Patent Publication Number: US-2009236194-A1

Title: Valve apparatus of shock absorber

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a valve apparatus mounted to a shock absorber to generate a damping force and, more particularly, to a valve apparatus of a shock absorber that improves an installation structure of discs on a piston provided to generate a damping force. 
     2. Description of the Related Art 
     In general, a vehicle is provided with a suspension system for enhancing driving comfort by buffering impact or vibration transmitted from a road to an axle during driving. One component constituting the suspension system is a shock absorber. The shock absorber is disposed between the axle and a vehicle body, and includes a cylinder and a piston rod reciprocating in the cylinder. The cylinder is filled with an operating fluid such as gas or oil, which is moved by a piston valve secured to one end of the piston rod to generate a damping force. 
       FIG. 1  is a cross-sectional view of a valve apparatus of a conventional shock absorber. Referring to  FIG. 1 , the shock absorber  10  includes a cylinder  12  connected to a wheel side, and a piston rod  14  with one end thereof movably disposed in the cylinder  12  and the other end connected to a vehicle body. 
     The piston rod  14  is provided at one end thereof with a valve apparatus  20  which controls a damping force between a compression chamber CC and a rebound chamber RC in the cylinder  12 . 
     The valve apparatus  20  includes a piston valve  22  provided toward the end of the piston rod  14  to divide an interior space of the cylinder  12  into the compression chamber CC and the rebound chamber RC. The piston valve  22  is formed with rebound passages  22   a  and compression passages  22   b  through which a fluid can flow between the compression chamber CC and the rebound chamber RC. 
     Further, an intake valve disc  23  for opening the compression passages  22   a  during a compression stroke, a retainer  24 , an intake spring  25 , and an upper washer  26  are sequentially stacked on the piston valve  22 . Further, a valve disc  27  is provided toward a lower side of the piston valve  22  to generate different damping forces by controlling an opening degree of the rebound passages  22   b  in low and high speed areas. Under the valve disc  27 , a retainer  28 , a lower washer  29 , and a nut  30  securing these components are provided in this order. Here, the number of valve discs  27  may be at least one. When plural valve discs  27  are provided for variation of damping force characteristics, the valve discs may have different shapes or some of the valve discs may be formed with slits. 
     In the valve apparatus  20  of the conventional shock absorber  10 , the valve disc  27  must have a large outer diameter in order to allow the damping force characteristics to be gradually generated at high speed. However, there is restriction in increasing the outer diameter of the valve disc  27  due to restriction in size of the piston valve  22 . Moreover, since the size of the piston valve  22  is decreased according to a recent trend of decreasing the size of the shock absorber  10 , it is necessary to decrease the outer diameter of the valve disc  27  which controls the opening degree of the rebound passages  22   b . However, when decreasing the outer diameter of the valve disc  27 , there is a problem in that the damping force characteristics cannot be easily controlled at low speeds. 
     BRIEF SUMMARY 
     The present disclosure is directed to solve the problems of the related art as described above, and one embodiment includes providing a valve apparatus of a shock absorber, in which a valve disc controlling an opening degree of rebound passages has an increased size to permit easy control of a damping force at various speeds, including low speeds, and a gradual increase of the damping force even at high speed while enabling a size decrease of the shock absorber. 
     In accordance with one aspect, a valve apparatus of a shock absorber is provided to a piston rod of the shock absorber and generates a damping force by controlling a fluid flow between a rebound chamber and a compression chamber. The valve apparatus includes a piston valve having rebound passages and compression passages allowing a fluid flow between the rebound chamber and the compression chamber, a sliding valve movably coupled to the piston rod under the piston valve configured to block and open the rebound passages, and at least one valve disc provided at a lower side of the sliding valve and separated a predetermined distance from a washer by a retainer, the washer being coupled to a lower side of the retainer, the valve disc being capable of bending while resiliently supporting an outer periphery of the sliding valve. 
