BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains generally to pumps, and more particularly to a piston type pump capable of pumping moderate volumes of liquid with reduced vibration and reduced thermal degradation, both which contribute to a quieter and longer life-cycle pump.

2. Description of the Related Art

Fluid pumps of many diverse constructions are found in countless devices to move an equally diverse set of fluids. In fact, fluid pumps are ubiquitous with both living things and machinery.

The impellers necessary to move fluids can take on such diverse geometries as one or more inclined blades spinning about a hub and either propelling the fluid axially or radially with respect to the spin axis, a piston reciprocating within a sleeve or cylinder, a gear pair that rotates to separate on an intake side and mesh on a discharge side, a screw turning within a cylinder, a rotary vane, a diaphragm that moves to change the volume of a chamber, a collapsible tube pinched in a progressive manner by an external object or roller, gas bubbles rising in a liquid, gravity moving a liquid from a higher point of elevation to a lower elevation, ions driven by an electrical field, magnetic particles or objects driven by a magnetic field, and others. There are, quite plainly, many diverse geometries and constructions of fluid impellers.

The fluids that are pumped may be even more diverse, ranging from gases such as air or other gases moved by a fan, to low viscosity liquids such as water, and to viscous liquids such as oils and greases pumped within machinery. In the modern world, many different procedures and chemical compositions have been developed that improve a process, formulation, or operation, and rather than manually carrying out these procedures and delivering these compositions, in most cases a mechanized pump will do the work.

There are many different characteristics that can be measured to both define the pump and also determine the suitability of the pump for different applications. A few common characteristics are: flow rate, both with no outlet pressure and at various outlet pressures; inlet suction; maximum outlet pressure; horsepower or equivalent energy consumption; pump complexity; initial pump cost; required pump maintenance; and expected operating life usually measured as Mean Time Between Failure (MTBF). Other characteristics can be estimated or calculated therefrom as well, such as pump efficiency and annual operating cost. Pump efficiency is defined as the ratio of the kinetic power imparted on the fluid by the pump in relation to the power supplied to drive the pump, which can be determined from the energy consumed to generate a flow rate at a pressure head. Other exemplary metrics that may be less common but which may be important or critical for some applications include: compatibility with one or many different fluids, including but not limited to slurries, chemical compositions, and varying viscosities; consistency of output through varying pressure heads; conservation of fluid being pumped; mechanical shear; priming requirements; consistency of output flow rate and pressure; starting current and torque; suitable energy sources for driving the pump; and other factors.

For different applications, these characteristics are often times quite divergent from other applications. For exemplary purpose, a washing machine drain pump has very low pressure head required, typically only lifting the drain water from a few inches to a few feet, and will preferably be of simple construction, have low initial fabrication cost, will have a long MTBF, and will require little maintenance. However, the drain water may include somewhat corrosive compositions such as sodium hypochlorite (chlorine bleach) and powerful detergents that will quickly dissolve grease used in many pump seals. Further, there may be relatively large particles that pass through the washing machine drum along with the water, such as small pins, nails, screws, sand, and other solid objects, that must be pumped without consequential harm or stoppage of the pump. As has been known in the art of washing machines, a simple centrifugal or radial vane pump may be used to meet all of these objectives. However, such a pump will be unable to generate much in the way a greater pressure head, and consequently the output and pump efficiency will vary greatly with changes in pressure head.

In many fluid applications, such as chemical applications, one or more fluids must be mixed with one or more additional fluids to achieve a desired fluid mixture. Commonly, mixing one fluid with another fluid is performed by measuring out a quantity of a first fluid, measuring out a quantity of a second fluid, and combining the measured amounts in a container where the fluids are mixed together. This process is routinely performed by hand, and thus is subject to inaccuracies attributed to human error. Thus, the fluid mixture achieved may not in fact possess the precise desired proportions of the fluids. Additionally, as fluid mixtures are typically mixed in batches (i.e., discrete quantities of a fluid mixture), inconsistencies in the proportions of the mixed fluids from one batch to the next batch may be experienced.

Many artisans over the years have applied various technologies to improve various facets of pumps and to expand the applicability of pumps into industries and applications not previously well addressed. The following patents are incorporated herein by reference as exemplary of the state of the art in a variety of fields, various advances being made therein, and for the teachings and illustrations found therein which provide a foundation and backdrop for the technology of the present invention. The following list is not to be interpreted as determining relevance or analogy, but is instead in some instances provided solely to illustrate levels of skill in various fields to which the present invention pertains: U.S. Pat. No. 1,003,479 by Lucas, entitled “Pump valve”; U.S. Pat. No. 1,632,948 by Cardenas, entitled “Water pump”; U.S. Pat. No. 1,736,593 by Harm, entitled “Circulating device”; U.S. Pat. No. 1,827,811 by Derrick, entitled “Bearing for rotary pumps”; U.S. Pat. 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A challenging application for a pump is the precise or predictable delivery of a volume of fluid in a given time. Piston-type pumps are known to provide a number of advantages over pumps of other construction. Among them is the ability to more precisely or predictably deliver a consistent volume, even with widely varying inlet and outlet pressures. This is because a piston reciprocating in a cylinder creates what is referred to as a positive displacement that is much more independent of inlet and outlet pressure than many other pump types.

