Patent ID: 12241472

DETAILED DESCRIPTION

The disclosure provided herein relates to a ceiling-mounted fan or a ceiling fan, and more specifically, to an impeller-type ceiling fan having an impeller, contained within a housing, to drive an airflow as opposed to a traditional ceiling fan having a set of radially-extending blades, external to a housing, and open to the environment. It should be understood that the impeller includes a set of mounted blades, but can be formed as a singular unit for driving a circumferential airflow, as opposed to individual blades each driving an airflow individually.

All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, forward, aft, etc.) are only used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of aspects of the disclosure described herein. A generally downward direction can be defined as a direction that is directed more away from the ceiling or structure from which the ceiling fan suspends, than in a direction toward the ceiling. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and can include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to one another. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto can vary. As used herein, the term “set” or a “set” of elements can be any number of elements, including only one. For example, a set of grommets or a set of blades as used herein can include one or more grommets, or one or more blades.

Referring toFIG.1, a ceiling fan10can include a body18that includes an inlet housing20and a deflector40, which is moveable relative to the inlet housing. In a non-limiting example, each of the inlet housing20and deflector40can have an annular shape and they can have a generally identical ornamental appearance. Additionally, and alternatively, the inlet housing20and the deflector40can have a generally dissimilar appearance. The inlet housing20defines an inlet22for drawing airflow into the body18. An outlet24can be provided on the side of the body18, with the deflector movable relative to the outlet24to control the direction of the air emitted through the outlet24. An optional light kit96can be carried by the body18, such as suspended from the inlet housing20. In one example, a controller (not shown) can be provided within the inlet housing20, which can be utilized for controlling or operating the ceiling fan10. In alternative non-limiting examples, a controller can be provided remote from the ceiling fan, such as a wall-mounted controller or a wireless controller.

Turning now toFIG.2, the major components of the ceiling fan10can be seen in a partially exploded view and include, in stacked arrangement, an outlet frame14, a set of guide vanes50, the deflector40, a motor80, a shroud30, an impeller70, the inlet housing20, an optional inlet grill98, and the optional light kit96.

Referring toFIG.3, the outlet frame14is illustrated as including a beam15, a ring16, and a set of posts17, where the beam15extends diametrically across the ring16. The beam15can also function as a mounting bracket to secure the body18to a structure, such as a ceiling. Rods can be provided transverse to the beam15to provide additional structural support.

Referring toFIG.4, the set of guide vanes50can include spaced, stationary foils, louvers, airfoils, or the like. For example, the set of guide vanes50can be a set of louvers in the form of vertically stacked, slanted rings. The set of guide vanes50can be connected by a set of receiving posts52, which can be spaced circumferentially about the set of guide vanes50. The set of receiving posts52can include openings53that receive the posts17of the outlet frame14(FIG.3). The posts17(FIG.3) can extend through the receiving posts52and couple to the inlet housing20(FIG.2).

In this non-limiting example, the set of guide vanes50is illustrated as including three vertically spaced rings, however, it is contemplated that the set of guide vanes50can include any number of vanes or spaced rings. Each vane of the set of guide vanes50can be orientated at an angle relative to the horizontal. Each vanes of the set of guide vanes50can have the same angle or different angle relative to the horizontal. The angle can be a non-zero angle relative to the horizontal or vary between 15 to −15 degrees relative to the horizontal. Additionally, or alternatively the angle of one or more vanes of the set of guide vanes50can be between 30 and −30 degrees or between 0 and −30 degrees when the ceiling fan is mounted to a horizontal surface. That is, optionally, the non-zero angle relative to the horizontal of one or more vanes of the set of guide vanes50can be below the horizon or below 0 degrees and equal to or above-30 degrees. Yet, another option would be a vertical orientation for the set of guide vanes. The illustrate guide vanes50show the guide vanes as horizontally-oriented rings, where the angle can vary relative to the horizontal. However, in a vertical orientation, the rings would be replaced by a plurality of vertical vanes circumferentially spaced about the periphery of the outlet. Each of the vertical vanes will have a body axis, when viewed from a horizontal plane, and the body axis can form an angle relative to a ray line emanating from the rotational axis of the fan. The body axis can be one and the same as the chord line or mean camber line for the guide vane. The vertical vanes can also have a span-wise axis, extending from the root to the tip, and, when the vertical vane is completely vertical, the span-wise axis is parallel to the vertical. However, the vanes can be angled off vertical, such that the span-wise axis forms an angle relative to the vertical.

