Patent Application
20200406300
Many applications call for filtering screens be secured to a machine, whether temporarily or permanently. Some examples of this include water treatment applications, hazardous material handling applications, and drilling applications. For example, in oilfield environments, fluid used in oilfield activities are generally filtered via a screening process. Failure to keep solids out of the drilling fluid could mean diminished rate of penetration, equipment damage, non-productive time, and higher costs. Further, efficient screening reduces the time required to filter the fluid.
One mechanism for separating the contaminants and/or undesirable objects from drilling fluid is the use of screen assemblies in vibratory separators (e.g., shale shakers). The screen assemblies include at least one shaker screen to filter contaminants and/or undesirable objects from the drilling fluid as the vibratory separator vibrates. The screen assemblies may include a screen clamping assembly to clamp at least one screen in a vibratory separator. Depending on the application, different screen configurations may be needed to filter the drilling fluid. For example, some screen configurations may have a single screen and other screen configurations may have multiple screens. In addition, the screen configurations may include a screen configuration with a shaker screen at one level and another screen configuration with a shaker screen at a first level and another shaker screen at a second level. Providing vibratory separators having different screen configurations for different applications can increase the time for filtering the drilling fluid. There exists a need to more efficiently provide different screen configurations for filtering drilling fluid with vibratory separators.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. However, many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limited the scope of the claimed subject matter.
In one embodiment, a screen assembly includes a lower shaker screen and an upper shaker screen. The screen assembly is configurable in a multi-screen configuration including the lower shaker screen and the upper shaker screen. A track is configured to be disposed on an inside wall of a vibratory separator and includes an upper retainer and a lower retainer. A screen clamping assembly is disposed in the track. The screen clamping assembly includes a small spacer having a first spacer dimension selected to correspond to the multi-screen configuration. The small spacer is disposed between the lower shaker screen and the upper shaker screen in the track to space the lower shaker screen at a lower level and the upper shaker screen at an upper level in the track when the screen assembly is in the multi-screen configuration. The screen clamping assembly further includes an actuator disposed in the track. The screen clamping assembly has a clamped position where the actuator is actuated to provide a clamping force to clamp the lower shaker screen, the upper shaker screen, and the small spacer between the upper retainer and the lower retainer of the track.
In another embodiment, a method for installing a screen assembly of a vibratory separator is provided. The method includes installing the screen assembly in a multi-screen configuration where the screen assembly has a lower shaker screen, an upper shaker screen, a track, and an actuator disposed in the track. Installing the screen assembly in the multi-screen configuration includes inserting in the track the lower shaker screen at a lower level, inserting in the track above the lower shaker screen a small spacer having a first spacer dimension selected to correspond to the multi-screen configuration, and inserting in the track above the small spacer the upper shaker screen at an upper level. Installing the screen assembly in the multi-screen configuration further includes actuating the actuator disposed in the track to provide a clamping force to clamp the small spacer, lower shaker screen, and the upper shaker screen inserted in the track between an upper retainer and a lower retainer of the track in a clamped position of the multi-screen configuration.
In another embodiment, a method for configuring a screen assembly on a vibratory separator between a multi-screen configuration and a single screen configuration is provided. The method includes installing the screen assembly in a multi-screen configuration where the screen assembly has a lower shaker screen, an upper shaker screen, a track, and an actuator disposed in the track. Installing the screen assembly in the multi-screen configuration includes inserting in the track the lower shaker screen at a lower level, inserting in the track above the lower shaker screen a small spacer having a first spacer dimension selected to correspond to the multi-screen configuration, and inserting in the track above the small spacer the upper shaker screen at an upper level. Installing the screen assembly in the multi-screen configuration further includes actuating the actuator disposed in the track to provide a clamping force to clamp the small spacer, lower shaker screen, and the upper shaker inserted in the track between an upper retainer and a lower retainer of the track in a clamped position of the multi-screen configuration. The method further includes installing the screen assembly in a single screen configuration including when the screen assembly is in the multi-screen configuration, removing the upper shaker screen and the small spacer from the track. The method of installing the screen assembly in a single screen configuration further including after removing the upper shaker screen and the small spacer from the track, inserting in the track above the lower shaker screen and adjacent the actuator a large spacer having a second spacer dimension larger than the first spacer dimension of the small spacer and selected to correspond to the single screen configuration. The method of installing the screen assembly in a single screen configuration further including actuating the actuator to provide a clamping force to clamp the large spacer and the first shaker screen between the upper retainer and the lower retainer of the track in a clamped position of the single screen configuration.
Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It is emphasized that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and:
In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments are possible. This description is not to be taken in a limiting sense, but rather made merely for the purpose of describing general principles of the implementations. The scope of the described implementations should be ascertained with reference to the issued claims. As used herein, the terms “upper” and “lower” and other like terms indicating relative positions to a given point or element are utilized to more clearly describe some elements.
The disclosure generally relates to screen assemblies for vibratory separators. Specifically, the disclosed systems, devices, apparatus, and/or methods relate to screen assemblies for improved installation of one or more screens in different configurations.
Track 210 includes an upper retainer 216, a lower retainer 218, and a fixture wall 220 extending between the upper retainer 216 and lower retainer 218. Both the upper retainer 216 and the lower retainer 218 extend from the fixture wall 220 and the inner wall 204. The track 210 has a “U” shape and has a track channel that runs the length of track 210. Track 210 is secured to the inner wall 204 by welding track 210 to the inner wall 204 or using one or more attachment devices, for example mechanical fasteners such as screws and bolts or other conventional attachment devices. The upper retainer 216 includes a bottom surface 222 and the lower retainer 218 includes a top surface 224.
Screen clamping assembly 214 includes an actuator 230, a large spacer 232, and a seal 234 disposed in the track 210 between the upper retainer 216 and the lower retainer 218. The actuator 230 is disposed adjacent to the bottom surface 222 of the upper retainer 216 in the embodiment shown in
In the embodiment shown, actuator 230 may be a bladder 236 having a nozzle 238. Bladder 236 may be actuated by inflating the bladder 236 and may be de-actuated by deflating the bladder 236. A fluid media such as air, water, or any similar item is pumped into the bladder 236 via nozzle 238 causing the bladder 236 to expand and press down on the large spacer 232, seal 234, and lower shaker screen 212-1 to clamp and secure the lower shaker screen 212-1 at a lower level in the track 210 of screen assembly 202 to form a lower deck. When inflated, the bladder 236 may clamp and secure the lower shaker screen 212-1 in a clamped position. Because the bladder 236 is restrained by the upper retainer 216, the bladder's expansion forces the bladder 236 downward onto the large spacer 232. The force on the large spacer 232 from the bladder 236 is transferred to the lower shaker screen 212-1. In this manner, the screen 212-1 is clamped and/or pinned in place between the upper retainer 216 and the lower retainer 218. This restricts movement of the lower shaker screen 212-1 along the length of the track 210. When deflated, the bladder 236 releases the downward force against the large spacer 232 and lower shaker screen 212-1, and the lower shaker screen 212-1 is in an unclamped position. In some embodiments, the actuator 230 may be a mechanical clamp or mechanical wedge.
