以下，根據圖所示之實施方式，說明本發明。如圖1及圖2所示般，一個實施方式之緩衝器D，其構成具備：缸1；活塞2，可移動地插入缸1內以將缸1內區隔成填充有液體的伸側室R1和壓側室R2；活塞桿3，可移動地插入缸1內並且連結於活塞2；槽4，用於儲存液體；第1通路P1及第2通路P2，分別並列且將伸側室R1和壓側室R2連通；第3通路P3，將壓側室R2和槽4連通；伸側抑振閥5，設置於第1通路P1並對於從伸側室R1朝向壓側室R2的液體流動給予阻力；壓側止回閥6，設置於第2通路P2並僅容許從壓側室R2朝向伸側室R1的液體流動；以及閥單元V，可拆卸地設置於第3通路P3的途中。而且，此緩衝器D的情況下，介設於未圖示之車輛的車體和車輪之間來使用，並抑制車體及車輪的振動。
以下，針對緩衝器D的各部進行詳細說明。如圖1所示般，於缸1的圖1中下端的內周，從缸外側依序，在重疊有環狀的蓋10、環狀的密封構件8及環狀的桿導件7的狀態插入。桿導件7，藉由缸1的外周的緊固部1a在缸1內固定。而且，蓋10及密封構件8，在桿導件7和缸1的下端的緊固部1b之間被夾住，固定於缸1。此外，蓋10、密封構件8及桿導件7的固定於缸1的手段，可以任意地變更設計。
另外，在缸1的圖1中上端裝設殼體11，該殼體11係將缸1的上端閉塞而將缸1和槽4連結並且收容閥單元V。而且，於前端裝設活塞2的活塞桿3，可移動地插入缸1內。
活塞桿3滑動自如地插穿密封構件8的內周及桿導件7的內周且插入於缸1內，藉由桿導件7導引朝軸方向的移動。密封構件8是滑接於活塞桿3的外周且將活塞桿3的外周密封而將缸1內密閉。
另外，缸1內藉由活塞2，區隔成填充有液體的伸側室R1和壓側室R2。此外，液體，在本實施方式中，設定為液壓油，但液壓油以外，可以使用例如水、水溶液這類液體。
在活塞桿3的圖1中成為上端的前端，連結活塞2。另外，在活塞桿3的圖1中下端，安裝有可與保持未圖示的車輛之車輪的構件連結的支架B1，筒狀的凸緣緩衝墊14裝設在圖1中下端附近的外周。
若凸緣緩衝墊14在緩衝器D最收縮時與固定於缸1的下端內周的蓋10抵接壓縮，而發揮反彈力來緩和緩衝器D的最收縮時的衝撃。
在活塞2，設置分別並列且將伸側室R1和壓側室R2連通的第1通路P1及第2通路P2。並且，在活塞2，設置：伸側抑振閥5，可將第1通路P1開閉並對於從伸側室R1朝向壓側室R2的液體流動給予阻力；以及壓側止回閥6，可將第2通路P2開閉並僅容許從壓側室R2朝向伸側室R1的液體流動。此外，第1通路P1及第2通路P2，由於將伸側室R1和壓側室R2連通即可，因而也可設置於活塞2以外，例如，也可以在缸1的外周設置未圖示的外筒而利用缸1和外筒之間的間隙形成。此外，由於伸側抑振閥5設置於第1通路P1的話即可，壓側止回閥6設置於第2通路P2的話即可，因而將伸側抑振閥5和壓側止回閥6的設置部位依據第1通路P1和第2通路P2的設置態樣來決定的話即可。
伸側抑振閥5，只要是對於從伸側室R1朝向壓側室R2的液壓油流動給予阻力，在緩衝器D的伸長作動時可以發揮妨礙緩衝器D的伸長的抑振力之閥的話即可。此外，具體來說，伸側抑振閥5，例如，設定成將環狀板複數片積層於活塞2的圖1中上端所構成且藉由伸側室R1的壓力彎曲時將第1通路P1開放的疊片閥等的話即可。
