Patent Publication Number: US-2023160453-A1

Title: Magnetorheological damper

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 17/209,930, filed Mar. 23, 2021, which is a continuation of U.S. patent application Ser. No. 16/025,662 (issued U.S. Pat. No. 10,995,816), filed Jul. 2, 2018, which is a continuation of U.S. patent application Ser. No. 15/170,380 filed on Jun. 1, 2016. The disclosures of the above applications/patents are incorporated herein by reference in their entirety. 
    
    
     FIELD 
     The present teachings relate to vehicle suspensions, and more particularly to magnetorheological dampers for computer controlled vehicle suspension systems. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     A critical performance criterion in control of a vehicle suspension magnetorheological (MR) damper is the control ratio. For high quality suspension performance, the MR damper needs to have a high control ratio. The control ratio is the maximum on-state force (e.g., the maximum force the damper can make with the fluid fully energized) relative to the minimum off-state force (e.g., the minimum force the damper can make with no flux acting on the fluid) for a wide range of damper velocities. Generally, to achieve a high control ratio it is desired to have an active length of a MR valve of the damper be as long as possible and an inactive length as short as possible. The active length is the section of the MR valve where the fluid is energized by a magnetic field, whereas the inactive length is the section of the MR valve where the fluid is not energized. 
     Known MR dampers typically have an energizing coil wherein the entire length of its external faces is exposed to the MR fluid within the damper. This subjects the coil to erosion by MR fluid and also defines a relatively long inactive length, e.g., an inactive length that is substantially equal to the length of the coil. Due to the exposed coil, the active length of most known MR dampers is typically about 50% of the longitudinal length of the valve, and hence, the inactive length of most known MR dampers is typically about 50% of the longitudinal length of the valve. 
     SUMMARY 
     A magnetorheological damper, wherein the damper comprises a housing that is at least partially filed with a magnetorheological fluid, and a magnetorheological valve disposed within the housing. The valve includes a magnetically permeable core having at least one coil reservoir formed therein, and at least one conductor coil, wherein each conductor coil is disposed around a portion of the core within a respective one of the coil reservoir(s). The valve additionally includes a fluid flow path adjacent the conductor coil(s). The fluid flow path is structured and operable to allow the magnetorheological fluid to flow adjacent the conductor coil(s). The valve further includes at least one coil cover, wherein each coil cover is disposed over a respective one of the coil(s) such that the respective coil is protected from exposure to magnetorheological fluid flowing through the fluid flow path. 
     In various embodiments, each coil cover comprises a multi-section coil cover that includes at least one magnetically permeable section fabricated of a magnetically permeable material such that each magnetically permeable section provides a portion of an active length of the valve, and at least one magnetic isolator section fabricated of a non-magnetically permeable material such that each magnetic isolator section provides at least a portion of an inactive length of the valve. 
     This summary is provided merely for purposes of summarizing various example embodiments of the present disclosure so as to provide a basic understanding of various aspects of the teachings herein. Various embodiments, aspects, and advantages will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments. Accordingly, it should be understood that the description and specific examples set forth herein are intended for purposes of illustration only and are not intended to limit the scope of the present teachings. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present teachings in any way. 
         FIG.  1    is a side view of a vehicle having a suspension system including at least one magnetorheological damper in accordance with various embodiments of the present disclosure. 
         FIG.  2    is block diagram of a generic embodiment of the magnetorheological damper shown in  FIG.  1    including a magnetorheological valve, in accordance with various embodiments of the present disclosure. 
         FIG.  3    is a schematic of a cross-section of the generic embodiment magnetorheological valve shown in  FIG.  2   , in accordance with various embodiments of the present disclosure. 
         FIG.  4    is an enlarged view of a portion of the schematic shown in  FIG.  3   , in accordance with various embodiments of the present disclosure. 
         FIG.  5    is an enlarged cross-sectional view of a portion of the magnetorheological valve shown in  FIGS.  2 ,  3  and  4   , in accordance with various embodiments of the present disclosure. 
         FIG.  6    is an isometric cross-sectional view of the magnetorheological valve shown in  FIGS.  2 ,  3 ,  4  and  5   , in accordance with various embodiments of the present disclosure. 
         FIG.  7    is an isometric cross-sectional view of the magnetorheological valve shown in  FIGS.  2 ,  3 ,  4  and  5   , in accordance with various other embodiments of the present disclosure. 
         FIG.  8    is an isometric cross-sectional view of the magnetorheological valve shown in  FIGS.  2 ,  3 ,  4  and  5   , in accordance with yet other various embodiments of the present disclosure. 
         FIG.  9    is a side cross-sectional view of  2 ,  3 ,  4  and  5 , in accordance with still yet other various embodiments of the present disclosure. 
         FIG.  10    is a side cross-sectional view of  2 ,  3 ,  4  and  5 , in accordance with yet still other various embodiments of the present disclosure. 
         FIG.  11    is a side cross-sectional view of  2 ,  3 ,  4  and  5 , in accordance with further other various embodiments of the present disclosure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of drawings. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is in no way intended to limit the present teachings, application, or uses. Throughout this specification, like reference numerals will be used to refer to like elements. Additionally, the embodiments disclosed below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art can utilize their teachings. As well, it should be understood that the drawings are intended to illustrate and plainly disclose presently envisioned embodiments to one of skill in the art, but are not intended to be manufacturing level drawings or renditions of final products and may include simplified conceptual views to facilitate understanding or explanation. As well, the relative size and arrangement of the components may differ from that shown and still operate within the spirit of the invention. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps can be employed. 