     The sliding valve may be formed toward an upper side thereof with at least one slit allowing the fluid flow between the rebound passages and the compression chamber. The valve apparatus may further include a slit disc disposed on the upper side of the sliding valve and having a slit formed on a circumference of the slit disc to allow the fluid flow between the rebound passages and the compression chamber. Further, a lower side of the sliding valve may extend outside the piston valve and may be formed at an end thereof with a stepped portion having a gradually increasing outer diameter. The valve apparatus may further include a guide bush interposed between the sliding valve and the piston rod to guide upward and downward movement of the sliding valve. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The above and other aspects, features, and advantages of the present invention will become apparent from the following description of exemplary embodiments given in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a cross-sectional view of a valve apparatus of a conventional shock absorber; 
         FIG. 2  is a partial cross-sectional view of a shock absorber according to one embodiment; 
         FIG. 3  is a cross-sectional view of a valve apparatus of a shock absorber according to one embodiment; 
         FIG. 4  is a cross-sectional view of the valve apparatus of the shock absorber during low speed driving according to one embodiment; 
         FIG. 5  is a cross-sectional view of the valve apparatus of the shock absorber during high speed driving according to one embodiment; 
         FIG. 6  is a cross-sectional view of a valve apparatus of a shock absorber according to another embodiment; and 
         FIG. 7  is a cross-sectional view of a valve apparatus of a shock absorber according to a further embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments, namely examples of embodiments, will now be described in detail with reference to the accompanying drawings. 
       FIG. 2  is a cross-sectional view of a shock absorber according to one embodiment of the present invention, and  FIG. 3  is a cross-sectional view of a valve apparatus of a shock absorber according to one embodiment of the present invention. 
     In  FIGS. 2 and 3 , a shock absorber  50  according to one embodiment includes a cylinder  52  connected to a wheel side of the vehicle, and a piston rod  54  connected to a vehicle body side. The cylinder  52  may have a double-tube structure comprising an inner tube  52   a  and an outer tube  52   b,  or it may have a single-tube structure in another embodiment. 
     The piston rod  54  is disposed in the cylinder  52  to reciprocate therein, and includes a valve apparatus  60  which is coupled toward one end of the piston rod  54  and divides the interior of the cylinder  52  into a compression chamber CC and a rebound chamber RC. 
     Referring to  FIG. 3 , the valve apparatus  60  includes a piston valve  62  which has a through-hole formed at the center thereof such that the center of the piston valve  62  can be coupled to the piston rod  54 . The piston valve  62  has compression passages  62   a  formed apart from the center of the piston valve  62  and rebound passages  62   b  formed between the center of the piston valve  62  and the respective compression passages  62   a . The compression and rebound passages  62   a  and  62   b  are formed to allow a fluid flow between the compression chamber CC and the rebound chamber RC during compression and rebound strokes for lowering and raising the piston rod  54 . 
     Further, an intake valve disc  63 , a retainer  64 , an intake spring  65 , and an upper washer  66  are stacked on an upper side of the piston valve  62 . The intake valve disc  63  can be bent to rapidly open the compression passages  62   a  during the compression stroke of the piston valve  62 . Further, the piston valve  62  is provided at a lower side thereof with a valve structure for rebound to generate a damping force during the rebound stroke. 
     The valve structure for rebound will be described in more detail hereinafter. The valve apparatus  60  includes a sliding valve  80  disposed toward a lower side of the piston valve  62  configured to block and open the rebound passages  62   b . The sliding valve  80  is coupled to the piston rod  54  to reciprocate along the piston rod  54 . 
     Further, a valve disc  67  is provided under the sliding valve  80  and can be bent while resiliently supporting an outer periphery of the sliding valve  80 . In some embodiments, the valve apparatus  60  may include one or more valve discs  67 , which may have different sizes and shapes according to a resilient supporting force of the sliding valve  80 . 
     The valve apparatus  60  may further include a guide bush  85  interposed between the sliding valve  80  and the piston rod  54 . The guide bush  85  enables more smooth upward and downward movement of the sliding valve  80  on the piston rod  54  and provides a space for movement of the sliding valve  80 . Further, the guide bush  85  contacts an upper side of the valve disc  67  to restrict upward movement of the valve disc  67 , thereby enabling more accurate control of damping force. 
     The piston valve  62  is provided toward the upper and lower sides thereof with valve sheets to divide the compression passages  62   a  and the rebound passages  62   b  and to support the valve disc  67 , respectively. The sliding valve  80  has a protrusion which contacts the valve sheet. 
     Further, the sliding valve  80  is formed at an upper side thereof with a slit  82  which permits a fluid flow between the rebound passages  62   b  and the compression chamber CC. The slit  82  may be formed in the protrusion of the sliding valve  80 . 
     The slit  82  of the sliding valve  80  allows a fluid passing through the rebound chamber  62   b  to flow into the compression chamber CC, and, particularly, affects generation of the damping force in low speeds. 
