Patent Publication Number: US-2023160452-A1

Title: Damper with compression damping force range increase

Description:
FIELD 
     The present disclosure generally relates to dampers. More particularly, the present disclosure relates to dampers with a single externally mounted control valve. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Vehicles generally include dampers that are used in conjunction with suspension systems to absorb vibrations and bumps during driving. In order to absorb vibration and bumps, dampers are generally connected between a body and the suspension system of the vehicle. A piston is located within the damper and separates a first working chamber and a second working chamber. The piston is connected to the vehicle body or the suspension of the vehicle through a piston rod. Dampers typically include one or more valves that control fluid flow between the first and second working chambers during extension and compression motions of the piston and piston rod. In current damper designs, fluid flow during compression strokes is limited by the piston rod volume entering the damper. As a result, the range of damping forces the damper can provide is more limited during compression strokes compared to extension (e.g., rebound) strokes because the volume of fluid inside the damper that is displaced by the piston increases during compression strokes and decreases during rebound strokes. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     In accordance with one aspect of the present disclosure, a damper is provided. The damper includes an inner tube that extends longitudinally between first and second inner tube ends. The damper includes a piston slidably disposed within the inner tube. The piston defines a first working chamber and a second working chamber within the inner tube. The first working chamber is longitudinally positioned between the piston and the first inner tube end and the second working chamber is longitudinally positioned between the piston and the second inner tube end. The damper also includes an outer tube disposed annularly around the inner tube. The outer tube extends longitudinally between a first outer tube end and a second outer tube end. An intermediate member assembly is disposed annularly about the inner tube and is positioned radially between the inner tube and the outer tube. A reservoir chamber is disposed radially between the intermediate member assembly and the outer tube. Additionally, an intermediate channel is disposed radially between the intermediate member assembly and the inner tube. The intermediate channel has a first intermediate channel portion and a second intermediate channel portion. 
     The damper includes an external control valve mounted on the outer tube. The external control valve includes a control valve inlet and a control valve outlet. The control valve inlet is positioned in fluid communication with the second intermediate channel portion and the control valve outlet is positioned in fluid communication with the reservoir chamber. 
     The damper further includes a first unidirectional blocking valve disposed annularly about the inner tube, which forms a first partition between the first and second intermediate channel portions. The first unidirectional blocking valve is a one-way valve that permits fluid flow in only a first direction moving from the first intermediate channel portion to the second intermediate channel portion. The first unidirectional blocking valve moves/deflects to an open position when a first break pressure of the first unidirectional blocking valve is reached. The first unidirectional blocking valve includes a first annular sealing surface that extends circumferentially about the inner tube, which is configured to move into and out of contact with a first annular seat. Thus, when the first unidirectional blocking valve is in the open position, a first annular opening extends annularly within the intermediate channel and is defined between the first annular sealing surface and the first annual seat. 
     In accordance with another aspect of the present disclosure, the intermediate channel portion of the damper may further include a third intermediate channel portion. A second unidirectional blocking valve is disposed annularly about the inner tube, and forms a second partition between the second intermediate channel portion and the third intermediate channel portion. The second unidirectional blocking valve is a one-way valve that permits fluid flow in only a second direction moving from the third intermediate channel portion to the second intermediate channel portion. The second unidirectional blocking valve moves/deflects to an open position when a second break pressure of the second unidirectional blocking valve is reached. The second unidirectional blocking valve includes a second annular sealing surface that extends circumferentially about the inner tube, which is configured to move into and out of contact with a second annular seat. Thus, when the second unidirectional blocking valve is in the open position, a second annular opening extends annularly within the intermediate channel and is defined between the second annular sealing surface and the second annual seat. 
     In accordance with another aspect of the present disclosure, the damper may further include a base valve assembly including a base valve body, a first base valve, and a second base valve. The base valve body defines a fluid transport chamber positioned between the second outer tube end and the base valve body. Furthermore, the first intermediate channel portion is arranged in fluid communication with the first working chamber via one or more inner tube openings. The inner tube openings extend through the inner tube between the first working chamber and the first intermediate channel portion. More specifically, the intermediate channel extends longitudinally between a first intermediate channel end and a second intermediate channel end, and the intermediate channel openings are positioned at the second intermediate channel end. As such, the third intermediate channel portion is arranged in fluid communication with the second working chamber via intermediate channel openings. 
     Advantageously, the damper design disclosed, with its unidirectional blocking valves, allows for the first working chamber and second working chamber to work independently, increasing the range of compression damping forces that can be provided by a damper with one, externally mounted, electro-mechanical valve. The disclosed damper design can therefore be tuned within a larger compression damping force range to suit a wide spectrum of vehicles compared to other dampers designs. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG.  1    is an illustration of a vehicle incorporating a suspension system constructed in accordance with the present disclosure; 
         FIG.  2    is a front perspective view of an exemplary damper constructed in accordance with the present disclosure; 
         FIG.  3    is a side cross-sectional view of the exemplary damper shown in  FIG.  2   ; 
         FIG.  4    is an enlarged exploded perspective view of the exemplary damper shown in  FIG.  3   ; 
         FIG.  5    is an enlarged side cross-sectional view of the exemplary damper shown in  FIG.  3   , where a first unidirectional blocking valve of the damper is illustrated in an open position and a second unidirectional blocking valve of the damper is illustrated in a closed position; 
         FIG.  6    is an enlarged side cross-sectional view of the exemplary damper shown in  FIG.  3   , where the first unidirectional blocking valve is illustrated in a closed position and the second unidirectional blocking valve is illustrated in an open position; 
         FIG.  7    is an enlarged exploded perspective view of another exemplary damper constructed in accordance with another aspect of the present disclosure; 
         FIG.  8    is an enlarged side cross-sectional view of the exemplary damper shown in  FIG.  7   , where a first unidirectional blocking valve of the damper is illustrated in an open position and a second unidirectional blocking valve of the damper is illustrated in a closed position; 
         FIG.  9    is an enlarged side cross-sectional view of the exemplary damper shown in  FIG.  7   , where the first unidirectional blocking valve is illustrated in a closed position and the second unidirectional blocking valve is illustrated in an open position; 
         FIG.  10    is an enlarged exploded perspective view of another exemplary damper constructed in accordance with another aspect of the present disclosure; 
