Patent Publication Number: US-2023146639-A1

Title: Damping force controlling shock absorber

Description:
TECHNICAL FIELD 
     The present disclosure relates to a shock absorber, in more detail, a damping force controlling shock absorber of which a damping force characteristic can be appropriately adjusted. 
     BACKGROUND 
     As a vehicle is popularized, the level of knowledge and demand of consumers for a vehicle are gradually increasing. Not only the use, convenience, and economics of a vehicle, but also functional performance such as the power, comfort, riding comfort, and steering stability are considered as important factors for selection of consumers who purchase vehicles. 
     A vehicle continuously receives vibration or shock from a road surface through wheels during driving. When vibration or shock that is transmitted through wheels is intactly transmitted to the car body and the steering wheel, riding comfort and driving stability are considerably deteriorated. Accordingly, vehicles have to be necessarily equipped with a suspension. A shock absorber, a spring, a suspension arm, etc. are main components that constitute a suspension. 
     A shock absorber is composed of a cylinder, a piston rod, a piston valve, etc. The piston valve is coupled to the piston rod and disposed in the cylinder, and generates a damping force. 
     A shock absorber has a characteristic that when the damping force is set at a low level, it can improve riding comfort by absorbing vibration due to unevenness of a road surface, whereas when the damping force is set at a high level, posture variation of a car body is suppressed, so steering stability is improved. Accordingly, it was general in the related art that shock absorbers in which different damping force characteristics are set are selectively used, depending on the purpose of use of vehicles. 
     Recently, a damping force controlling shock absorber that can appropriately adjust a damping force characteristic in accordance with the state of a road surface, a driving state, etc. by being equipped with damping force-variable valve that can appropriately adjust a damping force characteristic of a shock absorber has been developed. 
     For example, a damping force controlling shock absorber having a dual solenoid valve structure including a rebound solenoid valve for adjusting a damping force in a rebound stroke and a compression solenoid valve for adjusting a damping force in a compression stroke has been developed. 
     The inside of a cylinder included in a shock absorber is divided into a compression chamber and a rebound chamber by a piston valve, and these chambers are each filled with fluid, such as oil. 
     The piston valve presses the liquid in the compression chamber in the compression stroke, whereby the pressure of the compression chamber is increased and the pressure of the rebound chamber is relatively decreased. The piston valve presses the liquid in the rebound chamber in the rebound stroke, whereby the pressure of the rebound chamber is increased and the pressure of the compression chamber is relatively decreased. 
     The operation structure of the damping force controlling shock absorber having a dual solenoid valve structure in the related art is described. 
     In the compression stroke, the fluid in the compression chamber moves to a reservoir chamber through the compression solenoid valve and a portion of the fluid moves to the rebound chamber through a bypass channel of the piston valve. 
     In the rebound stroke, the fluid in the rebound chamber moves to the reservoir chamber through the rebound solenoid valve and a portion of the fluid moves to the compression chamber through the bypass channel of the piston valve. 
     According to the damping force controlling shock absorber having this operation structure in the related art, when a portion of the fluid in the compression chamber is sent to the rebound chamber through the bypass channel of the piston valve in the compression stroke, the channel of the rebound solenoid valve connected to the reservoir chamber at a low pressure relatively to the rebound chamber is opened. Accordingly, there is a problem that the damping force that is generated in the compression stroke depends on the rebound solenoid valve, so independence of the compression solenoid valve is deteriorated. 
     Meanwhile, when the amount of fluid that moves to the rebound chamber in the compression stroke is small, the amount of fluid in the rebound chamber may become insufficient and a lag may be generated when the compression stroke is changed into the rebound stroke. This phenomenon may depend on the kind of the valve that opens/closes the bypass channel in the piston valve. 
     For example, a compression stroke may be set into a hard mode to overcome a handling characteristic, and to this end, a shutoff valve of a bypass channel may be configured in a sandwich type having a disc stack structure. In this case, the amount of fluid that is sent is unavoidably small in comparison to the shutoff valve having a lifting structure. 
     As described above, when a lag is generated, a damping force is unavoidably decreased, but there is an alternative measure for preventing a lag in the damping force controlling shock absorber of the related art. 
     PRIOR ART DOCUMENT 
     
         
         
           
             (Patent Document 001) Korean Patent No. 10-0842031 (published on 2008 Jun. 27) 
           
         
       