     When an element, object, device, apparatus, component, region or section, etc., is referred to as being “on,” “engaged to or with,” “connected to or with,” or “coupled to or with” another element, object, device, apparatus, component, region or section, etc., it can be directly on, engaged, connected or coupled to or with the other element, object, device, apparatus, component, region or section, etc., or intervening elements, objects, devices, apparatuses, components, regions or sections, etc., can be present. In contrast, when an element, object, device, apparatus, component, region or section, etc., is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element, object, device, apparatus, component, region or section, etc., there may be no intervening elements, objects, devices, apparatuses, components, regions or sections, etc., present. Other words used to describe the relationship between elements, objects, devices, apparatuses, components, regions or sections, etc., should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). 
     As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. For example, A and/or B includes A alone, or B alone, or both A and B. 
     Although the terms first, second, third, etc. can be used herein to describe various elements, objects, devices, apparatuses, components, regions or sections, etc., these elements, objects, devices, apparatuses, components, regions or sections, etc., should not be limited by these terms. These terms may be used only to distinguish one element, object, device, apparatus, component, region or section, etc., from another element, object, device, apparatus, component, region or section, etc., and do not necessarily imply a sequence or order unless clearly indicated by the context. 
     Moreover, it will be understood that various directions such as “upper”, “lower”, “bottom”, “top”, “left”, “right”, “first”, “second” and so forth are made only with respect to explanation in conjunction with the drawings, and that components may be oriented differently, for instance, during transportation and manufacturing as well as operation. Because many varying and different embodiments may be made within the scope of the concept(s) herein taught, and because many modifications may be made in the embodiments described herein, it is to be understood that the details herein are to be interpreted as illustrative and non-limiting. 
     The term code, as used herein, can include software, firmware, and/or microcode, and can refer to one or more programs, routines, functions, classes, and/or objects. The term shared, as used herein, means that some or all code from multiple modules can be executed using a single (shared) processor. In addition, some or all code from multiple modules can be stored by a single (shared) memory. The term group, as used above, means that some or all code from a single module can be executed using a group of processors. In addition, some or all code from a single module can be stored using a group of memories. 
     The apparatuses/systems and methods described herein can be implemented by one or more computer programs executed by one or more processors. The computer programs include processor executable instructions that are stored on a non-transitory, tangible, computer-readable medium. The computer programs can also include stored data. Non-limiting examples of the non-transitory, tangible, computer-readable medium are nonvolatile memory, magnetic storage, and optical storage. 
       FIG.  1    illustrates, by way of example, a vehicle  10  that includes a suspension system (generally indicated at  14 ) that comprises a magnetorheological damper, in accordance with various embodiments of the present disclosure. The vehicle  10  can be any vehicle that generally includes a chassis (or frame)  22  to which a body  26  is connected (the body including such components as a front cowl, fenders, doors, side panels, quarter panels, a dash panel, etc.), two or more wheels  30 , and the suspension system  14  that operatively connects the wheels  30  to the chassis  22  and/or portions of the body  26 . For example, it is envisioned that the vehicle  10  can be a car, truck, motorcycle, sport utility vehicle (SUV), bus, recreational vehicle (RV), or any other vehicle designated for use on roadways, or vehicle  10  can be any full size and/or lightweight and/or utility and/or low-speed vehicle that is not designated for use on roadways, such as a maintenance vehicle, a cargo vehicle, a shuttle vehicle, a golf car, an all-terrain vehicle (ATV), a utility-terrain vehicle (UTV), a recreational off-highway vehicle (ROV), a side-by-side vehicle (SSV), a worksite vehicle, a buggy, a snowmobile, a tactical vehicle, etc. 
     Referring now to  FIGS.  1 ,  2  and  3   , in various embodiments, the suspension  14  includes at least one magnetorheological (MR) damper  34 . Each MR damper  34  operatively connects a respective one of the wheels to the vehicle chassis  22  and/or body  26 . Although the suspension  14  can include more than one MR damper  34 , for simplicity and clarity, only a single MR damper  34  of the present disclosure will be described herein. The MR damper  34  generally includes housing  38  at least partially filled with a magnetorheological (MR) fluid  40 , a piston  42  disposed within the housing  38 , a piston rod  46  connected to the piston  38 , and a magnetorheological (MR) valve  50 . The piston rod  46  extends through an end of the housing  38  and is operatively connectable to either a respective wheel  30  of the vehicle  10  or the chassis  22  and/or a portion of the body  26 . Depending on the connection location of the piston rod  46 , an opposing end of the housing  38  is operatively connectable to the other of the respective wheel  30  or the chassis  22  and/or a portion of the body  26 . Accordingly, when the MR damper  34  is mounted between a wheel  30  and the chassis  22  and/or a portion of the body  26 , travel of the vehicle  10  across a terrain will cause the wheels  30  and the body  26  to move relative to each other such that the MR damper  34  is subject to compression (or jounce) and extension (or rebound), which bidirectionally moves the piston  42  within the housing  38 . 
     Compression (or jounce) and extension (or rebound) of the MR damper  34  causes the piston  42  to move within the damper housing  38 . As the piston  42  moves within the housing  38  the MR fluid  40  is forced to flow through the MR valve  50 . More specifically, the MR fluid  40  is forced to flow through at least one fluid flow channel (or elongated orifice)  54  of the MR valve  50 . The channel(s)  54  is/are disposed, provided or formed between a magnetically permeable core  58  and a magnetically permeable flux ring  62  of the valve  50 . The MR valve  50  additionally includes at least one conductor coil  66  that is disposed within the core  58  and in close proximity of the channel(s)  54 . As the MR fluid  40  is forced through the channel(s)  54  and adjacent the conductor coil(s)  66 , the conductor coil(s)  66  is/are controllably energized to generate magnetic flux between the core  58  and the flux ring  62  through which the MR fluid  40  flows. The one or more areas of the channel(s)  54  through which the magnetic flux is directed are referred to herein as the active sections of the channel(s)  54 . Conversely, the one or more areas of the channel(s)  54  where no magnetic flux is directed, e.g., are not within a flux field, are referred to herein as the inactive sections of the channel(s)  54 . 