Referring now toFIG.5, the deflector is shown having an inner rim46from which extends an exterior surface42and an interior surface or lower angled surface44. The exterior surface42can have a downwardly sloping portion41and a lower vertical portion43in one non-limiting example. Alternatively, and additionally, the exterior surface42can have a downwardly curved shape. The lower angled surface44is shown as an angled surface, which is flared outwardly from the inner rim46and meets the vertical portion43at an outer rim47. A locking assembly or a set of lugs48extend from inner rim46and function as alignment keys to index the position of the deflector40with the inlet housing20. The set of lugs48can extend radially inward from the inner rim46and be coupled to or formed with the inner rim46.

Referring toFIG.6, the shroud30is shown in a diametric sectional view, which illustrates the truncated, cone-like sloped portion31, which transitions to a flat portion37. The truncated, cone-like sloped portion or cone portion31terminates in a central floor35, which collectively forms a motor chamber36for receiving the motor80, with the motor80resting on and/or coupled to the central floor35. The central floor35has mounting openings32and a drive shaft opening34for securing the motor80to the central floor35and permitting passage of a motor shaft or drive shaft12of the motor, respectively. A plurality of lugs33can be spaced circumferentially about the central floor35. The backside of the lugs33can form a seat38(FIG.11). The lugs can be used to locate the impeller70relative to the cone portion31. A set of fastener openings39, used in coupling the impeller70to the shroud, amongst other possibilities, can be provided in the shroud30.

Referring toFIG.7, the impeller70includes a set of blades72mounted to an outer ring74. While shown as including seven blades, the set of blades72can include any number of blades including one blade. Each of the blades72extends from a root81to a tip82, which are connected by a top edge73and a bottom edge75, thereby defining the boundary of the blades72. The blades72define a curved body78bounded by the root81, the tip82, the top edge73, and the bottom edge75. Each of the blades72can have a tab79near the tip82, which, along with a set of fasteners71, can secure the blades72along the bottom edge75to the outer ring74. In this way, the blades72are coupled to or cantilevered mounted to the outer ring74by the tips82, with the root81being free. It is contemplated that the outer ring74can have a flat edge portion76for fixing the blades72. The outer ring74can further include a sloped portion83radially interiorly of the flat edge portion76for guiding the airflow to the blades72to reduce drag or stagnation. The blades72have a set of openings77along the top edge73, some of which can align with the set of fastener openings39of the shroud30(FIG.6), with fasteners passing through the aligned openings77,39to secure the impeller70to the shroud30. Additionally, and alternatively, the blades72can be formed integrally with either the outer ring74or the shroud30. The roots81of the blades72abut the cone portion31of the shroud30. The roots81can have a tab85, which can be secured, by receipt in the seat38(FIG.11) formed by the backside of the lugs33or by a suitable fastener, to the cone portion31. Since the interior of the outer ring74is open, air is free to flow through the interior of the outer ring74between the blades72.

Turning now toFIG.8, the inlet housing20can include a top rim21. An inner angled surface23can be included in inlet housing20, sloping downwardly and inwardly away from the top rim21. In one non-limiting example, the top rim21can include a first surface25spaced radially and vertically from a second surface27, such that the surfaces25,27define steps. The first and second surfaces25,27can be generally flat. Additionally, and alternatively, the first surface25can be sloped or curved. An angled exterior surface28can extend outwardly from the top rim21, angled in a downward direction. It should be appreciated that the top rim21can incorporate any combination of raised surfaces, steps, sloped, and curved features. A set of key ways in the form of receptacles95are provided in the inlet housing20. The receptacles95are recessed into the top rim21and face or open outward. The receptacles95are located and sized to receive the set of lugs48of the deflector40to index or locate the deflector40relative to the inlet housing20.

