US2676545A - Rotary pump having a viscositycontrolled by-pass - Google Patents

Description

April 27, 1954 LE Ro'Y H. BARR ,676,

ROTARY PUMP HAVING A VIsCQSITY-CONTROLLED BY-PASS Filed Dec. 26, 195!) Carrier Like INVENTOR. lefoy H 500-2 BY Patented Apr. 27, 1954 ROTARY PUIWP HAVING A VISCOSITY- CONTROLLED BY-PASS Le Roy H. Barr, Elyria, Ohio, assignor to Lear, Incorporated, Grand Rapids, Mich.

Application December 26, 1950, Serial No. 202,751

ally accomplished by providing a reservoir for the water, and a positive displacement pump associated therewith to transfer water therefrom to a nozzle whereby the water is injected into the intake manifold of the engine. In the event the reservoir runs dry a positive displacement" pump, unless provision is made thereagainst, will then supply air to the injection nozzle, thus disturbing the then pre-set fuel-air ratio, and

6 Claims. (01. 103-41) causing the engine to misfire or even to fail completely.

In order to insure against this latter contingency this invention has for its object the provision of a positive displacement pump so constructed as to deliver water as long as an adequate supply thereof is maintained at its inlet, but when such supply fails, air sucked into the pump is by-passed automatically back to the inlet.

In the drawing which shows certain preferred modes of carrying the invention into practice:

Fig. 1 shows a longitudinal cross section through a rotary vane type of positive displacement pump embodying the invention;

Fig. 2 is a transverse cross section taken on the line 2-2 of Fig. 1;

Fig. 3 is a side elevational view of the pump liner;

Fig. 4 is a bottom plan view of the pump liner;

Fig. 5 is a view similar to Fig. 4, but in cross section;

Fig. 6 is a cross section taken on the line 66 of Fig. 3; and

Fig. 7 is a side-elevational view of a modified form of liner.

Generally regarded the invention is based on the diifering viscosities of air and water, and the greater resistance created by a passage of predetermined cross-sectional area to flow of water than of air, and comprehends the provision of a channel interconnecting the inlet and outlet ports and of such cross section that water will be pumped from inlet to outlet at a rated pressure and volume, but such that air will be by-passed through the channel and thus prevented from reaching the point of delivery of the pump.

Referring to Figs. 1 to 6 there is shown by way of example a rotary vane type of positive displacement pump broadly including features well known in this art, namely a casing I0, inlet and outlet ports II and I2 respectively, rotor bearings l4 and I5 supported in the casing, rotor l6, slidable'vanes ll-ll, and liner l9 having inletand outlet ports 2| and 22 in line respectively with ports I l and I2. Rotation is imparted to the rotor by a motor (not shown) coupled thereto at 23. Liner I9 is a press fit in the casing 10, and is additionally secured by a screw 24 entering a slot 25.

Directing attention specifically to Figs. 3 to 6, the liner I9 is provided with a pair of slots 26 and 21 extending substantially helically thereof, one end of each slot opening into the inlet and outlet ports 21 and 22 respectively, and the other or closed ends 28 and 29 terminating just beyond the center line'of the liner, and as clearly indicated in Fig. 3. By offsetting the ends 28 and 29 of the clots axially of the line there is no danger of unduly weakening the wall of the liner such as would be the case if a continuous slot were cut from port to port. However such alternative is within the scope of the invention, and will be explained hereinafter.

In the exemplificative pump, the bore 3| is 1.094" in diameter, its length 1.1263", and the pump is so designed otherwise that when operated at a speed of 3000 R. P. M. it will deliver 110 gallons of water per hour at 31 pounds per square inch. Accordingly slots 26 and 27 have been found to provide'adequate by-pass of air when made 1 5" wide and caused to overlap the center line 0.031" on each side. At the mid-plane indicated by the center line of Fig. 3 the thickness of the liner is 0.093". a

It will be noted that the outer edges of the vanes I! are arcuate throughout their length so that substantially a line contact is obtained between an edge of a vane and the wall of the liner. Consequently at no time may a vane completely overlap both ends 28 and 29 of the slots, and therefore constant communication is afforded between the inlet and outletports via the slots and the interior of the liner. While an insignificant volume of water may be by-passed from outlet to inlet during operation, this is never such proportion of the total volume as to affect seriously the rated performance. However if the supply of water should become completely exhausted, and air is pumped, the proportions of the by-pass route are such as to short circuit the pump, and air pressure built up on the dis- 3 charge side is never suflicient to cause flow thereof to the intake manifold of the engine. The viscosity of water at 20 C. is 1.005 centipoises, and of air at this same temperature is 180.8 micropoises. Since 1 centipoise is 0.01 poise, the

viscosity ratio of water to air is 10,000 to 1. Thus in the exemplificative pump channels as small in cross section as thosedescribedhavebeemfound sufficient to perform in'the mannerdescribed.