另外，壓側止回閥6，只要是可以不給予太大阻力地容許在緩衝器D的收縮作動時僅對於從壓側室R2朝向伸側室R1的液壓油流動之閥的話即可。此外，具體來說，壓側止回閥6，例如，設定成由重疊於活塞2的圖1中下端的環狀板和將該環狀板緊壓的彈簧常數較小的彈簧所構成且藉由壓側室R2的壓力而將第2通路P2開放的閥等的話即可。
在本實施方式中，殼體11，具備：上部蓋11a，裝設於缸1的圖1中上端；中空的筒部11b，與上部蓋11a的側方連接且具有收容閥單元V的閥孔h；以及筒狀的套筒11c，與筒部11b的圖1中下端連接且將槽4予以保持。
另外，上部蓋11a結合於缸1的圖1中上端而將缸1的上端閉塞，並且於圖1中上方具備可連結於未圖示的車輛之車體的支架B2。
在本實施方式的緩衝器D中，如圖1及圖2所示般，筒部11b其中一端與上部蓋11a的側方成為一體沿水平方向延伸，在開口端的內周具備螺紋部11b1。而且，筒部11b內成為閥孔h，在閥孔h收容閥單元V。另外，筒部11b內，通過形成於上部蓋11a內的埠11a1而連通於缸1內的壓側室R2。此外，埠11a1通往閥孔h的最深部。
套筒11c呈環狀且上端為筒部11b的側部，在圖1中一體連接於下方，往垂直下方延伸，在下端外周具備螺紋部11c1。而且，筒狀的槽4螺接於套筒11c的下端外周的螺紋部11c1。
套筒11c內，經由朝筒部11b的側部開口的埠11b2而通往筒部11b內。閥孔h，最深部經由埠11a1而連通於壓側室R2，中間部經由埠11b2而連通於套筒11c內。
在本實施方式中，槽4呈圓筒狀且螺接於套筒11c。而且，在槽4內，插入隔膜12，槽4內藉由隔膜12區隔成填充有液體的液室L、以及填充有氣體的氣室G。此外，在氣室G，以在緩衝器D的最伸長時至少氣室G內的壓力成為大氣壓以上的方式封入氣體。此外，槽4內的液室L和氣室G的區劃，除了利用隔膜12以外，也可以利用自由活塞及氣囊等。
槽4之液室L，經由朝套筒11c內開口的埠11b2、閥孔h及埠11a1而連通於壓側室R2。如此般，在本實施方式的緩衝器D中，藉由埠11b2、閥孔h及埠11a1來形成第3通路P3。
如此般，殼體11將缸1和槽4連結，並具備：將壓側室R2和槽4連通的第3通路P3、以及在第3通路P3的途中收容閥單元V的閥孔h。而且，殼體11，具備在將缸1的上端閉塞的上部蓋11a的側方形成閥孔h的筒部11b，具備在筒部11b的下方安裝槽4的套筒11c。所以，將閥單元V配置於缸1的側方而可以抑制緩衝器D的全長變長。此外，閥孔h，藉由相對於缸1沿著徑向配置的筒部11b形成，並且由於開口端朝向反缸側，因而閥單元V的裝卸也容易從緩衝器D的側方進行。
接下來，閥單元V，被收容於形成殼體11之第3通路P3的局部的閥孔h內，設置於第3通路P3的途中。另外，閥單元V，可拆卸地收容於形成殼體11的閥孔h的筒部11b。閥單元V，具備：壓側抑振通路PV1、壓側釋壓通路PV2、吸入通路PV3及抑振力調整通路PV4，並列地連接於第3通路P3的途中；壓側抑振閥V1，設置於壓側抑振通路PV1且對於從壓側室R2朝向槽4的液體流動給予阻力；壓側釋壓閥V2，設置於壓側釋壓通路PV2且並列配置於壓側抑振閥V1，在閉閥時阻斷壓側室R2和槽4的連通，並且當壓側室R2的壓力和槽4的壓力的差壓達到開閥壓時，開閥而容許從壓側室R2朝向槽4的液體流動；伸側止回閥V3，設置於吸入通路PV3且並列配置於壓側抑振閥V1而僅容許從槽4朝向壓側室R2的液體流動；以及針閥V4，設置於抑振力調整通路PV4且並列配置於壓側抑振閥V1，而對往來於槽4和壓側室R2的液體流動給予阻力，並且可藉由外部操作去調整該阻力。