Seal 234 is disposed between the large spacer 232 and the lower shaker screen 212-1. Seal 234 is a separate component in the embodiment shown
Screen assembly 202 further includes a spacer retainer assembly 242. The spacer retainer assembly 242 may secure the large spacer 232 in place when the actuator 230 is de-actuated. Spacer retainer assembly 242 includes a spacer retainer 246 and a spacer keyway 244, also referred to as a spacer slot, in the large spacer 232. The spacer retainer 246 has an elongated section and a head section 252 sized for the spacer keyway 244. The elongated section of the spacer retainer 246 extends through the spacer keyway 244. The elongated section of the spacer retainer 246 may extend into the fixture wall 220 of track 210 to secure spacer retainer 246 to the track 210 and inner wall 204 of the vibratory shaker 200. In some embodiments, spacer retainer 246 is mechanically attached to the track 210 and/or inner wall 204, for example by a press fit or screw threads on the spacer retainer 246 that screw into mating screw threads in the track 210 and/or inner wall 204. The spacer retainer 246 may be welded to the track 210 and/or the inner wall 204 of the vibratory separator 200 or the spacer retainer 246 may be screwed into a weld nut or threaded insert connected to the track 210 or inner wall 204. Welding the spacer retainer 246 provides a more permanent installation of the spacer retainer 246. A threaded installation of the spacer retainer 246 allows for removal of the spacer retainer 246 in case of damage and replaced with a spacer retainer 246 that is undamaged. The head section 252 of the spacer retainer 246 is sized to be larger than the spacer keyway 244 so as to abut against an inner surface of the large spacer 232 when the elongated section of the spacer retainer 246 is inserted in the spacer keyway 244 so as to secure the large spacer 232 in the track 210. In some embodiments, there may be multiple spacer retainer assemblies 342 spaced apart from one another along the length of the tracks 210 and the large spacers 232 to allow the large spacers 232 or small spacers 233 to be installed and supported in the tracks 210.
When in the multi-screen configuration, screen clamping assembly 214 includes the actuator 230, a small spacer 233, and a seal 234 disposed in the track 210 between the upper retainer 216 and the lower retainer 218. Large spacer 232 is not used in the screen clamping assembly 214 when the screen clamping assembly 214 is in the multi-screen configuration. Large spacer 232 has been replaced by the small spacer 233 for the multi-screen configuration.
Small spacer 233 is configured to have a first spacer dimension selected to correspond to the multi-screen configuration. Small spacer 233 is selected to have the first spacer dimension to accommodate at least the lower shaker screen 212-1, small spacer 233, and upper shaker screen 212-2 in the track 210. The first spacer dimension may be the height of the small spacer 233 when positioned in the track 210 between the lower shaker screen 212-1 and 212-2. In some embodiments, the height of the small spacer 233 may range from 2 inches (5.08 cm) to 3 inches (7.62 cm). In other embodiments, the height of the small spacer 233 may have different ranges.
For the single screen configuration, the large spacer 232 is configured to have a second spacer dimension selected to correspond to the single screen configuration. Large spacer 232-2 is selected to have the second spacer dimension to accommodate at least the lower shaker screen 212-1 and large spacer 232 within the track 210. The second spacer dimension may be the height of the large spacer 232 when positioned in the track 210 between the actuator 230 and the lower shaker screen 212-1. The height of the large spacer 232 may range from 3.5 inches (8.89 cm) to 4.5 inches (11.43 cm). In other embodiments, the height of the large spacer 232 may have different ranges. The multi-screen configuration needs to accommodate both the lower shaker screen 212-1 and the upper shaker screen 212-2 in the track 210, while the single shaker screen configuration does not need to accommodate both the lower shaker screen 212-1 and the upper shaker screen 212-2. Accordingly, the first spacer dimension of the small spacer 233 is less than the second spacer dimension of the large spacer 232.
When screen assembly 202 is in the multi-screen configuration, actuator 230 formed by bladder 236 may be actuated to place the screen assembly 210 in a clamped position and may be de-actuated to place the screen assembly 210 in an unclamped position. In the bladder 236 shown in
The large spacer 232 used for the single screen configuration, shown in
Lower shaker screen 312-1 is shown being slid into tracks 310 as part of the installation process to install or assemble the screen assembly 302 from an un-installed position to an installed position. Lower shaker screen 312-1 abuts the lower retainers 318 while being slid into the tracks 310. Seals 334 may be slid in the tracks 310 above the lower shaker screen 312-1 that has been installed in the tracks 310. Seals 334 may be a separate component that may be slid in separately into the tracks 310. In other embodiments, seals 334 may be integral with the large spacers 332. Large spacers 332 then may be placed in the tracks 310 above the seals 334 to place the screen assembly 302 in the single screen configuration. In some embodiments, bladders 336 are in a de-actuated position when the large spacers 332 are slid into the tracks 310 to allow for enough space for the large spacers 332 to be slid in the tracks 310 above the lower shaker screen 312-1. In some embodiments, the large spacers 332 may be positioned between the lower retainers 316 and the lower shaker screen 312-1 with the seals 334 positioned between the lower shaker screen 312-1 and the large spacers 332. In the embodiment where the large spacers 332 are positioned below the lower shaker screen 312-1, the large spacers 332 act as wear strip for supporting the screens.