         FIG.  11    is an enlarged side cross-sectional view of the exemplary damper shown in  FIG.  10   , where a first unidirectional blocking valve of the damper is illustrated in an open position and a second unidirectional blocking valve of the damper is illustrated in a closed position; 
         FIG.  12    is an enlarged side cross-sectional view of the exemplary damper shown in  FIG.  10   , where the first unidirectional blocking valve is illustrated in a closed position and the second unidirectional blocking valve is illustrated in an open position; 
         FIG.  13    is an enlarged exploded perspective view of another exemplary damper constructed in accordance with another aspect of the present disclosure; 
         FIG.  14    is an enlarged side cross-sectional view of the exemplary damper shown in  FIG.  13   , where a first unidirectional blocking valve of the damper is illustrated in an open position and a second unidirectional blocking valve of the damper is illustrated in a closed position; 
         FIG.  15    is an enlarged side cross-sectional view of the exemplary damper shown in  FIG.  13   , where the first unidirectional blocking valve is illustrated in a closed position and the second unidirectional blocking valve is illustrated in an open position; 
         FIG.  16    is an enlarged exploded perspective view of another exemplary damper constructed in accordance with another aspect of the present disclosure; 
         FIG.  17    is an enlarged side cross-sectional view of the exemplary damper shown in  FIG.  16   , where a first unidirectional blocking valve of the damper is illustrated in an open position and a second unidirectional blocking valve of the damper is illustrated in a closed position; 
         FIG.  18    is an enlarged side cross-sectional view of the exemplary damper shown in  FIG.  16   , where the first unidirectional blocking valve is illustrated in a closed position and the second unidirectional blocking valve is illustrated in an open position; 
         FIG.  19    is a side cross-sectional view of the exemplary damper shown in  FIG.  3   , where arrows are included illustrating the fluid flow path through the damper during a compression stroke; 
         FIG.  20    is another side cross-sectional view of the exemplary damper shown in  FIG.  3   , where arrows are included illustrating the fluid flow path through the damper during an extension/rebound stroke; 
         FIG.  21    is a plot illustrating damping force as a function of rod velocity during compression and extension/rebound strokes for the damper designs described herein; 
         FIG.  22    is a plot illustrating damping force as a function of rod velocity during compression and extension/rebound strokes for existing damper designs having one control valve; and 
         FIG.  23    is a plot illustrating damping force as a function of rod velocity during compression and extension/rebound strokes for existing damper designs having two control valves. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     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 may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements 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. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
       FIG.  1    illustrates an exemplary vehicle  20  incorporating a suspension system  22  in accordance with the present disclosure. The vehicle  20  may be driven by an internal combustion engine, an electric motor, a hybrid/electric powertrain, or equivalents thereof. The vehicle  20  includes a body  24 . The suspension system  22  of the vehicle  20  includes a rear suspension  26  and a front suspension  28 . The rear suspension  26  includes a transversely extending rear axle assembly (not shown) adapted to operatively support a pair of rear wheels  30 . The rear axle assembly is operatively connected to the body  24  by means of a pair of dampers  32  and a pair of helical coil springs  34 . Similarly, the front suspension  28  includes a transversely extending front axle assembly (not shown) that supports a pair of front wheels  38 . The front axle assembly is connected to the body  24  by means of another pair of the dampers  32  and a pair of helical coil springs  36 . In an alternative embodiment, the vehicle  20  may include an independent suspension unit (not shown) for each of the four corners instead of front and rear axle assemblies. 
     The dampers  32  of the suspension system  22  serve to dampen the relative movement of the unsprung portion (i.e., the front and rear suspensions  28 ,  26  and the front and rear wheels  38 ,  30 ) and the sprung portion (i.e., the body  24 ) of the vehicle  20 . While the vehicle  20  has been depicted as a passenger car, the dampers  32  may be used with other types of vehicles. Examples of such vehicles include buses, trucks, off-road vehicles, three-wheelers, ATVs, motor bikes, and so forth. Furthermore, the term “damper” as used herein will refer to dampers in general and will include shock absorbers, McPherson struts, and semi-active and active suspensions. 
     In order to automatically adjust each of the dampers  32 , an electronic controller  40  is electrically connected to the dampers  32 . The electronic controller  40  is used for controlling the operation of each of the dampers  32  in order to provide appropriate damping characteristics resulting from movements of the body  24  of the vehicle  20 . The electronic controller  40  may independently control each of the dampers  32  in order to independently control a damping level of each of the dampers  32 . The electronic controller  40  may be electrically connected to the dampers  32  via wired connections, wireless connections, or a combination thereof. 
     The electronic controller  40  may independently adjust the damping level, damping rate, or damping characteristics of each of the dampers  32  to optimize the ride performance of the vehicle  20 . The term “damping level”, as used herein, refers to a damping force produced by each of the dampers  32  to counteract compression and/or extension/rebound movements. A higher damping level may correspond to a higher damping force. Similarly, a lower damping level may correspond to a lower damping force. Adjustment of the damping levels is beneficial during braking and turning of the vehicle  20  to counteract brake dive during braking and body roll during turns. In accordance with one embodiment of the present disclosure, the electronic controller  40  processes input signals from one or more sensors (not shown) of the vehicle  20  in order to control the damping level of each of the dampers  32 . The sensors may sense one or more parameters of the vehicle  20 , such as, but not limited to, displacement, velocity, acceleration, vehicle speed, steering wheel angle, brake pressure, engine torque, engine speed in revolutions per minute (RPM), throttle pedal position, and so forth. The electronic controller  40  may further control the damping level of the dampers  32  based on a driving mode of the vehicle  20 . The driving mode may include a sport mode and a comfort mode. A button (not shown) may allow a driver of the vehicle  20  to choose the driving mode of the vehicle  20 . The electronic controller  40  may receive input signals based on an actuation of the button and control the dampers  32  accordingly. 
     In accordance with another embodiment of the present disclosure, the electronic controller  40  controls the damping level of each of the dampers  32  based on external road conditions, such as rain, snow, mud, and the like. In a further embodiment, the electronic controller  40  regulates the damping level of each of the dampers  32  based on internal vehicle conditions, such as a fuel level, occupancy of the vehicle, load, and so forth. 
     While the present disclosure is being illustrated with a single electronic controller  40 , it is within the scope of the present disclosure to utilize a dedicated electronic controller for each of the dampers  32 . The dedicated electronic controller may be located onboard each respective damper  32 . Alternatively, the electronic controller  40  may be integrated into an Electronic Control Unit (ECU) of the vehicle  20 . The electronic controller  40  may include a processor, memory, Input/Output (I/O) interfaces, communication interfaces, and other electrical components. The processor may execute various instructions stored in the memory for carrying out various operations of the electronic controller  40 . The electronic controller  40  may receive and transmit signals and data through the I/O interfaces and the communication interfaces. In further embodiments, the electronic controller  40  may include microcontrollers, application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and so forth. 