    
     SUMMARY 
     The present disclosure has been made in an effort to solve the problems of the related art described above and an objective of the present disclosure is to provide a damping force controlling shock absorber that can prevent reduction of a damping force by improving operational independence of a compression solenoid valve and a rebound solenoid valve. 
     Another objective of the present disclosure is to provide a damping force controlling shock absorber that can prevent a lag when a rebound stroke is entered by preventing the amount of fluid in a rebound chamber from becoming insufficient in a compression stroke. 
     In order to achieve the objectives, a damping force controlling shock absorber according to a preferred embodiment of the present disclosure includes: a cylinder formed in a double structure of an inside and an outside, having an internal space divided into a compression chamber and a rebound chamber by a piston valve, and having a reservoir chamber in an external space; a compression solenoid valve mounted on the cylinder; a rebound solenoid valve mounted on the cylinder; and a check valve disposed in the rebound solenoid valve, and opening and closing a channel connecting the reservoir chamber and the rebound chamber. 
     The damping force controlling shock absorber according to a preferred embodiment of the present disclosure further includes post member mounted outside the cylinder, and fixing and supporting the solenoid valves with a gap therebetween. 
     A communicating hole connecting the solenoid valves is formed in the post member. 
     The rebound solenoid valve has a rebound port that is connected to the rebound chamber and through which fluid flows inside and outside, and the channel connecting the reservoir chamber and the rebound chamber is formed in the rebound port. 
     The check valve is disposed in the channel. 
     The check valve includes: a shutoff member opening and closing the channel; and an elastic member elastically supporting the shutoff member. 
     The check valve allows for flow of fluid from the reservoir chamber to the rebound chamber and prevents flow of fluid in the opposite direction. 
     The check valve is opened in a compression stroke and is closed in a rebound stroke. 
     The rebound solenoid valve includes: a rebound valve housing that forms an external appearance of the valve and in which fluid in the rebound chamber flows and circulates in the rebound stroke; and the rebound port disposed at an inlet of the rebound valve housing, and the check valve is installed between the rebound port and the rebound valve housing. 
     The rebound port includes: a rebound body formed in a hollow pipe shape and connected to the rebound chamber at a first end; a rebound flange extending outward from a second end of the rebound body and having a rebound hole connected to the reservoir chamber; and an annular protrusion protruding toward the rebound valve housing from the rebound flange, having the channel therein, and forming a space in which the check valve is installed, and the channel is connected to the reservoir chamber, the rebound hole, the internal space of the protrusion, the inside of the rebound body, and the rebound chamber. 
     The shutoff member of the check valve is configured to open and close an upper end of the rebound hole in the check valve installation space, and the elastic member elastically supports the shutoff member with respect to the rebound valve housing in the check valve installation space. 
     Fluid in the reservoir chamber flows inside through a lower end of the rebound hole and pushes the shutoff member, so the rebound hole is opened in the compression stroke. 
     The shutoff member is an annular disc and a seat surface on which the shutoff member is seated in a close contact state is formed on the rebound flange. 
     The elastic member includes: an annular fixed portion fixed to the rebound valve housing; a plurality of elastic supporting portions formed to be inclined from the fixed portion toward the shutoff member, radially formed from a center of the fixed portion, and elastically supporting the shutoff member; and contact portions bending from ends of the elastic supporting members to be in contact with the shutoff member. 
     The post member includes: a hollow first fixing part in which the compression solenoid valve is inserted and fixed; a hollow second fixing part in which the rebound solenoid valve is inserted and fixed; and a connection part that connects the first and second fixing parts and has the communicating hole. 
     The compression solenoid valve controls a damping force by controlling flow of fluid that is sent from the compression chamber to the reservoir chamber in a compression stroke. 
     A portion of fluid in the rebound chamber is sent to the compression chamber through the rebound solenoid valve, the post member, and the compression solenoid valve in a rebound stroke. 
