US 1474769 A
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Nov. 20', 1923 mmmg v E. D. DUNNING COMPRESSION PUMP Origin? g iled April 29, 19%? Patented Nov. 20, 1923.
UNITED STATES crates.
" ELMER D. DUNNING, OF PHILADELPHIA, PENNSYLVANIA.
Application filed April 29, 1919, Serial No. 293,387. Renewed September 27,. 1923.
To all whom it may concern:
Be it known that I, E-LMER D. DUNNING, a citizen of the United States, and resident of Philadelphia, in the county of Phila- 6 delphia and State of Pennsylvania, have invented certain new and useful Improve ments in Compression Pumps, of which the following is a specification. I My present invention relates to compres- 10 sion pumps of the type commonly employed as tire pumps and particularly tothe sma ler and more compact types adapted to be installed on the frame of an automobile engine. Such pumps are required to deliver '15 compressed airat pressures up to say 60 pounds for the smaller tires and to operate with decreasing volume of output and decreasing1 efficiency at the higher pressures require for larger tires up to say 90 to 120 pounds.
For such purposes it is common to employ a double pump comprising two piston heads rigidly connected base to base and reciprocated in oppositely aligned cylinders by a special form of scotch yoke driver consisting of an eccentric fitted between the adjacent bases of the piston heads and acting alternately on one and then on the other to force the compression strokes of each the suction strokes being accomplished by traction through the rigid connection between the heads.
My present invention consists in certain important improvements in pumps of this type.
For instance, such pumps for such purposes so far as I am aware have the. ratio of piston area to stroke, usuall about 3 to 1, that is to-say, 3 square inc es of piston areafor one inch stroke, or 2 square inches for a 5} inch stroke. This gives a transverse strain on the drive shaft of say 300 pounds when pumping against 100 pounds back. pressure which is quite as high t as is safe for such devices as ordinarily constructed. Nevertheless, I have discovered that for the particular numerical values here involved, many advantages can be gained by doubling the piston area without increasin the stroke, for instance, if the stroke be kept i inch and the piston diameter increased to '23- inches the area will be about 41} inches which gives a ration ofpis ton area to-stroke of about 6 to 1 instead of 2 or 3 to l. I thereb double the volume of the pump space whi the circumference inch nor more than 1 inch with the clear- .ble leakage besides practically doubling the ca acity of the pump.
t is true the doubling of the piston area will bring the'transverse strain on the drive shaft up to 450 pounds when pumping at pounds per square inch, but this is taken care of by an improved bearing and pro portioning' for the drive shaft while the increased diameter of the pum heads gives added space for a much wi er and more centrally located driver, without encroaching on the space necessary for structural strength of the rigid member connecting the two piston heads. I
While certain variations are possible in these dimensions without departing from the spirit of this part of my invention, li prefer is that the ratio of piston area to stroke be not less than 5 to 1 nor more than 8 to l and that the stroke be not less than a of an Eli anoe at the end of the stroke not more than. one-sixth the stroke nor less than 3 g inch. The rotary crank element is preferably formed as an eccentric circle of relatively large diameter, said diameter being approx imately twice the stroke or four times the h radial distance between the t centric head and the axis of ti" drive This radius will be *3 inch for inch and as the load acts at right angles c radius only mid-stroke, when the pressure in the compression space is not about 15 pounds per square inch, its t load on the crank shaft even for 4;; l,
iston area, is not over 100 pounds plus rictional resistance which is small because of the peculiar design employed.
Many other features of my invention. late to structural improvements and most '5 them may be embodied in pumps of ent proportions, and some of them in pumps which have only a single piston hear pump chamber. These improvements clude the following:
in the double headed piston the two heads are connected by a solid longitudinaber unweakened by slotting for d shaft and guided and prevented from tion by contact with and face r rotary crank element. 'llhe friction ear of this sliding contact may be reduced bellowing. out the end thrust surface of rotor so as to leave an annulus oil at width, and the hollow may be extended deep enough to materially decrease the eccentric weight, provided the walls are kept thick a enough to have the necessary strength. The
and the outlet passages communicate with a straight outlet passage drilled in the wall of the cylinder from end to end therof.
The length of the shaft bearing is more than four times crank radius and 1s removably but rigidly secured by a cylindrical exterior bearing surface accurately machined to fit an opening formed therefor in the side of the cylinder casing and by an annular face fitting against the mouth thereof at right angles to the cylindrical bearing surface. The opening in which the c lindrical bearing fits is preferably of s ightly greater diameter than the eccentric driving head so that the bearing, drive shaftand head may be radially inserted in or removed from the cylinder by simply removing the screws which hold the annular flange in place.
Means for throwing the drive shaft into and out of driving engagement with asuitable source of power as for instance the cam shaft of an automobile engine, is provided in the form of a clutch collar splined to the drive shaft and movable endwise thereon b a swivel fork pinned to an endwise movaiile shaft slidably supported parallel with the drive shaft and adapted to be non-positively locked in the operative or inoperative osition of the clutch by a spring pressed all arranged to laterally enga suitably spaced notches in said movable s aft.
