US3394655A - Combined centrifugal and jet type fluid pump - Google Patents

Description

July 30, 1968 R. J. BROWN 3,394,655

' COMBINED CENTRIFUGAL AND JET TYPE FLUID PUMP Filed Sept. 19. 1966 2 Sheets-Sheet l 0%; L3 I HcHARDJ BROWN P a 2 av W 6. KM ATTORNEY July 30, 1968 R. J. BROWN 3,394,655

COMBINED CENTRIFUGAL AND JET TYPE FLUID PUMP Filed Sept. 19. 1966 v 2 Sheets-Sheet 2 V I 22L I ll /23 I l |l /6 Z IZ /P/CHARO J Bww/v M B) H6 4 F g 5 ATTORNEY United States Patent '0 3,394,655 COMBINED CENTRIFUGAL AND JET TYPE FLUID PUMP Richard J. Brown, 8758 Edgehill Road, Mentor, Ohio 44060 Filed Sept. 19, 1966, Ser. No. 580,289 9 Claims. (Cl. 103-5) ABSTRACT OF THE DISCLOSURE A centrifugal pump, operable in any position and designed for pumping fluids over a wide viscosity range. It incorporates an impeller and scroll assembly plus a jet and venturi arrangement carried by the scroll. The jet is fed from the high pressure region of the pump and discharges along the central axis of the venturi, which latter has a very short axial dimension. The pumped fluid is brought to the venturi in a symmetrical pattern about the jet. Flow directors or vanes are incorporated in the pump chamber to give a controlled turbulence to the pumped fluid and assure entrainment and ultimate discharge of any entrapped air. The jet inlets originate in a region remote from the axial centerline of the pump and thus assure delivery of liquid to the jet regardless of the space position or orientation of the pump. The passageways for the jet and pumped fluid are contained in a jet member which is removably mounted on the venturi. The pump is designed to offer very low resistance to flow therethrough when it is not in operation.

This invention relates to a fluid type pump of the variety involving the combination of centrifugal and jet type action. More specifically the invention relates to an improved jet and venturi construction and its association with the centrifugal pump scroll.

The subject invention concerns auxiliary pumps that are designed for the circulation of coolant fluid in ground vehicles of the internal combustion type during shutdown or stand-by periods; although the pump is capable of use in pumping other fluids, for example, liquid fueis. Liquid cooled engines generally have a main pump to circulate the coolant during operation of the engine whereby the heat generated in the cylinders is carried by means of the coolant to a radiating surface to be dissipated; in this fashion the vehicle engine is maintained at a safe operating temperature. However, when such engines are not in operation, i.e., at rest, and are subjected to sub-freezing temperatures the coolant therein may freeze and cause damage to the engine and associated parts; further, start-up difliculties may be encountered. To overcome these eflects, such engines, particularly those of the military class (and other equipment subjected to very low environmental temperatures), are supplied with a coolant heater that operates during the shutdown period of the engine and provides the necessary heat to prevent such freezing effect. In order to properly assure that all parts of the engine and apparatus are adequately heated during this shutdown period, it is necessary to employ a supplemental or auxiliary circulating pump means; this auxiliary pump is generally driven by a motor that'derives its electrical power from the storage batteries of the vehicle. It is to this latter problem that this invention is directed, and more specifically it is an object of this invention to provide such an auxiliary coolant circulating pump for use with an engine heater that will efliciently circulate the heated coolant to all parts of the system. As a practical matter, the circulating pump must operate efliciently over a wide range of operating temperature, must have a low power consumption, must be relatively small in size, must be readily serviceable, and be designed to permit circulation therethrough during normal operation of the vehicle engine.

Thus, it is an object of this invention to provide a circulatory pump of extremely compact design and light in Weight, involving a construction employing a combined centrifugal and jet action in which the nozzle, venturi and centrifugal scroll are combined as a unit and wherein such combination has a very short longitudinal dimension. A further object of the invention is to provide a combined centrifugal and jet type pump having -a high capacity, able to operate at relatively high output pressure, having a relatively low drive stream to pumping stream ratio and capable of operating at relatively high efliciency over a wide range of pumped fluid viscosities.

A further object of the invention is to provide a circulatory pump for land vehicles and other installations wherein the pump is readily serviceable. Since the apparatus of the subject invention is employed under very adverse atmospheric and weather conditions, including very low temperatures, it is an object of the invention that workmen shall be able to readily disassemble and service the apparatus under such conditions with a minimum of equipment and tools.