     A damping force controlling shock absorber according to a preferred embodiment of the present disclosure includes: a cylinder formed in a double structure of an inside and an outside, having an internal space divided into a compression chamber and a rebound chamber by a piston valve, and having a reservoir chamber in an external space; a compression solenoid valve mounted on the cylinder; a rebound solenoid valve mounted on the cylinder; and a check valve disposed in the rebound solenoid valve, and opening and closing a channel connecting the reservoir chamber and the rebound chamber, wherein, in a compression stroke, a portion of fluid in the compression chamber is sent to the reservoir chamber through the compression solenoid valve, and a portion of fluid in the reservoir chamber is sent to the rebound chamber through the channel due to opening of the check valve, and a portion of fluid in the rebound chamber is sent to the compression chamber through the rebound solenoid valve and the compression solenoid valve in a rebound stroke. 
     According to a damping force controlling shock absorber of the present disclosure, the following effects can be expected. 
     First, the fluid discharged from the rebound solenoid valve flows into the high-pressure compression chamber rather than the low-pressure reservoir chamber in the rebound stroke, so it is possible to improve operational independence of the compression solenoid valve and the rebound solenoid valve. Accordingly, it is possible to prevent reduction of a damping force which may occur due to cooperative operation of the solenoid valves. 
     Further, since the fluid in the reservoir chamber flows into the rebound chamber through the check valve in the compression stroke, it is possible to prevent a shortage of the fluid in the rebound chamber in the compression stroke. Accordingly, it is possible to prevent reduction of a damping force due to a lag when the compression chamber is changed into the rebound chamber. 
     Through these technological characteristics, when the rebound stroke is a soft mode, a soft mode and a hard mode both can be applied to the compression stroke, so it is possible to satisfy various wants of consumers. In particular, even though a hard mode is applied to the compression stroke to maximize a handling characteristic, stable driving is possible without reduction of a damping force due to a lag. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a view showing the external appearance of a damping force controlling shock absorber according to a preferred embodiment of the present disclosure. 
         FIG.  2    is a cross-sectional view of the damping force controlling shock absorber according to a preferred embodiment of the present disclosure. 
         FIG.  3    is an enlarged cross-sectional view of the part of a solenoid valve shown in  FIG.  2   . 
         FIG.  4    is an enlarged view of the part of a post member shown in  FIG.  1   . 
         FIG.  5    is a cross-sectional view of the post member shown in  FIG.  4   . 
         FIG.  6    is a cross-sectional view of a compression valve housing shown in  FIG.  3   . 
         FIG.  7    is a cross-sectional view of a compression port shown in  FIG.  3   . 
         FIG.  8    is a cross-sectional view of a rebound valve housing shown in  FIG.  3   . 
         FIG.  9    is a cross-sectional view of a rebound port shown in  FIG.  3   . 
         FIG.  10    is an enlarged cross-sectional view of an installation state of a check valve shown in  FIG.  3   . 
         FIG.  11    is a perspective view of a shutoff member and an elastic member constituting the check valve. 
         FIG.  12    is a cross-sectional view showing flow of fluid in a compression stroke. 
         FIG.  13    is a cross-sectional view showing flow of fluid in a rebound stroke. 
         FIG.  14    is a cross-sectional view showing flow of fluid through the check valve in the compression stroke. 
         FIG.  15    is a cross-sectional view showing a closed state of the check valve in the rebound stroke. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a damping force controlling shock absorber according to a preferred embodiment of the present disclosure is described in detail with reference to the accompanying drawings. 
     In the accompanying drawings,  FIG.  1    is a view showing the external appearance of a damping force controlling shock absorber according to a preferred embodiment of the present disclosure, and  FIG.  2    is a cross-sectional view of the damping force controlling shock absorber according to a preferred embodiment of the present disclosure. 
     A damping force controlling shock absorber according to a preferred embodiment of the present disclosure includes a cylinder  10 , a piston valve  20 , a piston rod  30 , a body valve  40 , a rod guide  50 , an upper cap  60 , a lower cap  70 , solenoid valves  80  and  90 , and a post member  100 . 
     The cylinder  100  has a double structure, in which an inner tube  12  is installed in a base shell  11  with a gap therebetween, and is filled with fluid. The piston valve  20  slides into the inner tube  12  and the internal space of the inner tube  12  is divided into a compression chamber  13  and a rebound chamber  14  by the piston valve  20 . Between the base shell  11  and the inner tube  12 , a compression separator tube  15  and a rebound separator tube  16  are mounted on the outer surface of the inner tube  12  with a gap therebetween. The compression separator tube  15  and the rebound separator tube  16  form intermediate chambers connected to the compression chamber  13  and the rebound chamber  14 , respectively, between the inner tube  12  and the compression separator tube  15  and the rebound separator tube  16 . 
