Patent Application
20060102860
This invention relates generally to liquid dispensing devices, and more particularly to improved seal assemblies for liquid dispensing devices.
Fluid dispensing assemblies can include a stem for assisting in actuating a poppet valve between opened and closed positions to control fluid flow between an inlet and outlet port. For instance, a fluid dispensing assembly is described in U.S. Pat. No. 3,811,486 (the '486 Patent) to Wood, the entire disclosure of which is hereby incorporated herein by reference.
A fluid dispensing assembly, or nozzle, typically comprises a main body with an inlet port adapted to communicate with a source of pressurized fluid, and an outlet port adapted to dispense fluid from the main body. A stem for actuating a valve is provided and includes an outer surface that slides relative to a packing (typically loose material stuffed or packed in a chamber around the stem). The stem, together with a lever, can assist in actuating the valve, such as a poppet valve, to control fluid dispensing. A guide is adapted to prevent contact between the stem and the main body, while the packing is provided to prevent fluid leakage from the nozzle along the stem and between the stem and main body. In such arrangements, a gland is typically disposed above the packing and has a spring acting thereon. A threaded retainer acts against the spring to maintain the packing in position and acts to pre-load the spring and packing. Pre-loading the packing is undertaken to help maintain a seal when the fluid dispensing assembly is in a low-pressure or zero-pressure mode.
Accordingly, it has been conventional to provide a packing, such as a ½ inch long member that is impregnated with graphite or Teflon material, to prevent leakage of fluid along the stem, and more particularly between the stem and portions of the main body. While advantageous for certain applications, however, such pre-loaded packings may cause an undesirably high friction force and thereby may cause higher required activation forces, and/or undue wear of the seal against the main body and/or stem.
Other sealing arrangements have also been developed and utilized as stem seals, such as those which include a ring-like base or shell (e.g., made of Buna nitrile) having a flared end, as well as an interior energizing member (e.g., an O-ring) disposed within the base to provide outward force on the flared end. However, such seals and sealing systems can exhibit problems with respect to sealing performance and/or durability, and particularly with respect to the unique characteristics encountered when attempting to seal axially sliding stems in fueling devices. For example, such seals may exhibit rapid deterioration and wear from friction and/or from contact with fuels and may also exhibit undesirable changes in size when in contact with such fuels.
Accordingly, it is desired to obviate problems and shortcomings of existing seal stem assemblies. More particularly, it is desired to provide improvements in durability and/or performance of sliding seal stem assemblies in fluid dispensing apparatus.
According to one embodiment, a sliding stem seal assembly is provided comprising a stem including an outer surface, and a fluorocarbon-polymer seal slidably received on the stem and comprising inner and outer sealing surfaces. The seal includes at least one recess between the inner and outer sealing surfaces. The inner sealing surface of the seal is adapted to contact the outer surface of the stem to provide a ring-like seal in use. The assembly further includes at least one cantilever spring at least partially disposed in the recess.
According to another embodiment, a fluid dispensing assembly is provided comprising a main body, a stem, a seal slidably received on the stem, and at least one spring. The main body includes an inlet port adapted to communicate with a source of pressurized fluid and an outlet port adapted to dispense fluid from the main body. The stem includes an outer surface, and the stem is adapted to assist in regulating fluid between the inlet port and the outlet port of the main body. A seal is slidably received on the stem and comprises inner and outer walls each having an inner surface. The seal includes at least one recess between the inner and outer walls and defined by the inner surfaces of the walls. At least one spring, comprising a plurality of fingers, is at least partially disposed in the recess.
In accordance with another embodiment, a fluid dispenser is provided comprising a main body, a stem, a polytetrafluoroethylene seal slidably received on the stem, a manual actuator adapted to control movement of the stem, and a shut off actuator adapted to shut off the flow of fluid. The main body includes an inlet port adapted to communicate with a source of pressurized fluid and an outlet port adapted to dispense fluid from the main body. The stem includes an outer surface, and the stem is adapted to assist in regulating fluid between the inlet port and the outlet port. The seal comprises inner and outer sealing surfaces, the inner surface contacting the outer surface of the stem to provide a first seal and the outer surface contacting a portion of the main body to provide a second seal. The manual actuator is adapted to control movement of the stem and control the flow of fluid through the main body, and the shut off actuator is adapted to shut off the flow of fluid upon sensing a fill condition.