Another object is to avoid heavy power drain on the vehicle electrical system, and this is accomplished in that the subject apparatus is designed to be self-protecting by virtue of the ability to relieve itself of gross overloads due to clogging of channels in various parts of the vehicle system and/or due to ice accumulation or sludge accumulation in the fluid being pumped.

It is a further object of the invention to provide a circulating pump which is readily adaptable to, and employable with, existing equipment; for example, one which can be driven from the same motor that drives the aforementioned heater.

More specifically it is an object of this invention to provide a novel jet or nozzle design in conjunction with an improved venturi design for a fluid pump, wherein a flow of drive fluid is symmetrical to and through the jet or nozzle of the equipment and wherein the fluid to be pumped is likewise symmetrically drawn into the venturi.

A further object of the invention is to provide a jet plate structure which permits proper spacing of the jet from the venturi and also permits symmetrical and adequate flow of pumped fluid and the driven or jet fluid.

A still furter object of the invention is to provide a drive stream for the jet or nozzle which is at pressure essentially equivalent to the delivery pressure at the outlet of the centrifugal pumping means; and further to provide that the drive stream shall be taken from a multiplicity of points that are subjected to the output pressure of the circulator pump means.

Still a further objective is to provide a combined jet and centrifugal pump having means for preventing cavitation of the pumped liquid and to assist in purging the pump of air that may be entrained in the pumped fluid; this means is designed to create a controlled turbulence in the high pressure region of the pump chamber.

The foregoing objects are attained in the embodiment of the invention illustrated in the accompanying drawings and while I shall proceed to describe this embodiment in detail I wish it to be understood that I do not limit myself thereto further than is required by the terms of the appended claims.

In the drawings, wherein like parts are designated by like reference characters thhroughout several views,

FIGURE 1 is a vertical, longitudinal, sectional view on an enlarged scale of the pump of my invention and parts of the motor to which it is mounted;

FIGURE 2 is a transverse offset sectional view along line II-II of FIG. 1 illustrating the constructional detail of the inlet chamber and part of the venturi section;

FIGURE 3 is a transverse offset sectional view along line IIIIII of FIG. 1 to illustrate the impeller construction and details of the flow directors;

FIGURE 4 is a bottom plan view of the orifice plate, i.e, a view from the pump inlet end;

FIGURE 5 is a sectional view along offset line VV of FIG. 4, to illustrate the nature and placement of the passageways for the pumped and driven (or jet) streams;

FIGURE 6 is a sectional view through along line VIVI of FIG. 2 showing only the construction details of the pump housing.

FIGURE 7 is a schematic view illustrating the use of my circulating pump in connection with a coolant heater and associated vehicle engine.

According to the present embodiment of the invention, and with particular reference to FIG. 1, my pump cornprises a pump housing 10 that is mounted on a mounting plate 30 to enclose a centrifugal pump means comprising an impeller 40 operating within a scroll casing 50; liquid is fed from an intake chamber through a nozzle plate 80 and a venturi section 60 to the impeller. A minor amount of the liquid discharged from the scroll 50 is recirculated through a jet nozzle 84 into the stream of liquid entering the venturi 60. Pumped liquid leaves at outlet 18.

Turning now to a detailed description of the invention, my pump consists of a housing 10 formed generally of cup shape to enclose a pump chamber within a sloping peripheral wall 11 and an end wall 12. A threaded inlet 13 communicates through a tunnel 14 with a centrally disposed inlet chamber 15, enclosed by an arcuate wall 16 in the end wall 12. An outlet from the pump chamber is formed at the convergent end of the housing 10 by a port 17 leading from the pump chamber 20 and communicating with a threaded outlet 18. The divergent or open end of the pump housing 10 is provided with a thickened rim 21 that has a cylindrical surface 22 machined about its inner diameter to a substantial depth terminating in a small circumferentially extending rib 23. The side walls 11 are provided with inwardly projecting tapered bosses or flow directors 25 at circumferentially spaced points about the wall 11; these flow directors extend from the rib 23 toward the convergent end of the housing and terminate by fading into the convergent wall 11 in a point opposite the upper surface of the inlet wall 16.

