Patent Application
20050123416
The present invention relates generally to fluid motor devices capable of converting a portion of the energy of a fluid flow into a reciprocating movement. More particularly, the present invention relates to devices comprised of a fluid motor coupled to a fluid pump.
Fluid pumps may be powered by electric motors or by fluid motors. Fluid pumps driven by electric motors have a number of undesirable attributes. For example, in some applications, fluid pumps using electric motors are undesirable for safety reasons. For instance, when pumping solvents, acids, oils, and flammable liquids, it can be disadvantageous or even dangerous to operate high voltage or high current electric motors to drive the pumps. As another example, fluid pumps using electrical motors do not easily start from a stalled condition and stop into a stalled condition. Such intermittent fluid flow is desired in some applications, requiring cyclic starting and stalling of the flow.
Current fluid motors and pumps may have valve ports that limit fluid flow through the unit in a manner that results in pressure drop and turbulence through the motor. When a powering fluid is saturated with a gas, for example, gas saturated carbonated water, too much pressure drop and turbulence through a fluid motor may cause the CO2 to bubble out of the solution, adversely affecting precision as a fluid powered proportioning pump for carbonated water and syrup. In addition, internal valve leakage in the motor while shifting may adversely affect precision as a fluid powered proportioning pump.
Three devices that may be representative of the art include: a nonelectric proportional dispenser from Dosatron International of 2090 Sunnydale Blvd., 40 Clearwater, Fla. 33765 (phone: 727-443-5404; fax: 727-447-0591); a brix pump from Shurflo of 12650 Westminister Ave., Santa Ana, Calif. 92706-2100 (phone: 714-554-7709; fax: 714-554-4721); and Dosmatic USA of 1230 Crowley Circle, Carrollton, Tex. 75006 (phone: 972-245-9765 fax: 972-245-9000). These devices use water pressure as the power source to operate a fluid powered, piston proportioning pump.
One exemplary aspect of the invention is directed to a device utilizing a fluid motor. The device comprises a housing and a reciprocating piston in the housing. The piston and the housing may be configured to define at least two variable-volume chambers. A multi-port valve may be associated with the piston, and may be in communication with the at least two chambers. A valve actuating mechanism may be configured to actuate the multi-port valve to affect a fluid path in the device. The device may also include a valve engagement-release mechanism configured to maintain the multi-port valve in a position when the valve is not being actuated. An inlet port and an outlet port may be in selective communication with each piston chamber through the multi-port valve.
In another exemplary aspect, a method for operating a fluid motor having a first and a second fluid chamber separated by a reciprocating piston is disclosed. The fluid motor may have an inlet port and an outlet port. The method may include introducing fluid to the first chamber through the inlet port, the inlet port being in fluid communication with the first chamber. The volume of the first chamber may be increased by moving the piston. Energy may be stored in a valve actuating means, wherein the energy may be provided by the moving piston. The method may also include shifting a valve member by releasing the stored energy to close the fluid communication between the inlet port and the first chamber, and to place the inlet port and the second chamber in fluid communication. Fluid may then be introduced to the second chamber through the inlet port. The volume of the second chamber may then be increased by moving the piston.
The device of the present invention may be used as a fluid motor coupled to a fluid pump. The flow and pressure of a first fluid through a reciprocating piston, fluid motor mechanically coupled to a reciprocating, fluid pump causes a flow and pressure of a second fluid in a predetermined ratio. It is not necessary for the flow and pressure of the first fluid to be the same as the flow and pressure of the second fluid.
The device of the present invention may have a utility for a variety of diverse applications without the need of electrical energy. Examples of such applications include, but are not limited to, proportioning, sampling, metering, flow detection, energy recovery, pressure intensification, and pumping. The device of the present invention may have advantages of cost, performance, simplicity and materials sufficient to displace devices in existing applications and enable potential new applications. Typically, two or more streams (liquid or gas) will be proportioned where one stream has a source pressure higher than its destination pressure and serves as an energy source to operate a reciprocating motor and the other streams have a source pressure lower than its destination pressure and use a pump powered by a motor to provide pressure and proportioning.