Referring now toFIG.9, additional details of the inlet housing20can be seen. The second surface27can be raised from the first surface25to define a step or a raised portion29. The angled surface23is spaced from the second surface27by the first surface25. Opposite the exterior surface28, the inlet housing20can include a lower surface67. In one non-limiting example, the lower surface67can include an outwardly sloping portion68and an inwardly sloping portion69. The inwardly sloping portion69defines a partial cone segment, which functions as a converging inlet to the impeller, which will accelerate the air flow because of the convergence. It is contemplated that the lower surface67can have any combination of curved, straight, or sloping portions. The lower surface67joins the innermost edge of the angled surface23at an inner lip112.

Openings26in the top rim21or second surface27can be used to fasten the inlet housing20to, for example, the outlet frame14. That is, the openings26can receive posts17.

FIG.10illustrates another sectional view of the inlet housing20with the section taken along X-X, through the diametrically opposed receptacles95, to illustrate the generally rectangular shape of the interior of the receptacles95. Each of the receptacles95can extend across the raised portion29and at least partially into the exterior surface28.

Turning now toFIG.11, a diametric cross section of the ceiling fan10is illustrated to show the relationship between the various components when assembled. The outlet frame14is affixed to the inlet housing20by the posts17of the outlet frame14passing through the receiving posts52(FIG.2andFIG.4) of the set of guide vanes50, with the posts17then being secured to the inlet housing20using suitable fasteners, such as screws, which fixes the position of the set of guide vanes50relative to the outlet frame14and inlet housing20.

The shroud30is affixed to the outlet frame14via the motor80. That is, one end of the motor80is mounted to the central floor35of the shroud30, while the opposing end of the motor is mounted to the beam15of the outlet frame14. It is contemplated that the shroud30could be mounted directly to the outlet frame14, instead of indirectly through the motor80. The impeller70is mounted to the motor80such that the sloped portion83is axially spaced above the angled surface23of the inlet housing20. The impeller70can be mounted directly to the motor80or indirectly through the shroud30. When the impeller70is mounted indirectly to the should30, the shroud is directly mounted to the motor80, such that the shroud30rotates with the impeller70, which, essentially makes the shroud30and impeller70an integral unit. The light kit96is mounted to the motor80, but could just as easily be mounted to the shroud30. The grill98is mounted to the inlet housing20. As shown, the grill98has fingers99that are received within openings in the inner lip112of the inlet housing20.

With this assembly, the set of guide vanes50is positioned between the ring16and the inlet housing20, specifically, the raised portion29. The set of guide vanes50can be arranged and positioned such that the upper most outlet vane of the set of guide vanes50seals against the bottom of the ring16. Furthermore, the flat portion37of the shroud30is substantially horizontally level with the upper-most vane to effectively, for practical purposes, form a closure with the upper-most vane for air passing through the impeller70. The impeller70is located interiorly to the set of guide vanes50. The lower-most outlet vane of the set of guide vanes50is vertically positioned above the flat edge portion76of the outer ring74. In another non-limiting example, the lower-most outlet vane can be vertically positioned below the flat edge portion76. The outer ring74of the impeller70terminates radially interior of the raised portion29.

The motor80can include the drive shaft12for driving rotation of the impeller70. A stator84and an external rotor or exterior rotor86driven by the stator84are included in the motor80. The exterior rotor86couples with the plurality lugs33in the shroud30to effect rotation of the shroud30. Since the impeller70is mounted to the shroud30, rotation of the shroud30effects rotation of the impeller70. The exterior rotor86provides for non-rotation of the drive shaft12, which enables the drive shaft12to connect the motor80to the outlet frame14and the light kit96.

With this configuration, the body18defines a plenum100that is bounded by the shroud30and the inlet housing20, specifically the surfaces23,25, and27of the inlet housing20. The impeller70, along with the blades72, are located within the plenum100. The plenum100fluidly connects the inlet22and the outlet24, such that air moved through the body18by the rotating impeller70, enters the inlet22, passes through the plenum100, and then exits the outlet24.