The pump housing 10 is adapted to be mounted on a mounting plate which closes the open end of the housing and for this purpose is provided with openings 26 (FIG. 6) to accommodate mounting screws 27 that are threaded into a flange 31 of the mounting plate (FIG. 3). This mounting plate is essentially cylindrical in form having a barrel section 32 terminating at its ends, respectively, in wide circumferential flanges 31 and 33. Flange 31 has a projecting integral circumferential sleeve 34 having an outer diameter slightly less than the diameter of the machined surface 22 on the housing 10. A circumferential notch is machined in the outer surface of this sleeve 34 to accommodate an O-ring 35 that is designed to effect a seal between the mounting plate 30 and the pump housing 10 when the parts are assembled.

Flange 33 of the mounting plate has a flat machined surface and is adapted for mounting against the end of a motor housing M by use of a series of circumferentially spaced mounting screws 37. The mounting plate 30 is adapted to be secured to the end of a motor M concentric with the axis of the motor shaft 70. To this end the hub or barrel 32 is provided with a central bore divided into two sections by a circumferentially extending rib 39; the bore 39a on the motor side is of a diameter suflicient to clear the motor shaft boss 71 and on the other side the bore 39]; is of a diameter sufficient to receive a seal means 72 to be described later.

The end of the motor shaft 70 is reduced in section and threaded with a hand of appropriate direction to accommodate a correspondingly threaded portion 41 in the hub 42 of the impeller 40. The hub is tightened on to the shaft so that shoulder 43 bears tightly against the corresponding portion of the shaft 70; the length of the shaft and the depth of the threaded portions are chosen such that the impeller 40 clears the face of flange 31 on the pump housing side. With reference to FIG. 3, it will be seen that the impeller is of the reverse blade variety adapted to throw the liquid off the back of the blades 44. In this view (FIG. 3), the direction of rotation of the impeller 40 is clockwise as indicative by the arrow. The impeller 40 is provided with an inlet opening 45 defined by a projecting cylindrical flange that extends upstream from the face 46 of the impeller.

Impeller 40 is enclosed within a volute or scroll 50- that surrounds the impeller and is mounted to the pump housing side of the flange 31 by screws 51 that pass through cars 52 made integral with the wall 53 of the scroll 50. Scroll 50 has discharge openings 54 (as best seen in FIG. 3) that communicate directly with the pump chamber 20.

Formed integral with the scroll housing 50 is a short venturi comprised of two main sections, a body portion 61 and an upstream flanged portion 62. A central opening of carefully designed shape extends through these sections and lies in axial alignment with the impeller 40. It originates upstream as an axially enlarged opening 62a that reduces in cross sectional area through a radi'used portion or inlet 63 to a throat section 64 with a short land and thence enlarges along a divergent wall 65 to form an outlet of a size approximately equal to that of the inlet for the impeller 40. A seat 66 is provided in the body portion 61 for the reception of a lip type seal 73 that is employed to seal off the high pressure space within the scroll 50 from the intermediate pressure region of the venturi outlet 65. The circular flange 62 is provided with spaced threaded openings that receive screws 68 which hold an orifice plate tightly against the upstream surface of the flange 62 in a manner now to be described.

Interposed between the inlet chamber 15 and the venturi 60 (and carried by the latter) is the above-referred-to orifice plate or jet member 80. With reference particularly to FIGS. 4 and 5, it will be seen that this member is in the general shape of a disc 81 having two distinct sets of fluid passageways, 82 and 83. The passageways 82 extend radially along radii of the disc and terminate at a central jet opening 84 that opens through a conical nozzle at the central axis of the disc. The other set of passageways 83 pass through the disc parallel to the axis thereof at spaced points about the aforesaid nozzle 85. The outer limits of the openings 83 are within the confines of the venturi inlet chamber 62a. The radial passageways 82 provide multiple inlet means for fluid from the high pressure region of the pump chamber 20' and feed the jet 84; the fluid to be pumped passes from inlet chamber 15 through the aforesaid passageways 83 where it is carried through the venturi by means of the jet action at the throat 64. In order to seal off the high pressure region 20' from the inlet chamber 15 the nozzle plate 81 is provided with a projecting cylindrical sleeve 88 that carries a ring seal 89 in a notch within its walls so that a tight seal is effected between the sleeve 88 and the wall 16 of the inlet chamber.