     The compression chamber  13  is formed at the lower portion of the cylinder  10  and the rebound chamber  14  is formed at the upper portion of the cylinder  10 . In correspondence to this configuration, the compression separator tube  15  are mounted at the lower portion of the inner tube  12  and the rebound separator tube  16  is mounted at the upper portion of the inner tube  12 . Connection holes  12   a  and  12   b  connecting the intermediate chambers to the compression chamber  13  and the rebound chamber  14 , respectively, are formed at the lower portion and the upper portion of the inner tube  12 , respectively. 
     A reservoir chamber  17  that compensates for variation of the internal volumes of the compression chamber  13  and the rebound chamber  14  when the piston valve  20  reciprocates is formed in the space between the base shell  11  and the inner tube  12  except for the intermediate chambers. 
     The piston valve  20  presses the fluid in the compression chamber  13  and the rebound chamber  14  while reciprocating in the internal space of the inner tube  12 . A bypass channel for enabling fluid to flow between the compression chamber  13  and the rebound chamber  14  in a compression stroke and a rebound stroke is formed in the piston valve  20 , and a shutoff valve is disposed in the bypass channel. 
     The piston rod  30  slidably passes through the rod guide  50  closing the upper end of the cylinder  10 . The piston valve  20  is mounted at the lower end of the piston rod  30  and the upper end of the piston rod  30  is fixed to a car body. 
     The body valve  40  is installed at the lower end of the inner tube  12  and separates the compression chamber  13  and the reservoir chamber  17 . A channel enabling fluid to flow between the two chambers  13  and  17  is formed in the body valve  40 . 
     The rod guide  50  closes the upper end of the cylinder  10  and a guide hole that guides up-down movement of the piston rod  30  is formed through the center of the rod guide  50 . 
     Meanwhile, an upper cap  60  and a lower cap  70  that cover the upper end and the lower end of the cylinder  10 , respectively, are mounted on the upper end and the lower end of the cylinder  10 , respectively. The upper cap  60  is mounted outside the upper end portion of the base shell  11  in the type of surrounding the upper end portion of the base shell  11  and the lower cap  70  is mounted inside the lower end portion of the base shell  11  in the type of surrounding the body valve  40 . 
     The solenoid valves  80  and  90 , which are mounted on the cylinder  10  through the post member  100 , are composed of a compression solenoid valve  80  variably controlling a damping force in the compression stroke and a rebound solenoid valve  90  variably controlling a damping force in the rebound stroke. 
     The post member  100  is mounted outside the cylinder  10 , thereby fixing and supporting the solenoid valves  80  and  90  with a gap therebetween. 
     In the accompanying drawings,  FIG.  3    is an enlarged cross-sectional view of the part of a solenoid valve shown in  FIG.  2   ,  FIG.  4    is an enlarged view of a post member shown in  FIG.  1   ,  FIG.  5    is a cross-sectional view of the post member shown in  FIG.  4   ,  FIG.  6    is a cross-sectional view of a compression valve housing shown in  FIG.  3   ,  FIG.  7    is a cross-sectional view of a compression port shown in  FIG.  3   ,  FIG.  8    is a cross-sectional view of a rebound valve housing shown in  FIG.  3   ,  FIG.  9    is a cross-sectional view of a rebound port shown in  FIG.  3   , and  FIG.  10    is an enlarged cross-sectional view of an installation state of a check valve shown in  FIG.  3   . 
     Herein, the post member  100  is described first, and the solenoid valves  80  and  90  and a check valve  93  to be described below are described later. 
     The post member  100  includes a hollow first fixing part  101  in which the compression solenoid valve  80  is inserted and fixed, a hollow second fixing part  102  that is spaced apart from the first fixing part  101  and in which the rebound solenoid valve  90  is inserted and fixed, and a connection part  103  that connects the first and second fixing parts  101  and  102 . A communicating hole  103   a  that directly connects the compression solenoid valve  80  and the rebound solenoid valve  90  by connecting the internal spaces of the first and second fixing parts  101  and  102  is formed in the connection part  103 . 
     A first accommodation space  101   a  in which the compression solenoid valve  80  is inserted and fixed is formed in the first fixing part  101 . A compression port  82  to be described below of the compression solenoid valve  80  is connected to a compression separator tube  15  through the lower end of the first fixing part  101 . 
     A second accommodation space  102   a  in which the rebound solenoid valve  90  is inserted and fixed is formed in the second fixing part  102 . A rebound port  92  to be described below of the rebound solenoid valve  90  is connected to a rebound separator tube  16  through the lower end of the second fixing part  102 . 
     The communicating hole  103   a  formed in the connection part  103  includes one or more communicating holes so that fluid that is discharged from the rebound solenoid valve  90  can be sufficiently guided to the compression solenoid valve  80 . The communicating hole  103   a  is formed parallel with the center axis of the bypass shell  11 . 