       FIGS.  2  to  6    illustrate an exemplary damper  32 , which may be any of the four dampers  32  of the vehicle  20  shown in  FIG.  1   . The damper  32  may optionally be configured as a continuously variable semi-active suspension system damper  32 . The damper  32  contains fluid. By way of example and without limitation, the fluid is hydraulic fluid or oil. The damper  32  includes an inner tube  42  that extends longitudinally between a first inner tube end  44  and a second inner tube end  46 . A piston assembly  48  includes a piston  50  slidably disposed within the inner tube  42 . The piston  50  defines a first working chamber  52  and a second working chamber  54  within the inner tube  42 . The first working chamber  52  is positioned longitudinally between the piston  50  and the first inner tube end  44  and acts as a rebound chamber during movement of the piston  50 . The second working chamber  54  is positioned longitudinally between the piston  50  and the second inner tube end  46  and acts as a compression chamber. The piston  50  includes first and second piston passages  56 ,  58  that extend longitudinally through the piston  50  between the first and second working chambers  52 ,  54 . 
     The piston assembly  48  further includes a first piston valve  60  and a second piston valve  62 . The first piston valve  60  is mounted on the piston  50  and configured to limit fluid flow through the first piston passage  56  from the second working chamber  54  to the first working chamber  52 . The second piston valve  62  is mounted on the piston  50  and configured to limit fluid flow through the second piston passage  58  from the first working chamber  52  to the second working chamber  54 . Each of the first piston valve  60  and second piston valve  62  includes at least one flex disc  64 . For the first piston valve  60 , the flex disc  64  is configured to flex toward the piston  50  and close the first piston passage  56  when a first pressure differential between the first and second working chambers  52 ,  54  is below a first pressure threshold. The flex disc  64  is configured to flex away from the piston  50  and open the first piston passage  56  when the first pressure differential between the first and second working chambers  52 ,  54  exceeds the first pressure threshold, thereby allowing fluid in the second working chamber  54  to flow through the first piston passage  56  and into the first working chamber  52 . For the second piston valve  62 , the flex disc  64  is configured to flex toward the piston  50  and close the second piston passage  58  when a second pressure differential between the first and second working chambers  52 ,  54  is below a second pressure threshold. The flex disc  64  is configured to flex away from the piston  50  and open the second piston passage  58  when the second pressure differential between the first and second working chambers  52 ,  54  exceeds the second pressure threshold, thereby allowing fluid in the first working chamber  52  to flow through the second piston passage  58  and into the second working chamber  54 . 
     The damper  32  also includes an outer tube  66  disposed annularly around the inner tube  42  and extends longitudinally between a first outer tube end  68  and a second outer tube end  70 . A closed end portion  72  is positioned in and closes off the second outer tube end  70 . A piston rod guide  76  is housed inside the first outer tube end  68 . The piston rod guide  76  includes a piston rod passage  78  that extends longitudinally between the first outer tube end  68  and the first working chamber  52  of the inner tube  42 . A piston rod  80  extends longitudinally between a first piston rod end  82  and a second piston rod end  84  along a longitudinal axis  86 , through the piston rod passage  78  of the piston rod guide  76 . The second piston rod end  84  is attached to the piston  50  and the first piston rod end  82  is configured to attach to a suspension component of the vehicle. 
     The damper  32  further includes a base valve assembly  88 . The base valve assembly  88  includes a base valve body  90 , a first base valve  92 , and a second base valve  94 . The base valve body  90  has projections  95  that abut the closed end portion  72  of the second outer tube end  70  and defines a fluid transport chamber  96  positioned between the closed end portion  72  and the base valve body  90 . The base valve body  90  includes a first and second base valve passage  98 ,  100  that extends longitudinally through the base valve body  90  between the second working chamber  54  and the fluid transport chamber  96 . The first base valve  92  includes at least one flex disc  64  that is configured to flex toward the base valve body  90  and close the first base valve passage  98  when a third pressure differential between the second working chamber  54  and the fluid transport chamber  96  is below a third pressure threshold. The flex disc  64  of the first base valve  92  is configured to flex away from the base valve body  90  and open the first base valve passage  98  when the third pressure differential between the second working chamber and the fluid transport chamber  96  exceeds the third pressure threshold, thereby allowing fluid in the fluid transport chamber  96  to flow through the first base valve passage  98  and into the second working chamber  54 . The second base valve  94  also includes at least one flex disc  64  that is configured to flex toward the base valve body  90  and close the second base valve passage  100  when a fourth pressure differential between the second working chamber  54  and the fluid transport chamber  96  is below a fourth pressure threshold. The flex disc  64  of the second base valve  94  is configured to flex away from the base valve body  90  and open the second base valve passage  100  when the fourth pressure differential between the second working chamber  54  and the fluid transport chamber  96  exceeds the fourth pressure threshold, thereby allowing fluid in the second working chamber  54  to flow through the second base valve passage  100  and into the fluid transport chamber  96 . 
     Further, the damper  32  includes an intermediate member assembly  102  disposed annularly about the inner tube  42  and positioned radially between the inner tube  42  and the outer tube  66 . The intermediate member assembly  102  extends longitudinally between a first intermediate member assembly end  104  and a second intermediate member assembly end  106 . 
     The intermediate member assembly  102  includes a third tube  108 , a control valve coupling sleeve  110 , and a base valve coupling sleeve  112 . The third tube  108  extends longitudinally between a distal end  114  and a proximal end  116 . Next, the control valve coupling sleeve  110  extends longitudinally between a first sleeve end  118  and a second sleeve end  120 . The control valve coupling sleeve  110  includes a control valve opening  122 . Finally, the base valve coupling sleeve  112  extends longitudinally between a first coupling end  124  and a second coupling end  126  that receives at least part of the base valve assembly  88 . 
     The control valve coupling sleeve  110  has an interior surface  174  that includes a first shoulder  176  and a second shoulder  178 . The proximal end  116  of the third tube  108  is received in the first sleeve end  118  of the control valve coupling sleeve  110  in a press-fit and the first coupling end  124  of the base valve coupling sleeve  112  is received in the second sleeve end  120  of the control valve coupling sleeve  110  in a press-fit. Furthermore, the base valve coupling sleeve  112  includes an interior sleeve surface  128  with a plurality of slots  130  that are circumferentially spaced. 
     The damper  32  also includes an intermediate channel  132  disposed radially between the intermediate member assembly  102  and the inner tube  42 . The intermediate channel  132  extends longitudinally between a first intermediate channel end  134  and a second intermediate channel end  136 , and has a first intermediate channel portion  138 , a second intermediate channel portion  140 , and a third intermediate channel portion  142 . At the first intermediate channel end  134 , a seal  144  is disposed and extends radially between the inner tube  42  and the first intermediate member assembly end  104 . As such, the first intermediate member assembly end  104  abuts the seal  144  and the second intermediate member assembly end  106  abuts the base valve assembly  88 . At the second intermediate channel end  136 , at least one intermediate channel opening  146  is positioned that allows for fluid communication between the second working chamber  54  and the third intermediate channel portion  142 . 