In accordance with another embodiment, the fluid dispenser comprises a main body including an inlet port adapted to communicate with a source of pressurized fluid and an outlet port adapted to dispense fluid from the main body. The dispenser further comprises a stem including an outer surface. The stem is adapted to assist in regulating fluid between the inlet port and the outlet port. The dispenser further comprises a seal comprising a friction-reducing material slidably received on the stem and comprising an inner sealing surface. The inner surface contacts the outer surface of the stem to provide a first seal. The dispenser further comprises a manual actuator adapted to control movement of the stem and control the flow of fluid through the main body.
Still other aspects of the present invention will become apparent to those skilled in the art from the following description wherein there are shown and described alternative illustrative embodiments including inventive aspects. These embodiments and descriptions are provided only as illustrative examples, and in no way are intended, nor should they be interpreted, as limiting. As will be realized, the invention is capable of other different embodiments, all without departing from the scope of the invention. These other possible embodiments will be understood by those skilled in the art based upon the description and teachings herein. Accordingly, the drawings and descriptions should be regarded as illustrative and exemplary in nature only, and not as restrictive.
While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed the same will be better understood from the following description taken in conjunction with the accompanying drawings in which:
a is a cross sectional view of an illustrative embodiment of an improved sealing system used in the stem seal assembly of
b is a top view of the sealing system of
a is a perspective view of an illustrative embodiment of the cantilever spring of the sealing system of
b is a perspective view of the sealing system of
a and 6b are an enlarged sectional views of embodiments of sealing systems having an additional double sealing arrangement, and which are made in accordance with principles of the present invention; and
a and 7b are enlarged sectional views of embodiments of sealing system having a wiper member, and which are made in accordance with principles of the present invention;
Turning now to the drawing figures in detail, wherein like numbers indicate like elements among corresponding views,
As further illustrated in
The sliding stem seal assembly 18 can also provide the improved seal 50 at a location between a guide or spacer 34 and a retainer, such as a threaded retainer 28. It is understood, however, that the sliding stem seal assembly 18 could be designed without a spacer 34 and/or retainer 28. For instance, the main body 12 can be designed to independently support and/or retain the seal 50. For example, the main body could be designed with retaining flanges defining a housing for the seal 50.
As an alternative, the seal 50 could reside in a module, which threads into the housing 12. The stem 20 can then be placed through the module, with the seal 50 sealing against the stem and the module, and a separate external seal can seal between the module and main body. The module could comprise a low friction material to reduce wear on the seal 50 caused by movement of the stem, and the module can isolate the external O-ring seal from movement of the stem. The module can comprise multiple rested components if desired.
Returning to
An example of retrofitting a convention fluid dispensing assembly with a sliding stem seal assembly embodying aspects of the present invention will now be described. After accessing the stem assembly, the retainer is unscrewed from the main body of the dispenser. The stem assembly including the stem, retainer, spring, gland, packing, and guide are then removed from the main body. Next, a new spacer 34 is mounted onto a stem 20 as will be appreciated from
As seen in
The seal 50 can also be arranged such that the outer flange 54 contacts an inner surface 74 of the main body 12 (or, alternatively, of a surface of the retainer 28 if the seal were housed within the retainer) to similarly create a seal therewith along a circumferential contact surface, edge or lip 66. Since the seal 50 is circular in cross section in this embodiment, the outer flange 54 provides a second or outer ring-like seal adjacent the contact surface, edge or lip 66. As illustrated in
As best shown in
With reference to
However, it has been found that particularly advantageous performance and durability (with respect to friction characteristics, and durability and size stability when in contact with fuel) can be attained by constructing substantially the entire seal 50 using a TEFLON material. In addition, the inner surface 74 of the main body 12 and/or the outer surface 22 of the stem 20 may be appropriately finished and/or coated or treated to further prevent undue friction and wear, and to optimize the service life of the assembly. In one example of a fuel dispenser nozzle stem, the outer surface 22 of the stem 20 may be optionally finished with a finish of at least 12 for use with a seal 50 having a TEFLON coating, or comprising or consisting of TEFLON. The material used to construct the seal 50, partially or completely, preferably results in a dynamic and/or static coefficient of friction relative to the stem of less than about 0.1, such as less than about 0.05 for example, which can result in improved performance of the fueling nozzle. In particular, according to one embodiment of the invention, using a seal made from TEFLON and a stem made of stainless steel can provide a coefficient of friction of the seal relative to the stem of about 0.04.