     As the MR fluid  40  flows though the active sections of the channel(s)  54 , and magnetic flux is being generated and directed across active sections, the flow properties of the MR fluid  40  are altered to controllably increase and decrease the pressure drop along the channel(s)  54 . Particularly, As the MR fluid  40  flows though the active sections of the channel(s)  54  the shear strength, or shear stress, of the MR fluid  40  is controllably altered, as a result of the controlled strength of the magnetic flux. More particularly, when the MR fluid  40  flows through the flux field directed across the active sections of the channel(s)  54 , metal particles within the MR fluid  40  align according to the flux field lines, thereby changing the shear strength of the MR fluid  40 , making the MR fluid  40  “stiff”, such that the MR fluid  40  does not flow through the channel(s)  54  as readily and easily as when it is not exposed to the flux field. By controlling the strength of the magnetic flux directed through the active sections of the channel(s)  54 , the pressure drop along the channel(s)  54  can be controlled, thereby controlling the speed, or velocity, of movement of the piston  42  within the housing  38 , thereby controlling the speed, or velocity, of the compression (or jounce) and extension (or rebound) of the MR damper  34 , and thereby controlling the speed, or velocity of the movement of the wheels  30  and the body  26  relative to each other to attenuate undesired shock or vibration of the vehicle  10 . 
     In various embodiments, operation of the MR valve  50 , e.g., generation of the magnetic flux field, is controlled by one or more MR valve control algorithms executed by a damper controller, which can be a stand-alone controller, or part of one or more computer based vehicle control system(s). For example, in various embodiments the damper controller can be a hardware based module that is structured and operable to implement the MR valve control algorithm(s). For example, it is envisioned that the damper controller can comprise one or more, or be part of, application specific integrated circuit(s) (e.g., ASIC(s)), combinational logic circuit(s); field programmable gate array(s) (FPGA); processor(s) (shared, dedicated, or group), that execute the MR valve control algorithm(s) to provide the MR damper functionality described herein; or a combination of some or all of the above, such as in a system-on-chip. Alternatively, the damper controller can be part of one or more computer based vehicle control system(s) wherein the MR valve control algorithm(s) are stored in electronic memory of the system(s) and executed by one or more processor of the system(s). Execution of vehicle control software and algorithms, such as the MR valve control algorithms, is well understood by those skilled in the art, and need not be described further herein. 
     As described above, to improve suspension performance of an MR damper, e.g., MR damper  34 , is it beneficial and desirable to have a high control ratio. As also described above, the control ratio is the maximum on-state force relative to the minimum off-state force. As used herein, the on-state of the MR fluid  40  is when the MR fluid  40  is exposed to the magnetic flux field, and the off-state of the MR fluid  40  is when the MR fluid  40  is not exposed to the magnetic flux field. Hence, the maximum on-state force of the MR fluid  40  is the maximum shear strength of the MR fluid  40  that relates to the maximum magnetic flux that can be generated by the respective coil(s)  66 , core  58  and flux ring  62 . That is, the maximum on-state force of the MR fluid  40  is the maximum resistive force to movement of the piston  42  within the housing  38  that is generated by the MR valve  50  when the MR fluid  40  is fully energized by the maximum flux field that can be generated by the respective coil(s)  66 , core  58  and flux ring  62 . Similarly, the minimum on-state of the MR fluid  40  is minimum shear strength of the MR fluid  40  that relates to the minimum magnetic flux, e.g., zero or no magnetic flux, that can be generated by the respective coil(s)  66 , core  58  and flux ring  62 . That is, the minimum on-state force of the MR fluid  40  is the minimum resistive force to movement of the piston  42  within the housing  38  that is generated by the MR valve  50  when the MR fluid  40  is not, or minimally, energized relative to the minimum flux field that can be generated by the respective coil(s)  66 , core  58  and flux ring  62 . 
     Furthermore, as described above, to achieve a high control ratio it is desirable to have a total active length of the MR valve, e.g., MR valve  50 , be as long as possible and a total inactive length be as short as possible. As used herein, the total active length the MR valve  50 , is the cumulative length of the one or more active sections of the channel  54 , e.g., the cumulative length of the sections of the channel where the MR fluid  40  is energized by a magnetic field. For example, the total active length of the channel  54  shown in  FIG.  3    is the cumulative length of active lengths  70 A and  70 B. Similarly, as used herein, the inactive length the MR valve  50 , is the cumulative length of the one or more inactive sections of the channel  54 , e.g., the cumulative length of the sections of the channel where the MR fluid  40  is not energized by a magnetic field. For example, the total inactive length of the channel  54  shown in  FIG.  3    is the length of inactive length  74 . 
     As used herein, the term length will be understood to refer to dimensions parallel with and/or collinear to a longitudinal, axis of the fluid flow channel  54  along which the MR fluid flows. 
     As further described above, the entire length of the external face of the conductor coil(s) of prior art MR valves is typically open to fluid flow channel and therefore exposed to MR fluid as the fluid flows through the channel, thereby subjecting coil(s) to erosion by the MR fluid. Additionally, due to the exposure of the entire face of the coil(s) to channel and MR fluid, the properties and characteristics of magnetic flux fields, the flux field generated by such prior art coil(s) will not be directed across the channel and through the fluid directly adjacent the face of the coil(s). Therefore, the inactive length of such prior art valves is substantially equal to the length of the coil face(s), which creates a relatively long inactive length of the valve, which affects the control ratio of the valve, e.g., limits the maximum control ratio. 
