Translational displacement pump and bulk fluid re-supply system
A novel method of designing a pump by utilizing a cylinder with pistons inserted from each end. The cylinder contains two ports along the top for connection of a prime fluid chamber, a bulk fluid supply chamber and a fluid reservoir. These ports and corresponding connection details are arranged in a fashion that is perpendicular to the axis of the cylinder that comprises the pump chamber. Directly below at a different relative position also perpendicular to the axis of the pump chamber is an exit port for extrusion of fluid. The pump contains no valves or ancillary passages to direct flow between the different machine states of prime, refill, translate and dispense. The states are activated by relative position of the pistons with respect to each port. Fluid moves by translation within the pump by filling the chamber volume between the two pistons with a liquid and synchronizing the advance of the left piston with the retreat of the right piston. Both pistons can be directed toward one another or one piston can remain stationary while the other advances toward it to dispense a liquid. Exceptionally accurate volumes of fluid can be deposited because of the absence of compliant members in the wetted path.
This application is entitled to the benefit of Provisional Patent Application Ser. No. 60/860,172 filed Nov. 20, 2006.
FEDERALLY FUNDED RESEARCHNot Applicable
SEQUENCE LISTING OR PROGRAMNot Applicable
BACKGROUND OF INVENTION1. Field of the Invention
This invention pertains to the field of liquid dispensing equipment. More particularly, it pertains to design of a pump that employs a novel method of pumping or extruding a fluid. The pump design is capable of accomplishing this task without the use of valves or redirection of fluid through ancillary pathways. Both pistons occupy a circular cavity or tube; each piston is inserted from opposite ends, a reservoir and a prime chamber are installed on the topside of the tube. The exit port is directly below and provides for connection of a nozzle or other passage for extrusion of the fluid.
2. Description of the Prior Art
At present there are four general types of pumps used to underfill electronic devices with viscous liquid: (1) A screw or auger type pump comprised of a rotating helix or thread turning inside a cylindrical chamber, the liquid is pumped as a result of shear of the fluid, forward pressure builds as a function of the cosine of the helix angle. (2) An air over type pump, constructed using a cylindrical cavity or syringe, utilizes a column of fluid or reservoir with a follower or concave disc placed on top, air pressure creates the force to move the liquid by acting on the surface area of the follower, toggling the air on and off starts and stops the flow. (3) A jet type pump constructed from a poppet valve, the poppet valve is a rod with a spherical end that moves in a translational fashion over a puddle of fluid, a carbide orifice below the puddle provides the path for a minute quantity of liquid to be expelled as the spherical end impacts the puddle. (4) A positive displacement type pump moves a column of liquid by displacement of a volume of fluid in the chamber equal to the quantity extruded through the exit port, the rate of flow through the exit port is a function of the speed the piston advances multiplied by the volume displaced.
Pumps made for dispensing of viscous fluids by positive displacement require a provision in the design to accomplish the three distinct tasks to ready the pump for its intended function. The three machine states are prime, refill and dispense.
The first state, prime, is performed apriori of dispensing the fluid. It is always required of this type of pump to fill the pump cavity with fluid that is free of air bubbles. Precision dispensing of fluid using the positive displacement technique is susceptible to error in the dispensed volume from air entrapped in the fluid. The problem has a negative impact on the pump repeatability due to the inherent compressibility of air in contrast to the relative incompressibility of most liquids. Two techniques commonly used to rid the pump of this nuisance variable are: Pushing the fluid through the cavity until all air is displaced and the entire volume is homogeneous with respect to fluid, the second is pulling the liquid through the cavity by use of vacuum to achieve the same. Both techniques require this task to be accomplished until all air is dispelled; usually this requires visual inspection of the fluid exiting the chamber via a clear tube. All pumps available for use in the semiconductor industry today discard primed fluid as waste; this practice is expensive due to the high cost of the fluid. Sensors or cameras can be used to detect the presence of oxygen or bubbles; it is possible to automate the process.
The second state, refill, is accomplished immediately after priming the pump and after the fluid in the chamber is depleted at the conclusion of a dispense. Refill of the chamber occurs when the piston in the pump is retracted at the same rate as liquid from the fluid reservoir advances. Fluid from the reservoir is pushed forward by gravity, air pressure or mechanical means, simultaneously filling the cavity, preventing entrapment of air in the liquid. Cavitation occurs when a liquid contains air or other compressible gas as a result of not advancing to fill the volume as rapidly as the piston retracts. If this happens, the pump must be primed again or accuracy and repeatability of the volume dispensed will be poor. Solutions used in semiconductor applications are expensive and pumps with no capacity to reuse the fluid expelled from the prime state are costly to operate.