具體來說，閥單元V，具備：筒狀的閥保持軸21，插入於殼體11之閥孔h內；針22，插入於閥保持軸21內；閥盤23，裝設於閥保持軸21的外周；軸環24，裝設於閥保持軸21的外周；環狀的間隔件25、環狀板26及環狀板27，可軸方向移動地嵌合於軸環24的外周；盤形彈簧28，同樣配置於軸環24的外周，將間隔件25、環狀板26及環狀板27朝向閥盤23側彈壓；螺帽29，將閥盤23和軸環24固定於閥保持軸21；閥體30及彈簧31，收容於針22內；以及筒狀的套32，裝設於閥保持軸21的基端開口部的內周。
如圖2所示般，閥保持軸21呈筒狀，在基端具備內外徑最大的大徑部21a，在前端具備內外徑最小的小徑部21b，在大徑部21a和小徑部21b之間具備內外徑為大徑部21a和小徑部21b的中間的中徑部21c。另外，閥保持軸21，具備：凸緣21d，係大徑部21a的外周且設置於軸方向中間；以及孔21e，將中徑部21c的內外連通。
另外，閥保持軸21，為大徑部21a的外周且在比凸緣21d更前端側具備環狀凹槽21f、螺紋部21g，將螺紋部21g與殼體11的筒部11b的開口端內周的螺紋部11b1螺紋嚙合而固定於殼體11。比大徑部21a的凸緣21d更基端側的外周形狀被形成為可用六角形等的工具把持的形狀，可以藉由工具的利用而容易將閥保持軸21螺紋結合於筒部11b。
另外，在大徑部21a的環狀凹槽21f的外周裝設密封環21i，當將閥保持軸21插入於筒部11b內時，密封環21i密合於筒部11b的內周而密封閥保持軸21和筒部11b之間。在閥保持軸21的小徑部21b的外周，裝設有嵌合於筒部11b的內周的閥盤23，當將閥保持軸21插入於由殼體11的筒部11b形成的閥孔h內直到凸緣21d抵接於筒部11b的端面為止時，閥孔h內藉由閥盤23區隔成經由埠11a1通往壓側室R2的室A、以及經由埠11b2通往槽4的室B。閥保持軸21的內部經由閥孔h內的室A及埠11a1而連通於壓側室R2，並且經由孔21e、閥孔h內的室B及埠11b2連通於槽4之液室L。
並且，閥保持軸21的大徑部21a的內周在途中前端側被縮徑，在縮徑的內周部設置螺紋部21h。階差部形成於為閥保持軸21的內周側且在中徑部21c和小徑部21b的邊境。如此般，形成於閥保持軸21之內周的前述階差部，形成針閥V4之環狀閥座33。
針22，具備頭部22a、以及連結於頭部22a的操作筒22b，可朝成為軸方向的圖2中左右方向移動地插入於閥保持軸21內。
頭部22a，具備：呈筒狀且設置於圖2中成為左端的前端外周並可插入環狀閥座33之內側的針部22a1、以及設置於外周的中間部且可離開或就座於環狀閥座33的凸緣22a2。針部22a1成為越朝前端越細的形狀，可插入於閥保持軸21之小徑部21b內。另外，針部22a1的基端的外徑成為比環狀閥座33的內徑稍小的直徑，當針22在閥保持軸21內朝軸方向移動時，可以將由針部22a1和環狀閥座33的內緣之間的間隙所形成的流路面積的大小進行大小調整。如此般，針22和環狀閥座33在連通壓側室R2和槽4的閥保持軸21內形成針閥V4，針閥V4可以藉由調整針22相對於閥保持軸21的軸方向位置，將在閥保持軸21內形成的抑振力調整通路PV4之流路面積進行大小調整。