     Referring now to  FIGS.  2 ,  3  and  4   , further to the description above, in various embodiments, the magnetically permeable core  58  comprises at least one coil reservoir  78  formed therein and each conductor coil  66  is disposed around a portion of the core  58  within a respective one of the coil reservoir(s)  78 . Additionally, in various embodiments, the MR valve  50  comprises at least one coil cover  82 . In various embodiments, each coil cover  82  scan be disposed over at least a portion of the external face  86  of a respective one of the coil(s)  66  (e.g., the face of the coil  66  closest to the fluid flow channel  54 ). For example, in various embodiments, each coil cover  82  is disposed over the entire external face  86  of a respective one of the coil(s)  66  such that the respective coil  66  is protected from exposure to the MR fluid  40  within the fluid flow channel  78 . In various implementations, each coil cover  82  is recessed within the core  58 , and extends across the entire coil reservoir  78  and coil external face  86  such that an external face  90  of each coil cover  82  (e.g., the face of the cover  82  exposed to the fluid follow channel  54  and the MR fluid  40  therein) is flush with an internal face  94  of the fluid flow channel  54 . Therefore, the flow of the MR fluid  40  through the fluid flow channel  54  is not disturbed, impeded, disrupted or interfered with by the respective coil cover  82 . 
     Referring now to  FIGS.  3 ,  4  and  5   , in various embodiments, each coil cover  82  is a multi-section coil cover comprising at least one active section  98  disposed over a portion of the respective coil  66  and fabricated of a magnetically permeable material, and at least one inactive section  102  disposed over a portion of the respective coil  66  and fabricated of a non-magnetically permeable material. Since the active section(s)  98  is/are fabricated of a magnetically permeable material, the flux field generated by the respective coil  66  will flow through the entire length of the active section(s)  98  and be directed across the fluid flow channel  54  into the flux ring  62  along the length of the active section(s)  98 . Conversely, since the inactive section(s)  102  is/are fabricated of a non-magnetically permeable material, the inactive section(s)  102  provide a magnetic isolator such that the flux field generated by the respective coil  66  will not flow through the inactive section(s)  102  and not be directed across the fluid flow channel  54  along the length of the inactive section(s)  102 . Hence, the active section(s)  98  of the coil cover  82  will provide at least a portion of the total active length of the MR valve  50 , and the inactive section(s)  102  will provide at least a portion of the total inactive length. 
     Moreover, by disposing the active section(s)  98  of the coil cover  82  over a portion of the respective coil  66 , the active length of the fluid flow channel  54  (and hence, the active length of the MR valve  50 ) is substantially greater than the active length of known MR valves, and furthermore, the inactive length of the fluid flow channel  54  (and hence, the inactive length of the MR valve  50 ) is substantially smaller than the inactive length of known MR valves. Therefore, the maximum control ratio of the MR valve  50  (e.g., the maximum on-state force relative to the minimum off-state force) can be greatly increased from that of known MR valves. Specifically, by disposing the active section(s)  98  of the coil cover  82  over a portion of the respective coil  66 , the active length of the fluid flow channel  54 , and hence, the active length of the MR valve  50 , is extended beyond the portion/length of the channel  54  that is adjacent the core  58 . For example, as shown in  FIG.  5   , the active length  70 A comprises the core active length  70 A 1  where the flux field (see  FIG.  3   ) is generated through and directed across the fluid flow channel  54  by the core  58 , plus the cover active length  70 A 2  where the flux field (see  FIG.  3   ) is additionally generated through and directed across the fluid flow channel  54  by the active cover section  98 ; and further, the active length  70 B comprises the core active length  70 B 1  where the flux field is generated through and directed across the fluid flow channel  54  by the core  58 , plus the cover active length  70 B 2  where the flux field is generated through and directed across the fluid flow channel  54  by another active cover section  98 . Accordingly, the total active length of the example MR valve  50  shown in  FIG.  5    is the active length  70 A (e.g., core active length  70 A 1  plus cover active length  70 A 2 ) plus the active length  70 B (e.g., core active length  70 B 1  plus cover active length  7062 ). Additionally, the total inactive length of the example MR valve  50  shown in  FIG.  5    is merely the length of the inactive section  102 . 
     As illustrated, in various embodiments, the total or comprehensive length of the active section(s)  98  of the coil cover  82  can be substantially greater than the total or comprehensive length of the inactive section(s)  102 . For example, in various embodiments, the comprehensive length of the active section(s)  98  can be 60% to 95% of the total length of the coil cover  82 , and the comprehensive length of the inactive section(s)  102  can be 5% to 40% of the total length of the coil cover  82 . Moreover, due to the active section(s)  98  of the coil cover  82 , the total active length of the MR valve  50  can be substantially greater than the total inactive length of the MR valve  50 . For example, in various embodiments that total active length of the MR valve  50  can be 60% to 95% of the total length of the fluid flow channel  54 , and the total inactive length of the MR valve  50  can be 5% to 40% of the total length of the fluid flow channel  54 . Furthermore, since the on-state and off-state forces of the MR valve  50  are directly related to the total active length and the total inactive length, respectively, the increased total active length and the decreased total inactive length provided by the multi-section coil cover  82 , MR valve  50  can be configured or structured to have a control ratio that is considerably higher than known MR valve. 
