Patent Application
20160354791
The present invention relates generally to fluid dispensers, and more particularly, to fluid dispensers for jetting fluid material.
Liquid dispensers for jetting fluid materials, such as epoxy, silicones, and other adhesives, are known in the art. Jet dispensers generally operate to dispense small volumes of fluid material to a substrate by rapidly impacting a valve seat with a valve member to create a distinct, high pressure pulse that ejects a small volume, or droplet, of fluid material from the nozzle of the dispenser, which flies from the nozzle through the air to impact a surface, or substrate, onto which the fluid material is being applied. Known jet cartridges used with jet dispensers include a cartridge body that houses the valve member and a nozzle, the cartridge body being adapted to couple to an actuator of the jet dispenser.
In applications for jetting heated fluid material, a heating element is coupled to the cartridge body, which then transfers heat to the fluid material as it flows through the internal passages of the jet cartridge. The viscosity of the fluid material may be temperature-dependent. Accordingly, the viscosity of the fluid material may be controlled by transferring heat to the fluid material as it flows through the jet cartridge, particularly in applications in which a low viscosity of the fluid material is desired.
In order to achieve uniform fluid flow characteristics and dispense weight repeatability, it is desirable to maintain a uniform, consistent temperature of the fluid material as it flows through the jet cartridge and into the nozzle for jetting. However, known heated jet cartridges fail to maintain a uniform temperature of the fluid material as the fluid material flows through the jet cartridge and into the nozzle. In particular, the fluid material is often exposed to heat for an insufficient length of time within the jet cartridge such that the fluid material experiences a drop in temperature (i.e., partially cools) by the time it reaches the nozzle. As a result, the fluid material flowing toward the nozzle experiences inconsistent temperatures and viscosities, thereby resulting in imprecise dispensing performance.
Known heated jet cartridges are further deficient in that many are not designed to be disassembled, and later reassembled, to fully expose the internal fluid passages for inspection and cleaning between uses. Alternatively, known heated jet cartridges that are disassembleable often require the assistance of an external tool, such as a wrench or a screw driver, for disengaging one or more tightened mechanical fasteners. Accordingly, exposure of the internal fluid passages of known jet cartridges for adequate inspection and cleaning is made difficult, if not impossible. In this regard, blind fluid paths and “dead zones” within jet cartridges, which may undesirably trap fluid during use and hinder fluid flow, may be insufficiently accessible for proper inspection and cleaning.
Therefore, a need exists for improvements to known jet cartridges for jet dispensers.
In accordance with one embodiment, a jet cartridge for jetting fluid material includes a body adapted to receive fluid material, and a fluid passage defined within the body and extending along a longitudinal axis thereof. At least a portion of the fluid passage extends obliquely relative to the longitudinal axis. Additionally, the body is adapted to receive heat from a heating element and to transfer the heat to the fluid material flowing through the fluid passage.
In accordance with another embodiment, a method is provided for jetting fluid material with a jet dispenser including an actuator and a jet cartridge operatively coupled to the actuator and having a nozzle. The method includes receiving fluid material into the jet cartridge, and directing the fluid material through the jet cartridge along a longitudinal axis thereof and obliquely relative to the longitudinal axis, in a direction toward the nozzle. The method further includes heating the fluid material directed through the jet cartridge to a target temperature, and maintaining the target temperature as the fluid material enters the nozzle. The method further includes jetting the heated fluid material through the nozzle.
In accordance with another embodiment, a jet cartridge for jetting fluid material includes an outer body, a flow insert received within the outer body, a fluid passage defined between the outer body and the flow insert, and a frictional connection between the outer body and the flow insert. The frictional connection is facilitated by a releasable sealing element disposed between the outer body and the flow insert, and is adapted to be disengaged for exposing the fluid passage without use of an independent tool. Additionally, the outer body is adapted to receive heat from a heating element and to transfer the heat to the fluid material flowing through the fluid passage.
Various additional features and advantages of the invention will become more apparent to those of ordinary skill in the art upon review of the following detailed description of the illustrative embodiments taken in conjunction with the accompanying drawings.
Referring to
Referring to
The flow insert 22 includes an insert head 24 and an insert shaft 26 extending axially from the insert head 24. The insert head 24 includes a planar upper surface 28 and an actuator socket 30 extending through the upper surface 28. The actuator socket 30 is sized and shaped to receive a driving portion 32 of the actuator 12 having a drive pin 34, as shown best in
The insert shaft 26 extends axially from a lower surface 50 of the insert head 24, and includes a cylindrical shaft portion 52 and a tapered end 54, as shown best in
As shown in
The helically-shaped fluid passage groove 56 may be formed with an axial width that remains substantially constant along an upper portion of the helical groove 56, and which then tapers as the fluid passage groove 56 approaches the outlet end 63. Additionally, the fluid passage groove 56 may be formed with a radial width that remains substantially constant along an entire length of the fluid passage groove 56. It will be appreciated that the helically-shaped fluid passage groove 56 may be formed with any suitable axial width, radial depth, pitch, and quantity of helical revolutions to achieve optimal flow characteristics in any desired application. In one embodiment, the fluid passage groove 56 may be formed with a pitch of approximately 3.5 mm.