Examples of applications where a fluid pumped or maintained under pressure include the pumping of water, solvents, acids, oils and flammable liquids. As stated above, in some of these applications, an electric motor is disadvantageous for safety reasons. Further, some of these applications require starting from a stalled condition and stopping into a stalled condition and are not easily accomplished with an electric motor. Double diaphragm gas operated pumps may be used. The present invention can use either a pressurized fluid or a pressurized gas.
For applications involving both the pressurization of a fluid and the discharge of a pressurized fluid, waste energy may be reclaimed by the present invention. An example is reverse osmosis where the feed water is pressured by a pump to drive the water through a semi-permeable membrane. Most of the pressurized water is discharged to drain with no re-use of pressurization energy. The present invention can use the energy of the pressurized discharge water to provide most of the pressurization of the feed water, consequently reducing the pump and motor requirements for feed water pressurization. For example, this is advantageous where available energy is limited such as on submarines or mobile potable, water purification equipment for soldiers.
The system of the present invention may be used in applications where a fluid is de-pressurized and then re-pressured. An example is an ambient pressure solar water heater where ambient temperature, pressurized domestic water is de-pressurized to fill an atmospheric pressure solar collector of the black bag type. Heated water from the collector is re-pressurized to provide flow to faucets and appliances. Use of the present invention, simplifies and lowers the cost of the solar system by using the pressure of the unheated incoming water to re-pressurize the heated collector water in a one to one ratio.
The system of the present invention may be used in applications where a small flow of high pressure fluid is desired and a large flow of low pressure fluid is available. An example is a hydraulic intensifier where the energy of a high flow of low pressure hydraulic oil may be used to operate the fluid motor of the present invention which in turn operates a smaller cross section pump to create a low flow of high pressure hydraulic oil. The increase in pressure is proportional to the ratio of the flows and therefore the cross sections of the motor and pump.
The system of the present invention may be used in applications where two or more fluids are mixed in a predetermined adjustable or non-adjustable ratio. Examples include: diluting and mixing herbicides and pesticides into water for agricultural spraying, diluting and mixing fertilizer into irrigation water for agricultural and horticultural use, diluting and mixing soap concentrate into water for washing equipment for clothes, dishes, parts and the like, diluting and mixing an oil concentrate into water for machine tool lubrication, and for the addition of chemical into the make-up water of process tanks. The present invention may function in this application by using the flow and pressure of the water as the first fluid for the fluid motor. The additive fluid as the second fluid is pumped by the fluid pump in a ratio proportional to the cross sections of the fluid motor and fluid pump times their effective stroke. The discharge of both may then be mixed.
The system of the present invention may be used in applications that require indicating a flow rate or totalizing a flow. The flow to be measured is used as the fluid through the fluid motor. At least one sensor may detect the reciprocating motion of the piston. The signal from the sensor provides information convertible into flow rate or total flow information. A sensor may be provided that can detect the piston motion without direct contact, without a shaft penetrating the housing.
The system of the present invention may be used in sampling applications. The fluid to be sampled powers the fluid motor. The fluid pump may draw some of the discharge fluid of the fluid motor as a second fluid. The flow from the fluid pump may be the sample. The sampling ratio may be proportional to the ratio of the cross section of the fluid pump and motor.
A common application particularly suited to the present invention is the post mix beverage dispenser. Since pressurized domestic water is almost always available the device of the present invention may be substituted for the compressed, carbon dioxide gas operated “bag-in-the-box” syrup pump by using the domestic water as an energy source and then sending the spent water to drain. Using the energy of the carbonated water to pump and proportion the syrup may make an even more advantageous use of the present invention. In this way, the present invention replaces both the conventional syrup pump and the proportioning part of the dispensing valve, further simplifying the dispenser and lowering its manufacturing cost.
The system of the present invention may be used in applications such as fuel cells that use different phases. Compressed air can power the reciprocating motor that powers a fuel pump and a water pump in a desired proportion. The discharge of all three may then be directed into a reformer.
The present invention has advantages in these applications because no electricity is required for power or control. The invention operates as a fluid motor, a fluid pump, a combined fluid motor and pump, or proportioning device as needed by the application. The present invention ceases operation when the flow of one or more fluids is ended, and the invention will resume operation when the flow is re-established, i.e. the device is stallable.