Thus, it will be seen that the pump housing encloses all of the working parts of the pump but is supported separately from and removable independently of the jet-venturi-scroll means. Further, it should be noted that the enclosed region is divided into several zones of different pressure: for example, the inlet chamber at negative pressure is sealed from the high pressure dis charge region by means of the aforesaid seal 89, the outlet from the venturi section 60' at intermediate pressure is sealed from the high pressure region of the scroll '50 by means of the lip seal 73 seated in pocket 66 and bearing respectively against the side of the scroll 50 and the inlet flange 45 of the impeller. The other side of the impeller has aspecial rotary sealing means comprising a ring 72a that bears against the outer surface 48 of the impeller 40 about hub 4 2 and is connected through a flexible diaphragm 72 containing a springlike means that has its seat at a second ring 72b in the hub 32this latter seal prevents escape of fluid into the region about the motor shaft.

Whereas the pump housing 10 encloses all of the working parts of the pump, none of the principal parts of the pump (such as jet, venturi or scroll) are attached thereto so that removal of this housing exposes all such working parts and makes them readily accessible. Thus, if it is necessary for any reason to change the nozzle plate 80, that plate can easily be dismounted from the venturi section 62 and replaced. Likewise, if access is needed to the impeller 40, it is merely necessary to remove the entire scroll-venturi-jet plate assembly by removal of mounting screws 51. This is one of the principal advantages of the subject invention; namely, that field service is readily accomplished because all parts are easily accessible and their working relationship accurately ascertainable.

Reference to FIGURE 7 will show the manner in which the pump of my invention is commonly employed. For example, this figure illustrates an engine block E having a radiator section R connected thereto by ap propriate conduit lines C; thus, when the engine is in operation, a pump associated with the engine circulates the coolant between the block E and the radiator R to keep the engine at proper operating temperature. In order to heat the engine during standby period, coolant is drawn from the engine block B through lines L1 and L2 (which may include a heat exchange coil 0 in series therewith) to the pump P of this invention from which the fluid is then pumped under pressure into the heater H through line L3. The same motor M may drive the coolant heater H and furnish motive power for my pump P. Whereas the pump P is shown to be driven by the same motor M as employed with the heater H, it may also be driven by a separate motor and mounted at any convenient location about the engine. It will be obvious that a pump used in the installation described has to satisfactorily pump fluid when the temperature thereof may be extremely low, as for example -65 F. and also pump that same fluid when it is much less viscous and at a higher temperature which may be as high as 250 F. In addition, it is important that the auxiliary heating system allow a limited flow of coolant therethrough when the vehicle engine is in operation; this is necessary in order to protect the heater, pump and associated parts from freeze up when exposed to low ambient temperatures. The design of my pump permits this free circulation, since there are open passageway-s therethrough which assure such flow. 1

The operation of my pump will be apparent from the above description. Fluid to be heated passes from the engine block E (or from any other source) to the pump inlet 13 and enters the inlet chamber 15; this fluid is indicated by the dot-dash arrowed lines in FIG. 1. From this point it travels through the orifice plate openings 83 into the venturi inlet 62a, thence through the throat 64 and into the inlet 45 of the impeller 40; the impeller blades 44 pick up' the fluid and discharge it at high velocity through the scroll discharge openings 54 (FIG. 3) into the pump chamber 20 from whence it flows through channel 17 to outlet 18. The output stream of pumped fluid is shown by solid line arrows in FIG. 1. A small amount of the liquid reaching pump chamber 20 is forced'into the radial passageways 82 in the orifice plate or jet member and travels to the centrally disposed jet or nozzle 84 where it is ejected under presure into the venturi throat 64. The flow of this recirculated stream is indicated by dashed line arrows in FIG. 1. By a well-known mechanism, the ejection of this stream at fairly high velocity creates a jet action and the momentum of the jet stream is transferred to the stream of pumped fluid which reaches the venturi region by means of the route previously described. This jet action greatly increases the flow of pumped fluid to the impeller intake 45 and the impeller is designed to handle this increased volume and discharges it into the pump region 20. The principal reason for the introduction of the jet action is to assure a maximum volume of liquid flow to the impeller 40 and thereby increase the delivery rate of the impeller. In conventional installations wherein only centrifugal pump action is relied upon to circulate fluid, it has been found that when the fluid to be circulated is highly viscous (as for example at very low temperatures) there is a tendency .for the liquid to cavitate, that is to form a void at the inlet to the impeller. This naturally reduces the delivery of the pump and in addition is liable to create an undesirable condition because of excessive vibration and wear. If the condition becomes aggravated enough to interrupt flow through the pump this may result in a hazardous condition at the heater where flashing of certain inflammable coolants could occur. It has been found that the pump of this invention is able to deliver many times the amount of fluid at temperatures of 65 F. that a simple centrifugal pump delivers. In addition, the combined jet and centrifugal action permits the pump to be used in any position, for example, the inlet may be below, above, level with or in any other position with respect to the impeller means.

