US 3272134 A
Description (OCR text may contain errors)
P 13, 1966 H. s. WILBURN, JR 3,272,134
CENTRIFUGAL PUMP 5 Sheets-Sheet 1 Filed April 23, 1964 INVENTOR HERBERT S. W|LBURN,JR.
BY ciwm D W ATTORNEYS Sept. 13, 1966 H. s. WILBURN, JR 3,
CENTRIFUGAL PUMP Filed April 25, 1964 5 Sheets-Sheet z INVENTOR HERBERT S. WILBURN,JR.
ATTORNEYS l 1966 H. s. WILBURN, JR 3,272,134
CENTRIFUGAL PUMP Filed April 23, 1964 :5 Sheets-Sheet 5 FIG. 3
INVENTOR HERBERT S. WILBURN, JR
ATTORNEYS United States Patent 3,272,134 CENTRIFUGAL PUMP Herbert S. Wilburn, Jr., 707 Glenbrook Road, Fairfax, Va. Filed Apr. 23, 1964, Ser. No. 362,042 Claims. (Cl. 10325) This invention relates to centrifugal pumps and has particular reference to improved constructions therefor suitable for a small portable type pump used for bailing boats and the like.
A primary object of this invention is in the prov1s1on of a highly efficient pump which requires only a low energy source of motive power.
Another object of the present invention is to provide an improved impeller having thereon a particular arrangement of vanes which not only produces more effective pumping but also gives greatly increased resistance to back pressure, thus allowing the pump to efliciently maintain a constant head at low speed.
A further object of the present invention is the provision of a pump which, in addition to being simple, reliable and durable, is also economical to produce.
The foregoing objects of the invention relating to general as well as specific details will become apparent from the following description read in conjunction with the drawings in which:
FIG. 1 is an exploded partial section view of the pump showing the simplicity of construction;
FIG. 2 is a sectional view showing the assembled pump;
FIG. 3 is a bottom elevation of the impeller showing the design of the vanes thereon;
FIG. 4 is a section of a float switch used to actuate the pump.
In the present illustrations of this invention the numeral 1 indicates the main housing of the pump in which is housed a motor 2 having a protruding driving shaft 3. The motor 2 is sealed in housing 1 by gasket 4, and the shaft 3 is sealed by mercury seal 5 which is frictionally fit within gasket 4. On the end of shaft 3 is key-fitted an impeller 6 that is held in place by cap 7 which may be made of plastic or other suitable material. Surrounding impeller 6 is a casing 8 having a threaded portion 9 which mates with threaded portion 10 of housing 1. As the casing 8 is screwed into housing 1, gasket 4 is pressed tightly against rim 11 of housing 1, thus sealing off the motor 2 from the remainder of the pump.
The gasket 4, which may also be made of plastic or other suitable material, has a recess 12 into which is fitted the mercury seal 5. The seal 5 is preferably in the form of a resilient cup, as seen most clearly in FIG. 2. This cup may be made of rubber, plastic or other suitable deformable material. Along the innermost surface of the cup is a piece of gauze-like material 13 on top of which is disposed the mercury 14. Over the mercury 14 is another piece of gauze-like material 13. This gauze-like material aids in preventing loss of mercury around the shaft 3. Mercury is used here as a sealant because it provides a virtually frictionless seal.
The impeller 6 is of the semiopen type and comprises a disk 15 to which is attached a plurality of curved, tapered vanes 16. The inlet edges 17 of vanes 16 form an imaginary cylinder, the interior of which is known as the entrance or the eye of the impeller. At the edges 17, the vanes 16 are tangent to the imaginary cylinder thus formed. This arrangement allows the vanes to slice the water with little drag being produced.
Most semiopen impellers have vanes which spiral in such a manner that the distance between any two adjacent vanes increases as the vanes spiral radially outwar-d. In the present impeller, the distance between any 3,272,134 Patented Sept. 13, 1966 ice adjacent pair of vanes 16 remains approximately equal along nearly the entire length of the vanes 16. This particular spiral design of the vanes 16 results in considerable overlapping of one vane with the next. This overlapping results in a situation in which at least one vane is always in a position to retard any back pressure from the fluid outlet 23. In addition, the vanes 16 taper in depth from a maximum at the inlet edge 17 to a minimum at the discharge edge 18. The ratio of inlet edge depth to discharge edge depth is preferably 2 to 1.
Closely surrounding the impeller 6 is the casing 8 which has a sloping portion 19 that conforms closely with the bottom edge of the impeller. This portion 19 of casing 8 forms the outer wall of the pressure chamber within which the impeller rotates and in addition this portion 19 defines an inlet opening 20 which has approximately the same diameter as the eye of the impeller. By tapering the pressure chamber in this manner, the inlet area is greater than the peripheral area of the chamber thus reducing eddy formation in the pressure chamber. At the outer edge of casing 8 is a ridge 21 which supports the pump in the preferred upright operating position. The ridge 21 defines a plurality of narrow elongate slots 22 around the circumference of the casing 8. These narrow slots 22 allow fluid to enter; however solid particles large enough to damage the pump cannot. The combination of these narrow elongate slots 22 with the downward sloping portion 19 of casing 8 allows the inlet orifice 20 to be close to a bottom surf-ace of, for example, a boat while still providing a large and eifective straining portion through which liquid must flow.