另外，凸緣22a2於環狀閥座33在軸方向上相對向，當針22相對於閥保持軸21往成為前端側的圖2中左側移動而抵接於環狀閥座33時，可以將閥保持軸21的小徑部21b內和中徑部21c內的連通遮斷。相反地，凸緣22a2在從環狀閥座33離開的狀態下，使閥保持軸21的小徑部21b內和中徑部21c內連通。
操作筒22b，具備：凹槽22b3，為具備筒部22b1和外徑大於筒部22b1的底部22b2的有底筒狀，作為可進行來自形成於底部22b2的外部之操作的操作部；以及通孔22b4，形成於筒部22b1的側部而將筒部22b1的內外連通。而且，比頭部22a的凸緣22a2更後方側的後端22a3被壓入嵌合於操作筒22b之筒部22b1內，操作筒22b和頭部22a連結成一體。
操作筒22b的底部22b2，具備：袋孔22b5，從側方開口；以及螺紋部22b6，在外周且比袋孔22b5更前端側與形成於閥保持軸21的大徑部21a的內周的螺紋部21h螺合。另外，密封環22b7裝設於操作筒22b的筒部22b1的外周。
而且，針22插入於閥保持軸21內，將螺紋部22b6與螺紋部21h螺合來裝設於閥保持軸21。當針22插入於閥保持軸21內時，密封環22b7滑接於閥保持軸21的中徑部21c的內周，針22和閥保持軸21之間被密封。
另外，由於將針22的螺紋部22b6螺合於螺紋部21h，因而當將圖外的螺絲起子插入操作筒22b的後端的凹槽22b3來使針22旋轉時，針22在閥保持軸21內朝成為圖2中左右方向的軸方向移動。
當在閥保持軸21內將針22如前述般收容時，在針22的操作筒22b的底部22b2的外周和閥保持軸21的大徑部21a的內周之間形成環狀的間隙。而且，將針22插入於在閥保持軸21內後，當將套32壓入於閥保持軸21的大徑部21a的內周時，操作筒22b的底部22b2和閥保持軸21的大徑部21a之間的間隙被閉塞。由於套32呈筒狀，容許插穿操作筒22b的底部22b2的後端，因而不會對於螺絲起子的插入於操作筒22b之凹槽22b3造成妨礙，也容許相對於閥保持軸21的針22的軸方向的移動。
套32將沿著軸方向的凹槽32a在周方向等間隔設置於成為內周的前端側的圖2中左端側。當將套32壓入且固定於閥保持軸21的大徑部21a時，前述凹槽32a相對向於操作筒22b的袋孔22b5。在袋孔22b5內，插入：球34、以及將球34從袋孔22b5內朝頂出方向彈壓的彈簧35。套32、球34及彈簧35形成掣子機構，只要當球34相對向進入於凹槽32a時不以掣動力矩以上的力矩使針22旋轉，就可以限制針22相對於閥保持軸21的朝周方向的旋轉。由於如此般藉由掣子機構維持針22和環狀閥座33的位置關係，因而可以防止在跨騎型車輛的行走中針閥V4之流路面積任意變化的情形。
另外，在針22內，收容閥體30和彈簧31。詳細來說，閥體30形成為球體，將針22之頭部22a的環狀後端作為釋壓閥閥座36，藉著在操作筒22b的筒部22b1內沿軸方向移動而可離開或就座於釋壓閥閥座36。另外，在閥體30和操作筒22b的底部22b2之間，介設線圈彈簧亦即彈簧31，將閥體30往釋壓閥閥座36彈壓。
閥體30的直徑形成為比頭部22a的後端的內周徑更大的直徑，當就座於釋壓閥閥座36時，阻斷針部22a1內和操作筒22b內的連通，當從釋壓閥閥座36離開時使針部22a1內和操作筒22b內連通。