The present invention may have a fluid motor similar in construction to the common air and hydraulic tie rod design and actuating cylinders. This construction is easy and economical to manufacture and capable of withstanding pressures from 100 psi to thousands. The present invention may be used in applications under such pressures. The present invention may have a hydraulically balanced multi-port valve with substantially no internal leakage when shifting. This feature provides several important advantages over products currently commercially available: (1) The force required to shift the multi-port valve does not vary substantially with either an increasing pressure differential across the motor or increase of the valve port cross sectional area. (2) Therefore, a given valve actuation mechanism and a given valve release mechanism can operate over a wider range of flows and pressures than fluid motors now manufactured. (3) Since there is no design penalty for larger valve port cross sections, a motor of the present invention can be made with large valve ports thereby reducing the pressure drop and turbulence through a motor.
Thus, the present invention aids in avoiding at least two problems that limit the utility and applications of other designs: (1) when a powering fluid is saturated with a gas, like carbonated water is, too much pressure drop and turbulence through a fluid motor will cause the CO2 to bubble out of solution and adversely affect precision as a fluid powered proportioning pump for carbonated water and syrup; and (2) a multi-port valve allowing internal leakage while shifting also adversely affects precision as a fluid powered proportioning pump.
The present invention may be compatible with embodiments having different features. The present invention describes two exemplary types of valve actuation means: spring and magnetic, although other types of actuation means are considered. In the magnetic, the valve actuating mechanism may include at least two magnets having a polarity oriented in a manner that one magnet repels the other magnet. The present invention also describes three exemplary types of valve release mechanisms: mechanical trigger, mechanical over-the-center, and magnetic, although other types are considered. The present invention may include a stroke compensator to make the ratio of a fluid powered proportioning pump with double acting pump the same in both stroke directions. The present invention contemplates the use of single acting, double acting, external, internal, fixed ratio, adjustable ratio, multiple, and single pumps. The present invention describes a stroke signal means usable for flow control, flow rate measurement and flow totalizing.
This invention may provide device functioning as a combined fluid motor and pump of unusual simplicity and low part count.
This invention is consistent with requirements for injection molded, polymer parts and automated or mechanized assembly allowing the potential for low cost mass production. It is also consistent with requirements for metallic parts in applications where stresses are too great for polymer parts.
This invention has numerous useful embodiments suitable for a wide range of applications. Although the invention may be used with additional features, some exemplary embodiments include the following:
It is another object of the present invention to provide a device that converts a first fluid flow and pressure into mechanical motion by means of a fluid motor part of the device and using this mechanical motion converts it into fluid flow and pressure by means of a fluid pump part of the device.
It is another object of the present invention to provide a fluid motor where the energy for valve actuation is supplied by piston displacement.
It is another object of the present invention to provide a fluid motor where the energy for valve actuation is stored and released in springs.
It is another object of the present invention to provide a fluid motor/pump where valve actuation is enabled by proximity of the piston to the end of its chamber.
It is another object of the present invention to provide a device that operates without need of electrical control or power.
It is another object of the present invention to provide a device that will stop and restart in response to a first fluid's flow and pressure.
It is another object of the present invention to provide a device that will stop and restart in response to a second fluid's flow and pressure.
It is another object of the present invention to provide a fluid motor that will stop and restart in response to input fluid flow and pressure.
It is another object of the present invention to provide a fluid motor that will stop and restart in response to shaft pressure.
It is another object of the present invention to provide accurate, volumetric proportioning of two or more fluids.
It is another object of the present invention to provide fluid motor driven proportioning pump of a fixed ratio.
It is another object of the present invention to provide a fluid motor driven proportioning pump of an adjustable ratio.
It is another object of the present invention to provide a device where the fluids may be either liquid or gas.
It is another object of the present invention to provide a device with a means of sensing the reciprocating motion for control and measurement purposes.
The above objects are exemplary only, and this invention contemplates devices and systems that may meet or fulfill one or more of these objects. Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. In addition to the structural and procedural arrangements set forth above, the invention could include a number of other arrangements such as those explained hereinafter. It is to be understood that both the foregoing general description and the following detailed description are exemplary only.
The accompanying drawings illustrate embodiments of the invention and together with the description, serve to explain some exemplary embodiments and principles of the invention.