The inlet22can include an inlet opening122defined by the inner lip112of the inlet housing20. The inlet opening122can be described as a two-dimensional, generally circular opening. The inlet22can include an inlet passage126, which includes the inwardly sloping portion69defining the converging portion, such that air flow is accelerated toward the inlet opening122. The converging portion can be thought of as an inlet nozzle.

Other features such as the light kit96can provide a part of the surface boundary for the inlet passage126. The inlet passage126can also include the grill98, which can have surfaces for controlling the air flow entering the inlet22upstream of the inlet opening122. For example, the grill98can include a set of louvers to direct the incoming air. In a non-limiting example, the grill98can support a filter covering at least a portion of the inlet22to filter the air drawn into the inlet22.

The outlet24includes an outlet opening124shown to include a gap that extends between the shroud30and the raised portion29. In other words, the outlet opening124has a generally cylindrical shape, for example following the peripheral gap between the ring16and the raised portion29.

The outlet24can include an outlet passage128. The outlet passage128can include the space near the outlet opening124. For example, the outlet passage128can include space around and between the set of guide vanes50. The outlet passage128can be at least partially defined by the lower angled surface44when the deflector40is in a first upper position or a first position as shown inFIG.11.

Turning now toFIG.12, the ceiling fan10is shown with the deflector40in a second lower position or a second position, moved vertically downward from that of the first position as shown inFIG.11. Some of the blades72have been removed for clarity or truncated due to the perspective sectional view. The deflector40can be moved to and held in the second position by an actuator90. In one example, the actuator90can be a threaded shaft, which can be used to manually or automatically adjust the position of the deflector40by twisting movement of the threaded shaft. Adjusting the deflector40can include raising or lowering the deflector40, for example.

In the second position, the set of lugs48are received within the set of receptacles95such that the set of lugs48are flush with the raised portion29. The actuator90can be housed within the inlet housing20at the set of receptacles95. The actuators90or guides thereof can mount to and extend from the receptacles95in the inlet housing20, and extend to the shroud30to permit movement of the deflector40between the shroud30and the inlet housing20. It should be understood that other implementations are possible, and other methods of positioning the deflector40are contemplated. In one example, the actuator90can be a mechanical actuator controlled by a controller, which can be used to mechanically move the deflector between the first position (FIG.11) and the second position (FIG.12). In another example, the actuator can be a manually operated, where the user can manually change between the first position and the second position, or positions therebetween.

Turning now toFIGS.13and14, the airflow through the ceiling fan10will be described in more detail. WhileFIGS.13and14illustrate only a portion of the ceiling fan10, the description applies to the entire ceiling fan10due to the circular/annular shape of the ceiling fan10. A primary air flow path or a primary air flow passage can be defined as extending between the inlet opening122and the outlet opening124, while passing through the plenum100. Air flowing along the primary air flow passage is identified as a primary air flow62.

A secondary air flow path or a secondary air flow passage, which bypasses the blades72, is defined by the inlet opening122, the outlet opening124, and a space or interior passage123formed between the sloped portion83of the impeller70and the sloped surface23of the inlet housing20. Air flowing along the secondary air flow passage is identified as secondary air flow64. As illustrated, the secondary air flow64bypasses the blades72of the impeller70.

In one non-limiting example, the secondary air flow64can begin at the inlet passage126, flowing through the grill98and inlet opening122. The secondary air flow64can continue beyond the inlet opening122between the outer ring74and inner angled surface23, over the raised portion29to exhaust through the outlet24. It is contemplated that the inlet housing20can include any combination of raised, sloped, and curved portions to effectively guide airflow along the primary air flow62or the secondary air flow64.

In the configuration shown inFIG.13, where the deflector40is in the first position, the air flow through the outlet passage128is directed by the set of guide vanes50, the lower angled surface44, and the exterior surface28. By way of non-limiting examples, the lower angled surface44can include a curve or sloped surface or include steps to direct airflow in a generally downward direction. The contoured step as defined by the raised portion29reduces the cross-sectional area of the secondary air flow path, which accelerates the secondary air flow64and enhances the flow attachment of the secondary air flow64due to the Coanda effect. The acceleration also provides the secondary air flow64with improved performance as an air curtain or shield.