The third state, dispense, occurs after the pump has been primed, refilled and the piston is at the top of the cylinder poised to push the column of fluid through the exit port. The exit port provides a mechanical connection for a nozzle or attachment of another passage for extrusion of the fluid.
The current trend in the industry is to construct and design pumps of the positive displacement type using one piston for each fluid cavity. Pumps are generally mounted in the upright configuration; the chamber attitude is perpendicular to the surface of the earth. Some manufacturers employ the concept of dual chambers side by side with one piston per cavity. This method is used to mask refill time, one chamber can dispense while the other refills.
OBJECTS AND ADVANTAGESAccordingly, the design and the method of operation of a translational displacement pump have inherent objects and advantages that were not described earlier in my patent. Several additional objects and advantages of the present invention are:
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- (1.) To provide a method of moving a liquid using the positive displacement principle wherein no valves or ancillary passages are necessary to change the state of the pump from the prime position, to the refill position, to the dispense position. The three different machine states occur in a single cylindrical chamber.
- (2.) To provide a design for a pump which is capable of using liquid that is dispelled during the prime operation and reuse it to refill the pump chamber for a dispense cycle. This obsoletes any requirement for operator contact with the solution.
- (3.) To provide a design for a pump that is capable of rotating the exit port around the piston to facilitate placing a fluid deposit at angles other than perpendicular with respect to the surface of the earth.
- (4.) To provide a design for a pump that can be held close to the mounting platform of a robot and limit force acting on robot mechanics; to prevent a pendulum effect under high acceleration and deceleration. The chamber attitude is parallel to the surface of the earth.
- (5.) To provide a design for a pump that has the capability to shut off the exit port from fluid flow without interfering with the dispense cycle.
- (6.) To provide a design for a pump that has the capacity to increase flow-rate by an order of magnitude from the inherent design detail of dual pistons occupying the same cavity. Both pistons separated by a column of fluid can push from either end of the fluid column positioned over the exit port of the chamber.
- (7.) To provide a pump design with a high degree of rigidity in comparison to existing industry designs through the absence of valves that contain seals or packing that must comply under pressure to stop leakage. The act of compliance changes chamber volume and increases error in the fluid deposit.
- (8.) To provide a pump design with the ability to accept a variety of different size pistons and chamber sets. This tailors the dispensed quantity of liquid to the application, since positional error present in piston location can act over a smaller or larger cross sectional area, impacting the percentage of the error present in the volume of material deposited from variance in piston placement.
- (9.) To provide a pump design with a fluid path that is as short as possible. The length of the exit port is equal to the thickness of the wall. The wall thickness is sized to resist the internal pressure that results from force exerted by piston advancement on the column of liquid without deflection as a result of hoop stress acting on the wall from pressure inside the chamber, plus the length of the detail required for connection of the nozzle.
- (10.) To provide a pump design capable of refilling from a bulk fluid supply.
- (11.) To provide a pump design that is able to transport a fluid between two ports by piston movement in opposite directions at the same rate. The right piston would move forward, the left piston would move backward, the column of liquid would occupy the volume between the two.
- (12.) To provide a pump design that can switch reservoirs without stopping to change a reservoir that is depleted of fluid.
- 13.) To provide a pump design that has the ability to suck fluid back to alleviate excess fluid extrusion.
- 14.) To provide a pump design that can create vacuum by pulling back the piston, eliminating the use of air pressure to push fluid from the prime chamber, reservoir or bulk supply.
- 15.) To provide a pump design that has the capacity to support formulation of a compressibility offset for fluids like sealants and silicones that have a high degree of elasticity and move sluggishly until compressed slightly.
The invention is a novel method of designing such a pump for delivering a measured quantity of viscous liquid or other liquids through a nozzle for deposit or connection to another passage for extrusion of the fluid. Fluid forced through the exit port of the pump enters a nozzle that directs it for deposit. A translational displacement pump comprises:
A hollow cylindrical chamber with a series of ports through the wall perpendicular to the longitudinal axis, enabling connection of a prime chamber, reservoir, a bulk supply of fluid and a nozzle. Two smaller diameter cylindrical bodies are inserted from each end of the hollow cylindrical chamber; they are slightly smaller than the inside diameter, of the hollow cylindrical chamber. A thin ring of compliant material at the end of each smaller diameter cylindrical body seals against the high pressure created from extrusion of fluid out the exit port, through the nozzle onto the work.