由於在針22之操作筒22b的筒部22b1，設置有通孔22b4，因而操作筒22b內通過通孔22b4而連通於閥保持軸21的中徑部21c內。由於閥保持軸21的中徑部21c內經由孔21e及室B連通於槽4，因而操作筒22b內連通於槽4。另外，操作筒22b內，通過針22的頭部22a內而通往閥保持軸21的小徑部21b內。由於閥保持軸21的小徑部21b內經由室A及埠11a1而連通於壓側室R2，因而操作筒22b內也連通於壓側室R2。如此般，針22內，形成相對於在閥保持軸21內形成的抑振力調整通路PV4而並列配置成的壓側釋壓通路PV2，在壓側釋壓通路PV2設置由閥體30、彈簧31及釋壓閥閥座36構成的壓側釋壓閥V2。
壓側釋壓閥V2，在壓側室R2內的壓力和槽4內的壓力的差壓到達開閥壓為止，被維持在閥體30藉由彈簧31繼續抵接於釋壓閥閥座36的閉閥狀態。另外，壓側釋壓閥V2，當壓側室R2內的壓力和槽4內的壓力的差壓成為開閥壓時，閥體30藉由壓側室R2內的壓力壓著，將彈簧31壓縮且從釋壓閥閥座36離開而將壓側釋壓通路PV2開放。此壓側釋壓閥V2開閥的前述開閥壓，被設定成比將活塞桿3的外周密封的密封構件8可承受的最大壓力更低的壓力。
此外，廢除針閥V4的情況下，只要以蓋取代針22而將閥保持軸21的後端閉塞，將閥體30、以及配置於閥體30和前述蓋之間的彈簧31收容於閥保持軸21內，以小徑部21b和中徑部21c之邊境的階差部作為釋壓閥閥座，構成壓側釋壓閥V2的話即可。
在閥保持軸21的小徑部21b的外周，閥盤23、與軸環24藉由小徑部21b和中徑部21c之間的外周之階差部以及螺合於小徑部21b前端之外周的螺帽29夾住而固定。另外，環狀的間隔件25、環狀板26、環狀板27及環狀的盤形彈簧28，嵌合於軸環24的外周。
閥盤23，具備：複數個埠23a，呈環狀，排列設置於同一圓周上而將閥盤23的厚部朝軸方向貫穿；環狀窗23b，設置於圖2中左端且由通往各埠23a的環狀凹部所形成；環狀的閥座23c，從圖2中左端朝軸方向突出而包圍各埠23a的出口端亦即環狀窗23b；以及密封環23e，裝設於設置於外周的環狀凹槽23d內。如前述般，當閥盤23安裝於閥保持軸21的小徑部21b的外周且插入於閥孔h內時，嵌合於筒部11b的內周而將閥孔h內區隔成室A和室B。設置於閥盤23的外周的密封環23e，密合於筒部11b的內周而將閥盤23和筒部11b之間密封，通過閥盤23和筒部11b之間來防止室A和室B連通。
埠23a將通往壓側室R2的室A和通往槽4的室B連通，在本實施方式的緩衝器D中，作為壓側抑振通路PV1和吸入通路PV3發揮功能。
軸環24，具備：嵌合筒部24a，呈筒狀，以在外周嵌合間隔件25、環狀板26、環狀板27及環狀的盤形彈簧28；以及凸緣24b，設置於嵌合筒部24a的圖2中左端，使嵌合筒部24a的圖2中右端抵接於閥盤23的圖2中左端的內周而重疊於閥盤23。
閥盤23和軸環24，在如前述般重疊的狀態以閥保持軸21的外周的階差部和螺帽29夾住，相對於閥保持軸21固定成不動。
間隔件25是小徑的圓環狀的環狀板，可滑動地嵌合於軸環24的嵌合筒部24a的外周，可以相對於閥盤23朝軸方向移動，並可以對於閥盤23遠離或接近。此外，間隔件25的外徑，以不將埠23a閉塞的方式形成為小徑。