It is contemplated that the exterior surface28and the lower angled surface44can have any combination of sloped or curved surfaces. For example, the deflector40can have a trapezoidal or triangular profile. The lower angled surface44can be complementary to the exterior surface28of the inlet housing20. For example, the lower angled surface44can include the inner rim46shaped to complement a curved portion49in the inlet housing20.

In the enlarged view ofFIG.13, the deflector40can be positioned adjacent the ring16, with an exterior surface42abutting at least a portion of the ring16reducing or preventing the leakage of air therebetween. In this configuration, the lower angled surface44can guide airflow exhausting from the outlet24in a generally downward direction, illustrated, by way of example, by the primary air flow62and the secondary air flow64. The set of guide vanes50can affect the airflow prior to the deflector40, such as providing a directionality, or increasing or decreasing local pressures or air speeds, or can rectify cyclical pressure waves that can otherwise generate noise, thereby providing noise reduction. Similarly, the raised portion29can further downwardly influence the directionality of the airflow at the outlet24via flow attachment along the raised portion29.

In one example, the horizontal, relative to level or the structure containing the ceiling fan10, can define a line of delineation between determining a generally downward direction away from a ceiling versus a generally upward direction toward the ceiling. Thus, it should be understood that a downward direction need not be away from the ceiling in a perpendicular or orthogonal manner, but angled in a direction away from the ceiling, relative to a direction parallel to the ceiling, such as the horizontal. Non-limiting examples of angles in a generally downward direction can include 30-degrees, 45-degrees, 60-degrees, or any suitable angle between 0-degrees and 90-degrees, relative to the horizontal. It should be appreciated that the ceiling fan10may utilize variable angles, such as by varying or changing the deflector40, as different angles may be beneficial to different environments, air flow speeds or volumes, or considering factors such as volume of the room or use within the room, in non-limiting example.

Turning toFIG.14, the deflector40is positioned in the second position adjacent to the inlet housing20such that the inlet housing20and the deflector40abut each other. In this position, the inner rim46and the curved portion49can fit together, such as the deflector seating relative to the inlet housing20. While shown as slightly spaced, it is contemplated that the inner rim46and the curved portion49are sized and shaped complementary to one another. Optionally, when in the second position or seated position, at least a portion of the exterior surface28of the inlet housing20and lower angled surface44of the deflector40abut or contact one another.

As illustrated, when seated, the deflector40is aligned with the raised portion29when in the second position. This alignment provides for a smooth transition on the downstream side of the raised portion29by the sloping portion41.

In the second position, the outlet passage128includes the set of guide vanes50and the sloping portion41. The deflector40guides air exhausting from the interior passage123or the blades72in a generally outward direction, in a direction generally perpendicular to the vertical direction defined through the outlet opening124. In the second lower position, the flow of air is unobstructed by the lower angled surface44of the deflector40, permitting the outward flow of air along the ceiling, opposed to the downward flow of air away from the ceiling when the deflector40is in the first position. It is further contemplated that the deflector40need not be limited to a first and second position as described herein, but can be positioned in variable positions, between the first position and the second position. In such a position, it is contemplated that the airflow can be exhausted from the outlet24in both a generally upward direction and a generally downward direction.

It is noted that the upper-most vane of the set of guide vanes50abuts the ring16of the outlet frame14, which effectively prevents air escaping the plenum100above the upper-most vane and running along the ceiling. In most uses of the ceiling fan10, it is not desirable for the air to run directly along the ceiling because the Coanda effect can lead to the air being entrapped against the ceiling. Additional, air exiting between the vanes of the set of guide vanes50can be carried by the air flow along the ceiling and not circulate within the room as desired.

In operation, air is drawn into the inlet opening122through the inlet22by the impeller70. After entering the inlet opening122, the air flow splits into the primary air flow62and the secondary air flow64. When the primary air flow62and the secondary air flow64combine downstream of the impeller70, the secondary air flow64functions more like a curtain to keep the primary air flow62from immediately re-entering the inlet22, and creating an undesired recirculation flow, which does not flow throughout the room.