The conical shape of the interior of the thin ring of compliant material contains a concave cone made to an angle more obtuse than the angle of the cone and conjoined stem. Tensile force applied to the stem connected to the acutely angled cone that resides in the conical shape of the interior of the thin ring of compliant material energizes the compliant material, forcing the forward edge of the thin ring of compliant material outward, creating a surface capable of holding back high pressure. In operation, when pressure resulting from extrusion of the liquid through the nozzle builds, compressive force acts on the flat face of the end of the cone and conjoined stem, further forcing the forward edge of the thin ring of compliant material outward, enhancing seal effectiveness. Low pressure caused by the effect of gravity acting on the fluid in the reservoir is held back by the small difference in size between the small diameter cylindrical body and the hollow cylindrical chamber.
In contrast to conventional positive displacement pumps used in the industry that use a valve or stopcock to switch between prime, refill and dispense, a translational displacement pump has no such device in the circuit to divert the flow of fluid; however, to accomplish the required machine states of prime, refill and dispense it is necessary to introduce a fourth state, translate. This state is necessary to divert flow before dispense of fluid through the exit port.
When the pump is in operation, small diameter cylindrical bodies within the hollow cylindrical chamber move in concert with one another to expose or cover ports that form the passages for connection of the prime chamber, reservoir or a bulk supply of fluid for automated refill of the reservoir and a nozzle. The device moves both the small diameter cylindrical bodies at identical rates of speed in opposite directions to move the volume of liquid contained between them to the appropriate port to accomplish the intended function. To clarify the position of the left and right small diameter cylindrical bodies with respect to the ports, the rearward edge of the port is the side that uncovers the port; the forward edge is the side that covers the port.
The first machine state, Prime, is achieved by movement of the right small diameter cylindrical body to a position within the hollow cylindrical chamber tangent to the rearward edge of the prime port, exposing the port. The left small diameter cylindrical body is moved to a position tangent to the rearward edge of the reservoir port, exposing the port. This exposes a path for fluid to flow between the two openings. The force required to move the liquid can be produced by a number of methods, air pressure acting on the area of the column of fluid contained in the reservoir can be applied to push the fluid, vacuum can be applied to the prime chamber to pull the liquid from the reservoir through the hollow cylindrical chamber into the prime chamber or movement of the two small diameter cylindrical bodies can be used to create a vacuum. This can be accomplished by movement of both small diameter cylindrical bodies to a position under the reservoir port, with ends touching each other that bisect the opening across its diameter. The left small diameter cylindrical body retracts to a position tangent to the rearward edge of the reservoir port and stops at that position, the right small diameter cylindrical body moves backward and parks tangent to the rearward edge of the prime chamber port. The left small diameter cylindrical body moves from the stationary position forward, closing the reservoir port, pushing the fluid column into the prime chamber and comes to rest against the right small diameter cylindrical body. The right small diameter cylindrical body moves forward and the left small diameter cylindrical body moves backward with ends touching each other, bisecting the reservoir opening across its diameter to repeat the process, if required to expel air entrapped in the fluid.
The second machine state, Refill, is achieved by positioning the left small diameter cylindrical body at the forward edge of the reservoir port, the right small diameter cylindrical body resides in the same location with the ends of the thin ring of compliant material in contact with each other.
The right small diameter cylindrical body remains stationary while the left small diameter cylindrical body moves backward creating a negative pressure, allowing fluid from the reservoir to advance to fill the increasing volume formed by the retreat of the left small diameter cylindrical body. Retreat of the left small diameter cylindrical body is halted once a position tangent to the forward edge of the exit port is reached.
The third machine state, Translate, occurs after Refill or when movement of fluid is desired without displacement or extrusion. The Translate state is a function of the specific application of the pump. The right small diameter cylindrical body advances while the left small diameter cylindrical body retreats, the volume of fluid flanked by the two cylindrical bodies is moved; therefore, in this machine state the velocity of advance of the right small diameter cylindrical body is equal to the retreat of the left small diameter cylindrical body.