     It should be noted, however, that the active section(s)  98  and inactive section(s)  102  of the coil cover  82  can have any desired length such that, should it be desirable, the comprehensive length of the inactive section(s)  102  can be greater than the comprehensive length of the active section(s)  98 . For example, should it be desirable, the comprehensive length of the inactive section(s)  102  can be as much as 90% to 95% of the total length of the coil cover  82 , while the comprehensive length of the active section(s)  98  can be little 5% to 10% of the total length of the coil cover  82 . 
     Referring now to  FIGS.  6 ,  7  and  8   , in various embodiments the MR valve  50  can be incorporated in the piston  42  of the MR damper  34 . That is, in such embodiments, the piston  42  comprises the MR valve  50 . 
     Referring particularly to  FIGS.  6  and  7   , in various implementations wherein the piston  42  comprises the MR valve  50 , the flux ring  62  comprises an annular ring sized to fit within an interior of the damper housing  38  such that the MR fluid  40  (not shown) cannot pass between the flux ring  62  and the housing  38 . In various instances, the MR damper  34  can include a sealing device (not shown), e.g., one or more O-ring, disposed between the flux ring  62  and the housing  38  to seal the interface therebetween so that MR fluid  40  cannot flow between the flux ring  62  and the housing  38 . Additionally, in such implementations, the core  58  is cylindrically shaped and centrally disposed within the annular flux ring  62  such that an annular fluid flow channel  54  is defined between the flux ring  62  and the core  58 . The cylindrical core  58  can comprise one or more core sections that are connectable or mateable to provide the core  58 . The at least one coil reservoir  78  can be formed within one or more of the core sections and the conductor coil(s)  66  is/are disposed around a portion of the core  58  within a respective coil reservoir  78 . Further, in such implementations, the piston  42  includes at least one non-magnetically permeable end cap  106  disposed on at least one end of the piston  42 . The end cap(s)  106  are connected, or mounted, to both the flux ring  62  and the core  58  such that the annular fluid flow channel  54  is maintained therebetween and has a consistent width W throughout the channel  54 . The end cap(s)  106  is/are fabricated of a non-magnetically permeable material and comprise a plurality of orifices  110  aligned with the fluid flow channel  54  to allow the MR fluid  40  (not shown) to flow through fluid flow channel  54  as the piston  42  moves within the housing  38 . 
     As illustrated by way of example in  FIG.  6   , in various embodiments the cylindrical core  58  can comprise a plurality of cylindrical core sections that are connectable or mateable to provide the core  58 . For example, the core  58  can include a first core section  58 A and a second core section  58 B. As described above, in various embodiments, each coil cover  82  can be a multi-section coil cover comprising at least one active section  98  disposed over a portion of the respective coil  66  and fabricated of a magnetically permeable material, and at least one inactive section  102  disposed over a portion of the respective coil  66  and fabricated of a non-magnetically permeable material. For example, as illustrated in  FIG.  6   , in various implementations, the first core section  58 A can be formed or fabricated to comprise a magnetically permeable active section  98  (e.g., a first active section) that is integrally formed therewith and extends over a first portion of the respective coil reservoir  78  such that the active section  98  is disposed over a first portion of the respective conductor coil  66 . In such implementations, the cover  82  can include an inactive section  102  that comprises a magnetic isolator band disposed over a second portion of the respective conductor coil  66 . It is envisioned that, in various embodiments, the first and second portions of the coil  66  can comprise the entire external coil face  90  such that the active section  98  (e.g., the first active section) extends over the entire coil face  90  except for the portion of the coil face  90  covered by the inactive section  102 . 
     Alternatively, in various other embodiments, the second core section  58 B can be formed or fabricated to comprise another magnetically permeable active section  98  (e.g., a second active section) that is integrally formed therewith and extends over a third portion of the respective coil reservoir  78  such that the active section  98  (e.g., the second active section) is disposed over a third portion of the respective conductor coil  66 . In such embodiments, the inactive section  102  can be disposed around a longitudinal center portion of the coil face  90 , and the active sections  98  (e.g., the first and second active sections) can be disposed over the substantially equal length remaining portions of the coil face  90  on both sides of the inactive section  102  of the cover  82 . 
     As illustrated by way of example in  FIG.  7   , in various embodiments the cylindrical core  58  can comprise a single piece core  58  or comprise a plurality of cylindrical core sections that are connectable or mateable to provide the core  58 . As described above, in various embodiments, each coil cover  82  can be a multi-section coil cover comprising at least one active section  98  disposed over a portion of the respective coil  66  and fabricated of a magnetically permeable material, and at least one inactive section  102  disposed over a portion of the respective coil  66  and fabricated of a non-magnetically permeable material. For example, as illustrated in  FIG.  7   , in various implementations, the multi-section coil cover  82  can be separate and independent from (e.g., not integrally formed with) the core  58 . For example, the multi-section coil cover  82  can include a first active section  98  comprising a first band disposed over a first portion of the respective conductor coil  66 , the inactive section comprising a magnetic isolator band disposed over a second portion of the conductor coil  66 , and a second active section comprising a second band disposed over a third portion of the conductor coil  66 . In various implementations, the inactive section  102  can be disposed around a longitudinal center portion of the coil face  90 , and the first and second active sections  98  can be disposed over the substantially equal length remaining portions of the coil face  90  on both sides of the inactive section  102  of the cover  82 . 
     Alternatively, in various other implementations, the inactive section  102  can be disposed around the coil face  90  at a longitudinal location other than the center portion of the coil face  90 , and the first and second active sections  98  can be disposed over the unequal length remaining portions of the coil face  90  on both sides of the inactive section  102  of the cover  82 . In still other implementations, it is envisioned that the multi-section coil cover  82  can include a plurality of the inactive sections  102  comprising a plurality of magnetic isolator bands disposed over a plurality of portions of the conductor coil  66 , and three or more of active sections  98  disposed over a plurality of portions of the conductor coil  66 , at least one of the active sections  98  being disposed between two adjacent inactive sections  102 . 