Reference will now be made in detail to exemplary embodiments of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
An exemplary fluid pump is comprised of housing segments 228, 230 and 232. Segment 230 contains pump inlet port 162 and pump outlet port 236. Segments 232, 230, 228, and end cap 210 may be held together in compression by fasteners 192, such as, for example, rods and bolts. Pump ports 162 and 236 are shown as tubes suitable for the “instant” type tube connection. These ports along with fluid motor ports 180 and 182 could just as well be another type of fitting such as, for example, screw, flange, or flare.
A shaft 118 may be fastened to a piston assembly. Shaft 118 may penetrate end cap 186 and may be sealed by a shaft seal assembly comprised of seal 129, seal bushing 128, and seal retainer 192. In the exemplary embodiment shown, the piston assembly is comprised of piston body 216 and piston body 214. Variable volume chamber 212 and variable volume chamber 204 are isolated by piston ring seal 70 and o-ring 72.
A multi-port valve may be located within a piston assembly. An exemplary multi-port valve is shown in
Inlet port 180 (shown in
Outlet port 182 (shown in
A valve magnet 94 may be fixed in position within piston body 214 and piston body 216. Valve magnet 94 may exert an attractive force upon spring mount 97 due to its proximity holding a slidable poppet assembly in place at its limit of travel in direction 213.
In some exemplary embodiments, when a poppet assembly shifts from one position to another, at least a portion of the fluid may flow from the inlet to the outlet without acting on a piston, thereby forming a leak. The volume leaked can be reduced by, for example, shifting the poppet assembly quickly. Leakage can also be reduced by providing poppets that substantially block the undesirable flow path even as the poppets shift, as in a low leakage valve of
In use, a piston assembly advances in direction 213. A powering fluid enters the fluid motor through inlet port 180 (shown in
Countering the force in spring 100 is a force on a poppet assembly biasing it in direction 213 by magnetic attraction between magnet 94 and spring mount 97. By design, with the continued advance of the piston and the subsequent further compression of spring 100, the force from spring 100 in direction 41 will eventually exceed the opposing force in direction 213 by magnet 94 and mount 97. At that time, a poppet assembly will slidably shift rapidly to its alternate limit of travel in direction 41. The increased distance between magnet 94 and spring mount 97 results in negligible attractive force. However, with the shift of the poppet assembly, magnetic 94 and spring mount 96 are in proximity and the attractive force is significant and sufficient enough to hold a poppet assembly in place at the limit of travel in direction 41.
With a shift of a poppet assembly, the powering fluid may be re-directed. Thus, the powering fluid may enter inlet port 180 and ultimately into cylinder chamber 212. Since there is no exit from chamber 212, the volume increases as a piston is displaced in direction 41. With the displacement of a piston in direction 41, the volume of cylinder chamber 204 is reduced, expelling a powering fluid to outlet port 182. As a piston advances in direction 41, actuating spring 98 will eventually make contact with end cap 186. Further advance causes further compression of spring 98. Ultimately, the force resulting from compression of spring 98 will exceed and overcome the force between magnet 94 and spring mount 96 causing a rapid, slidable shift of a poppet assembly in direction 213. Thus, another cycle begins, with the reciprocation of a piston within its cylinder and with the reciprocation of a poppet assembly within its valve.
In the exemplary embodiment shown, the fluid path is from the inlet to a valve in the piston, and from a valve to a variable volume cylinder chamber, and from the other cylinder chamber to a valve in the piston, and from a valve to the outlet. The fluid does not flow from one cylinder chamber through a piston to the other cylinder chamber as in other devices of prior art.
In some exemplary embodiments, multiple seals may be utilized to isolate a fluid motor and pump. The seals may be spaced to provide a gap between the seals greater than the piston stroke so that no part of the shaft that is exposed to the fluid of the motor is exposed to the fluid of the pump. In the exemplary embodiment shown in
A pump housing may be comprised of housing segments 228, 230 and 232. The segments may be connected together and to motor end cap 121 by a fastener 192. The fastener could be any system or method that holds the different components together. Segments 228, 230, 232 and end cap 121 may be sealed using any seal, such as, for example, o-rings 351.
The reciprocating motion of a motor piston may be transmitted to a pump piston 353 that may be fixed to shaft 118 by a fastener, such as fastener 355. Piston 353 may slide in a pump bore 359 separating the bore into two variable volume chambers 357 and 358. Chamber 357 may be defined by surfaces of pump bore 359, piston 353, and housing segments 230 and 232. Likewise, chamber 358 is defined by surfaces of pump bore 359, piston 353, and housing segments 228 and 230. Chamber 357 may be isolated from chamber 358 using any seal or system, such as, for example, piston seal 354. Depending on the application, seal 354 may be an o-ring, lip seal, piston ring, or other seal or gasket.