     The second intermediate channel portion  140  is positioned between the first intermediate channel portion  138  and the third intermediate channel portion  142 . More specifically, the first intermediate channel portion  138  is defined between the third tube  108  and the inner tube  42 , the second intermediate channel portion  140  is defined between the control valve coupling sleeve  110  and the inner tube  42 , and the third intermediate channel portion  142  is defined between the base valve coupling sleeve  112  and the inner tube  42 . Additionally, the first intermediate channel portion  138  is arranged in fluid communication with the first working chamber  52  via at least one inner tube opening  148  that extends through the inner tube  42  between the first working chamber  52  and the first intermediate channel portion  138 . 
     The damper  32  includes a first unidirectional blocking valve  300  and a second unidirectional blocking valve  302 . The first unidirectional blocking valve  300  is disposed annularly about the inner tube  42  and forms a first partition  304  (see  FIG.  6   ) between the first intermediate channel portion  138  and the second intermediate channel portion  140 . The first unidirectional blocking valve  300  is positioned adjacent to and is held between the proximal end  116  of the third tube  108  and the first shoulder  176  in the control valve coupling sleeve  110 . The second unidirectional blocking valve  302  is disposed annularly about the inner tube  42  that forms a second partition  306  (see  FIG.  5   ) between the second intermediate channel portion  140  and the third intermediate channel portion  142 . The second unidirectional blocking valve  302  is positioned adjacent to and is held between the second shoulder  178  in the control valve coupling sleeve  110  and first coupling end  124  of the base valve coupling sleeve  112 . The first and second unidirectional blocking valves  300 ,  302  are one-way valves that permit fluid flow in only one direction (i.e., the first and second unidirectional blocking valves  300 ,  302  only allow fluid flow into the second intermediate channel portion  140  from the first and third intermediate channel portions  138 ,  142 ). 
     The damper  32  further includes a reservoir chamber  150 , disposed radially between the intermediate member assembly  102  and the outer tube  66 , extending longitudinally between a first reservoir chamber end  152  and a second reservoir chamber end  154 . The first reservoir chamber end  152  is positioned adjacent to the piston rod guide  76  and the second reservoir chamber end  154  is positioned adjacent to the closed end portion  72 . The reservoir chamber  150  is filled with fluid and gas where gas rises toward the first reservoir chamber end  152  and fluid fills the reservoir chamber  150  from the second reservoir chamber end  154  toward the first reservoir chamber end  152 . At least one reservoir chamber passage  156  is positioned between the projections  95  on the base valve body  90  that provides fluid communication between the reservoir chamber  150  and the fluid transport chamber  96 . 
     The damper  32  includes an outer tube opening  158 , positioned between the first outer tube end  68  and the second outer tube end  70 , that extends through the outer tube  66 . A control valve seat  160  is positioned within the outer tube opening  158 , extends through the reservoir chamber  150 , and abuts the intermediate member assembly  102 . An external control valve  162  abuts the control valve seat  160  and is externally mounted to the outer tube  66 . The external control valve  162  includes a control valve inlet  164  aligned and arranged in fluid communication with the second intermediate channel portion  140  via a control valve inlet passage  166 . The control valve inlet passage  166  extends through the control valve seat  160 . The external control valve  162  further includes a control valve outlet  168  positioned in fluid communication with the reservoir chamber  150  via a control valve outlet passage  170 . 
     The external control valve  162  is a two-position, solenoid actuated electro-mechanical valve. The electronic controller  40  may regulate the external control valve  162  in order to control the damping level of the damper  32 . The external control valve  162  may be controlled by an input current provided to the solenoid of the external control valve  162 . The electronic controller  40  generates the input current in order to control the operation and the damping level of the damper  32 . The solenoid of the external control valve  162  may be connected in electrical communication with the electronic controller  40 . Further, the input current may vary between lower and upper limits, which correspond to least and most restrictive positions (i.e., an open position and a closed position) of the external control valve  162 . The electronic controller  40  may control the damping force or level by controlling a degree of restriction of the external control valve  162 . Specifically, the electronic controller  40  may regulate the input currents to vary a restriction of the external control valve  162 . Sending a low current to the external control valve  162  may correspond to low damping ratio or damping level. Similarly, sending a high current to the external control valve  162  may correspond to a high damping ratio or damping level. 
     The first unidirectional blocking valve  300  permits fluid flow in a first direction  308  (see  FIG.  5   ) moving from the first intermediate channel portion  138  to the second intermediate channel portion  140  when the first unidirectional blocking valve  300  is in an open position. The second unidirectional blocking valve  302  permits fluid flow in a second direction  310  (see  FIG.  6   ) moving from the third intermediate channel portion  142  to the second intermediate channel portion  140  when the second unidirectional blocking valve  302  is an open position. 
     As shown in  FIG.  5   , the first unidirectional blocking valve  300  is configured to open a first fluid flow path  312  when a first fluid pressure differential between the first intermediate channel portion  138  and the second intermediate channel portion  140  exceeds a first break pressure of the first unidirectional blocking valve  300 . The first fluid flow path  312  is configured to permit the fluid in the first intermediate channel portion  138  to flow in the first direction  308  into the second intermediate channel portion  140 . Additionally, the first unidirectional blocking valve  300  is configured to close the first fluid flow path  312  when the first fluid pressure differential between the first intermediate channel portion  138  and the second intermediate channel portion  140  is less than the first break pressure of the first unidirectional blocking valve  300  (see  FIG.  6   ). 
     The first unidirectional blocking valve  300  includes a first annular sealing surface  314  that extends circumferentially about the inner tube  42  and is configured to move into and out of contact with a first annular seat  316 . When the first unidirectional blocking valve  300  is in the open position ( FIG.  5   ), a first annular opening  318  extends annularly within the intermediate channel  132  and is defined between the first annular sealing surface  314  and the first annular seat  316 . When the first unidirectional blocking valve  300  is in the closed position ( FIG.  6   ), the first annular sealing surface  314  contacts the first annular seat  316 . 
     As shown in  FIG.  6   , the second unidirectional blocking valve  302  is configured to open a second fluid flow path  320  when a second fluid pressure differential between the third intermediate channel portion  142  and the second intermediate channel portion  140  exceeds a second break pressure of the second unidirectional blocking valve  302 . The second fluid flow path  320  is configured to permit fluid in the third intermediate channel portion  142  to flow in the second direction  310  into the second intermediate channel portion  140 . Additionally, the second unidirectional blocking valve  302  is configured to close the second fluid flow path  320  when the second fluid pressure differential between the third intermediate channel portion  142  and the second intermediate channel portion  140  is less than the second break pressure of the second unidirectional blocking valve  302  (see  FIG.  5   ). 