     Although  FIGS.  6  and  7    illustrate example embodiments of the MR valve  50  comprising the piston  42  having the annular flux ring  62  and the core  58  (e.g., single piece or multi-piece core  58 ) disposed within the flux ring  62  to define the annular fluid flow channel  54 , wherein the MR valve  50  includes only a single conductor coil  66  and a single coil cover  82  (e.g., a multi-section cover  82 ), it is envisioned that in various embodiments, the MR valves  50  of  FIGS.  6  and  7    can includes a plurality of conductor coils  66  disposed within the core  58  and a plurality of respective coil covers  82 , wherein each cover  82  is disposed over a respective one of the coils  66  (as described below with regard to  FIG.  8   ). Still further, it is envisioned that in various embodiments of the piston MR valve  50  illustrated and described with regard to  FIGS.  6  and  7   , the annular flux ring  62 , as illustrated, can be eliminated and the cylindrical housing  38  can provide or comprise the flux ring  62  (as described below with regard to  FIG.  8   ). 
     Referring now to  FIG.  8   , in various embodiments, wherein the piston  42  of the MR damper  34  comprises the MR valve  50  and the cylindrical housing  38  can comprise the flux ring  62 . That is, in such embodiments the housing  38  can be fabricated from a magnetically permeable material and comprise the flux ring  62  of the MR valve  50 . In such embodiments, the core  58  is cylindrically shaped and centrally disposed within the annular housing/flux ring  38 / 62  such that the annular fluid flow channel  54  is defined between the housing/flux ring  38 / 62  and the core  58 . In such embodiments, the annular fluid flow channel  54  can have a larger annular diameter (e.g., the diameter defined by the diameter of the core  58 ), and a narrower width W than the embodiments shown in  FIGS.  6  and  7   , thereby reducing the off-state force and increasing the on-state force of the MR fluid flowing through the channel  54 , which in turn, further increases the control ratio of the MR valve  34 . 
     The core can be a single piece core, as illustrated by way of example, or a multi-piece core having two or more core sections that are connectable or mateable to provide the core  58 . Additionally, in such embodiments, the MR valve  50  can include a single end cap  106  connected to a distal end of the core  58  (e.g., the end opposite the piston rod  46 ), wherein the end cap  106  comprises a scalloped peripheral edge comprising a plurality of semi-circular openings  114  aligned with the fluid flow channel  54  to allow the MR fluid  40  (not shown) to flow through fluid flow channel  54  as the piston  42  moves within the housing  38 . Additionally, in various embodiments, the MR valve  50  can comprise a plurality of coil reservoirs  78  formed within the core  58  and a plurality of conductor coils  66 , wherein each conductor coil  66  is disposed around a portion of the core  58  within a respective one of the coil reservoirs  78 . In such embodiments, the MR valve  50  additionally includes a multi-section coil cover  82  comprising a plurality of inactive sections  102  and three or more active sections  98  disposed between and/or adjacent the inactive sections  102 . 
     Referring now to  FIGS.  5 ,  6 ,  7  and  8   , it should be noted that in various embodiments wherein the housing  38  comprises the flux ring  62 , as shown by way of example in  FIG.  8   , the MR damper  34  can reject heat quicker and easier than the embodiments wherein the MR damper  34  includes a flux ring  62  that is disposed within the housing  38 , as shown by way of example in  FIGS.  6  and  7   . Particularly, having the housing  38  function as the flux ring  62  provides a shorter dissipation path for the heat generated within the MR damper  34 . More particularly, the exposure of the outside of the housing to the ambient environment helps maintain the housing/flux ring  38 / 62  at a cooler temperature such that the housing/flux ring  38 / 62  will absorb and dissipate the generated heat more efficiently. 
     Additionally, in various embodiments, the ends  54 A and  54 B of the fluid flow channel  54  can be chamfered, angled, funnel shaped or include a bezel to provide a larger diameter at the ends  54 A and  54 B from that of a central portion of channel  54 . The chamfered, angled, funnel shaped or bezelled ends  54 A and  54 B are structured and operable to allow the MR fluid to enter and exit the channel  54  more easily and with less turbulence and/or disruption, thereby increasing the on-state force, and decreasing the off-state force of the MR fluid flowing through the channel  54 , which in turn, further increases the control ratio of the MR valve  34 . Additionally, in various implementations, the orifices  110  and/or the openings  114  of the end cap(s)  106  can be chamfered, angled, funnel shaped or include a bezel to reduce the turbulence and/or disruption of the MR fluid entering and exiting the channel  54 . 
     Referring now to  FIG.  9   , in various embodiments, the MR damper  34  can comprise an inner cylindrical body  118  that defines a cylindrical chamber  120  that is at least partially filled with MR fluid  40  (not shown) and in which the piston  42  is disposed. The inner cylindrical body  118  is centrally disposed within an outer cylindrical housing  122  such that an outer annular chamber  126  is defined between the inner cylindrical body  118  and the outer cylindrical housing  122 . The outer annular chamber  126  is at least partially filled with MR fluid  40  and is fluidly connected with the inner cylindrical chamber  120  via windows  130  formed in the ends of the inner cylindrical body  118 . In such embodiments, the MR valve  50  is disposed within the outer annular chamber  126 . More particularly, in such embodiments, the core  58  comprises and annular (single piece or multi-piece) core having one or more coil reservoir  78  formed therein, each reservoir having a respective conductor coil  66  disposed therein as described above with regard to  FIGS.  1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7  and/or  8   . Additionally, the MR valve  50  further includes a coil cover  82  disposed over each of at least one respective coil  66 , wherein each coil cover  82  can be a single piece or a multi-section coil cover as described above with regard to  FIGS.  1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7  and/or  8   . In various embodiments, the outer cylindrical housing  122  can comprise the flux ring  62 , as described above with reference to  FIG.  8   , such that the annular fluid flow channel  54  is defined between the core  58  and the outer cylindrical housing/flux ring  122 / 62 . Alternatively, although not shown, it is envisioned that the MR valve  50  can include a flux ring  62  that is separate from the outer cylindrical housing  122 , as described above with reference to  FIGS.  6  and  7   . 