While the fluid passage groove 56 is shown and described herein as being helical in shape in connection with the illustrated exemplary embodiment, it will be appreciated that various alternative shapes of the fluid passage groove 56 may also be provided. For example, the fluid passage groove 56 may be formed with any suitable spiral shape that extends along (e.g., parallel to) and circumferentially about the longitudinal axis of the flow insert 22. The one or more revolutions of such spiral shapes may define one or more angles relative to the longitudinal axis of the flow insert 22, such that the spiral may be non-helical, and may define one or more diameters of the spiral about the longitudinal axis. In this regard, it will be understood that the term “spiral,” as used herein, encompasses any three-dimensional path extending parallel to and circumferentially about the longitudinal axis of the flow insert 22. Furthermore, it will be understood that a “spiral” path is not limited in shape to a path defining a constant angle relative to the longitudinal axis, nor to a path defining a constant or uniformly changing diameter about the longitudinal axis.
More generally, the fluid passage groove 56 may be shaped so as to define any path that extends along (e.g., parallel to) the longitudinal axis of the flow insert 22, as demonstrated by the helically-shaped fluid passage groove 56, and having at least one portion that extends obliquely relative to the longitudinal axis. In other words, having at least one portion that extends obliquely relative to the longitudinal axis and having at last one portion of the fluid passage groove 56 that defines a directional path which traverses across the longitudinal axis and is neither directly parallel to nor directly perpendicular to the longitudinal axis in a plane spaced from the longitudinal axis (e.g., a plane tangent to the outer surface of the cylindrical shaft portion 52). For example, each revolution of the helically-shaped fluid passage groove 56, when viewed head-on from a side view as shown in
It will be appreciated that the fluid passage groove 56 may be formed with various alternative shapes, other than helical and spiral, that extend along the longitudinal axis of the flow insert 22 and which include at least one portion that extends obliquely relative to the longitudinal axis, as understood in view of the description provided above. For example, though not shown, the fluid passage groove 56 may define a zig-zag-like pattern that weaves back and forth across the longitudinal axis to define one or more obliquely extending segments that are axially spaced from one another. Additionally, the fluid passage groove 56, in whole or in part, may extend fully circumferentially about (i.e., at least 360 degrees) the longitudinal axis of the flow insert 22, or only partially circumferentially about the longitudinal axis of the flow insert 22 (i.e., less than 360 degrees).
The outer cartridge body 20 is in the form of a heat-transferring shell having a planar upper surface 64 and an insert socket 66 extending through the upper surface 64 and being sized and shaped to receive the insert shaft 26 of the flow insert 22. The outer cartridge body 20 includes a contoured side surface 68 having a pair of diametrically opposed flat faces 70, and extending radially outward to define an extension portion 72 of the outer cartridge body 20. As shown in
Referring to
As shown best in
The actuator socket 30 of the flow insert 22 extends through the insert head 24 and the cylindrical shaft portion 52 of the insert shaft 26, as shown in
A valve member 108 including a valve head 110 and a valve stem 112 having a stem tip 114 is supported by the flow insert 22 with a spring washer 116. The spring washer 116 may be supported at an upper end of the tapered face 104 and includes a central aperture through which the valve stem 112 is received such that the valve head 110 abuts the spring washer 116. The valve stem 112 extends through the lower aperture 106 of the flow insert 22 and is sealingly engaged by an annular valve seal 118. As described in greater detail below, the valve member 108 may be rapidly actuated between an upward position and a downward position to eject material through the nozzle 88.
During assembly, the flow insert 22 is aligned with the outer cartridge body 20 in the manner generally shown in
When the flow insert 22 is received by the outer cartridge body 20 as shown, the cylindrical shaft portion 52 of the insert shaft 26, including the fluid passage groove 56, confronts the upper and lower cylindrical faces 76, 78 of the insert socket 66. In this manner, the fluid passage groove 56 and the upper and lower cylindrical faces 76, 78 collectively define the main fluid passage 58 between the flow insert 22 and the outer cartridge body 20. As shown in the exemplary embodiment illustrated herein, the fluid passage groove 56 and main fluid passage 58 may be helical in shape. However, as described above, the fluid passage groove 56 may be formed with various alternative shapes to thereby define a variety of corresponding alternatively shaped main fluid passages 58, such as a non-helical spiral fluid passage for example. The inlet end 62 of the fluid passage groove 56 is aligned directly with the fluid inlet passage 92 such that the fluid inlet passage 92 communicates with the main fluid passage fluid passage 58.