     The second unidirectional blocking valve  302  includes a second annular sealing surface  322  that extends circumferentially about the inner tube  42  and that is configured to move into and out of contact with a second annular seat  324 . When the second unidirectional blocking valve  302  is in the open position ( FIG.  6   ), a second annular opening  326  extends annularly within the intermediate channel  132  between the second annular sealing surface  322  and the second annular seat  324 . When the second unidirectional blocking valve  302  is in the closed position ( FIG.  5   ), the second annular sealing surface  322  contacts the second annular seat  324 . 
     As shown in  FIGS.  4  to  18   , the first unidirectional blocking valve  300  and the second unidirectional blocking valve  302  may be constructed in a number of different ways. However, many of the elements of the damper  32  previously described are the same or substantially the same amongst the multiple embodiments. Equivalent elements shared between the embodiments have the same or corresponding reference numbers. For example, reference numerals  300  and  302  in  FIGS.  4  to  6    correspond to reference numerals  400  and  402  in  FIGS.  7  to  9   , reference numerals  500  and  502  in  FIGS.  10  to  12   , reference numerals  600  and  602  in  FIGS.  13  to  15   , and reference numerals  700  and  702  in  FIGS.  16  to  18   . 
     In the embodiment shown in  FIGS.  4  to  6   , the first unidirectional blocking valve  300  includes a first oil seal  330  disposed annularly about the inner tube  42  and the second unidirectional blocking valve  302  includes a second oil seal  332  disposed annularly about the inner tube  42 . The inner tube  42  has an outer surface  172  such that the first and second annular seats  316 ,  324  of the first and second unidirectional blocking valves  300 ,  302  are portions of the outer surface  172  of the inner tube  42 . Each of the first oil seal  330  and the second oil seal  332  includes a cylindrical seal portion  336  that is arranged in abutting contact with the control valve coupling sleeve  110  and that extends longitudinally between a first seal end  338  and a second seal end  340 . Furthermore, each of the first oil seal  330  and second oil seal  332  includes a funnel shaped portion  342  that extends radially inward at a first angle  344  from the cylindrical seal portion  336  to the first and second annular sealing surfaces  314 ,  322 , respectively, such that the innermost lip of the funnel shaped portion  342  contacts the outer surface  172  of the inner tube  42  as the first and second annular sealing surfaces  314 ,  322 . 
     The first and second oil seals  330 ,  332  may be made of a resilient material. The funnel shaped portion  342  of the first and second oil seals  330 ,  332  is flexible such that the first and second annular sealing surfaces  314 ,  322  of the funnel shaped portion  342  are configured to move into and out of contact with the first and second annular seats  316 ,  324  on the outer surface  172  of the inner tube  42 . More specifically, the funnel shaped portion  342  of the first oil seal  330  is configured to flex away from the inner tube  42  and toward the cylindrical seal portion  336  to open the first fluid flow path  312  and the second oil seal  332  is also configured to flex away from the inner tube  42  and toward the cylindrical seal portion  336  to open the second fluid flow path  320 . The first fluid flow path  312  between the funnel shaped portion  342  of the first oil seal  330  and the inner tube  42  opens when the first fluid pressure differential between the first intermediate channel portion  138  and the second intermediate channel portion  140  exceeds the first break pressure of the first unidirectional blocking valve  300 . The second fluid flow path  320  between the funnel shaped portion  342  of the second oil seal  332  and the inner tube  42  opens when a second fluid pressure differential between the third intermediate channel portion  142  and the second intermediate channel portion  140  exceeds the second break pressure of the second unidirectional blocking valve  302 . 
     As shown in  FIGS.  7  to  9   , the damper  32  includes a spring oil sealing assembly  428  with a first sealing ring  430  that extends annularly about the inner tube  42  and a second sealing ring  432  that extends annularly about the inner tube  42 . Each of the first and second sealing rings  430 ,  432  extends longitudinally between a first sealing ring end  434  and a second sealing ring end  436 , and includes an outer sealing ring surface  438  that is formed with a plurality of grooves  440  that allow fluid to pass between the first and second sealing rings  430 ,  432  and the control valve coupling sleeve  110 . The second sealing ring end  436  of the first sealing ring  430  is positioned to face the second sealing ring end  436  of the second sealing ring  432 , which are arranged to contact the first and second shoulders  176 ,  178 , which act as travel stops for the first and second sealing rings  430 ,  432 . 
     The first sealing ring  430  is arranged in sliding contact with the inner tube  42  and the control valve coupling sleeve  110 . The first sealing ring  430  is spring biased such that the first sealing ring end  434  is positioned in contact with the proximal end  116  of the third tube  108  in a seated position ( FIG.  9   ) and is configured to slide longitudinally away from the proximal end  116  of the third tube  108  in an unseated position ( FIG.  8   ) to open a first fluid flow path  412  through the first unidirectional blocking valve  400 , which points in a first direction  408  moving from the first intermediate channel portion  138  to the second intermediate channel portion  140 . As such, at least a portion of proximal end  116  of the third tube  108  acts as a first annular seat  416  against which a first annular sealing surface  414  of the first sealing ring  430  rests when the first sealing ring  430  is in the seated position, creating a first partition  404 . As shown in  FIG.  8   , the first unidirectional blocking valve  400  opens when the first fluid pressure differential between the first intermediate channel portion  138  and the second intermediate channel portion  140  exceeds the first break pressure of the first unidirectional blocking valve  400 , creating a first annular opening  418  between the first annular seat  416  and the first annular sealing surface  414 , which allows fluid to pass through the first unidirectional blocking valve  400 . 
     The second sealing ring  432  is arranged in sliding contact with the inner tube  42  and the control valve coupling sleeve  110 . The second sealing ring  432  is spring biased such that the second sealing ring end  436  is positioned in contact with the first coupling end  124  of the base valve coupling sleeve  112  in a seated position ( FIG.  8   ) and is configured to slide longitudinally away from the first coupling end  124  of the base valve coupling sleeve  112  in an unseated position ( FIG.  9   ) to open a second fluid flow path  420  through the second unidirectional blocking valve  402 , which points in a second direction  410  moving from the third intermediate channel portion  142  to the second intermediate channel portion  140 . As such, at least a portion of the first coupling end  124  of the base valve coupling sleeve  112  acts as a second annular seat  424  against which a second annular sealing surface  422  of the second sealing ring  432  rests when the second sealing ring  432  is in the seated position, creating a second partition  406 . As shown in  FIG.  9   , the second unidirectional block valve opens when the second fluid pressure differential between the third intermediate channel portion  142  and the second intermediate channel portion  140  exceeds the second break pressure of the second unidirectional blocking valve  402 , creating a second annular opening  426  between the second annular seat  424  and the second annular sealing surface  422 , which allows fluid to pass through the second unidirectional blocking valve  402 . 