The flow directors 25 also operate to reduce the tenency toward cavitation by breaking up the circular flow of liquid in the chamber 20, and by assuring intimate admixture of any air entrapped in the chamber 20 with the pumped liquid. Thus, the purpose of these directors is to interrupt the circular flow of fluid as it is discharged from the centrifugal scroll 50. By this means a proper turbulence is imparted that assures delivery of liquid into the radial pasageways 82 of the nozzle plate.

It thus appears that there is required a balance of three fundamental features for optimum operation of the pump of this invention which when obtained assure a decidedly higher efliciency and output over conventional forms; these features are: A balanced jet action, a short venturi section and turbulent flow in the high pressure region.

To compare the operation of the subject pump with pumpmg means of usual design, I have shown the table performance data of my invention compared with a conventional centrifugal typ'e pump and with a positive displacement-type pump. Referring to this table, it Will be seen that delivery pressure and delivery volume are compared when engine coolant is pumped at two different temperatures (wherein the viscosity is different) and a further comparison is shown for the pumping of water at normal room temperature. It will be seen that my pump 1s capable of delivering fluid at a relatively high rate regardless of temperature and regardless of viscosity. Furthermore, my pump will deliver at fairly uniform pressure over wide temperature range (comparing the outlet pressure at 65 F. with the pressure at room temperature) which means that the pump is delivering uniformly over a wide vlscosity range.

l Speed decreases 2 Speed decreases 40%.

While the exact theoretical relationships between the various elements of my pump are not understood in detail, I have found that the following dimensions and relative spacings of the various elements have proven effective:

Ratio of nozzle area to throat area 0.25

Ratio of throat length to throat diameter 1.5

Nozzle spacing from throat, approximately twothirds diameter of nozzle.

The above values will be seen to be substantially different from the conventional design factors employed heretofore. For example, the ratio of nozzle area to throat area of my design is considerably less than .that called for by conventional design. A more pronounced departure from previous design lies in the throat configuration; normally the prior art has called for a throat length about six times the diameter of the throat and has recommended that the longer the throat, the more eflicient the operation. On the other hand, in my design the throat has a smoothly curved inlet 63 and a very short flaring outlet portion which opens at a wide angle (as shown at 65). This has proven very effective in transmitting the momentum of the jet stream to the pumped fluid as it is injected into the inlet 45 of the centrifugal pump impeller. Further, by making the nozzle diameter 84 small with respect to the throat diameter 64, a minimum of driven fluid is circulated (less power consumption) and the opportunity of transmitting a greater proportion of the jet energy to the pumped stream is possible; in addition, the nozzle being smaller offers less interference with flow of pumped fluid into the venturi. It follows that a greater efliciency is obtained when the minimum amount of liquid is recirculated as the driven stream through the jet. In the embodiment shown there are four inlets 82 to the jet nozzle 85 spaced radially and equidistantly apart around the circumference of the nozzle plate 80. Any other reasonable configuration is considered adequate provided the pumped fluid is admitted to the venturi in a symmetrical pattern, but a multiplicity of inlet passageways 82 leading to the jet nozzle is preferred in order to assure delivery of fluid through the nozzle in the event one or more of the inlets 82 becomes plugged because of sludge or other foreign material. Greater efliciency is obtained when the pumped liquid is drawn into the venturi in a symmetrical stream pattern. Furthermore, the multiplicity of inlets is desirable because there can be assurance of liquid feed to the jet 84 regardless of the position of the pump and in the event that air entrapment or vapor entrapment temporarily occurs in the upper or high part of the pump chamber 25 at any given time of operation. The spacing of the jet nozzle 85 from the venturi throat 64 is reason-ably critical, and that shown and described in the present embodiment has been found to be the optimum for all range of viscosities and types of fluid. As previously mentioned, the spacing of my jet or nozzle 84 from the venturi throat 64 is appreciably less than that of conventional jet pumps, the reason being that the pumped fluid is brought to the jet in a symmetrical pattern. Such close spacing contrib- TABLE OF COMPARATIVE VALUES Values Equipment Tgrigp, Coolant (Eth. Glycol Soln) Water Pressure, D elivery, Pressure, Delivery, p.s.i. gage g.p.h. p.s.i. gage g.p.h.