A spacer retainer assembly 342 in an un-installed position is shown in
Spacer retainer assembly 346 may be placed in an installed position by inserting the elongated section 350 of the spacer retainer 346 in the spacer keyway 344 and in the track retainer slot 348. In some embodiments, there may be multiple spacer retainer assemblies 342 spaced apart from one another along the length of the large spacers 332 for use in holding the large spacers 332 in place in the tracks 310. Spacer retainers 342 provides the benefit of holding the large spacers 332 in place in the tracks 310 when the screen assembly 302 is in the unclamped position and to secure the large spacers 332 in alignment in the tracks 310.
With the spacer retainer 342 in the installed position, screen assembly 302 is in the single screen configuration shown in
Lower shaker screen 312-1 is shown being slid into tracks 310 as part of the installation process to install or assemble the screen assembly 302 from an un-installed position to an installed position. Lower shaker screen 312-1 abuts the lower retainers 318 while being slid into the tracks 310. Seals 334 may be slid in the tracks 310 above the lower shaker screen 312-1 that has been installed in the tracks 310. In some embodiments, seals 334 may be integral with the small spacer 333. Small spacers 333 may be placed into the tracks 310 above the seals 334. Small spacers 333 are secured to the tracks 310 by the spacer retainers 346. In some embodiments, the small spacers 333 hang from the spacer retainers 346 in the tracks 310. In some embodiments, there may be multiple spacer retainer assemblies 342 spaced apart from one another along the length of the tracks 210 and small spacers 333 to allow the small spacers 233 to be secured with the multiple space retainer assemblies 342 in the tracks 210. Upper shaker screen 312-2 is inserted in the tracks 310 above the small spacers 333.
In some embodiments, bladders 336 are in a de-actuated position when the large spacers 332 are slid into the tracks 310 to allow for enough space for the upper shaker screen 312-2 to be slid in the tracks 310 above the small spacers 332 and lower shaker screen 312-1 to place the screen assembly 302 in the multi-screen configuration shown in
A clamping assembly includes the actuator and is used to clamp the lower shaker screen and the upper shaker screen in the track. The installer actuates the actuator disposed in the track to provide a clamping force to clamp the small spacer, lower shaker screen, and the upper shaker screen inserted in the track between an upper retainer and a lower retainer of the track in a clamped position of the multi-screen configuration (block 408). When in the installed position, the screen assembly in the multi-screen configuration clamps the lower shaker screen and the upper shaker screen in the track so that the screen assembly is ready to withstand the vibrations during operations.
In operation, the screen assembly in the multi-screen configuration has a lower screen deck formed by the lower shaker screen and an upper screen deck formed by the upper shaker screen. Drilling fluid, along with drill cuttings and debris, may be deposited on top of the upper shaker screen at the feed end. The screen assembly may be vibrated (e.g., 25-40 Hz frequency range) by a motor or motors for the purpose of screening or separating the drilling fluid on the upper shaker screen. The liquid and fine particles of the drilling fluid may pass through the upper shaker screen by force of gravity and acceleration caused by the motor and flows through the space between the upper shaker screen and the lower shaker screen and is deposited on the lower shaker screen forming a spaced-apart, lower screen deck. The liquid and fine particles of the drilling fluid after filtering by the upper shaker screen may pass through the lower shaker screen by force of gravity and acceleration caused by the motor and may be recovered underneath the lower shaker screen and screen assembly.