In use, a pumped fluid enters tube inlet port 162 (shown in
In other exemplary embodiments, shaft 118 is extended and additional pumps are added and stacked in series. Thus, the motor is able to operate multiple pumps. In addition, by varying the cross section of pump piston and pump bore, displacement per stroke can be set independently. By this means, a powering fluid operating a fluid motor of this invention can pump one to multiple fluids in predetermined proportions. In the exemplary embodiment shown, the pump is a piston type. However, any type pump using the power of a reciprocating shaft may be used, including a diaphragm type pump. Furthermore, it should be noted that the disclosed design is compatible with all fluids, including liquids and gases. Thus, a gas may be substituted for one or more liquids, including a powering liquid.
The exemplary end port motor includes a housing assembly comprised of case 196, end cap 121, end cap 350, seals 120, and fasteners 224. Shaft 118 is fixed to a piston assembly and protrudes through end cap 121 and into a pump. A piston assembly includes piston member 400 and piston member 401 that are joined by fastener 140 (not shown). A piston assembly may include a multi-port valve. The exemplary multi-port valve shown includes a valve retainer 403 and a valve retainer 404. Outlet distribution spool 405 is fixed between piston member 400 and piston member 401 and may be sealed at piston members 400 and 401 by o-rings 406. An annular chamber 407 in spool 405 may be communication with an outlet port 182. The pathway from outlet port 182 to annular chamber 407 may include passageway 183, outlet piston tube 195, chamber 207, and passageway 208 all of which are not shown except piston tube 195. Valve holes 408 in spool 405 may provide communication between annular chamber 407 and cylinder chamber 204. Valve holes 408 in spool 405 may also provide communication between annular chamber 407 and cylinder chamber 212.
In the exemplary embodiment shown, an outlet valve poppet 409 with piston ring seal 410 slidably occupies spool 405. The width of seal 410 is slightly wider than the diameter of holes 408 that seal 410 slides over. Therefore, holes 408 are configured to avoid communication with chamber 212 and chamber 204 at the same time. Fixed to poppet 409 on one side is rack member 411 and the other side is detent member 412. Detent member 412 may be slidably restrained on three sides by valve retainer 404 and on the fourth side by roller 421. Rack member 411 is slidably restrained on three sides by valve retainer 403 and on the fourth side by spur gear 414.
Inlet distribution spool 415 may be fixed between piston member 400 and piston member 401 and may be sealed at piston members 400 and 401 by o-rings 406. An annular chamber 416 in spool 415 may be in communication with an inlet port 180. The pathway from inlet port 180 to annular chamber 416 may include passageway 184, inlet piston tube 194, chamber 206, and passageway 240 all of which are not shown except piston tube 194. Valve holes 408 in spool 415 provide communication between annular chamber 416 and cylinder chamber 204. Valve holes 408 in spool 415 also provide communication between annular chamber 416 and cylinder chamber 212.
An inlet valve poppet 417 with piston ring seal 418 slidably occupies spool 415. The width of seal 418 may be slightly wider than the diameter of holes 408 that seal 418 slides over. Therefore, holes 408 do not communicate with chamber 212 and chamber 204 at the same time. Fixed to poppet 417 on one side is rack member 419 and the other side is detent member 420. Detent member 420 may be slidably restrained on three sides by valve retainer 404 and on the fourth side by roller 421. Rack member 419 may be slidably restrained on three sides by valve retainer 403 and on the fourth side by spur gear 414. Additionally, spring mount 96 and valve actuating spring 100 may be fixed to rack 419. A shoulder on mount 96 may make contact with valve retainer 403 to limit the travel of an inlet poppet assembly. Spring mount 97 and valve actuating spring 98 may be fixed to detent member 420. A shoulder on mount 97 may make contact with valve retainer 404 to limit the travel of an inlet poppet assembly.
