Collapsible Bilge Pump

Abstract

A collapsible bilge pump includes outer and inner cylinders telescopable between retracted and extended posiions. A piston is movable up and down within the inner cylinder. Check valves in the bottom of the outer cylinder and in the piston permit the pump to take in water at the bottom end of the pump and discharge it from the top end. The collapsible pump is easily stowed, and its short stroke, limited to the length of the inner cylinder, is substantaially easier to perform.

Description

CROSS-REFERENCE TO RELATED APPLICATION

My related and copending Provisional Applicaton No. 61/459,755 was filed on Dec. 20, 2010. That filing date is claimed for this application.

BACKGROUND INFORMATION

This invention is a collapsible, manually operated, bilge pump. The pump collapses to approximately 60% of its full operating length for stowage, and extends to full length for use.

Manually operated bilge pumps are commonly used for water removal from kayaks and other small water craft. A bilge pump is a prudent safety device for small boats. Kayakers in particular use them for water removal after a capsize.

Commonly used bilge pumps include a cylinder with a piston, piston rod, and handle movable relative to it. The cylinder body includes suitably valved intake and discharge ports, and a foam float. Such pumps are typically about 2.5″ diameter and 20″ high. A pump of that size will lift water from the bottom of the hull and expel it over the cockpit rim of a kayak or gunwales of a canoe. A substantially shorter pump will not perform well. Other pump types, such as foot-operated, are available but their popularity in small craft and, particularly in kayaks, is limited.

One problem with typical prior art bilge pumps is the size of the pump and the difficulty of stowing it in the boat when not in use. In a kayak, the pump must be readily accessible, not stowed in forward or aft compartments, and storing it in the cockpit is difficult because of limited space. The most common solution for kayakers is to secure the bilge pump on the deck under bungee lines. However, this is also problematic as bungee layouts on decks often do not provide secure attachment and pumps can be lost at sea due to natural boat movements or washed off the deck by waves. If it is secured on the back deck, it may be difficult to reach by a seated kayaker, and the pump's presence there can interfere with common rescue techniques such as the cowboy reentry, the paddle float rescue, and numerous assisted rescues. If secured on the fore deck, the pump can interfere with paddle strokes, particularly sweep strokes used to turn the vessel. A bilge pump secured on the fore deck may also preclude use of this area for other items the kayaker needs to be visible and readily accessable, such as navigation charts, tide tables, and the like.

My collapsible design greatly alleviates the storage problem experienced by small boat operators and kayakers. A 20″ extended pump can be collapsed to 12.5″. And a kayaker can find space for my pump, either inside the cockpit behind the seat back, or hung under the fore deck, or attached to the hull between and below the legs.

Another benefit of my invention is the surprisingly improved ergonomics of its operation. A manual bilge pump is a two-stroke device. The upward stroke pulls water into a the cylinder below the piston while water above the piston is lifted and expelled through the discharge port. Then, the downward stroke transfers water from below the piston to above the piston. This water is then expelled on the next upward stroke. In a typical pump, stroke length is determined by the length of the piston rod which is a few inches less then the overall length (or height) of the pump. The volume of water lifted on the upward stroke is the area of the cylinder's internal cross-section times the stroke length. One commonly available pump has a stroke length of 13″ and stroke volume of about 27 cubic inches. This is about a pound of water being lifted by the operator on each upward stroke. The operator also has to work against internal friction of the device. With a kayaker in a seated position and pumping out his cockpit, the stroke involves arm movement from approximately chest height to head height. This motion is derived from smaller arm and shoulder muscles, such as triceps and deltoids which tire easily. In these conditions, stroke frequency is relatively low.

Compared with the prior art, my collapsible pump has a stroke that is only half as long, the “work zone” where operator effort is applied is lower and more conveniently located in front of the chest, and each pump stroke lifts only half as much weight of water. In these conditions, strokes are easier, and it becomes natural to stroke at a rate more than double the stroke rate for a conventional pump. The net result is that my invention pumps faster than a conventional bilge pump with seemingly less input effort.

SUMMARY OF THE INVENTION

The collapsible bilge pump of this invention includes outer and inner cylinders telescopable between retracted and extended positions. A piston is movable up and down within the inner cylinder. Check valves in the bottom of the outer cylinder and in the piston permit water intake at the bottom end of the pump and discharge from the top end. The collapsible pump is easily stowed, and its short stroke, limited to the length of the inner cylinder, is substantially easier to perform.

