve in such chamber and operable when moved in said direction to move the valve to open the outletf of such chamber, and a spring in each chamber to move the bellows in the other direction and cause the connected valve to close the outlet of, such chamber, said'inner housing provided with a passage for connecting the interior of each bellows to said inlet chamber, whereby the pressure within each bellows is equalized and whereby on fracture of the bellows the leak therethrough unloads the pump. l

4. A fuel supply unit for oil burners, comprising, an outer housing made up of a body member and a cover member, said members affording between them a fuel supply chamber; a pump casing madeup of a pump plate having holes ex-. tending therethrough, first and second side plates located one on each side oi the pump plate and closing said holes, and a cover plate adjacent the second side plate: said casing being fastened to an end wall of the body member with the first side plate adjacent thereto, a drive shaft mounted in said end wall and extending through the first side plate and into the pump plate, interengaging rotary pumping elements mounted in the openings .of the pump plate, registering openings extending through the second side plate and the pump plate and forming a chamber closed by the cover plate, an .outlet passage extending from th last-named chamber through the first side plate and said body member, a valve in said lastnamed chamber forv controlling the outlet passage, said casing having a passage connecting the pressure side of said pumping elements to said chamber and a passage connecting the suction side of the pumping elements to said fuel supply chamber, and means in said chamber responsive to a predetermined pressure of the pumped fuel for opening said valve and outlet passage.

5. A fuel supply unit for oil burners, comprising, an outer housing made up of a body member and a cover member, said members affording between them a fuel supply chamber; a pump casing made up of a pump plate having holes extending therethrough, first and second side.

plates located one on each side of th pump plate last-named chamber through the first side plate and said body member, a valve in said last-named chamber for controlling the outlet passage, said casing having a passage connecting the pressure side of said pumping elements to said chamber and a passage connecting the suction side of. the pumping elements to said fuel supply chamber, a movable wall in said chamberactuated in one direction by the pressure of the pumped oil to open said valve, a spring for actuating said wall in the other direction, and an adjustable seat for said spring mounted in said cover plate.

6. A fuel supply unit for oil burners, comprising, an outer housing made up of a 'body member and a cover member, said members affording between them a fuel supply chamber; a pump casing made up of a pump plate having holes extending therethrough, first and second side plates located one on each side of the pump plate and closing said holes, and a cover plate adjacent the second side plate; said casing being fastened to an end wall of the body member with the first side plate adjacent thereto, a drive shaft mounted in said end wall and extending through the first side plate and into the Pump P interengaglng rotary pumping elements mounted in the openings of the pump plate, registering openings extending through the second side plate and the pump plate and forming a chamber closed by the cover plate, an outlet passage extending from the lastnamed chamber through the first side plate and said body member, a valve in said last-named chamber for controlling the outlet passage, said casing having a passage connecting the pressure side of said pumping elements to said chamber and a passage connecting the suction side of the pumping elements to said fuel supply'chamber, a disc clamped between the second side plate and cover plate and having a bellows extending into said chamber and engaging said valve, a spring within the bellows for moving the latter to close the valve, and an adjustable seat for said spring mounted in the cover plate.

7. A fuel supply unit for oil burners, comprising,.an outer housing made up of a body member and a cover member, said members affording between them a fuel supply chamber; a pump casing made up of a pump plate having holes extending therethrough, first and second side plates located one on each side of the pump plate and closing said holes, and a cover plate adjacent to the second side plate; said casing being fastened to an end wall of the body member with the first side plate adjacent thereto, a drive shaft mounted in said end wall and extendingthrough the first side plate and into the pump plate, interengaging rotary pumping elements mounted in the openings of the pump plate, registering openings extending through the second side plate and the pump plate and forming a chamber closed by the cover plate, a burner outlet passage, a return passage extending from the last-named chamber through the first side plate and into and through said body member, a valve in said last-named chamber for controlling the return passage, said casing having a passage connecting the pressure sid of said pumping elements tosaid burner outlet passage and to said last-named chamber and a passage connecting the suction side of the pumping elements to said fuel supply chamber, and means in said chamber responsive to a predetermined pressure of the pumped fuel for opening said valve and outlet, said plates having registering holes therethrough forming an internal by-pass communicating at one end with said return passage in said body member and at the other end with said fuel supply chamber, and means for closing the return passage when the internal by-pass is desired and for closing the internal by-pass when the return passage is desired.