環狀板26是圓環狀的環狀板，可滑動地嵌合於軸環24的嵌合筒部24a的外周且重疊於間隔件25的反閥盤側，可以相對於閥盤23朝軸方向移動，並可以對於閥盤23遠離或接近。此外，環狀板26的外徑形成為比閥座23c的內徑更小的直徑，由於將環狀窗23b設置於閥盤23，因而容許朝外周側的閥盤23側的彎曲。
環狀板27是圓環狀的環狀板，可滑動地嵌合於軸環24的嵌合筒部24a的外周且重疊於環狀板26的反閥盤側，可以相對於閥盤23朝軸方向移動，並可以對於閥盤23遠離或接近。環狀板27的外徑，成為比閥座23c的外徑更稍大的直徑以使可離開或就座於閥盤23之閥座23c。另外，環狀板27，具備排列設置於同一圓周上且將環狀板27朝軸方向貫穿的複數個孔27a。各孔27a的外接圓的直徑成為未達環狀板26的直徑，在環狀板26抵接於環狀板27的狀態下，環狀板27之孔27a被閉塞著，當環狀板26的外周朝向閥盤23側彎曲而從環狀板27離開時，孔27a被開放。所以，在環狀板26抵接於環狀板27的狀態下，當環狀板27就座於閥座23c時，將埠23a閉塞而阻斷室A和室B的連通，但由於即使當環狀板27就座於閥座23c，環狀板26仍朝閥盤23側彎曲且從環狀板27離開使孔27a開放因而室A和室B連通。並且，當環狀板27的外周朝反閥盤側彎曲，或當環狀板27在軸環24上朝從閥盤23離開的方向移動時，埠23a開放而室A和室B連通。
盤形彈簧28嵌合於軸環24的嵌合筒部24a的外周，並且在給予初期彎曲的狀態下介設於凸緣24b和環狀板27之間，始終將間隔件25、環狀板26及環狀板27朝向閥盤23側彈壓。
對於從壓側室R2朝向槽4通過埠23a的液體流動，環狀板27承受壓側室R2的壓力和盤形彈簧28的彈壓力而就座於閥座23c並將埠23a閉塞，但環狀板26通過孔27a承受壓側室R2的壓力且以間隔件25的外緣作為支點彎曲而從環狀板27離開並開放埠23a，容許從壓側室R2朝向槽4的液體流動，並且對於此液體流動給予阻力。此外，間隔件25決定環狀板26的彎曲的支點，可以藉間隔件25的外徑的設定來調整環狀板26給予液體流動的阻力的大小。如此般，環狀板26作為壓側抑振閥V1之閥體發揮功能，環狀板27作為閥座發揮功能，環狀板26和環狀板27形成壓側抑振閥V1。此外，將環狀板26的內周以閥盤23直接支撐的情況下，也可以省略間隔件25，也可以將複數片的環狀板積層而形成壓側抑振閥V1的閥體。
另一方面，對於從槽4朝向壓側室R2來通過埠23a的液體流動，環狀板27承受槽4的壓力而彎曲從閥座23c離開，或將盤形彈簧28壓縮而從閥盤23離開來將埠23a開放，不給予從槽4朝向壓側室R2的液體流動太大阻力地容許此液體的流動。在此情況下，環狀板26從槽4側承受壓力而抵接於環狀板27且與環狀板27一起彎曲，或在軸環24上移動而從閥盤23遠離。如此般，環狀板26、環狀板27作為伸側止回閥V3之閥體發揮功能，閥盤23作為伸側止回閥V3之閥座發揮功能，藉由閥盤23、環狀板26、環狀板27、盤形彈簧28及軸環24形成伸側止回閥V3。
另外，在本實施方式中，壓側抑振閥V1和伸側止回閥V3並列配置於閥盤23的埠23a，埠23a作為容許從壓側室R2朝向槽4的液體流動的壓側抑振通路PV1、以及容許從槽4朝向壓側室R2的液體流動的吸入通路PV3發揮功能。