In Fig. 7 is shown a modification wherein the slots 26 and 21 find equivalent in a single slot 31. However such construction, while lessening the cost of manufacture, decreases the str n th of the liner as compared to the construction heretofore detailed. It will be apparent thatkboth ithe modified and preferred forms of the invention function similarly.

Having in mind that the casing I is generally a casting, and that production of small passages therein by means fUf cores is to be regarded :as a practical impossibility, ,it' will .he compre- .hended that the use of ,a separate lliner; having the by-pass slots :cut therein represents a simple, ,inexpensivesolution-of the problem pontcmrilated Jay the invention. Moreover, that the cross sectionalareanf the by-passslots may be controlled within close limits by simply choosing .a-saw of suitable width for cutting ,the slots. 4 The inven- .tion may :be carried into practice ,by, forming recesses in the suriace ofthe liner, in lieu of the slots through the wall thereof, as heretofore described.

While I have shown particular embodiments of my invention, it will .be understoodpf .course, that I do not wish to be limited thereto since :many modifications may he ,made, ,and I there- .fore .contemplate by the ..appended claims to cover any such modifications as ran within the .true spirit and scope of my invention.

Having thus described my invention, what I claim and desire to secure by L-Letters LPaLten't is:

.l. .A rotary vaneeliquid pump comprising a easing having an aperture, .a liner defining the pump bore secured within said aperture, a rotor supported for rotation withinsaid bore, a plural- :ity of vanes slidably supported in said rotor and coactive with the bore to ;.disp1ac.e liquid through ;the pump, said casing and liner lhav'ing aligned inlet and outlet ,ports, said liner having a .con-

, tinuousl-y open channel in the wall thereof for providing communication between said inlet and --outlet ports, said channel .having a transverse cross-sectional area such as to provide an effective block to .-fiuid.flow at .all normal. .rated pressures of the ,pump and forlall viscosities'of liquid for which the pump is .designed but to allow air :to "be by-passed therethrough in the absence .of liquid at the inlet.

2; .A rotary vane pump comprising a casing :having an aperture, .a liner defining the pump :bore secured within said aperture, a .rotor sup- ;ported for rotation within said bore, a plurality of vanes slidably supported .insaid .rotor and ooacti-ve with the bore to displaceiluid through the pump, said .casing .and liner having aligned .inlet and outlet ports, ,said liner haviing a ,pair' having an aperture, a iliner defining the pump bore secured within said aperture, a rotor sup- ,ported for rotation within said here, a plural- .ity .of vanes slidably supported in said rotor and gcoactive with "the bore to displace fluid through the pump, said casing and liner having aligned iinletend outlet ports, said liner having a pair of slets "in the wall thereof, said slots being in fluid communication at one end with the inlet and outlet ports respectively, said slots extending .substantially helically around the periphery of the liner in opposite directions and each terminating beyond .an axial element of the liner in overlapping relation, the closed terminal ends of the slots ,being spaced apart along sa'idele- ,ment.

4. A rotary vane liquid pump comprising .a casing having an aperture, a liner defining the pump .bore secured within said aperture, a .rotor supported for rotation within said .bore, .a plu- ,rality of vanes .s'lidably supported in said rotor and reactive with the'bore 'to displace liquid through the pump, said casing and "liner having aligned inlet and outlet ports, said liner having a continuously open passage thereinior providingcommunication between said inlet and outlet ports, said passage having a transverse crosssectional area such .as to provide an effective .block to fluid fiowra't all normal rated pressures of the pump and for all viscosities of ,liquidfor which the pump is designed lbuttoallowair to be by-passed therethrough in the absence of liquid at the inlet.

.5, ..A,p.um.-p as recited in claim 4 in which said passage comprises a slot through the wall of the liner.

-6.,A ,ro'tary vane liquid pump comprising a body defining a pump'ingcham'ber, fluid displac- ,ing means insaid body,

inlet and outlet ports for said chamber, said body having a continuously open passage therein for providing communication between said inlet and outlet ports,

,said passage having ,atransverse cross-sectional .areasuchas .to ,providean effective'block to fluid flow at any normal rated pressures of the pump and .for all viscosities of liquid for which the pump is designed but 'to allowair to be by-pa'ssed therethrough in theabsence of liquid at the inlet.

References Cited in the file of this patent UNITED STA' IES PATENTS

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