The exemplary multi-port valve shown, utilizes inlet and outlet poppet assemblies that shift positions when a piston reaches the end of its stroke to cause reversal of a piston's travel. An actuating spring compressed by a piston's advance on its end cap provides the force needed to accomplish the shift of poppet assemblies. Inlet and outlet poppet assemblies are configured to shift equal amounts, yet in opposite directions because of linkage provided by gear 414 and inlet rack 419 and outlet rack 411. Gear 414 is rotatably fixed in valve retainer 403. This feature is important in another regard, a multi-port valve having poppet assemblies that are linked and balanced on a common fulcrum may be hydraulically balanced. In a hydraulically balanced valve, regardless of the differential pressure from one cylinder chamber 204 to the other cylinder chamber 212, the force required to actuate the valve shift is substantially constant. This allows the design of valve ports with generous openings resulting in lower pressure drop while keeping the valve actuating mechanism and valve release mechanism compact and subject to lower forces than is otherwise possible.
A valve release mechanism may be necessary to hold valve poppet assemblies in place while a valve actuating spring is compressed. Further, in the exemplary embodiments shown, a valve release mechanism should release valve poppet assemblies when an actuating spring is sufficiently compressed so that a valve actuating spring may act to shift valve poppet assemblies quickly and completely to the limit of their travel. Three types of exemplary release mechanisms are described in the present invention, although others are within the scope of the invention: first—a magnetic release as described in
The valve release mechanism may include a torsion spring 425 to which detent roller 423 and detent roller 427 are fixed, yet free to rotate. Torsion spring 425 may act on detent roller 423 and detent roller 427 biasing them toward one another. The flexural extension of torsion spring 425 may be sufficient to allow detent roller 423 to clear a detent slot 424 in detent member 420, yet insufficient to clear trapping slot 422 in valve retainer 404. The flexural extension of torsion spring 425 may be sufficient to allow detent roller 427 to clear a detent slot 428 in detent member 412 yet insufficient to clear trapping slot 426 in valve retainer 404. The flexural extension may be altered or adjusted as desired for a particular application. In the exemplary embodiment shown, since there are two detent positions in each detent member, the poppet assemblies may be biased in two positions. The detent positions may be sufficiently shallow to allow the detent rollers to ramp out of them when the actuating spring force is sufficiently high by means of a wedging action. Accordingly, the valve release occurs when the force of the shifting means overcomes the force of the restraining means. The action of this mechanism is referred to as a spring biased, over-the-center mechanical release, and may be described as “snap action” and “over-the-center.”
Alternatively, the mechanical release described can be modified into a trigger type mechanical release. This may accomplished by allowing torsion spring 425 to make contact with end cap 350. As a piston advances, torsion spring 425 will be increasingly flattened, eventually arriving at the point where detent member 420 is released. Accordingly, the valve actuation is triggered at a specific location during the piston stroke, when physical interference restrains an energy source biased toward shifting. Since such a release mechanism requires contact by definition, a mechanical release may be duplicated on the opposite side of a piston as well as the side shown. The exemplary valve release mechanisms described above utilize the piston advance for accumulating energy to shift a valve. However, valve release mechanisms other than those described may be used.
Fixed onto case 196 is a position detector 431 such as a reed switch with signal wires 430. Fixed into piston member 401 is a position transmitter 429 such as a magnet. A signal from detector 431 can be used for purposes including starting and stopping the fluid motor by means of a solenoid valve, controlling the fluid motor speed, counting strokes, computing the flow rate, and totalizing the flow.
In use, a pressurized, powering fluid flows into a piston of a motor through inlet port 180 (shown in
Where a fluid powered proportioning pump makes one complete cycle (i.e., a complete stroke in both directions), the proportioning accuracy may be substantially maintained. However, if highly accurate proportioning should be maintained and the cycle is not complete, then additional design details may be incorporated to achieve even increased accuracy. In order to keep the proportioning substantially accurate, the system may be modified to either (1) make the ratio substantially constant in each stroke direction, or (2) make the displacement substantially constant in each stroke direction. One example of a way to make the displacement substantially constant in both directions is to extend the pump shaft through a seal in the pump end cap and extend the motor shaft through a seal in the motor end cap in a way to insure the swept area on both sides of a piston are the same. Another example of a way to make the displacement substantially constant is to make the ratio substantially constant in each stroke direction using carefully chosen cross sections for shaft 118, inlet piston tube 194, and outlet piston tube 195. One example for determining the ratio is set forth below. The following equations assume a 1 to 5 proportion of fluid pump displacement to fluid motor displacement. The ratio is chosen for exemplary purposes only, and it should be apparent that other, different ratios could also be used. A ratio of 1 to 5 is a typical ratio for post mix beverages. The actual ratio will be dependent on the application requirements.