DRAWINGS

In the accompanying drawings:

FIGS. 1A, 1B are elevation and sectional views of my pump in its collapsed state.

FIGS. 2A, 2B show the pump, and an enlarged detail, in its extended state.

FIGS. 3A, 3B, 3C show the pump, and enlarged details, operating in an upward stroke.

FIGS. 4A, 4B, 4C show the pump, and enlarged details, operating in a downward stroke.

FIG. 5 is an enlarged sectional detail of an alternate configuration.

DESCRIPTION OF THE INVENTION

FIGS. 1A, 1B are elevation and sectional views of my pump 10 in its collapsed state. An inner cylinder 11 is nested within an outer cylinder 12. The top end of the outer cylinder 12 is necked down to a diameter matching the outside diameter of the inner cylinder 11. The bottom end of the inner cylinder 11 is flared outward to a diameter matching the inside diameter of the outer cylinder 12. The flaring and necking are over a relatively short dimension, for example 20 mm, and at a relatively small angle, for example 2 degrees. These cylinders and their conical portions may be produced by secondary forming of extruded tubes, or by injection molding, or by other known methods.

The bottom end of the outer cylinder 12 includes a fluid inlet check valve 13. The inlet valve 13 includes passages 14 for water intake into the pump intake chamber 15. The passages 14 also act as coarse filters to prevent large debris from entering the pump. The inlet valve 13 includes a top planar valve seat 19. The annular bottom edge of the outer cylinder 12 abuts the valve seat 19.

An inlet valve flap 18 is a flexible membrane of elastomeric material such as viton or neoprene. The inlet valve 13 is a check valve. In operation, piston upstroke draws water into the pump inlet chamber 15 (below the piston) with the valve flap 18 flexed upward. At the end of the upstroke, the valve flap 18 lies back over the valve seat 19 to hold that water in the inlet chamber 15.

A nozzle housing 30 on the top of the inner cylinder 11 includes a bearing through which a pump shaft 20 is movable up and down, and a discharge port 17 to expel water in a generally horizontal direction. Shaft 20 is of a rust-proof material such as stainless steel, brass, or plastic. The shaft 20 includes a handle 21 on its upper end. Its lower end is shouldered and threaded. A lift check valve 22 includes an axial bore to fit onto the shaft 20 and is secured to the lower end of the shaft by a nut 23. The lift check valve 22 includes a lower body with water passages 24 through it. The lower body is shouldered to a diameter slightly smaller than the inside diameter of the inner cylinder 11 allowing it to slide loosely within the inner cylinder 11. The shoulder of the lower body forms a seat for a lift check valve membrane 26.

The lift check valve membrane 26 is a thin flexible membrane with a circular perimeter and an axial hole. The membrane 26 is mounted on the valve housing 22 by stretching it over a flange in the axial portion of the diaphragm valve housing. The lift check valve 22 is constrained in this location between the housing shoulder and flange. The diaphragm valve membrane is typically 0.5 mm thick, and its diameter is slightly less than the inside diameter of the inner cylinder 11.

The pump shaft 20, lift check valve 22, valve membrane 26, and nut 23 together form the piston subassembly.

A flotation collar 35 of a durable foam material fits snugly over the outer cylinder 12 and extends along its length. The flotation collar 35 is thick enough to float the entire pump. As an example, the flotation collar of FIG. 1 is about 2.5″ diameter and volume about 14.9 cubic inches.

FIG. 2 shows the pump in the extended position. Detail A shows the necking of the outer cylinder 12 mating with the flare of the inner cylinder 11 to form a water tight seal. Interference between the two conical sections creates a wedge lock. The desired angle of the mating conic sections produces a lock sufficient to resist normal pumping forces, though not sufficient to resist a sharp axial shock or a twisting push. If the angle is too large, the inner and outer cylinders may not lock. If the angle is too small, one or both cylinders could fracture from stress, or lock too tightly. Because the pumping operation requires two hands, one to hold the pump and one to operate the piston, the holding hand can resist the downward force of pumping action and minimize the tendency of the cylinders to unlock.

FIG. 3 shows the extended pump with the piston moving upward. Upward motion of the piston creates a slight vacuum pressure under the piston, causing the diaphragm valve to seal against the seat area of the diaphragm valve housing, and the inlet valve 2 to flex off its seat on the inlet valve housing. If the lower end of the pump is immersed in water, water will flow into the chamber intake below the piston, and water above the piston will be expelled through the nozzle 17.

