Patent Application
20080260559
Water can be pumped from a well using a pumping tube with a check valve so that up and down motion of the tube will cause water to rise in the tube. The up and down motion of the pumping tube may be imparted by hand or by a mechanical device. The inventor routinely pumps 2″ diameter groundwater monitoring wells using a Rotapump™, a portable, surface mounted well pump (U.S. Pat. No. 7,069,986) as the mechanical device to move the pumping tube up and down. The impetus for this invention was to eliminate the weight of the pumping tube and contained water from the pumping effort, thereby increasing pump efficiently and permitting more economical pumping of deeper wells. The invention removes the weight of the pumping tube and contained water from the pumping effort and exploits the harmonic motion of a free vibration system such as a weight hung from a spring.
A pumping tube with a check value and full of water is positioned in a water well supported and held in tension by extension springs. The lower spring is stretched between the pumping tube and a dead weight resting on the bottom of the well. The upper spring is stretched between the pumping tube and a rigid frame at the well head. With the weight of pumping tube and contained water supported by the upper spring, the pumping tube is moved up and down to pump water from the well. The only resistance to pumping tube movement is the force required to accelerate the mass of the pumping tube and contained water and the increase in tension in the top spring on the upstroke and in the top spring on the downstroke, which depend on the amount the pumping tube is displaced. The effect of gravity is eliminated. If the pumping tube is moved up and down harmonically at the free vibration frequency of the system, the pumping effort is minimized.
The invention is described in greater detail with reference to the accompanying line drawing.
A pumping tube means (1) with a check value means (2) is placed in a water well or body of water (3) and moved up and down to fill the pumping with water. The water filled pumping tube (1) is supported and held in tension by extension springs means (4) and (5) attached at both ends. The lower spring means (4) is stretched between the pumping tube means (1) and a dead weight means (6). The upper spring means (5) is stretched between the pumping tube means (1) and a rigid frame means (7). With the weight of pumping tube means (1) and contained water supported by the upper spring means, the pumping tube means (1) is moved up and down to pump water from the well (3). Movement of the pumping tube means (1) is resisted by the mass of the pumping tube means (1) and contained water and by the increased tension in the bottom spring means (4) on the upstroke and in the top spring means (5) on the downstroke, which two resistances depend on the distances the top and bottom spring means (4 and 5) are extended. The effect of gravity is eliminated. The force required overcome the inertia of the mass of the pumping tube means (1) and contained water is proportional to the acceleration imposed on the mass by the motion of the pumping tube means (1).
When freely vibrating, the pumping tube means (1) will oscillate harmonically at a frequency determined by stiffness of the bottom and top springs (4 and 5) and the combined mass of the pumping tube (1) and contained water. With kb and kt being the stiffness factors of the bottom and top spring means (4 and 5), respectively, in pounds per foot, and m being the combined mass of the pumping tube (1) and contained water in slugs, the free vibration frequency, f, of the pumping tube means (1) in cycles per second is given by the square root of kb plus kt divided by m: f=SQRT{(kb+kt)/m}. Because of energy losses, the amplitude of the free vibrations will decrease with time. To prevent this amplitude decrease, an escapement means (8) may be used to give a restoring impulse to the pumping tube (1) on the upstroke and on the downstroke when the pumping tube is moving at its maximum velocity, analogous to the impulse given a clock pendulum when the pendulum is moving at its maximum velocity at its lowest (vertical) position. The motion of the pumping tube means (1) may be made harmonic at any frequency, including the free vibration frequency, by a scotch yoke means (9). When the pumping tube means (1) is vibrated at its free vibration frequency the pumping effort is minimized.