Pump of this invention 70 5 140 6 170 Centrifugal Pump L 70 0.25 0.3

1 65 Cavitates, Will Not Pump Positive Displacement Typo Pump 70 5 70 5 8. 0

utes to the shortening of the axial dimension of the pump, an important objective of the design.

By way of further detailed illustration, the optimum dimensions of the important parts of my pump have been found to be as follows:

Spacing nozzle to throat Optimum impeller rotational speed r.p.m 6000-8000 A pump of the foregoing specifications will pump fluid under the conditions and in the amounts indicated in the foregoing table.

Whereas the parts of this invention are manufactured and assembled to provide a working relationship in accordance with a carefully designed plan, the working relationships are not so critical as to require extremely close tolerances as are found in conventional pumps employed for the purpose that the subject pump has been designed. For example, the design of conventional pumps now employed for comparable use require that their parts have very close interfitting relationships including hardened parts requiring grinding and lapping, all of which processes are critical and expensive in nature. For this reason, therefore, the fluid pumped by the devices has to be carefully filtered to assure the absence of foreign particles which would have an adverse effect on the close tolerances and cause deterioration of the parts. On the other hand, the design of my pump requires no such close tolerances and consequently a reasonable amount of sludge, foreign material, grit, etc. is easily pumped through and has no adverse effect on its operation. Thus, both from the standpoint of original cost as well as maintenance cost, my pump has a great advantage over competitive devices. This same advantage holds true for the pumping of fluids that may have a corrosive effect since such action is far less detrimental in the case of my pump than in case of pumps having close and critical tolerances between the working parts.

The prior art shows that the combination of a centrifugal pump with a jet-type action is not novel, per se; however, the application of such a pump to the environment under discussion has not heretofore been practical for the reason that all such prior centrifugal-jet-type pumps have required a very long venturi relative to the axial dimension of the pump, so that the application of such equipment to a motor vehicle would be bulky and introduce severe problems of installation, operation, maintenance and repair. The pump of my invention overcomes these disadvantages, particularly because it is of very compact design, highly efiicient and requires little power for its operation throughout the entire temperature range over which it may be in use.

The above described pump of this invention has proven particularly satisfactory when pumping very cold fluids of high viscosity and is capable of eflicient operation on fluids up through the range of room temperatures and higher wherein the viscosity is very low. Further, my pump fulfills the limitations of low power consumption; thus in the pump of this invention there is no tendency for the pump to build up to high electrical power demand when pumping viscous fluids, or when the pressure in the circulating system becomes high on the outlet side (as, for example, due to plugging of any of circulation lines). This plugging sometimes occurs when scale, sludge or foreign material clogs the line passages in the coolant systern. A most important feature of my invention lies in the fact that it is extremely compact and is readily adaptable to existing systems; this feature, plus the fact that it is readily serviced and functions in any position, enables the pump to be easily installed and reduces the servicing problem to a minimum.

Throughout the preceding discussion, the emphasis has been on use of my invention as a circulating pump for the coolant of motor vehicles. However, this pump can be employed to advantage in the circulation of other fluids, as for example fluid fuel used in the vehicles. Thus when the engines employ diesel fuel, the pump means therefor has to operate properly at the very low temperatures. For example, diesel fuel of military specifications is known to precipitate small wax-like particles at extremely low temperatures which tend to obstruct the fuel lines; unless the fuel is delivered at sufiicient pressure and by a pump means that is not adversely affected by such clouding or wax precipitation, difficulty in the circulation is encountered. For this reason, the pump of my invention has proven extremely useful since the presence of foreign material such as the wax particles does not adversely affect its operation and the pump has been found capable of delivering fuel at uniform rates and pressure even though the fuel is relatively viscous at the low ambient operating temperature. Accordingly, it should be understood that I intend my pump for uses other than merely coolant circulation. Such uses would include pumping of fuel and other fluids.