     The compression solenoid valve  80  includes a compression valve housing  81  and a compression port  82 . The compression valve housing  81  forms the external appearance of the valve and is inserted and fixed in the first fixing part  101  of the post member  100 . A damping force is variably controlled by adjusting a electric current that is applied to the valve while fluid flows through the compression valve housing  81 . The compression port  82 , which is disposed at the inlet of the compression valve housing  81  and at which fluid flows inside and outside, is inserted and fixed in the first fixing part  101  of the post member  100 . 
     In the compression stroke, a portion of the fluid in the compression chamber  13  is guided toward the compression valve housing  81  through the compression port  82  and is discharged to the reservoir chamber  17  after circulating in the compression solenoid valve  80 . The compression solenoid valve  80  has an anti-backflow structure to prevent backflow to the compression chamber  13  in this process. 
     A first compression hole  81   a  for discharging fluid, which circulates in the compression solenoid valve  80 , toward the reservoir chamber  17  is formed in the side of the compression valve housing  81 . 
     The compression port  82  includes a hollow compression body  821  connected at a first end to the compression separator tube  15 , and a compression flange  822  extending outward from a second end of the compression body  821  in a direction that perpendicularly crossing the center line of the compression body  821 . 
     The second end of the compression body  821  is in close contact with the compression valve housing  81  in a surface contact type. Accordingly, in the compression stroke, fluid that flows inside through the first end of the compression body  821  can be guided into the compression valve housing  81  without leaking to the outside. 
     A plurality of second compression holes  822   a  for guiding fluid, which has circulated in the compression solenoid valve  80 , to the reservoir chamber  17  is formed parallel with and around the center hole in the compression body  821 . 
     A plurality of third compression holes  822   b  connected to the post member  100  is formed in the compression flange  822  to perpendicularly communicate with the center hole in the compression body  821 . 
     The second compression holes  822   a  and the third compression holes  822   b  are spaced apart from each other without communicating with each other. The third compression holes  822   b  are formed between the second compression holes  822   a.    
     The rebound solenoid valve  90  includes a rebound valve housing  91 , a rebound port  92 , and a check valve  93 . The rebound valve housing  91  forms the external appearance of the valve and is inserted and fixed in the second fixing part  101  of the post member  102 . A damping force is variably controlled by adjusting a electric current that is applied to the valve while fluid flows through the rebound valve housing  91 . The rebound port  92 , which is disposed at the inlet of the rebound valve housing  91  and at which fluid flows inside and outside, is inserted and fixed in the second fixing part  102  of the post member  100 . The check valve  93  is installed between the rebound valve housing  91  and the rebound port  92 . 
     In the rebound stroke, a portion of the fluid in the rebound chamber  14  flows inside through the rebound port  92 , is guided toward the rebound valve housing  92 , and is then discharged after circulating in the rebound solenoid valve  90 . The rebound solenoid valve  90  has an anti-backflow structure to prevent backflow to the rebound chamber  14  in this process. 
     A plurality of first rebound holes  91   a  for discharging fluid, which has passed through the rebound solenoid valve  90 , is formed in the side of the rebound valve housing  91 . Fluid that is discharged through the first rebound hole  91   a  is sent to the communicating hole  103   a  of the connection part  103  through between the rebound valve housing  91  and the inner surface of the second fixing part  102  constituting the post member  100 . 
     The rebound port  92  has a hollow rebound body  921  connected at a first end of a separator tube  16 , a rebound flange  922  extending outward from second end of the rebound body  921  in a direction perpendicular to the center line of the rebound body  921 , and an annular protrusion  923  protruding toward the rebound valve housing  91  from a surface of the rebound flange  922  in close contact with the rebound valve housing  91 . A fluid movement passage and an installation space of the check valve  93  are formed inside the protrusion  923 . 
     A plurality of second rebound holes  922   a  connecting an internal space  923   a  formed by the protrusion  923  and the reservoir chamber  17  to each other is formed in the rebound flange  922 . The second rebound holes  922   a  is formed parallel with and around the center hole of the rebound body  921 . 
     The check valve  93  opens/closes a channel such that a portion of the fluid in the reservoir chamber  17  flows into the rebound chamber  14  through the rebound solenoid valve  90  in the compression stroke. The check valve  93  is opened only in the compression stroke and is closed in the rebound stroke. 