The fourth machine state, Dispense, requires the left small diameter cylindrical body be positioned at the rearward edge of the exit port. The right small diameter cylindrical body is separated from the left small diameter cylindrical body by the volume of fluid. Advance of the right small diameter cylindrical body toward the left small diameter cylindrical body causes pressure inside the hollow cylindrical chamber to build and the fluid is displaced through the exit port and out the nozzle for deposit on the work. Alternately, the column of liquid can also be positioned in the center of the exit port and left and right small diameter cylindrical bodies can advance toward each other extruding the fluid out the exit port at a rate of flow equal to twice the rate possible from the advance of one small diameter cylindrical body.
Ordinarily, width of the fluid deposit is a function of the nozzle diameter selected, the flow rate through the pump and the velocity the pump is moved over the work; however, the translational displacement pump can rotate the exit port to which the nozzle is attached to angles other than 90° with respect to the surface of the earth. This attribute enables further control of line width by virtue of the following relation: √ØInside Nozzle2−Z2=X Approximate Line Width Effect The XApproximate Line Width Effect requires application of fluid along the positive or negative Y axis, convention for axis orientation is established according to the, “right-hand rule”. No XApproximate Line Width Effect is observed as a result of the nozzle angle if the fluid dispensed by the pump is oriented in a direction parallel to the angle, the pump must dispense fluid perpendicular to the angle of the nozzle for the angle to have an effect on the width of the line. Rotation of the exit port is also useful to move the nozzle out of the way to clear components to move the pump to a different dispense location and aid in fluid break off without a change in Z-axis height.
Additionally, the design of the translational displacement pump lends itself to replenishment of the onboard fluid reservoir by mating to a bulk supply of fluid. The addition of a bulk supply port allows the pump to position the small diameter cylindrical bodies tangent to the bulk feed supply port. The right small diameter cylindrical body remains tangent to the rearward edge of the bulk feed supply port, exposing the port and the left small diameter cylindrical body retreats to the rearward edge of the onboard fluid reservoir port exposing the port. Providing the path for fluid to flow from the bulk fluid supply to refill the onboard fluid reservoir. The prime operation in this configuration is accomplished using the bulk fluid supply port for connection to a prime chamber to act as the repository for expulsion of fluid in the prime state.
These and other objects of the invention will become clearer when one reads the following specification, taken together with the drawings that are attached hereto. The scope of protection sought by the inventor may be gleaned from a fair reading of the Claims that conclude this specification.
Turning now to the drawings wherein elements are identified by numbers and like elements are identified by like numbers throughout the seven figures, the prior art is depicted in
Referring now to the drawings wherein the showings are for the purpose of illustrating preferred embodiments of the invention only and not for the purpose of limiting it.
The invention is a novel design for a Translational Displacement Pump. The inventive Translational Displacement Pump is depicted in
To clarify the position of the left and right small diameter cylindrical bodies 5 with respect to the ports, the rearward edge of the port is the side that uncovers the port; the forward edge is the side that covers the port.
If the on board reservoir is depleted of fluid, the smaller diameter cylindrical bodies 5 in the pump return to the position illustrated in
Some liquids like sealants and silicones exhibit a degree of compressibility, it is desirable when pumping fluids with these attributes to determine the compressibility offset. This is useful because pressure must be exerted on the fluid to compress it before it actually moves. In these instances the illustration in
While the invention has been described with reference to a particular embodiment thereof, those skilled in the art will be able to make various modifications to the described embodiment of the invention without departing from the true spirit and scope thereof. It is intended that all combinations of elements and steps, which perform substantially the same function in substantially the same way to achieve substantially the same result, be within the scope of this invention.
Claims
1) A translational displacement pump assembly comprising:
- a) A hollow cylindrically shaped chamber open at each end with a plurality of ports perpendicular to the longitudinal axis;
- b) A second slightly smaller diameter cylindrical body is inserted into each end of said hollow cylindrically shaped chamber that is capable of movement in a translational fashion along the longitudinal axis;
- c) A means for connection of a nozzle to said hollow cylindrically shaped chamber;
- d) A means for rotation of said hollow cylindrically shaped chamber 180 degrees with respect to a plane parallel to the surface of the earth;
- e) A means for connection to a source of fluid re-supply.
2) The translational displacement pump assembly of claim 1, wherein said hollow cylindrically shaped chamber divided by the number of said slightly smaller diameter cylindrical bodies within is equal to one half.
3) The translational displacement pump assembly of claim 1, wherein said slightly smaller diameter cylindrical body is approximately 1 mm to 125 mm in diameter.
4) The translational displacement pump assembly of claim 1, wherein said hollow cylindrically shaped chamber has an inside diameter about 1 mm to 125 mm and a length of about 7 mm to 500 mm.