     The spring oil sealing assembly  428  includes a spring  444  that extends longitudinally between the first and second sealing rings  430 ,  432  and helically about the inner tube  42 . The spring  444  is compressible between a first spring position and a second spring position, such that the spring  444  is compressed when one of the first and second sealing rings  430 ,  432  is pushed toward an unseated position by a pressure differential between the second intermediate channel portion  140  and the first or third intermediate channel portions  138 ,  142 . 
     In another embodiment shown in  FIGS.  10  to  12   , the damper  32  includes an intake disc spring assembly  528  with a first sealing ring  530  that extends annularly about the inner tube  42  and a second sealing ring  532  that extends annularly about the inner tube  42 . Each of the first and second sealing rings  530 ,  532  extends longitudinally between a first sealing ring end  534  and a second sealing ring end  536 , and includes an outer sealing ring surface  538  that is formed with a plurality of grooves  540  that allow fluid to pass between the first and second sealing rings  530 ,  532  and the control valve coupling sleeve  110 . The second sealing ring end  536  of the first sealing ring  530  is positioned to face the second sealing ring end  536  of the second sealing ring  532 , which are arranged to contact the first and second shoulders  176 ,  178 , which act as travel stops for the first and second sealing rings  530 ,  532 . 
     The first sealing ring  530  is arranged in sliding contact with the inner tube  42  and the control valve coupling sleeve  110 . The first sealing ring  530  is spring biased such that the first sealing ring end  534  is positioned in contact with the proximal end  116  of the third tube  108  in a seated position ( FIG.  12   ) and is configured to slide longitudinally away from the proximal end  116  of the third tube  108  in an unseated position ( FIG.  11   ) to open a first fluid flow path  512  through the first unidirectional blocking valve  500 , which points in a first direction  508  moving from the first intermediate channel portion  138  to the second intermediate channel portion  140 . As such, at least a portion of proximal end  116  of the third tube  108  acts as a first annular seat  516  against which a first annular sealing surface  514  of the first sealing ring  530  rests when the first sealing ring  530  is in the seated position, creating a first partition  504 . As shown in  FIG.  11   , the first unidirectional blocking valve  500  opens when the first fluid pressure differential between the first intermediate channel portion  138  and the second intermediate channel portion  140  exceeds the first break pressure of the first unidirectional blocking valve  500 , creating a first annular opening  518  between the first annular seat  516  and the first annular sealing surface  514 , which allows fluid to pass through the first unidirectional blocking valve  500 . 
     The second sealing ring  532  is arranged in sliding contact with the inner tube  42  and the control valve coupling sleeve  110 . The second sealing ring  532  is spring biased such that the second sealing ring end  536  is positioned in contact with the first coupling end  124  of the base valve coupling sleeve  112  in a seated position (FIG.  11 ) and is configured to slide longitudinally away from the first coupling end  124  of the base valve coupling sleeve  112  in an unseated position ( FIG.  12   ) to open a second fluid flow path  520  through the second unidirectional blocking valve  502 , which points in a second direction  510  moving from the third intermediate channel portion  142  to the second intermediate channel portion  140 . As such, at least a portion of the first coupling end  124  of the base valve coupling sleeve  112  acts as a second annular seat  524  against which a second annular sealing surface  522  of the second sealing ring  532  rests when the second sealing ring  532  is in the seated position, creating a second partition  506 . As shown in  FIG.  12   , the second unidirectional block valve  502  opens when the second fluid pressure differential between the third intermediate channel portion  142  and the second intermediate channel portion  140  exceeds the second break pressure of the second unidirectional blocking valve  502 , creating a second annular opening  526  between the second annular seat  524  and the second annular sealing surface  522 , which allows fluid to pass through the second unidirectional blocking valve  502 . 
     The intake disc spring assembly  528  includes a first intake disc spring  544  and a second intake disc spring  546 . Each of the first intake disc spring  544  and second intake disc spring  546  have a flat ring  548  and a plurality of resilient fingers  550  that extend from the flat ring  548  at an angle  552 . The first intake disc spring  544  is positioned longitudinally between the second sealing ring end  536  of the first sealing ring  530  and the first shoulder  176 . The second intake disc spring  546  is positioned longitudinally between the second sealing ring end  536  of the second sealing ring  532  and the second shoulder  178 . The plurality of resilient fingers  550  of the first and second intake disc springs  544 ,  546  abut the plurality of grooves  540  of the first and second sealing rings  530 ,  532 . The plurality of resilient fingers  550  are compressible between an uncompressed position and a compressed position, such that the plurality of resilient fingers  550  are flattened in the compressed position when one of the first and second sealing rings  530 ,  532  is pushed toward an unseated position by a pressure differential between the second intermediate channel portion  140  and the first or third intermediate channel portions  138 ,  142 . 
     In another embodiment shown in  FIGS.  13  to  15   , the damper  32  includes a wave spring assembly  628  with a first sealing ring  630  that extends annularly about the inner tube  42  and a second sealing ring  632  that extends annularly about the inner tube  42 . Each of the first and second sealing rings  630 ,  632  extends longitudinally between a first sealing ring end  634  and a second sealing ring end  636 , and includes an outer sealing ring surface  638  that is formed with a plurality of grooves  640  that allow fluid to pass between the first and second sealing rings  630 ,  632  and the control valve coupling sleeve  110 . The second sealing ring end  636  of the first sealing ring  630  is positioned to face the second sealing ring end  636  of the second sealing ring  632 , which are arranged to contact the first and second shoulders  176 ,  178 , which act as travel stops for the first and second sealing rings  630 ,  632 . 
     The first sealing ring  630  is arranged in sliding contact with the inner tube  42  and the control valve coupling sleeve  110 . The first sealing ring  630  is spring biased such that the first sealing ring end  634  is positioned in contact with the proximal end  116  of the third tube  108  in a seated position ( FIG.  15   ) and is configured to slide longitudinally away from the proximal end  116  of the third tube  108  in an unseated position ( FIG.  14   ) to open a first fluid flow path  612  through the first unidirectional blocking valve  600 , which points in a first direction  608  moving from the first intermediate channel portion  138  to the second intermediate channel portion  140 . As such, at least a portion of proximal end  116  of the third tube  108  acts as a first annular seat  616  against which a first annular sealing surface  614  of the first sealing ring  630  rests when the first sealing ring  630  is in the seated position, creating a first partition  604 . As shown in  FIG.  14   , the first unidirectional blocking valve  600  opens when the first fluid pressure differential between the first intermediate channel portion  138  and the second intermediate channel portion  140  exceeds the first break pressure of the first unidirectional blocking valve  600 , creating a first annular opening  618  between the first annular seat  616  and the first annular sealing surface  614 , which allows fluid to pass through the first unidirectional blocking valve  600 . 