     In operation, the MR fluid  40  is moved within the inner cylindrical chamber  120  as the piston  42  is bidirectionally moved within the inner cylindrical chamber  120 . The MR fluid  40  then passes through the windows  130  and into the outer annular chamber  126  at a respective end of the inner cylindrical body  118 . Consequently, the MR fluid  40  is forced through the annular fluid flow channel  54  where the shear strength, or shear stress, of the MR fluid  40  is controllably altered as a result of the controlled strength of the magnetic flux generated by coil(s)  66 , as described above. Accordingly, the compression (or jounce) and extension (or rebound) of MR damper  34  can be controlled. Moreover, when the coil cover(s)  82  is/are multi-section covers, as described herein, the control ratio of the MR valve  50 , and hence the MR damper  34 , is significantly increased. 
     Referring now to  FIG.  10   , in various embodiments, the MR damper  34  can comprise a cylindrical body  134  having a valve head  138  formed or disposed at a distal end thereof. The valve head  138  comprises an outer housing  140  and an inner wall  142  that define an annular recess  146  therebetween. The outer housing  140  and inner wall  142  can each be connected to the cylindrical body  134 , integrally formed with the cylindrical body  134 , or be combination thereof. The valve head  138  further includes an end wall  150  that seals the end of the MR damper  34 , and a separator piston  154  disposed within the valve head  138 . The separator piston  154  defines a MR fluid chamber  158  disposed on one side of the separator piston  154  and a gas chamber  162  disposed on the other side of the separator piston  154 . The MR fluid chamber  158  includes the annular recess  146  formed between the outer housing  140  and the inner wall  142  of the valve head  138 . The MR valve piston  42  is disposed within the interior of the cylindrical body  134 . The portion of the cylindrical body interior disposed on the opposite side of the piston  42  from the piston rod  46  is at least partially filled with MR fluid  40  (not shown). 
     In such embodiments, the MR valve  50  includes a generally cup-shaped core positioner  160  having an annular wall  166  that is disposed within the annular recess  146  such that a substantially U-shaped annular fluid flow channel  54  is defined between annular wall  166  of the core positioner  160 , a portion of the outer housing  140 , and the inner wall  142 . Moreover, an annular core  58  is integrally formed with, or disposed on the annular wall  166  of the core positioner  160  such that the core  58  is positioned within the annular recess  146  such that the substantially U-shaped annular fluid flow channel  54  passes along both an interior side of the core  58  (e.g., the side facing the inner wall  142 ) and an exterior side of the core  58  (e.g., the side facing the outer housing  140 ). Still further, the annular core  58  includes one or more coil reservoir  78  formed therein. A respective conductor coil  66  is disposed within each reservoir  78  such that, when energized, each coil  66  will generate a magnetic flux field that will be directed across the U-shaped annular fluid flow channel  54  along the portion of the channel  54  passing between core/coil  58 / 66  and the outer housing  140 , and additionally directed across the U-shaped annular fluid flow channel  54  along the portion of the channel  54  passing between the core/coil  58 / 66  and the inner wall  142 . Still yet further, the MR valve  50  of such embodiments includes a pair of coil covers  82 , wherein one coil cover  82  is disposed over the interior side of the respective coil  66  (e.g., the side facing the inner wall  142 ) and the other coil cover  82  is disposed over the exterior side of the core  58  (e.g., the side facing the outer housing  140 ). Each coil cover  82  can be a single piece or a multi-section coil cover as described above with regard to  FIGS.  1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7  and/or  8   . In various embodiments, the valve head outer housing  140  and inner wall  142  can comprise flux rings. In various other embodiments, the MR valve  50  can comprise flux rings  62  be independent structures disposed between the core  58  and respective outer housing  140  and inner wall  142 . 
     In operation, when the MR damper  34  is compressed (e.g., jounce motion) the MR fluid  40  is moved within the cylindrical body  134  as the piston  42  is moved toward the MR valve  50 . Consequently, the MR fluid  40  is forced through the substantially U-shaped annular fluid flow channel  54  where the shear strength, or shear stress, of the MR fluid  40  is controllably altered, as a result of the controlled strength of the magnetic flux generated by coil(s)  66  and directed across both the portion of the channel  54  passing between the core/coil  58 / 66  and the outer housing  140 , and the portion of the channel  54  passing between the core/coil  58 / 66  and the inner wall  142 . Subsequently, the MR fluid  40  is forced into the MR fluid chamber  158  and forces the separator piston  154  move toward the end wall  150 , thereby compressing the gas within the gas chamber  162 . Thereafter, when the compressive forces on the MR damper  34  are removed, and/or extension forces are exerted on the MR damper  34  (e.g., rebound motion), the compressed gas within the gas chamber  162  forces the MR fluid  40  within the MR fluid chamber  158  back through the substantially U-shaped annular fluid flow channel  54  where the shear strength, or shear stress, of the MR fluid  40  is controllably altered, as a result of the controlled strength of the magnetic flux generated by coil(s)  66  and directed across both the portion of the channel  54  passing between the core/coil  58 / 66  and the outer housing  140 , and the portion of the channel  54  passing between the core/coil  58 / 66  and the inner wall  142 . Accordingly, the compression (or jounce) and extension (or rebound) of MR damper  34  can be controlled. Moreover, when the coil cover(s)  82  is/are multi-section covers, as described herein, the control ratio of the MR valve  50 , and hence the MR damper  34 , is significantly increased. 