Where A is the area of a pump piston, F is the area of a shaft connecting a pump piston and motor piston, C is the area of a motor piston, and E is the summed area of the inlet piston tube and the outlet piston tube.
Tube 304 may be slidably positioned with respect to end cap 310 to achieve the desired, adjustable pump displacement and then fixed in position by screwing in jam nut 306 that compresses o-ring 308 providing a static seal and locking tube 304 in position by friction. When a piston travels in direction 325 and while the tip of pump tube 304 is past seal 316 on the side of chamber 318, the interior volume of chamber 318 may be increasing as pump tube 304 is withdrawn. The increased volume of chamber 318 may be filled with a pumped fluid drawn into pump inlet barb fitting 300 through one way check valve 302 and through the interior of pump tube 304 into pump chamber 318. Pump chamber 318 may be isolated from fluid motor chamber 212 by a seal assembly. An appropriate exemplary seal assembly may comprise of seal bushing 314, seal ring 316, and seal retainer 312. In use, as a piston travels in direction 326, a pumped fluid is displaced from pump chamber 318 by the intrusion of tube 304. The only path open to the displaced pump fluid is through check valve 320 since flow in the opposite direction is blocked by check valve 302. Pumped fluid exits pump chamber 318 through one way check valve 320 and into passageway 329 that communicates with inlet piston tube chamber 206 (not shown). A pumped fluid mixes with a powering fluid in chamber 206 (not shown). The reciprocating motion of a piston causes a pumped fluid to enter a device of the present invention and mix with a powering fluid in an adjustable proportion. The adjustable pumping feature is associated with the tip of tube 304 clearing a seal 316 on the side of motor chamber 212. This is possible because tube 304 may be positioned where the tip of tube 304 is within pump chamber 318 for only a portion of a reciprocating stroke of a motor piston rather than its entire stroke. Positioning tube 304 further into the fluid motor in direction 325 increases the pumped volume per piston stroke while positioning tube 304 further out of the fluid motor in direction 326 decreases the pumped volume per piston stroke. Consider a piston stroke where the tip of tube 304 is within pump chamber 318 for part of a piston stroke in direction 325. Beginning with the tip of tube 304 within pump chamber 318, a pumped fluid enters chamber 318 through tube 304 to replace the volume of tube 304 that is withdrawn. However, as the stroke continues, the tip of tube 304 clears seal 316 and pump chamber 318 is in communication with motor chamber 212 and the flow of a pumped fluid ceases for the remainder of the stroke. Fluid flows through check valve 320 only from chamber 318 to passageway 329 because a pump is designed to create a pressure greater than a motor inlet pressure when tube 304 is within chamber 318 and advancing in direction 325. Otherwise, there is no flow through check valve 320 because the pressure is always higher on the passageway 329 side of check valve 320 in communication with inlet piston tube chamber 206 (not shown). When a piston reverses to travel in direction 326, the tip of tube 304 approaches seal retainer 312. Retainer 312 has a leading bevel to guide in the tip of tube 304. The tip of tube 304 is rounded to facilitate entry. As the stroke continues, the tip of tube 304 passes seal 316 and enters chamber 318 to function as previously described displacing a portion of the volume of chamber 318. The embodiment of this invention allows a first powering fluid to adjustably proportion and pump a second pumped fluid. Furthermore, with a piston of sufficiently large cross section, additional pump sets may be incorporated into a fluid motor allowing a powering fluid to proportion and pump multiple pumped fluids. Another embodiment allows pumps with pump tubes 304 of different diameters to achieve more or less displacement per stroke. It is a substantial advantage of this invention that it combines simplicity with great versatility.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure and methodology described herein. Thus, it should be understood that the invention is not limited to the examples discussed in the specification. Rather, the present invention is intended to cover modifications and variations.
This application claims the benefit of the filing date of U.S. Provisional Application No. 60/527,699, filed Dec. 6, 2003.
| Number | Date | Country | |
|---|---|---|---|
| 60527699 | Dec 2003 | US |