     The second sealing ring  632  is arranged in sliding contact with the inner tube  42  and the control valve coupling sleeve  110 . The second sealing ring  632  is spring biased such that the second sealing ring end  636  is positioned in contact with the first coupling end  124  of the base valve coupling sleeve  112  in a seated position ( FIG.  14   ) and is configured to slide longitudinally away from the first coupling end  124  of the base valve coupling sleeve  112  in an unseated position ( FIG.  15   ) to open a second fluid flow path  620  through the second unidirectional blocking valve  602 , which points in a second direction  610  moving from the third intermediate channel portion  142  to the second intermediate channel portion  140 . As such, at least a portion of the first coupling end  124  of the base valve coupling sleeve  112  acts as a second annular seat  624  against which a second annular sealing surface  622  of the second sealing ring  632  rests when the second sealing ring  632  is in the seated position, creating a second partition  606 . As shown in  FIG.  15   , the second unidirectional block valve  602  opens when the second fluid pressure differential between the third intermediate channel portion  142  and the second intermediate channel portion  140  exceeds the second break pressure of the second unidirectional blocking valve  602 , creating a second annular opening  626  between the second annular seat  624  and the second annular sealing surface  622 , which allows fluid to pass through the second unidirectional blocking valve  602 . 
     The wave spring assembly  628  includes a first wave spring  644  and a second wave spring  646 . Each of the first wave spring  644  and the second wave spring  646  are formed by at least one coil  648 . The first wave spring  644  is positioned longitudinally between the second sealing ring end  636  of the first sealing ring  630  and the first shoulder  176 . The second wave spring  646  is positioned longitudinally between the second sealing ring end  636  of the second sealing ring  632  and the second shoulder  178 . The first and second wave springs  644 ,  646  have an uncompressed position and a compressed position, such that the first wave spring  644  and the second wave spring  646  are flattened in the compressed position when one of the first and second sealing rings  630 ,  632  is pushed toward an unseated position by a pressure differential between the second intermediate channel portion  140  and the first or third intermediate channel portions  138 ,  142 . 
     In another embodiment shown in  FIGS.  16  to  18   , the damper  32  includes an intake spring assembly  728 . Certain components of this embodiment ( FIGS.  16  to  18   ) share similar, but not the same, components with the previously described embodiments ( FIGS.  3  to  15   ). Equivalent elements in  FIGS.  16  to  18    are represented with a prime after the reference numerals. For example, elements of the intermediate member assembly  102  in  FIGS.  2  to  15    correspond to elements of an intermediate member assembly  102 ′ in  FIGS.  16  to  18   . 
     With reference to  FIGS.  16  to  18   , the intermediate member assembly  102 ′ extends longitudinally between a first intermediate member assembly end  104 ′ and a second intermediate member assembly end  106 ′. The intermediate member assembly  102 ′ includes a third tube  108 ′, a control valve coupling sleeve  110 ′, and a base valve coupling sleeve  112 ′. The third tube  108 ′ extends longitudinally between a distal end  114 ′ and a proximal end  116 ′. Next, the control valve coupling sleeve  110 ′ extends longitudinally between a first sleeve end  118 ′ and a second sleeve end  120 ′. A first shoulder  176 ′ is disposed adjacent to the first sleeve end  118 ′ and a second shoulder  178 ′ is disposed adjacent to the second sleeve end  120 ′. The control valve coupling sleeve  110 ′ includes a control valve opening  122 ′. Finally, the base valve coupling sleeve  112 ′ extends longitudinally between a first coupling end  124 ′ and a second coupling end  126 ′ that receives at least part of the base valve assembly  88 . The base valve coupling sleeve  112 ′ includes an interior sleeve surface  128 ′ with a plurality of slots  130 ′ that are circumferentially spaced. 
     The intake spring assembly  728  includes a first sealing ring  730  that extends annularly about the inner tube  42  and a second sealing ring  732  that extends annularly about the inner tube  42 . Each of the first and second sealing rings  730 ,  732  extends longitudinally between a first sealing ring end  734  and a second sealing ring end  736 . The second sealing ring end  736  of the first sealing ring  730  is positioned to face the second sealing ring end  736  of the second sealing ring  732 , which are arranged to contact the first and second shoulders  176 ′,  178 ′, which act as travel stops for the first and second sealing rings  730 ,  732 . 
     The first sealing ring  730  is arranged in sliding contact with the inner tube  42  and the control valve coupling sleeve  110 ′. The first sealing ring  730  is spring biased such that the first sealing ring end  734  is positioned in contact with the proximal end  116 ′ of the third tube  108 ′ in a seated position ( FIG.  18   ) and is configured to slide longitudinally away from the proximal end  116 ′ of the third tube  108 ′ in an unseated position ( FIG.  17   ) to open a first fluid flow path  712  through the first unidirectional blocking valve  700 , which points in a first direction  708  moving from the first intermediate channel portion  138  to the second intermediate channel portion  140 . As such, at least a portion of proximal end  116 ′ of the third tube  108 ′ acts as a first annular seat  716  against which a first annular sealing surface  714  of the first sealing ring  730  rests when the first sealing ring  730  is in the seated position, creating a first partition  704 . As shown in  FIG.  17   , the first unidirectional blocking valve  700  opens when the first fluid pressure differential between the first intermediate channel portion  138  and the second intermediate channel portion  140  exceeds the first break pressure of the first unidirectional blocking valve  700 , creating a first annular opening  718  between the first annular seat  716  and the first annular sealing surface  714 , which allows fluid to pass through the first unidirectional blocking valve  700 . 