此外，也可以在閥盤23設置相當於壓側抑振通路PV1的埠，並且設置相當於吸入通路PV3的埠，設置將相當於壓側抑振通路PV1的埠開閉的壓側抑振閥V1，設置將相當於吸入通路PV3的埠開閉的伸側止回閥V3。
另外，壓側抑振閥V1雖然如前述般構成，但只要是可對於從壓側室R2朝向槽4的液體流動給予阻力而在緩衝器D的收縮作動時產生抑振力的閥的話即可，因而可在其限度內將閥的構造做適當設計變更。
並且，伸側止回閥V3雖然如前述般構成，但只要是可以僅容許從槽4朝向壓側室R2的液體流動之閥的話即可，因而可在其限度內將閥的構造做適當設計變更。
此外，也可以將與壓側抑振閥V1和伸側止回閥V3同樣構成的閥作為活塞2之伸側抑振閥5和壓側止回閥6使用。
具體所構成的閥單元V，具備：彼此並列的壓側抑振通路PV1、壓側釋壓通路PV2、吸入通路PV3及抑振力調整通路PV4，且將壓側抑振閥V1、壓側釋壓閥V2、伸側止回閥V3及針閥V4並列設置。所以，當將閥單元V插入於殼體11的閥孔h內時，可以在第3通路P3的途中，將壓側抑振閥V1、壓側釋壓閥V2、伸側止回閥V3及針閥V4彼此並列地設置。
而且，將如上述般構成的閥單元V的組裝方法的一例在以下進行說明。首先，在軸環24的嵌合筒部24a的外周，依盤形彈簧28、環狀板27、環狀板26、間隔件25的順序來將盤形彈簧28、環狀板27、環狀板26及間隔件25進行嵌合且組合。接下來，在閥保持軸21的小徑部21b的外周，將閥盤23、以及組裝有盤形彈簧28、環狀板27、環狀板26及間隔件25的軸環24依序嵌合且組合後，將螺帽29螺合於小徑部21b的前端外周。於是，閥盤23、以及組裝有盤形彈簧28、環狀板27、環狀板26及間隔件25的軸環24藉由螺帽29，固定在閥保持軸21的小徑部21b的外周。
接著，將彈簧31及閥體30依序插入針22之操作筒22b內，將頭部22a的後端22a3壓入嵌合於操作筒22b的開口端，將頭部22a結合於操作筒22b，將壓側釋壓閥V2及針22組裝。接下來，將彈簧35和球34依序插入於朝針22的操作筒22b的底部22b2的側方開口的袋孔22b5內後，將針22插入於閥保持軸21內的同時，使底部22b2的外周的螺紋部22b6螺合於閥保持軸21的螺紋部21h。
針22螺合且收容於閥保持軸21內後，於閥保持軸21的大徑部21a的內周和操作筒22b的外周之間的環狀間隙，一邊將凹槽32a側朝向閥保持軸21內一邊將套32插入，將套32壓入嵌合於大徑部21a的內周。於是，套32被固定於閥保持軸21，防止從針22的閥保持軸21脫落。
如此般，將閥盤23、軸環24、間隔件25、環狀板26、環狀板27、盤形彈簧28、收容壓側釋壓閥V2的針22及套32，組合於閥保持軸21後，即結束閥單元V的組裝。完成的閥單元V，成為具備壓側抑振閥V1、壓側釋壓閥V2、伸側止回閥V3及針閥V4的1個單元。而且，閥單元V，插入於殼體11的筒部11b內，並且藉由螺紋部11b1與閥保持軸21的大徑部21a之外周的螺紋部21g的螺合，收容於閥孔h內並且固定於殼體11。閥單元V，由於被螺絲緊固於殼體11，因而可容易安裝及拆卸於殼體11。此外，只要是將閥單元V可拆卸於殼體11的緊固手段的話，也可以採用螺絲固定以外的緊固手段。
緩衝器D，如上述般構成，在以下對作動進行說明。在活塞2相對於缸1往圖1中下方移動的緩衝器D的伸長行程中，液體從藉由活塞2壓縮的伸側室R1經由第1通路P1往壓側室R2移動。緩衝器D在此伸長行程中，伸側抑振閥5對於通過第1通路P1的液體流動給予阻力，產生妨礙伸長的伸側的抑振力。