     A retainer  68  is disposed under the valve disc  67  and maintains a predetermined distance between the valve disc  67  and a lower washer  69  located under the retainer  68 . The lower washer  69  restricts a bending degree of the valve disc  67 . Further, the retainer  68  provides a bending space for the valve disc  67 . The valve apparatus  60  is secured by a nut  70 , which is coupled to a lower side of the piston rod  54 . 
     Next, operation of the valve apparatus of the shock absorber according to one embodiment will be described. 
       FIG. 4  is a cross-sectional view of the valve apparatus  60  of the shock absorber  50  during low speed driving according to one embodiment, and  FIG. 5  is a cross-sectional view of the valve apparatus  60  of the shock absorber  50  during high speed driving according to one embodiment. 
     Referring to  FIG. 4 , when the piston valve  62  in the valve apparatus  60  of the shock absorber  50  moves at low speeds during a rebound stroke, a fluid passes through the rebound passages  62   b  and is discharged into the compression chamber CC through the slit  82  of the sliding valve  80 . At this time, while passing though the slit  82 , the fluid undergoes fluid resistance, which generates a damping force when the vehicle travels at low speeds. 
     Referring to  FIG. 5 , when a rebound speed of the shock absorber  50  is increased or pressure is increased thereby, the damping force generated by the valve apparatus  60  of the shock absorber  50  increases. At this time, the amount of fluid passing through the rebound passages  62   b  increases to cause a greater amount of fluid than the amount of fluid passing through the slit  82  to pass through the rebound passages  62   b . Then, the fluid compresses the sliding valve  80  to bend the valve disc  67  which resiliently supports the sliding valve  80 , thereby generating a damping force when driving at high speed. 
     As such, the valve apparatus  60  of the shock absorber  50  according to one embodiment has been described with reference to the drawings, but it should be noted that the present invention is not limited to the embodiment and various modification and changes can be made by a person having ordinary knowledge in the art without departing from the scope and spirit of the present invention defined by the accompanying claims. 
     For example, although the slit  82  is directly formed on the upper side of the sliding valve  80  in the above embodiment, a valve apparatus  160  according to another embodiment may include a slit disc  182  as shown in  FIG. 6 , instead of forming the slit on the upper side of the sliding valve  80 . 
     Referring to  FIG. 6 , which is a cross-sectional view of the valve apparatus according to another embodiment, the sliding disc  182  is located on the upper side of the sliding valve  80 , and is formed with at least one slit  182   a  which allows a fluid to flow between the rebound passages  62   b  and the compression chamber CC. 
     The slit disc  182  allows a fluid passing through the rebound chamber  62   b  to flow into the compression chamber CC through the slit  182   a  thereof during the rebound stroke, and, particularly, allows the fluid to generate a low speed damping force when passing through the slit  182   a  when driving at low speed. 
       FIG. 7  is a cross-sectional view of a valve apparatus of a shock absorber according to a further embodiment. Referring to  FIG. 7 , in a valve apparatus  260  according to this embodiment, a sliding valve  280  may have an increased lower outer diameter in order to increase an outer diameter of a valve disc  267 . 
     A lower side of the sliding valve  280  extends outside the piston valve  62  and is formed toward an end thereof with a stepped portion  281  which has a gradually increasing outer diameter. Therefore, the stepped portion  281  of the sliding valve  280  does not block the compression passages  62   a,  so that the outer diameter of the valve disc  267  can be increased. 
     As such, when the valve disc  267  has an increased outer diameter, the damping force characteristics can be more smoothly controlled at high speeds. Further, the shape, size and number of the valve discs  267  can be more freely adjusted to control the damping force characteristics. 
     As apparent from the above description, the valve apparatus of the shock absorber according to embodiments of this invention includes a valve disc which controls an opening degree of rebound passages and has an increased size, thereby permitting easy control of a damping force at low speed and a gradual increase of the damping force even at high speed while obtaining a size decrease of the shock absorber. Further, the valve apparatus of the shock absorber according to embodiments of this invention includes a sliding valve which controls an opening degree of rebound passages and has an increased outer diameter at a lower side thereof, so that the size of the valve disc resiliently supporting the sliding valve can be increased, thereby achieving gradual increase and decrease of damping force between high speed areas. 
     Although some exemplary embodiments have been described herein, it will be apparent to those skilled in the art that the embodiments are given by way of illustration, and that various modifications and changes can be made without departing from the spirit and scope of the present invention. Accordingly, the scope of the present invention should be limited only by the accompanying claims and equivalents thereof. 
     The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments. 
     These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.