There are several challenges with prior art piston pumps. One of these is the inherent pulsations that are created by the movement of the pistons. A typical prior art pump may employ a rotary shaft driven from a motive power source such as an engine or motor, such as might for exemplary purposes be electrically or gasoline powered. The pump may typically have either one or two pistons that reciprocate within a corresponding number of cylinders. Even in the case of a dual piston pump, the moment where one piston has just finished the expelling travel and the other piston is about to begin expelling, there is no driving force on the liquid being expelled. Since there will likely be a hose or pipe of indeterminate length at the outlet of the pump, and since the mass of the liquid within that pipe or outlet has momentum created by the expulsion from the pump, during this moment there is no fluid being expelled from the pump and the momentum of the liquid must be broken. This start and stop of the expulsion leads to a certain amount of pulsation in a small pump of low flow rate. However, when the flow rate is substantially increased, the pulsations increase and become hammering and vibration. As is well established, in most mechanical systems extreme vibrations are detrimental and can lead to early failure.

In addition, as the flow rate is increased, there will also be a concomitant increase in the load imposed upon bearings that support the rotary shaft. This leads to elevated temperature within the bearing, which is also known to be detrimental, particularly when operated in an already hot environment.

The increased flow rate and pulsations not only increase the load upon the bearings, but also increase the load and also potentially the wear of the valves, pistons, cylinders, and seals. In consideration thereof, various artisans have developed multi-piston pumps having three or more pistons that are radially arranged about a rotary drive shaft. These pumps are configured in some instances to resemble well known internal combustion and steam engines, including connecting rods between a central shaft or drive wheel. Exemplary U.S. patents and published applications, the teachings which are incorporated herein by reference, include: U.S. Pat. No. 4,645,428 by Arregui et al, entitled “Radial piston pump”; and 2009/0074591 by Courier, entitled “High pressure radial pump”. Unfortunately, this construction requires a large number of bearings and couplings that drastically increase the initial pump cost. These additional parts also tend to decrease the average reliability of such pumps, reflected in a shorter Mean Time Between Failure (MTBF). In order to improve the reliability of such pumps, and like prior art steam engines and internal combustion engines, the internal components are often required to be either immersed in a lubricant such as an oil bath, or sprayed or splashed with lubricant on a relatively continuous basis. Unfortunately, at any pressure there will be some leakage past the seal between the piston and cylinder, and this leaked fluid may migrate to the region of the connecting rods and bearings and can cause early failure. This can be particularly disadvantageous in some applications, particularly where non-lubricant fluids are being pumped at very increased pumping pressures.

Other artisans have avoided the need for connecting rods through the use of cams defining an eccentric cam surface about the rotary shaft to drive the pistons. In some of these instances, the artisans have relied upon return springs to keep the pistons in contact with the cam. Exemplary U.S. patents, the teachings which are incorporated herein by reference, include: U.S. Pat. No. 935,655 by Haire, entitled “Gaseous fluid compressor”; U.S. Pat. No. 2,461,121 by Markham, entitled “Fluid pump”; U.S. Pat. No. 2,801,596 by Sewell, entitled “Multi-cylinder pump”; U.S. Pat. No. 5,032,065 by Yamamuro et al, entitled “Radial piston pump”; U.S. Pat. No. 5,167,493 by Kobari, entitled “Positive-displacement type pump system”; U.S. Pat. No. 5,382,140 by Eisenbacher et al, entitled “Radial-piston pump”; U.S. Pat. No. 5,383,770 by Hisahara, entitled “Radial piston pump with vent in hollow piston”; and U.S. Pat. No. 6,162,022 by Anderson et al, entitled “Hydraulic system having a variable delivery pump”. Unfortunately, the return springs must be sufficiently powerful to drive the pistons into contact with the cam, regardless of the state of the fluid flow. In other words, if a viscous liquid is being pumped, and the spring is acting to move the fluid into the piston cylinder, then the return spring must be strong enough to overcome the thick liquid and still draw the liquid in. Yet, with a thin or much less viscous liquid, this must be accomplished without causing the piston to bounce. Furthermore, any separation between the piston and cam will also lead to subsequent impact, either in the form of taps or rattling, or in extreme cases in the form of severe hammering. Clearly, none of these are desirable. The spring itself is also being cycled rather violently, storing substantial energy when the piston is moving in a first direction and then releasing it when the piston is moving in the opposite direction. This energy storage and release leads to both substantial heating within the spring and also to potential work hardening or molecular reorientation, which will lead to spring breakage and failure. Finally, any separation or failure of the piston to fill the cylinder on the intake stroke or to empty the cylinder on the outlet stroke will result in a decrease in pump flow rate or output volume. Such a decrease in output defeats the precise volume displacement with each piston stroke that is otherwise a primary benefit of a positive displacement pump such as a piston pump.