Solid particles greater than a certain size may migrate and vibrate across both the upper shaker screen and the lower shaker screen where they may be discharged at the discharge end. The filtering elements of the upper shaker screen may define the largest solid particle capable of passing therethrough. The filtering elements of the lower shaker screen may define the largest solid particle capable of passing therethrough. In some embodiments, the filtering elements of the upper shaker screen may define larger solid particles capable of passing through the filter elements of the upper shaker screen compared to the filtering elements of the lower shaker screen. In some embodiments, the filtering elements of the upper shaker screen and the lower shaker screen are the same.
In operation, the screen assembly in the single screen configuration has a lower screen deck formed by the lower shaker screen. Drilling fluid, along with drill cuttings and debris, may be deposited on top of the lower shaker screen at the feed end. The screen assembly may be vibrated (e.g., 25-40 Hz frequency range) by a motor or motors for the purpose of screening or separating the drilling fluid on the lower shaker screen. The liquid and fine particles of the drilling fluid may pass through the lower shaker screen by force of gravity and acceleration caused by the motor and flows and may be recovered underneath the lower shaker screen and screen assembly.
Spacer keyway 644 includes a first slot section 660 and a second slot section 662. For example, the spacer keyway 644 may be configured to allow vertical movement of the large spacer 632 hooked on the spacer retainer 246 to accommodate movement of the large spacer 632 when positioned between the clamped position and the unclamped position in the track 210. This vertical movement of the large spacer 632 when attached to the spacer retainer 246 allows the large spacer 632 to be vertically moved in the track 210 to unhook the large spacer 632 from the spacer retainer 246 to remove the large spacer 632 from the track 210.
When the large spacer 632 is positioned in the clamped position, the second slot section 662 of the spacer keyway 644 is adjacent to and abuts against the head section 252 of the spacer retainer 246 preventing the large spacer 632 from moving outwardly and away from the track 210, as shown in
Spacer keyway 644 and spacer retainer 246 form a spacer retainer assembly 642. Multiple spacer retainer assemblies 642 are spaced apart from one another along the length of the large spacer 632.
Actuator 230 is actuated to provide a force that holds the large spacers 632 and lower shaker screen 212-1 in place in the tracks 210 when in the clamped position of the single screen configuration or the small spacers 233, lower shaker screen 212-1, and upper shaker screen 212-2 in place in the tracks 210 when in the clamped position of the multi-screen configuration. An actuator seal 669 may be disposed between the upper retainer 216 and the bladder 236 of the actuator 230. When moving from the unclamped position to the clamped position, the force from the actuator 230 may move the large spacers 632 downwards and the spacer keyways 644 may move downward with respect to the spacer retainers 246 that are fixed with respect to tracks 210 to position the retainer head sections 252 in the second slot sections 662 of the respective spacer keyways 644. Retainer head sections 252 block the large spacers 632 from moving out of the tracks 210 when the vibratory separator 200 vibrates the screen assembly 602.
Spacer retainers 746 allow an installer to position the screen assembly 702 between the single screen configuration and the multi-screen configuration without the use of tools. When the screen assembly 702 is in the uninstalled screen configuration, large spacers 732 may be attached to the spacer retainers 746 so that each large spacer 732 may be suspended in one of the tracks 710, and the lower shaker screen 712-1 and seal 734 may be inserted into each track 710 to place the screen assembly 702 in the single screen configuration. Likewise, when the screen assembly 702 is in the uninstalled screen configuration, small spacers 733 may be attached to the spacer retainers 746 so that each small spacer 733 may be suspended in one of the tracks 710, and the lower shaker screen 712-1, upper shaker screen 712-2, and seal 734 may be inserted into each track 710 to place the screen assembly 702 in the multi-screen configuration.