When the deflector is in the first raised position, the shape of the deflector40and the shape of the inlet housing20direct the air flow at the outlet24downward and away from the ceiling fan10. That is, the air flow exiting the ceiling fan10makes a downward, non-zero angle with the horizontal.

The surface features of the inlet housing20such as the raised portion29enhance flow attachment to for improved control of the air flow direction in a downward direction, which is important for user satisfaction of the air circulation in a room.

When the deflector40in the second position, the primary air flow62is exhausted from the outlet24in more of a generally outward direction, as compared to when the deflector40is in the first position, because the deflector40no longer deflects the primary air flow62. The secondary air flow64still functions like an air curtain to direct the primary air flow62from forming a recirculation loop.

While the deflector40is described as moving between the two positions in a binary manner, it should also be appreciated that an embodiment of the ceiling fan can be configured such that the actuator90can move the deflector in a continuous, cyclical manner, cycling between or among the first position or the second position, which the rate of variation can be controlled by the user. Such a system can provide for variation in the airflows generated from the ceiling fan10.

Further, it is contemplated that the alignment of the top-most or upper most guide vane of the set of guide vanes50with the ring16and shroud30can reduces airflow leakage. Additionally, the alignment of the top-most of the set of guide vanes50with the ring16and shroud30can reduce noise.

Referring toFIG.15, variations to the embodiment shown inFIGS.1-14are shown. In one variation, a housing196can have a bullnose shape. Optionally, the housing196can include a light source or define a light kit. Benefits of the bullnose shape of the housing196is that the housing196does not interfere with the inlet air flow into the inlet22as much as the light kit96(FIG.2andFIGS.11-14), where the light kit96is has an outwardly flared shape. The outwardly flared shape of the light kit96can negatively impact the air flow into the inlet opening, which can be compensated for by increasing the speed of the fan. However, increased fan speed results in increased noise, which is not desirable for most consumers.

In another variation, in addition to or in place of lights in the housing196, lights198can be included in the inlet housing20, such that light emanates from the lower surface67. The lights198can be one or more LED lights, which can be mounted to the lower surface67. Alternatively, lower surface67can be a non-opaque panel and the light198and reside inside the inlet housing20, behind the non-opaque panel, and transmit light through the non-opaque panel.

In yet another variation, the deflector40can include a hinged portion115, such that the angle of the deflector40can be altered by the user to improve the airflow as it moves through the outlet passage128and into the room. With this variation, not only can the deflector still move vertically, the deflector can also pivot and/or change its angle of attack to influence the direction of the air flow prior to exiting the ceiling fan10at the outlet24.

There are many benefits to the ceiling fan as disclosed in the multiple embodiments. One of the benefits comes from the presence of the secondary air flow path regardless of the position of direction of the primary air flow path, which is a function of the deflector position. The deflector, regardless of its position, does not close the secondary air flow path. The secondary air flow path functions as a shield or curtain to prevent the primary air flow path from immediately turning as it leaves the outlet opening and re-entering the inlet opening to form an undesirable recirculation loop from the outlet opening, around the inlet body, and back into the inlet opening. The shielding function occurs primarily when the deflector is in the raised or deflecting position as shown inFIG.13. The secondary air flow path also performs a guiding function to keep the primary air flow path from staying along the ceiling. The secondary air flow path is desirably higher speed that the primary air flow path, which generates a lower pressure area into which the primary air flow path is drawn. The lower pressure area will tend to draw the primary air flow path toward the secondary air flow path, which can happen regardless of whether the deflector is in the raised position (FIG.13) or lowered position (FIG.14), but is more beneficial in the lowered position as the lower pressure area draws the primary air flow path away from the ceiling to encourage better circulation. While the faster air flow in the secondary air flow path can draw the primary air flow path toward the secondary air flow path, the secondary air flow path still functions as a shield or curtain to prevent a recirculation loop. Thus, the always present secondary air flow path encourages better recirculation throughout the room in which the ceiling fan is located, regardless of the position of the deflector.

Although the embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.