     The second sealing ring  732  is arranged in sliding contact with the inner tube  42  and the control valve coupling sleeve  110 ′. The second sealing ring  732  is spring biased such that the second sealing ring end  736  is positioned in contact with the first coupling end  124 ′ of the base valve coupling sleeve  112 ′ in a seated position ( FIG.  17   ) and is configured to slide longitudinally away from the first coupling end  124 ′ of the base valve coupling sleeve  112 ′ in an unseated position ( FIG.  18   ) to open a second fluid flow path  720  through the second unidirectional blocking valve  702 , which points in a second direction  710  moving from the third intermediate channel portion  142  to the second intermediate channel portion  140 . As such, at least a portion of the first coupling end  124 ′ of the base valve coupling sleeve  112 ′ acts as a second annular seat  724  against which a second annular sealing surface  722  of the second sealing ring  732  rests when the second sealing ring  732  is in the seated position, creating a second partition  706 . As shown in  FIG.  18   , the second unidirectional block valve  702  opens when the second fluid pressure differential between the third intermediate channel portion  142  and the second intermediate channel portion  140  exceeds the second break pressure of the second unidirectional blocking valve  702 , creating a second annular opening  726  between the second annular seat  724  and the second annular sealing surface  722 , which allows fluid to pass through the second unidirectional blocking valve  702 . 
     The intake spring assembly  728  includes a first intake spring  744  and a second intake spring  746 . The first intake spring  744  is positioned longitudinally between the second sealing ring end  736  of the first sealing ring  730  and the first shoulder  176 ′. The second intake spring  746  is positioned longitudinally between the second sealing ring end  736  of the second sealing ring  732  and the second shoulder  178 ′. The first intake spring  744  and the second intake spring  746  are compressible coil springs that extend helically about the inner tube  42 . The first and second intake springs  744 ,  746  are compressible between an uncompressed position and a compressed position, such that the each of the first and second intake spring  744 ,  746  is compressed when one of the first and second sealing ring  730 ,  732  is pushed toward an unseated position by a pressure differential between the second intermediate channel portion  140  and the first or third intermediate channel portions  138 ,  142 . 
     Operation of the damper  32  during a compression stroke and an extension (e.g. rebound) stroke will now be explained in greater detail. 
     With reference to  FIG.  19   , the damper  32  is shown in the compression stroke. A compression flow path F 1  is defined when the external control valve  162  is opened. The piston  50  moves toward the second inner tube end  46  where fluid in the second working chamber  54  flows through the first piston valve  60  of the piston assembly  48  to the first working chamber  52  along flow path F 2 . Additionally, fluid in the second working chamber  54  flows through the second base valve  94  of the base valve assembly  88  and through the reservoir chamber passages  156  to the reservoir chamber  150  along flow path F 3 . Fluid in the second working chamber  54  also flows to the third intermediate channel portion  142  via the intermediate channel openings  146  and the plurality of slots  130  in the base valve coupling sleeve  112  along flow path F 4 . As the second unidirectional blocking valve  302  opens and the first unidirectional blocking valve  300  is closed due to fluid pressure, fluid in the third intermediate channel portion  142  flows into the second intermediate channel portion  140  via the second fluid flow path  320  through the second unidirectional blocking valve  302 . Fluid in the second intermediate channel portion  140  flows to the control valve inlet  164  through the control valve inlet passage  166 . Finally, fluid from the control valve inlet  164  flows to the control valve outlet  168  and into the reservoir chamber  150  via the control valve outlet passage  170  along the compression flow path F 1 . 
     With reference to  FIG.  20   , the damper  32  is shown in an extension/rebound stroke. An extension flow path F 5  is defined when the external control valve  162  is opened. The piston  50  moves toward the first inner tube end  44  where fluid in the first working chamber  52  flows through the second piston valve  62  of the piston assembly  48  to the second working chamber  54  along flow path F 6 . Fluid in the reservoir chamber  150  flows through the reservoir chamber passages  156  and through the first base valve  92  of the base valve assembly  88  to the second working chamber  54  along flow path F 7 . Fluid in the first working chamber  52  flows to the first intermediate channel portion  138  via the inner tube opening  148  along flow path F 8 . As the first unidirectional blocking valve  300  opens and the second unidirectional blocking valve  302  is closed due to fluid pressure, fluid in the first intermediate channel portion  138  flows into the second intermediate channel portion  140  via the first fluid flow path  312  through the first unidirectional blocking valve  300 . Fluid in the second intermediate channel portion  140  flows to the control valve inlet  164  via the control valve inlet passage  166 . Finally, fluid from the control valve inlet  164  flows to the control valve outlet  168  and into the reservoir chamber  150  via the control valve outlet passage  170  along the extension flow path F 5 . 
       FIG.  21    illustrates a compression and extension damping curve  184 ,  186  in accordance with the present disclosure. For comparison,  FIG.  22    illustrates the compression and extension damping curves  184 ,  186  for existing dampers having one external control valve and  FIG.  23    illustrates the same for existing dampers having two external control valves. Each of the compression and extension damping curves  184 ,  186  represent damping force as a function of rod velocity during compression and extension/rebound strokes, respectively, for a particular damping level. As explained above, the degree and speed in which the external control valve  162  opens during compression and extension/rebound strokes can be controlled by the electronic controller  40  to control or change the damping force. Therefore,  FIGS.  21  to  23    each illustrate a compression region  188  and an extension region  190  to represent a range of compression and extension damping forces that the damper can be tuned to provide, where damping curve  181  represents a lower limit of the compression region  188 , damping curve  183  represents an upper limit of the compression region  188 , damping curve  185  represents a lower limit of the extension region  190 , and damping curve  187  represents an upper limit of the extension region  190 . 
       FIG.  22    shows that for existing dampers with one external control valve, the range of damping forces available during the compression stroke are shown to be notably less than the range of damping forces available during the extension/rebound stroke. In contrast,  FIG.  23    shows that the range of damping forces available during compression and extension/rebound stroke for existing dampers with two external control valves are comparable. Therefore, existing dampers with one external control valve allow for a smaller range of damping forces provided during the compression stroke when compared against existing dampers with two external control valves. Thus, existing dampers with one external control valve are limited in the range of damping forces provided during the compression stroke. 
     Comparing  FIGS.  21  and  22    reveals that the upper limit  183  of the compression region  188  is greater in magnitude for the dampers  32  described herein (and shown in  FIG.  21   ) compared to existing dampers with one external control valve (and shown in  FIG.  22   ). Comparing  FIGS.  21  and  23    reveals that the upper limit  183  of the compression region  188  has almost the same magnitude of the dampers  32  described herein (and shown in  FIG.  21   ) compared to existing dampers with two external control valves (and shown in  FIG.  23   ). 
     Therefore, the dampers  32  of the present disclosure allow for an increased range of damping force provided during the compression stroke compared to existing dampers with one external control valve. The range of damping force provided during the compression stroke of the dampers  32  of the present disclosure is shown to be similar to the results attained by existing dampers having two external control valves. In other words, the disclosed designs, which use just one external control valve  162 , can provide similar damping force ranges as existing dampers with two external control valves. Thus, the dampers  32  of the present disclosure, which use just one external control valve  162 , can be tuned for a greater range of vehicle application without the extra cost and complexity of a second external control valve. 
     While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed dampers without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.