As shown in
Energizing the seal 50 can be achieved in a variety of ways. In one example, the flared end 51 of this embodiment may be energized by the choice of materials or other geometrical characteristics of the flared end. In another example, the flared end may be a composite of different materials having different properties, the materials energizing the flared end. In still further embodiments of the present invention, the energizing of the flared end is achieved with an energizing member 60. As illustrated, the energizing member 60 can be at least partially located within the recess 62 of the seal 50. It is understood that the energizing member 60 may alternatively be substantially or entirely located within the recess. Furthermore, the energizing member 60 may be encapsulated within the flared end of the seal. For example, the energizing member may be fabricated from a different material and then embedded and concealed within the flared end. Due to differing material properties, the energizing member 60 could then act to energize the flared end 51 of the seal. In other examples, a wedge could be used as the energizing member to cause the flanges to bias away from one another. In still other examples, the energizing member could take the form of a pressurized bladder, an O-ring, or material compressed within the flared end of the seal, or any material or component suitable to cause the flanges 52 and 54 to bias away from one another. With respect to other aspects of the inventions, it will be understood that other shapes of energizing members could be used, such as energizing members with square, rectangular, triangular, wedge-shaped, or other cross sectional shapes, or that the energizing member could be removed. Moreover, while a single energizing member is illustrated in the embodiments, it is understood that a plurality of energizing members could be provided, and that the energizing member need not be unitary in nature. For example, a plurality of spaced, or overlapping energizing members might be placed within a recess. For instance, a plurality of O-rings could be stacked, one upon another, or concentrically arranged. In addition, a plurality of energizing members, such as spheres or ball bearings could be radially arranged at least partially within the recess of the seal. Similarly, it will be understood that the seal could be formed with a plurality of recesses that can each receive one or more energizing members. With respect to some embodiments incorporating aspects of the inventions, the energizing member could take other forms, such as a hollow ring. In still other embodiments, the energizing member may take the form of a coil spring, or similar arrangement, connected end-to-end in the shape of a torus.
Returning to
In addition, in this embodiment, the fingers 92 are connected at their ends 93, such as by an integral connection, which allows the spring 60 to form a single continuous unit from its two end points. By positioning and retaining the spring 60 in the recess 62 in this manner, the fingers 92 of the spring provide a substantially uniform or constant force or load on the inner and outer walls 94 and 96 of the seal 50. It has been found that this arrangement can provide improved sealing performance of the lip 64 against the stem 20 and of the lip 66 against the main body 12, even under varying loads, pressures, and conditions.
As an alternative to the cantilever spring 60, other finger-type springs, flexible fingers, or flexible linear members might be utilized. Such members can be disposed, bent, or compressed between the inner and outer walls 94 and 96 to provide force on these walls to improve the performance of the seal 50.
As best illustrated in
The operation of the lever assembly 119 with respect to the stem assembly 102 can be similar to that described above with respect to the other embodiments. In particular, movement of the poppet stem 102 by the lever 119 can move the skirt 110 and disc 109 off of their seat, permitting fuel to flow through the housing, and in particular, from the inlet end 180, around the poppet stem 102 and shut off components held within the housing (described below), and out the spout end 190.
Another spring 143 can be provided between a body cap 113 and a vapor valve 141, which can comprise, for example, a valve body, a stem 142, a lip seal, an insert, retaining rings, and a disc and disc holder. The spring 143 can be used for biasing the vapor valve. Another retaining ring 135 can be provided for retention of components. The vapor valve can operate as known in the art for flow of vapors.