8. A fuel supply unit for oil burners, comprising, a driving motor having a casing and including an end member chambered in its outer end, a cover member closing said outer end and cooperating with the end member to form a fuel supply chamber; the exterior peripheral contour of said casing, end and cover members being substantially uniform and presenting a substantially smooth unbroken streamlined surface: fuel inlet, burner outlet and return passages formed in said end member; a pump casing secured to the latter, pumping elements in said pump casing connected to be driven from said motor, a pressure regulating valve housed in the pump casing;

the latter having a suction passage from the fuel supply chamber to the pumping elements, a discharge passage from said elements to the burner outlet, and a passage from said elements to said return passage and controlled by said valve; :1 filter in the fuel supply chamber surrounding the pump, said fuel inlet passage opening into the fuel supply chamber at a point outside the filter and said suction passage having its intake end inside the filter.

9. A fuel supply unit for oil burners, comprising, a driving motor having a casing and including an end member chambered in its outer end, a cover member closing said outer end and cooperating with the end member to form a fuel supply chamber; the exterior peripheral contour ofsaid casing, end and cover members being substantially uniform and presenting a substantially smooth unbroken streamlined surface; fuelinlet, burner outlet and return passages formed in said end member; a pump casing secured to the latter, pumping elements in said pump casing passage opening into the fuel supply chamber at a point outside the filter and said suction passage having its intake end inside the filter.

10. A fuel pumping unit, comprising a casing made up of a plurality of plates fastened together face to face, an intermediate plate of the series having two intersecting cylindrical openings through it extending from one face to the other, inter-engaging rotary pumping elements mounted one in each of said openings, the abutting plates on opposite sides of said intermediate plate closing said openings, said casing having pump inlet and outlet ports, said casing also having a cylindrical chamber with its axis paralleling the axes of said elements and closed at its ends by two of said plates together with a passage connecting the chamber and pump outlet and an outlet passage for the chamber, a valve for controlling said outlet and housed in said chamber, and means also housed in said chamber and responsive to the as the pressureof' the pumped fuel rises above or falls below a predetermined value.

11. A fuel pumping unit, comprising a casing made up of a plurality of plates fastened together face to face, an intermediate plate of the series having two intersecting cylindrical openings through it extending from one face to the other, inter-engaging rotary pumping elements mounted one in each of said openings,

termediate plate closing said openings, said casing having pump inlet and outlet ports, said casing also having two cylindrical chambers each disposed with its axis parallelingthe axes of said elements and each closed at its ends by two of said plates, said casing having a passage connecting the pump outlet to each of said chambers and separate outlet passages for said chambers, a burner cut-off valve housed in one chamber and controlling the outlet passage of that chamber, means also housed in the last-named chamber and responsive to the pressure of the pumped fuel for actuating said valve opening and closing the same as the pressure of the pumped fuel exceeds or falls below a predetermined value,

a by-pass valve housed in the other chamber and controlling the outlet passage of that chamber, and means also housed in the last-named cham-. her and responsive to the pressure of the pumped fuel for actuating the second-named valve opening and closing the same accordingly as the pressure of'the pumped fuel rises above or falls below another and higher predetermined value.

12. A fuel pumping unit, comprising a cylindrical casing made up of a plurality of plates elements mounted one in each of said openings,

the abutting plates on opposite sides of said intermediate plate closing said openings, said casing having pump inlet and outlet ports, said casing also having two cylindrical chambers each disposed with its axis paralleling the axes of said elements and each closed at its ends by two of said plates, said chambers including openings passing through, said intermediate plate, the four openings in said intermediate plate being distributed in angularly spaced relation around the axis of said casing with the two pump openings and the two chamber openings located on opposite sides of a diameter of said casing, said casing having a passage connecting the pump outlet to each of said chambers and separate outlet passages for said chambers, a the abutting plates on opposite sides of said in- 1 burner cut-off valve housed in one chamber and controlling the outlet passage of that chamber, means also housed in the last-named chamber and responsive to the pressure of the pumped fuel for actuating said valve opening and closing the same as the pressure of the pumped fuel exceeds or falls below a predetermined value, a by-pass valve housed in the other chamber and controlling the outlet passage of that chamber, and means also housed in the last-named chamber and responsive to the pressure of the pumped fuel for actuating the second-named valve opening and closing the same accordingly as the pressure of the pumped fuel rises above or falls below another and higher predetermined value.

VIRGIL E. DUEMLER.

REFERENCES CITED The following references are of record in the Number Name Date 1,103,053 Kiefer July 14, 1914 1,787,700 Persons Jan. 6, 1931 2,036,028 Evans, Jr Mar. 31, 1936 2,079,922 Owen May 11, 1937 2,090,035 Fellows Aug. 17, 1937 2,108,771 Laird Feb. 15, 1938 2,119,740 Fellows June 7, 1938 2,189,614 Parker Feb. 6, 1940 2,209,856 Smith .et a1. July 30, 1940 2,233,709 Osborne Mar. 4, 1941 2,309,803 Wahlmark Feb. 2, 1943 2,350,502 Garday June 6, 1944 2,354,992 Gottlieb Aug. 1, 1944

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