The tapered end 54 of the insert shaft 26 is suspended above the lower tapered face 82 of the insert socket 66, thereby defining an annular tapered fluid chamber 120 that communicates at an upper end with the main fluid passage 58 and at a lower end with a lower fluid chamber 122 defined by the nozzle hub 86. As shown, the valve stem 112 extends into the lower fluid chamber 122 and is suspended above the nozzle 88.
As indicated by the directional arrows in
The assembled jet cartridge 14 is coupled to the actuator 12 of the jet dispenser 10 such that the driving portion 32 is received within the actuator socket 30 and the drive pin 34 abuts the valve head 110. As described below, the actuator 12 is operable to rapidly actuate the drive pin 34 downward (see
The heating element 18, shown in phantom herein, is releasably coupled to and surrounds a periphery of the outer cartridge body 20, such that the heating element 18 directly contacts at least a lower annular shoulder 126 of the outer cartridge body 20. In alternative embodiments, the heating element 18 may directly contact other portions of the outer cartridge body 20 as well. As best shown in
The heating element 18 is energized by power supply 19 to heat the outer cartridge body 20, which then transfers heat to the fluid material flowing along the fluid flow path 124, as described in greater detail below. The power supply 19 is controllable to provide the heating element 18 with a suitable degree of electrical power for achieving any desired heating effect of the cartridge body 20 and the fluid material flowing along the fluid path 124. For example, the power supply 19 may be controlled dynamically during operation of the jet dispenser 10 to adjust a temperature, and thus a resultant viscosity, of the fluid material being jetted. The heating element 18 and/or the jet cartridge 14 may include one or more thermal sensors (not shown) for sensing a temperature of the outer cartridge body 20 and/or a temperature of the fluid material flowing along the fluid flow path 124. The power supply 19 may then be selectively controlled in response to temperatures sensed by the thermal sensors in order to achieve or otherwise maintain a target temperature of the outer cartridge 20 and/or the fluid material flowing along the fluid flow path 124.
Referring to
As the fluid material flows through the main fluid passage 58 and into the tapered fluid chamber 120 toward the nozzle 88, the fluid material is forced into contact with the inner surfaces of the outer cartridge body 20. Heat generated by the heating element 18 is transferred to the outer cartridge body 20 through the annular shoulder 126, and from the outer cartridge body 20 to the fluid material flowing along the fluid flow path 124. Accordingly, the outer cartridge body 20 functions as a heat exchanger. More specifically, heat is transferred through the upper and lower cylindrical faces 76, 78 of the outer cartridge body 20 to fluid material flowing through the main fluid passage 58, and through the lower tapered face 82 to fluid material flowing through the tapered fluid chamber 120. Heat from the heating element 18 may also be transferred through the lower collar 84 and through the nozzle hub 86 to fluid material within the lower fluid chamber 122. In this manner, fluid material flowing through the jet cartridge 14 may be heated along substantially an entire portion of the fluid flow path 124, including at least the main fluid passage 58 and the tapered fluid chamber 120. As described above, the temperature to which the fluid material is heated may be selectively adjusted during dispensing operations via control of the power supply 19 that energizes the heating element 18.
Referring to
Advantageously, the main fluid passage 58, whether helical, spiral, or otherwise in shape, contributes in defining a heated fluid path having a length sufficient to expose the fluid material to heat for a period of time sufficient to establish and substantially maintain a uniform target fluid temperature within the fluid cartridge 14, including at the nozzle 88. Consequently, a substantially consistent and uniform target viscosity of the fluid material may be maintained throughout the jet cartridge 14 as the fluid material flows toward and into the nozzle 88 for jetting. As a result, undesirable decreases in temperature of the fluid material at the nozzle 88 prior to and during jetting are substantially prevented, thereby improving dispense weight repeatability and enabling jetting with high fluid flow rates for high throughput applications.
Additional benefits are also provided by the configuration of the jet cartridge 14 shown and described herein. For example, the releasability of the fluid-tight seal established between the flow insert 22 and the outer cartridge body 20 by the upper sealing element 60 facilitates easy disassembly and reassembly of the flow insert 22 and the outer cartridge body 20 without use of an independent tool. Accordingly, all fluid-contacting portions of the outer cartridge body 20 and flow insert 22 may be quickly and easily exposed for comprehensive inspection, cleaning, and maintenance between uses. In particular, the fluid passage groove 56 formed on the flow insert 22 and the inner faces 76, 78, 82 of the outer cartridge body 20 are readily accessible upon disassembly, and thus may be easily inspected, cleaned, and maintained. Furthermore, the shape of the fluid passage groove 56 provides a single, continuous fluid passage 58 that enables a substantially constant and steady flow of fluid material toward the nozzle 88 without generating “dead flow zones” in which fluid flow would become hindered and form blockages, and without causing air entrapment along the fluid flow path 124.
While the present invention has been illustrated by the description of specific embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features discussed herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope of the general inventive concept.