Also formed on the outer wall of the casing 8 is an outlet 23 which has .a rectangular orifice. By using a rectangular orifice, the pump can be made smaller and more compact than a pump using a circular outlet orifice. In addition, the rectangular orifice presents a larger area than would a circular orifice having a diameter equal to the width of the rectangle. By presenting a greater area, the rectangular outlet 23 will allow for an increased volumetric flow at a given pressure.
FIG. 4 shows the float switch (shown generally as 30) that actuates the pump motor 2 when the water in which the pump is setting reaches a predetermined level. The switch 30 has an outer casing 31 defining upper and lower openings 32 and 33, respectively. Pivotally mounted within casing 31 is a strip 34 of spring metal which has a float 35 attached to one end and a lightweight mercury switch 36 attached to the other end. Mounted on the casing in a position just above the end of strip 34 which is opposite the float 35 is a magnet 37.
When there is no water in casing 31, the float 35 remains in the position shown in solid lines and the end of strip 34 is attracted to magnet 37. In this position, the float 35 covers the lower opening 33; thus, at first water can only enter through the upper opening 32. When the water level reaches opening 32 and starts to fill the casing 31, the float 35 will begin to rise causing the strips 34 to bend upward. As soon as the float 35 raises off of opening 33 water will pour in and flood the casing 31. As the float 35 rises with the increasing water level in the casing 31, the strip 34 bends more until finally the attractive force of the magnet 37 is less than the spring force of strip 34. When this happens, the strip 34 springs away from the magnet and into the position shown in dotted lines. In this tilted position the mercury in switch 36 makes contact with the two wires 38 and thus completes the circuit to the pump motor through wires 24 (FIG. 2) which are attached to a power source (not shown) as well as wires 38. The tubular portion 39 shown in dotted lines may be attached if it is desired that a greater fluid depth be attained before the pump starts.
As the water level decreases, the float 35 drops and the magnet 38 attracts the strip 45 once again. As the switch 36 moves back to the position shown in solid lines, the contact is broken and the pump stops.
Although this invention is successfully practiced in the preferred embodiment shown, it is to be understood that the invention may be accomplished by making various changes or modifications which may fairly be deemed within the scope of the invention.
Having thus described the invention, what I claim and desire to protect by Letters Patent is:
1. A centrifugal pump comprising driving means; a housing for said driving means; a semiopen type impeller formed of a disk having spiral tapered vanes attached thereto, said impeller being connected to said driving means, said impeller vanes spiralling continuously outward from the eye of the impeller through an extent of approximately two and one-half quadrants with a short initial portion of each vane being substantially straight adjacent the 'eye of the impeller, the distance between two adjacent vanes being substantially equal along the length of each vane from that portion of each vane beyond the first octant of said vane to the outer periphery thereof, and said vanes tapering from a maximum depth at the eye of the impeller to a minimum depth at the outer periphery of the impeller; and a casing surrounding said impeller, said casing having a sloping center portion which conforms closely to the taper of the impeller vanes, said sloping portion defining an inlet opening, and said casing forming an outlet orifice which is substantially rectangular in shape.
2. A pump as claimed in claim 1 in which said initial portion of each vane is tangent to the circular eye of the impeller.
3. A pump as claimed in claim 1 in which the ratio of the depth of the vanes at the eye to the depth of the vanes at the periphery is two to one.
4. A pump as claimed in claim 1 in which the casing forms a rim on which the pump rests, said rim having narrow elongate slots formed therein for straining in- 4 coming fluid.
5. A centrifugal pump comprising driving means; a housing for said driving means; a semiopen type impeller formed of a disk having spiral tapered vanes attached thereto, said impeller being connected to said driving means, said impeller vanes spiralling continuously outward from the eye of the impeller through an extent of approximately two and one-half quadrants with a short initial portion of each vane being substantially straight adjacent the eye of the impeller, said vanes tapering from a maximum depth at the eye of the impeller to a minimum depth at the outer periphery of the impeller; and a casing surrounding said impeller, said casing having a sloping center portion which conforms closely to the taper of the impeller vanes, said sloping portion defining an inlet opening, said casing forming an outlet orifice which is substantially rectangular in shape; and said pump having a starting means comprising a switch casing defining upper and lower orifices, a strip of spring metal pivotally attached to said switch casing, said strip having a float attached to one end and a mercury switch attached to the other end, said mercury switch being electrically connected to said driving means, and magnetic means mounted on said switch casing in a position immediately above that end of the strip having the switch thereon.
References Cited by the Examiner UNITED STATES PATENTS 2,046,226 6/1936 Weightman etal. 103 2,165,808 8/1939 Murphy 103 115 2,240,607 5/1941 Buck 103 25 2,250,271 7/1941 Morgan 10326 2,589,089 5/1952 Johnson 10326 2,875,694 3/1959 Carter 103 87 2,890,660 6/1959 Umbricht 103-111 2,930,867 3/1960 Nash 103 26 2,949,859 8/1960 Gramberg 103 113 3,021,788 2/1962 Kaaly 103-87 3,179,058 4/1965 Meagher 103 87 0 MARK NEWMAN, Primary Examiner.
DONLEY J. STOCKING, Examiner.
W. L. FREEH, Assistant Examiner.