In addition, a shut-off valve assembly 132 can be provided for automatic shut off of the fuel flow upon detection of a full condition in a fuel tank. This assembly can include a diaphragm biased by a spring, a support cup, a support, and other components such as a snubber, a wear washer, and a cap. In addition, a diaphragm sub-assembly 133 can be provided, which can include a diaphragm and diaphragm support, a lower diaphragm connector, a flat washer, and an upper pin and spring pin. Additional shut-off components can include a diaphragm spring 114, a latch spring 115, a latch ball 122, a latch ring 134, and a latch plunger 116, and the shut-off components can connect with the lever 119 via a plunger pin 120 and push nut 121. These components can operate in ways known in the art, or later to be developed, for automatic shut off of the nozzle, such as by using Venturi vacuum principles for example.
The spout end of the fueling nozzle can include a spout sub-assembly 118 including a tube, spring, poppet, bleeder seat ring, outer tube, sleeve, and ferrule, as well as various O-rings for sealing, and retaining rings for securing components. A vapor escape guard 148, and clamp 149 therefor, can also be provided to prevent escape of vapors. An anchor spring 155 and ring 156 can also be utilized. The spout components can operate as known in the art or in a desired manner.
Other components can also be provided, as needed or desired, to create the appropriate fueling nozzle for the application at issue. For example, rivets 125 and screws 130 can be provided for securing components together, insulating material 126 and 140 can be provided to insulate the metal pieces from the user, identification washer 136 and screw 137 can be provided for identification of the nozzle, and O-rings 138, 139, 128, 129, and 124 can be provided for appropriate sealing of components.
a depicts another embodiment of a seal 250 made in accordance with principles the present invention. The seal 250 includes an energized flared end 251 with a pair of inner flanges, 252a, 252b and a pair of outer flanges 254a, 254b forming a double sealing arrangement. The double sealing arrangement can improve the stability of the seal (i.e., by providing support at two locations rather than one location) while increasing the sealing strength of the seal. It should be noted, however, that only the flared end 251 includes a cantilever spring 260 in recess 262. In this example, the additional flanges 252b and 254b can provide more conventional or less-energized seals in use. It is contemplated that a second recess and energy member (not shown) could be provided adjacent base 256 of seal 251 if it were desirable to equip the seal with a double pair of energized inner and outer seals.
a illustrates yet another embodiment of a seal 350 with an energized flared end 351. At least one circumferential wiper 380 is provided to help prevent debris and other contaminants from traveling through the seal. This arrangement might be desirable where the application is subjected to dust, particles, grit or other contaminants, which could undermine the seal or otherwise foul the dispensing operation or fluid delivery. It will be understood that the features of
The seal of the present invention may be made in any conventional manner, such as by injection molding or other molding processes. In some embodiments, the material of the seal 50 might also be selected from a material with low swell/shrink characteristics. Low swelling is often desirable since exposure to fluids could result in fluid absorption, and thereafter swelling of the seal. This can change the dimensions and/or performance characteristics of the material. For fuel dispensing applications, it has been found that using a TEFLON seal and a stainless steel stem can provide ideal durability, and minimize shrinking and swelling when in the presence of fuel. For example, in
The foregoing description of the various embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the inventions to the precise form disclosed. Many alternatives, modifications and variations will be apparent to those skilled in the art of the above teaching. For example, although multiple inventive aspects have been presented, such aspects need not be utilized in combination, and various combinations of aspects are possible in light of the various embodiments provided above. Accordingly, it is intended to embrace all possible alternatives, modifications, combinations, and variations that have been discussed and suggested herein, and all others that fall within the principles, spirit and broad scope of the inventions as defined by the claims.
This application is related to U.S. patent application Ser. No. ______ (Attorney Docket No. 3356-185) filed on Nov. 18, 2004 and entitled Liquid Dispenser with Sealing Module, the entire disclosure of which is hereby incorporated herein by reference.