The above and other features of my invention may be more fully understood from the following description of a desirable embodiment thereof in connection with the accompanying drawings, in which- Figure 1 is a horizontal section on the axis of the device, and
Figure 2 is a vertical section at right angles to the axis.
As shown in these drawings. the body of the pump comprises a cylindrical casting 1 having a straight cylindrical bore and formed exteriorly with radiating flanges 3, suitable standards or supports 4, formed with bolt holes 5 for securing the same. a longitudinal rib 6 having a straight outlet passage 7 drilled therethrough and a transverse outlet passage 8; also a lateral opening 9 having straight walls 10 and a fiat face 11. The opening is of size sufficient to permit crank shaft and rotor to be inserted or withdrawn, the said opening being normally closed by the crank shaft bearing when the latter is in position.
Fitting the cylinder bore 2 is a double faced piston comprising oppositely facing piston heads 13. which may be provided with elastic steel rings '14 of t 1e typecommonly employed for pistons of automobile motors. Said piston heads are rigidly connected and preferably cast integral with a longitudinal member 15 having a strengthenin rib l6 and a fiat face 17 extending para lel with the axis of the cylinder. At'r-ight angles to the ends of said face, are parallel bearing surfaces 18, said surfaces 18 and 17 being of shape and dimensions adaptedto fit the rotary driving member on two sides and the end thereof, respectively.
The cylinder is closed by similar heads 20 each comprising a circular casting having air inlet and outlet passages drilled therein, preferably all in the same straight line. These passages are preferably formed by drilling a through hole of the size of the central part of the passage 22, reaming enlargements 23 from each end to form shoulders 24, a then screw-threading for screw-plug 25 and sleeve 26. The inner end of the screw sleeve 26 is formed with a valve seat 27 for inlet valve 28 normally held in the closed position by spring 29. resting on shoulder 24. The other shoulder 24 forms a valve seat for outlet valve 31 normally held closed by spring 32 abutting against screwplug 33. The passage 22 has a central open ing 34 ommunicating with the pump chamber. preferably at the center thereof.
The outlet passages have lateral openings 35 registering with the outlet passage 7 formed in the wall of the cylinder. The cylinder heads are held in place by suitable screws or bolts not shown.
The removable bearing member fits into and closes the opening 10 and has a projecting portion 42 su portin the drive shaft 43 up to a point e osely a jacent the rotor 44, and of reduced diameter toward the end so as not to interfere with rearward movements of the piston heads. It also has a rear extension 45 which makes the total length of the bearing very great as compared with the crank radius. lit also has an extended bearin 46 contacting firmly with the interior of walls 10 and an annular flange 47 adapted to be secured by screws 48.
As a means for connecting-the drive shaft and source of power, I provide a clutch collar 50 having longitudinal projecting lugs 51 slidably secured on the drive shaft by a semi-circular spline 52 engaging slot 53.
The clutch collar has a swivel groove 54 ltl) inverse around which fits fork 55 secured to shaft 56 by taper pin 57. The shaft 56 is slidabl supported in a lug 58 on the cylinder, pre erably integral therewith and in a In 59 preferably integral with the drive s aft bearing, adapted to support shaft 56 close up to the plane of the clutch collar.
The shaft 56 may be supplied with operating handle 60 for shifting it endwise and may be non-positively secured in the operative or inoperative position by pressure of spring 61 on ball 62 located in drill hole 63 and engaging notches 64 on the under side of shaft 56.
structurally the device is extremely simple and composed of extreme-1 few parts very unlikely to get out of or er and very easy to replace or repair, the essentials exelusive of fittings, consisting of a single piece cylinder, a single piece piston, a single piece drive shaft and eccentric and single piece bearing, and two single piece cylinder heads. The fittings also are simple and few in number comprising; only the four valve plugs, balls and springs, the four piston rings and 16 screws, 6 for each head and l for the hearing. The clutch device is equally simple comprising only spline, collar, fork, shaft, pin, ball and spring.
The pump is well adapted for operation at 6 to 8 hundred revolutions per minute and can be driven up to a thousand or fifteen hundred revolutions for short periods.
Hence, it is peculiarly adapted for driving from any exposed rotating shaft or other part of the motor or transmission by either positive or frictional connection which be either a clutch or a gear.
1. In a double pump, a single straight bore tube forming opposed cylinders, a one piece web connected, double faced piston, single piece combined eccentric and drive shaft, a suitable bearing support for tit shaft, and one piece detachable c lind heads with inlet and outlet valves coated therein.
2. In a pump, a one iece cylinder, an out-- let passage through t e cylinder wall and extending in the direction of the length of the cylinder, a one piece detachable c tinder head closing one end of the cylin er, an opening Or passage extending through said cylinder head, and connecting the cylinder with the outlet passage.
3. In a pump, a one piece cylinder, an opening or passage through the cylinder wall and extending in the direction of the length of the cylinder, one piece detachable cylinder heads closing the ends of the cylin dcr, an opening or passage extending through said cylinder heads and opening into the outlet passage and the cylinder, and valves placed in the cylinder head passage (t1o form inlet and outlet valves for the cylin- Signed at New Yorlr city, in the county f New York and State of New York, this 21th day of April, A. D. 1919.
ELMER D. fDUllNlll lG.