FIG. 4 shows the piston in downward motion. Positive pressure is now created in the chamber below the piston, closing the inlet valve against its seat and stopping flow in the lower end of the pump. The positive pressure below the piston opens the lift check valve 22 upward, allowing water to flow into the upper pump chamber. This action transfers water from the lower inlet chamber to the upper discharge chamber for discharge (on the following upstroke) through the nozzle 17.

While the preferred embodiment utilizes interference of flared and necked sections of the inner and outer cylinders respectively to limit extension, and to lock the cylinders in position, other arrangements might instead be employed. One example is shown in FIG. 5 in which extension limitation and locking are accomplished with threaded sections of inner and outer cylinders. Another arrangement might include tabs on the inner cylinder and slots in the outer cylinder to limit extension and lock the cylinders in the extended position.

In the following claims, any terms indicative of orientation (e.g. upper, lower; top, bottom; horizontal, vertical) are meant only to correspond with the illustrations and to facilitate an understanding of the claimed invention. Such terms are not intended as positive limitations.

The foregoing description, including any dimensions, of a preferred embodiment is illustrative. The concept and scope of the invention are not limited by such details but only by the following claims.

Claims

1. A collapsible bilge pump including:

a hollow outer cylinder with top and bottom ends, a hollow inner cylinder with top and bottom ends, and a piston axially movable up and down within said inner cylinder;

said cylinders axially movable relative to each other between retracted and extended positions, the top end of said outer cylinder and the bottom end of said inner cylinder adapted for mutual sealing engagement in said extended positions;

said outer cylinder including a fluid inlet check valve on the bottom end thereof to permit fluid intake into said outer cylinder and to prevent fluid backflow from said outer cylinder;

said piston including a lift check valve on said bottom end thereof for fluid transfer from said outer cylinder into said inner cylinder;

whereby, upward movement of said piston closes said lift check valve to draw fluid through said inlet check valve into said outer cylinder, and downward movement of said piston closes said inlet check valve and opens said lift check valve to admit fluid from said outer cylinder into said inner cylinder for discharge from said top end thereof.

2. A collapsible bilge pump as defined in claim 1 wherein said engagement of said inner and outer cylinders is by circumferential frictional contact.

3. A collapsible bilge pump as defined in claim 1 wherein said inner and outer cylinders are adapted for mating engagement in said extended condition of said pump.

4. A collapsible bilge pump as defined in claim 3 wherein said mating engagement of said inner and outer cylinders is threaded.

5. A collapsible bilge pump as defined in claim 1, further including a foam flotation collar surrounding said outer cylinder.

6. A collapsible bilge pump including:

an outer cylinder with top and bottom ends, an inner cylinder with top and bottom ends, and a piston rod axially movable in said inner cylinder in reciprocal strokes defined by the height of said inner cylinder;

said cylinders axially movable relative to each other between retracted and extended positions, the top end of said outer cylinder and the bottom end of said inner cylinder adapted for mutual sealing engagement in said extended positions;

said outer cylinder including a fluid inlet check valve on the bottom end thereof to permit fluid intake into said outer cylinder and to prevent fluid backflow from said outer cylinder;

said inner cylinder being open at the bottom end thereof, and including a discharge nozzle on the top end thereof;

said piston rod including a piston within said inner cylinder, and a handle extending from the top end of said inner cylinder;

said piston including a lift check valve to permit fluid transfer therethrough from said outer cylinder into said inner cylinder, and to prevent fluid backflow from said inner cylinder;

whereby, upward movement of said piston closes said lift check valve to draw fluid through said inlet check valve into said outer cylinder, and downward movement of said piston closes said inlet check valve and opens said lift check valve to admit fluid from said outer cylinder into said inner cylinder for discharge therefrom.

7. A collapsible bilge pump as defined in claim 6 wherein said engagement of said inner and outer cylinders is by circumferential frictional contact.

8. A collapsible bilge pump as defined in claim 6 wherein said inner and outer cylinders are adapted for mating engagement in said extended condition of said pump.

9. A collapsible bilge pump as defined in claim 8 wherein said mating engagement of said inner and outer cylinders is threaded.

10. A collapsible bilge pump as defined in claim 6, further including a foam flotation collar surrounding said outer cylinder.