Whereas the above description relates to the presently preferred embodiment of the invention, the said description is not to be taken as a limitation on the design or features thereof, but rather the invention is to be measured in terms of the accompanying claims.

I claim:

1. In a circulating pump of the type embodying both centrifugal and jet type action and including a rotary driven impeller, a scroll surrounding said impeller and having discharge openings, a venturi member having an inlet and an outlet and formed integral with said scroll and having its outlet axially disposed with respect to the scroll, a jet member with a jet opening and mounted on and solely supported by the inlet side of the venturi, a pump housing surrounding the aforesaid impeller, scroll, venturi and jet member to provide a chamber to receive the discharge from the scroll of the centrifugal pump means, said housing having an inlet in communication with a face of the jet member opposite the jet opening, and a fluid outlet passageway in communication with the pump chamber, said pump housing being removably secured to a mounting plate from which it is separately removable without disturbing the scroll-venturi-jet assembly to expose the assembly for inspection, servicing or repair, a first series of passageways leading from the pump chamber in the region thereof remote from the venturi axis and extending through the jet member and terminating in communication with the jet opening in axial alignment with the venturi inlet and a second series of passageways through said jet member providing communication between the housing inlet and the region proximate the inlet to the venturi, whereby the jet stream receives its fluid from the pump chamber at a multiplicity of points substantially at the same pressure as the discharge from the centrifugal pump means.

2. A pump as described in claim 1 characterized further in that the venturi member has a relatively short dimension in the direction of fluid flow therein.

3. The pump described in claim 1 wherein the scroll, venturi and jet member are removably carried by said mounting plate to which the pump housing is separately mounted.

4. A pump as described in claim 1 above wherein the jet member is demountable from the venturi member.

5. A pump as described in claim 1 wherein the inlets for first series of passageways are distributed symmetrically about the jet body and wherein the second series of passageways are distributed symmetrically about the jet so that the pumped fluid is brought to the inlet region of the venturi in a symmertical pattern.

6. A pump as described in claim 1 wherein the pump housing is provided with a plurality of flow directors in the form of protuberances integral with the wall of the housing and extending from the scroll end of the housing toward the inlet end of the housing and diminishing in size in the region of the jet member.

7. A combined centrifugal and jet type fluid pump having as its centrifugal pumping means a rotary-driven impeller surrounded by a scroll, a venturi formed integral with said scroll and having its outlet located axially with respect to the impeller, a jet member removably carried by the venturi and having a jet opening in axial alignment with the inlet for the venturi; a pump housing surrounding the aforesaid scroll-venturi-jet assembly and formed to enclose a pump chamber into which fluid is delivered from the scroll, a multiplicity of passageways through the jet member in communication at one end with spaced points in the pump chamber and at the other end with a jet opening that lies along the axis of the venturi inlet, a second series of passageways through the jet member originating in the region in communication with an inlet through the housing for fluid to be pumped and terminating in outlets for said second series symmetrically spaced about the aforesaid jet opening, the pump housing being mounted independent of and removable separately from the scroll-venturi-jet assembly, and outlet means in the housing for discharge of pumped fluid.

8. A pump as defined in claim 7 wherein the pump housing is removably mounted on a mounting plate which also supports the scroll and impeller.

9. An improved jet structure for a pump embodying centrifugal and jet type action, comprising a jet member in the form of a disc having a plurality of radiating passageways originating at their outer ends in the region subjected to the full discharge pressure of the centrifugal pump means and terminating at their inner ends in communication with an axially disposed jet opening, and further openings through the member out of communication with the aforesaid passageways for providing conduit means for the liquid to be pumped and extending from the pump main inlet through the jet member and into the region proximate the jet opening.

References Cited UNITED STATES PATENTS 1,661,960 3/1928 Riehl 103278 X 2,466,812 4/ 1949 Jacobsen. 2,677,327 5/ 1954 MacNeille. 2,934,021 4/ 1960 Conery. 2,941,474 6/ 1960 Hall 1035 3,291,051 12/ 1966 Ekey.

FRED C. MATTERN, JR., Primary Examiner. W. J. KRAUSS, Assistant Examiner.

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