5) The translational displacement pump assembly of claim 1, wherein a volume of fluid is moved by translation resulting from simultaneous motion of both said slightly smaller diameter cylindrical bodies at the same velocity in the same direction.
6) The translational displacement pump assembly of claim 1, wherein a volume of fluid is extruded from said hollow cylindrically shaped chamber, through said ports by a difference in velocity of said slightly smaller diameter cylindrical bodies.
7) The translational displacement pump assembly of claim 1, wherein the longitudinal axis of said hollow cylindrically shaped chamber is orientated parallel to the surface of the earth in service.
8) The translational displacement pump assembly of claim 1, wherein the position of said slightly smaller diameter cylindrical body blocks or exposes said ports perpendicular to the longitudinal axis of said hollow cylindrically shaped chamber whereby enabling or disabling the flow of fluid.
9) The translational displacement pump assembly of claim 1, wherein the fluid path through said ports perpendicular to the longitudinal axis is equal to the thickness of the wall of said hollow cylindrically shaped chamber.
10) The translational displacement pump assembly of claim 1, wherein a fluid path of large diameter is provided through the wall thickness of said hollow cylindrically shaped chamber whereby enabling refill of the onboard pump reservoir by connection to said source of fluid re-supply.
11) The translational displacement pump assembly of claim 1, wherein said hollow cylindrically shaped chamber that said slightly smaller diameter cylindrical bodies are fit, utilizes o-rings or compliant material acting against a sealing surface for containment of fluid at or between said ports.
12) The translational displacement pump assembly of claim 1, wherein location and rate of advance and retreat of said slightly smaller diameter cylindrical bodies along the longitudinal axis of said hollow cylindrically shaped chamber is monitored and controlled.
13) The translational displacement pump assembly of claim 1, wherein said ports perpendicular to the longitudinal axis provide a means for connection of chambers for an onboard fluid supply and the means for connection to a containment vessel for collection of dispelled prime fluid for re-use.
14) The translational displacement pump assembly of claim 1, wherein angular position of said hollow cylindrically shaped chamber rotation is monitored and controlled whereby enabling deposit of fluid at angles other than perpendicular to the surface of the earth.
15) The translational displacement pump assembly of claim 1, wherein a plurality of said hollow cylindrically shaped chambers can be constructed adjacent to one another whereby allowing uninterrupted flow of fluid by overlap of individual pump discharge cycles.
16) A translational displacement pump assembly comprising:
- a) A frame having a means to mount said hollow cylindrically shaped chamber;
- b) A plurality of motors mounted on said frame for producing rotational energy;
- c) A means for conversion of said rotational energy to translational energy;
- d) A means for coupling translational energy to each said slightly smaller diameter cylindrical body;
- e) A thin ring of compliant material surrounds the end of each said slightly smaller diameter cylindrical body;
- f) An onboard panel mounted on said frame for connection of accessories that require power for operation and a diagnostic port for predetermined monitoring of pump parameters, output information and fluid conditions.
17) The translational displacement pump assembly of claim 16, wherein said smaller diameter cylindrically shaped body uses said thin ring of compliant material energized by a concave cone formed into the center of said thin ring of compliant material made to an angle more obtuse than the angle of the cone and conjoined stem that pull against it in tension forcing the forward edge of said thin ring of compliant material symmetrically outward radially against the interior wall of said hollow cylindrically shaped chamber.
18) The translational displacement pump assembly of claim 16, wherein said slightly smaller diameter cylindrical body contains a hole through the longitudinal axis to allow tensile force application to said thin ring of compliant material through said cone and conjoined stem by use of a potential energy source.
19) A bulk fluid reservoir assembly comprising:
- a) An enclosed cavity capable of holding a large volume of fluid at positive or negative pressure that is enclosed;
- b) A cavity capable of holding a large volume of fluid;
- c) A means for control of temperature of liquid within said cavity;
- d) A means for automated control of flow of liquid out of said cavity;
- e) A means for automated connection of a fluid delivery device to said cavity;
- f) A means for movement of fluid out of said cavity;
- g) A means for connection to a cavity to contain fluid expelled from the prime state.
20) The bulk fluid reservoir assembly of claim 19, wherein said cavity is enclosed and capable of supporting positive or negative pressure.
Type: Application
Filed: Nov 17, 2007
Publication Date: May 22, 2008
Inventor: Brian Leonard Verrilli (Carlsbad, CA)
Application Number: 11/985,652
International Classification: F04B 49/00 (20060101);