     Referring now to  FIG.  11   , in various embodiments, the MR damper  34  can comprise a cylindrical body  170  and a valve canister  174  formed or disposed along an exterior side of the cylindrical body  170 . In such embodiments, the MR damper  34  additionally includes a conduit cap  178  connected to ends of, and fluidly connecting, the cylindrical body  170  and the valve canister  174 . The valve canister  174  comprises an outer housing  182  and an end wall  186  that seals the end of the valve canister  174 , and a separator piston  190  disposed within the valve canister  174 . The separator piston  190  defines a MR fluid chamber  194  disposed on one side of the separator piston  190  and a gas chamber  198  disposed on the other side of the separator piston  190 . The MR valve piston  42  is disposed within the interior of the cylindrical body  170 . The portion of the cylindrical body interior disposed on the opposite side of the piston  42  from the piston rod  46 , and an interior of the conduit cap  178  are at least partially filled with MR fluid  40  (not shown). 
     In such embodiments, the core  58  is disposed within the valve canister between the MR fluid chamber  194  and the conduit cap  178  such that the annular fluid flow channel  54  passes between the core  58  and the flux ring  62 , fluidly connecting the interior space of the conduit cap  178  with the MR fluid chamber  194 . In various embodiments the flux ring  62  can comprise the outer housing  182 , or in various other embodiments the flux ring  62  can be an independent structure disposed between the core  58  and the outer housing  182 . Additionally, in various embodiments the core  58  can be a single piece core or in various other embodiments the core  58  a multi-piece core. The core  58  includes one or more coil reservoir  78  formed therein. A respective conductor coil  66  is disposed within each reservoir  78  such that, when energized, each coil  66  will generate a magnetic flux field that will be directed across the fluid flow channel  54  along the portion of the channel  54  passing between the core/coil  58 / 66  and the flux ring  62 . Additionally, the MR valve  50  a coil cover  82  disposed over each coil  66 . Each coil cover  82  can be a single piece or a multi-section coil cover as described above with regard to  FIGS.  1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7  and/or  8   . 
     In operation, when the MR damper  34  is compressed (e.g., jounce motion) the MR fluid  40  is moved within the cylindrical body  170  as the piston  42  is moved toward the conduit cap  178 . Consequently, the MR fluid  40  is forced through the conduit cap  178  and directed into the annular fluid flow channel  54  by a diverter dome  202  disposed within the conduit cap  178  and connected to, or positioned adjacent, the core  58 . As the MR fluid  40  passes through the fluid flow channel  54  the shear strength, or shear stress, of the MR fluid  40  is controllably altered, as a result of the controlled strength of the magnetic flux generated by coil(s)  66  and directed across the channel  54 . Subsequently, the MR fluid  40  is forced into the MR fluid chamber  194  and forces the separator piston  190  move toward the end wall  186 , thereby compressing the gas within the gas chamber  198 . Thereafter, when the compressive forces on the MR damper  34  are removed, and/or extension forces are exerted on the MR damper  34  (e.g., rebound motion), the compressed gas within the gas chamber  198  forces the MR fluid  40  within the MR fluid chamber  194  back through the fluid flow channel  54  where the shear strength, or shear stress, of the MR fluid  40  is controllably altered, as a result of the controlled strength of the magnetic flux generated by coil(s)  66  and directed across the channel  54  passing. Accordingly, the compression (or jounce) and extension (or rebound) of MR damper  34  can be controlled. Moreover, when the coil cover(s)  82  is/are multi-section covers, as described herein, the control ratio of the MR valve  50 , and hence the MR damper  34 , is significantly increased. 
     Referring now to  FIGS.  9 ,  10  and  11   , although not specifically shown in the various embodiments of the MR valve  50  illustrated, by way of example, in  FIGS.  9 ,  10  and  11   , it is envisioned that, in various embodiments, the ends of the respective fluid flow channel  54  can be chamfered, angled, funnel shaped or include a bezel to provide a larger diameter at the ends from that of a central portion of the respective fluid flow channel  54 . As described above, the chamfered, angled, funnel shaped or bezelled ends are structured and operable to allow the MR fluid to enter and exit the respective fluid flow channel  54  more easily and with less turbulence and/or disruption, thereby increasing the on-state force, and decreasing the off-state force of the MR fluid flowing through the channel  54 , which in turn, further increases the control ratio of the MR valve  34 . Additionally, it should be noted that in various embodiments wherein the respective housing (e.g., housing  122 ,  140  and/or  182 ) comprises the flux ring  62 , the MR damper  34  can reject heat quicker and easier than the embodiments wherein the MR damper  34  includes a flux ring  62  that is disposed within the respective housing. Particularly, having the housing  38  function as the flux ring  62  provides a shorter dissipation path for the heat generated within the MR damper  34 . More particularly, the exposure of the outside of the housing to the ambient environment helps maintain the housing/flux ring  38 / 62  at a cooler temperature such that the housing/flux ring  38 / 62  will absorb and dissipate the generated heat more efficiently. 
     The description herein is merely exemplary in nature and, thus, variations that do not depart from the gist of that which is described are intended to be within the scope of the teachings. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions can be provided by alternative embodiments without departing from the scope of the disclosure. Such variations and alternative combinations of elements and/or functions are not to be regarded as a departure from the spirit and scope of the teachings.