Referring to
Large spacer 732 or small spacer 733 may be attached to the spacer retainers 746 by inserting the spacer retainers 746 into respective spacer keyways 744. Each spacer retainer 746 is aligned with one of the spacer keyways 734. Each spacer retainer 746 includes an elongated section 750 and the head section 752. Head section 752 of the spacer retainer 746 is inserted into the first slot section 760. Head section 752 is configured to fit within the first slot section 760 and to be slidable into the second slot section 762 as the large spacer 732 or small spacer 733 is moved downward with respect to the spacer retainer 746. As the head section 752 moves into the second slot section 762, the head section 752 moves through an opening between the first slot section 760 and the second slot section 762 and the head section is disposed in the sockets 764. The large spacer 732 or the small spacer 733 are positioned in a locked position when the head section 752 is positioned in the sockets 764. End portions of the head section 752 are disposed in the sockets 764 with opposing internal surfaces 765, 766 of the large spacer 732 or small spacer 733 adjacent to the head section 752 to block the large spacer 732 or small spacer 733 from moving outwardly from the track 710.
Referring to
After the large spacer 732 or the small spacer 733 has been attached to the spacer retainers 746, the other components of either the multi-screen configuration or the single screen configuration may be installed in the tracks 710. In some embodiments, the components of the screen assembly 732 may be installed in a different order. Actuator 230 may be actuated to provide a downward force to move either the large spacer 732 or the small spacer 733 downwards in the tracks 710 to position the large spacer 732 or small spacer 733 in a locked position. Each spacer retainer 746 is configured to move in its respective spacer keyway 744 to allow for downwards movement of the large spacer 732 or the small spacer 733 when the screen assembly 702 is placed in the clamped position. Likewise, each spacer retainer 746 is configured to move in its respective spacer keyway 744 to allow for upwards movement of the large spacer 732 or the small spacer 733 when the screen assembly 702 is placed in the unclamped position, Large spacer 732 or small spacer 733 may be uninstalled from the tracks 710 by moving the moving the large spacer 732 or the small spacer 733 upwards to align each spacer retainer 746 in the first section 760 of the matching spacer keyway 744 so that the spacer retainers 746 can be removed from the spacer keyways 734. Spacer retainers 746 are disposed in the spacer keyways 734 during operation of the vibratory separator 200. Spacer retainers 746 are protected from drilling fluids and contaminants during operation because the spacer retainers 746 are in the body of the large spacer 732 or the small spacer 733 during operations. The positioning of the spacer retainers 746 in the body of the large spacer 732 or small spacer 733 may help reduce maintenance needs and contaminant build-up on the spacer retainers 746 allowing for more effective attachment of the large spacer 732 and the small spacer 733 in the track 710.
The disclosed systems, devices, apparatus, and/or methods disclose screen assemblies for improved installation of one or more screens in different configurations. The screen assembly is positionable in a multi-screen configuration where the screen assembly includes a single screen deck that may be formed by a lower shaker screen. The screen assembly also allows for the screen assembly to be positioned in a multi-screen configuration that has a dual screen deck with a lower deck and an upper deck formed by the lower shaker screen and the upper shaker screen spaced apart by the small spacer. The screen assembly uses an actuator in the track to clamp the at least one shaker screen in both the single screen configuration and the multi-screen configuration.
The screen assembly of embodiments of the present disclosure provides the benefit of using one actuator for two different configurations. The screen assembly of embodiments of the present disclosure provides the benefit of using only one pair of tracks on opposite walls of the vibratory separator for the at least one shaker screen used for the different screen configurations that include a single screen deck formed by the lower shaker screen and a multi-screen deck formed by the lower shaker screen and the upper shaker screen. The screen assembly of embodiments of the present disclosure helps avoid the need for two different vibratory separators that would each have a separate screen configuration that may be needed for different operations. The screen assembly of embodiments of the present disclosure helps avoid the need to make substantial modifications to a vibratory separator to re-configure a vibratory separator to a different configuration. The screen assembly of embodiments of the present disclosure is configurable between the multi-screen configuration and single screen configuration without the need for tools.
Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims. The scope of the invention should be determined only by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open group. The terms “a,” “an” and other singular terms are intended to include the plural forms thereof unless specifically excluded. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. It is the express intention of the applicant not to invoke 35 U. S. C. § 112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words “means for” together with an associated function.