     The flow path of fluid through the check valve  93  is connected to the reservoir chamber  17 , the second rebound holes  922   a  of the rebound flange  922 , the internal space  923   a  surrounded by the protrusion  923 , the center hole of the rebound body  921 , the intermediate chamber formed by the rebound separator tube  16 , and the rebound chamber  14 . 
     The check valve  93  includes a shutoff member  931  that opens/closes a channel, and an elastic member  932  that elastically supports the shutoff member  931 . The shutoff member  931  opens/closes the upper ends of the second rebound holes  922   a  in the internal space  932   a  surrounded by the protrusion  923 . The elastic member  932  is disposed between the shutoff member  931  and the rebound valve housing  91  in the internal space  923   a  and elastically supports the shutoff member  931  with respect to the rebound valve housing  91 . 
     In the accompanying drawings,  FIG.  11    is a perspective view of a shutoff member and an elastic member constituting the check valve. 
     The shutoff member  931 , which is an annular disc, is disposed in the internal space  932   a  of the protrusion  923  constituting the rebound port  92 . A seat surface on which the shutoff member  931  is seated in a close contact state is formed on the rebound flange  922 . The shutoff member  931  opens/closes the upper ends of the second rebound holes  922   a  in the internal space  932   a  of the protrusion  923 . The shutoff member  931  is operated in a lifting type in which it is entirely lifted from the upper ends of the second rebound holes  922   a , that is, the seat surface of the rebound flange  922  when it is opened. 
     The elastic member  932  includes an annular fixed portion  932   a  fixed to the rebound valve housing  91 , a plurality of elastic supporting portions  932   b  formed to be inclined from the fixed portion  932   a  toward the shutoff member  931 , radially formed from the center of the fixed portion  932   a , and elastically supporting the shutoff member  931 , and contact portions  932   c  bending from ends of the elastic supporting portions  932   b  to come in surface contact with the shutoff member  931 . 
     Meanwhile, in the rebound stroke, fluid flowing inside through the rebound port  92  from the rebound chamber  14  is sent into the rebound valve housing  91  after passing through between the plurality of elastic supporting portions  932   b . In this process, the check valve  93  is maintained in a closed state without opening. 
     In the accompanying drawings,  FIG.  12    is a cross-sectional view showing flow of fluid in a compression stroke. 
     As shown in the figure, the fluid in the compression chamber  13  is compressed in the stroke in which the piston valve  20  moves down, that is, in the compression stroke. Accordingly, the inside of the compression chamber  13  becomes a high pressure state and the inside of the rebound chamber  14  becomes a low pressure state. 
     As the piston valve  20  moves down, a portion of the fluid in the compression chamber  13  flows into the rebound chamber  14  through the bypass channel formed in the piston valve  20 , thereby generating a damping force. 
     Further, a portion of the fluid in the compression chamber  13  is sent to the intermediate chamber in the compression separator tube  15  through the connection hole  12   a  formed at the lower portion of the inner tube  12 , and is then guided to the compression solenoid valve  80  through the compression port  82  and circulates in the compression solenoid valve  80 . When the fluid circulates in the compression solenoid valve  80 , a damping force is variably controlled by changing the electric current that is applied to the compression solenoid valve  80 . 
     The fluid that has passed through the compression solenoid valve  80  is discharged to the reservoir chamber  17  through the first compression hole  81   a  of the compression valve housing  81  and the second compression hole  822   a  of the compression port  82 . 
     In the accompanying drawings,  FIG.  13    is a cross-sectional view showing flow of fluid in a rebound stroke. 
     As shown in the figure, the fluid in the compression chamber  14  is compressed in the stroke in which the piston valve  20  moves up, that is, in the rebound stroke. Accordingly, the inside of the rebound chamber  14  becomes a high pressure state and the inside of the compression chamber  13  becomes a low pressure state. 
     As the piston valve  20  moves up, a portion of the fluid in the rebound chamber  14  flows into the compression chamber  13  through the bypass channel formed in the piston valve  20 , thereby generating a damping force. 
     Further, a portion of the fluid in the rebound chamber  14  is sent to the intermediate chamber in the rebound separator tube  16  through the connection hole  12   b  formed at the upper portion of the inner tube  12 , and is then guided to the rebound solenoid valve  90  through the rebound port  92  and circulates in the rebound solenoid valve  90 . When the fluid circulates in the rebound solenoid valve  90 , a damping force is variably controlled by changing the current that is applied to the rebound solenoid valve  90 . 