Other artisans have overcome this deficiency of spring return using other mechanisms. Exemplary U.S. patents, the teachings which are incorporated herein by reference, include: U.S. Pat. No. 4,690,620 by Eickmann, entitled “Variable radial piston pump”; and U.S. Pat. No. 5,613,839 by Buckley, entitled “Variable rate pump”. Each of these patents requires an inlet pressure greater than atmosphere to drive the piston on the inlet stroke, and then uses the cam to drive the piston in the opposite direction on the outlet stroke. In other words, there must be a pump in the fluid flow path preceding these pumps to provide the fluid pressure required to fill the cylinder on the inlet stroke. While there are certain applications where this can be of great benefit, the applications for such a pump are much more restricted and of course more expensive, owing to the need for two pumps instead of one.

A few artisans have heretofore recognized the limitations of the piston return springs or need for pressurized inlet fluid. Exemplary U.S. patents, the teachings which are incorporated herein by reference, include: U.S. Pat. No. 759,828 by Olney, entitled “Engine”; U.S. Pat. No. 5,030,065 by Baumann, entitled “Reciprocating compressor”; and U.S. Pat. No. 8,333,572 by Hsieh, entitled “Pump”. These patents describe various yokes that are designed to positively reciprocate the pistons. As already noted herein above, the yokes can thereby be used to simultaneously increase the reliability and life of the pump, improve the operation of the pump with diverse viscosities of fluids, maintain high precision in pump volume, and also avoid the need for a second inlet pump. In addition to these multi-piston pumps, there are a number of patents for inventions developed by Cook and Cook et al and owned by the present assignee referenced herein above with regard to single or dual piston pumps that illustrate yokes of similar purpose and function.

In spite of the many advantages of these yokes and the existence of the aforementioned multi-cylinder piston pumps, the many characteristics of pumps described herein above have continued to be contrary in the marketplace. As is very apparent from a review of the multi-piston pumps described herein above, the complexity of these prior art pumps makes the initial pump cost very high, and many such pumps are often also associated with a shorter expected life as measured by MTBF.

As may be apparent, in spite of the enormous advancements and substantial research and development that has been conducted, there still remains a need for a positive displacement pump that is capable of precise or predictable delivery of a volume of fluid in a given time independent of reasonable inlet and outlet pressures pump, that is also capable of increased volume pumping while reducing the associated vibration of the prior art, and which is also better able to withstand extremes of temperature and load.

In addition to the foregoing patents, Webster's New Universal Unabridged Dictionary, Second Edition copyright 1983, is incorporated herein by reference in entirety for the definitions of words and terms used herein.

SUMMARY OF THE INVENTION

In a first manifestation, the invention is a pump body having an intake manifold with internal inlet conduits, an outlet manifold having internal outlet conduits, and a plurality of heads affixed to the intake and outlet manifolds. Captured between each head and the intake manifold are a plurality of one-way inlet valves and seals. Captured between each head and the outlet manifold are a plurality of one-way outlet valves and seals.

In a second manifestation, the invention is a pump having a fluid intake manifold with fluid internal inlet conduits and a first rotary drive shaft bearing affixed thereto, an outlet manifold having internal outlet conduits and a second rotary drive shaft bearing affixed thereto, a working fluid operatively flowing through the inlet conduits and outlet conduits and thereby cooling the first and second rotary drive shaft bearings.

In a third manifestation, the invention is a pump head machined from four bores open on a first end and closed internally within the pump head on a second end distal to the first end, a first bore defining a radial inlet bore, a second bore defining a radial outlet bore, a third bore defining a piston cylinder, and a fourth bore passing through each of said first three bores and defining both a longitudinal inlet bore and a longitudinal outlet bore.

OBJECTS OF THE INVENTION

Exemplary embodiments of the present invention solve inadequacies of the prior art by providing a positive displacement reciprocating multi-cylinder pump having a cam, bearing(s), and yokes that cooperatively and positively reciprocate the pistons. The fluid flow paths are configured to provide intrinsic cooling of the bearings through specially configured fluid flow paths at distal ends of the pump. An intentional head geometry that may be readily machined captures valves and provides essential fluid flow paths about the cylinders.

The present invention and the preferred and alternative embodiments have been developed with a number of objectives in mind. While not all of these objectives are found in every embodiment, these objectives nevertheless provide a sense of the general intent and the many possible benefits that are available from embodiments of the present invention.

A first object of the invention is to provide a pump that can provide precise or predictable delivery of a volume of fluid in a given time, independent of reasonable ranges of inlet and outlet pressures and viscosity of fluid. A second object of the invention is to provide a pump that can provide increased volume pumping while reducing the associated vibration and pressure pulsation during pump operation. Another object of the present invention is to provide a pump that is also better able to withstand extremes of temperature and load. A further object of the invention is to provide a pump that requires a minimum of components, and most preferably components that can easily be machined or produced in a low cost manner, and that further can be readily assembled without special tools. Yet another object of the present invention is to provide a pump that may use sealed bearings within an atmospheric chamber, thereby reducing the need for special lubricant sprays or immersion baths and allowing any leakage to be either released to atmosphere or if so desired, collected and removed without harming bearings or other internal components.