     The fluid that has passed through the rebound solenoid valve  90  flows through the first rebound hole  91   a  of the rebound valve housing  91 , between the rebound valve housing  91  and the post member  100 , the communicating hole  103   a  of the connection part  103 , the third compression hole  822   b  of the compression port  82 , and the compression port  82 , and then flows into the compression chamber  13 . 
     In the accompanying drawings,  FIG.  14    is a cross-sectional view showing flow of fluid through the check valve in the compression stroke, and  FIG.  15    is a cross-sectional view showing a closed state of the check valve in the rebound stroke. 
     As described above, when the piston valve  20  moves down in the compression stroke, the fluid in the compression chamber  13  is compressed, the inside of the compression chamber  13  increases in pressure, and a portion of the compression chamber  13  flows into the rebound chamber  14  through the bypass channel formed in the piston valve  20 , whereby a damping force is generated. 
     In the compression stroke, when the fluid in the rebound chamber  14  is insufficient, a lag may be generated when the compression stroke changes into the rebound stroke. Accordingly, according to the damping force controlling shock absorber of the present disclosure, in order to prevent a lag, the fluid in the reservoir chamber  17  is sent into the rebound chamber  14  through the rebound solenoid valve  90  in the compression stroke. 
     When the high-pressure fluid in the compression chamber  13  flows into the reservoir chamber  17  through the compression solenoid valve  80  in the compression stroke, the fluid pressure in the reservoir chamber  17  is also increased. As described above, the pressure in the rebound chamber  14  decreases in the compression stroke. 
     Accordingly, in the compression stroke, as shown in  FIG.  14   , a portion of the fluid in the reservoir chamber  17  flows inside through the lower ends of the second rebound holes  922   a  formed in the rebound flange  922  and flows into the internal space  923   a  of the protrusion  923  while pushing up the shutoff member  931 . That is, in the compression stroke, the pressure of the fluid flowing inside through the second rebound holes  922   a  is larger than the pressing force of the elastic member  932  of the check valve  93 , so the check valve  93  is opened. 
     The fluid flowing in the internal space  923   a  of the protrusion  923  flows into the rebound chamber  14  through the center hole of the rebound body  921 , the intermediate chamber formed by the rebound separator tube  16 , and the connection hole  12   b  formed at the upper portion of the inner tube  12 . 
     Meanwhile, as described above, in the rebound stroke, the pressure of the inside of the rebound chamber  14  is increased and the pressure of the inside of the compression chamber  13  is decreased. Accordingly, the internal space of the rebound port  92  connected to the rebound chamber  14  is also increased. 
     Accordingly, since the fluid pressure in the rebound chamber  14  is increased and the fluid pressure in the reservoir chamber  17  is relatively decreased in the rebound stroke, as shown in  FIG.  15   , the shutoff member  931  closes the upper ends of the second rebound holes  922   a  while being pressed by the pressing force of the elastic member  932 . Therefore, fluid is prevented from flowing into the rebound port  92  from the reservoir chamber  17 . 
     Although the damping force controlling shock absorber according to a preferred embodiment of the present disclosure was described above with reference to the accompanying drawings, the present disclosure is not limited to the embodiment described above and may be modified in various ways within the claims. 
     
       
         
           
               
             
               
                   
               
               
                 [Detailed Description of Main Elements] 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 10: Cylinder 
                 11: base shell 
               
               
                 12: inner tube 
                 13: compression chamber 
               
               
                 14: rebound chamber 
                 15: compression separator tube 
               
               
                 16: rebound separator tube 
                 17: reservoir chamber 
               
               
                 20: piston valve 
                 30: piston rod 
               
               
                 40: body valve 
                 50: rod guide 
               
               
                 60: upper cap 
                 70: lower cap 
               
               
                 80: compression solenoid valve 
                 81: compression valve housing 
               
               
                 82: compression port 
                 90: rebound solenoid valve 
               
               
                 91: rebound valve housing 
                 92: rebound port 
               
               
                 93: check valve 
                 100: post member 
               
               
                 101: first fixed portion 
                 102: second fixed portion 
               
               
                 103: connection part