另外，在緩衝器D的伸長行程中，由於活塞桿3從缸1退出，因而在壓側室R2內活塞桿3從缸1退出的體積量的液體不足，但此不足量的液體，隔膜12膨漲而使氣室G擴大且從槽4的液室L經由伸側止回閥V3供給壓側室R2。詳細來說，由於環狀板27承受槽4的壓力而從閥座23c離開且伸側止回閥V3開閥，因而液體通過埠23a而從槽4往壓側室R2移動。
另一方面，在活塞2相對於缸1往圖1中上方移動的緩衝器D的收縮行程中，藉由活塞2壓縮的壓側室R2內的液體，使壓側止回閥6開閥而經由第2通路P2往伸側室R1移動。另外，在緩衝器D的收縮行程中，由於活塞桿3侵入缸1內，因而在缸1內活塞桿3侵入缸1內的體積量的液體過剩，但此過剩量的液體，經由壓側抑振閥V1往槽4內的液室L排出，隔膜12收縮來將氣室G縮小。在如此般緩衝器D的收縮行程中，壓側抑振閥V1及針閥V4對於從壓側室R2朝向槽4的液體流動給予阻力。所以，在緩衝器D的收縮行程中，由於第2通路P2開放因而缸1內的伸側室R1和壓側室R2處於連通狀態，壓側抑振閥V1及針閥V4對於從壓側室R2朝向槽4的液體流動給予阻力。所以，在緩衝器D的收縮行程中，伸側室R1內和壓側室R2內的壓力皆上昇而成為大致相同壓力。在本實施方式的緩衝器D中，由於面向伸側室R1的活塞2的面積相較於面向壓側室R2的活塞2的面積僅減少活塞桿3的面積量，因而收縮作動的緩衝器D，將缸1內的壓力乘以活塞桿3的面積之值的抑振力，朝妨礙前述收縮作動的方向發揮。換言之，設定為僅在前述的活塞2的單方存在活塞桿3的單桿式之緩衝器D的情況下，產生與在收縮作動時活塞桿3的剖面積成比例的抑振力。
此外，由於在本實施方式的緩衝器D中閥單元V具備針閥V4，藉由針閥V4之流路面積的調整可使針閥V4給予液體流動的阻力變化，因而緩衝器D可調整壓側的抑振力。
另外，在緩衝器D的收縮行程中，當壓側室R2內的壓力和槽4內的壓力的差壓達到壓側釋壓閥V2的開閥壓時，由於球34從釋壓閥閥座36後退且壓側釋壓閥V2開閥，因而藉由壓側釋壓通路PV2連通壓側室R2和槽4。藉由壓側釋壓通路PV2的開放，缸1內的液體往槽4洩出，調整成為缸1內的壓力不超過壓側釋壓閥V2的開閥壓。
在此，在比較輕量的跨騎型車輛所採用的緩衝器中，為了強度上無問題地謀求緩衝器的輕量化，所以有縮減活塞桿的外徑的情況。緩衝器的在收縮作動時產生的抑振力，如前述般與活塞桿3的剖面積成比例。因此，當欲在以如此般的緩衝器縮減活塞桿的外徑的同時在收縮作動時發揮較大抑振力時，須要將缸內的壓力形成高壓。要讓收縮作動時缸內的壓力形成高壓，壓側抑振閥V1給予液體流動的阻力加大的話即可，但當在緩衝器D的收縮作動時以高速進行收縮作動時，有缸內的壓力成為過大而超過將活塞桿的外周密封之密封構件的耐壓的情況。然而，在本實施方式的緩衝器D中，如上所述，閥單元V具備與壓側抑振閥V1並列配置的壓側釋壓閥V2。所以，即使在緩衝器D的收縮作動時緩衝器D的收縮速度成為高速，仍可以防止壓側釋壓閥V2開閥而缸1內的壓力成為過大的情形，可以保護將活塞桿3的外周密封的密封構件8以及防止來自於活塞桿3和密封構件8之間的液體洩漏。
另外，當從殼體11將閥單元V拆下，筒部11b的開口藉由未圖示的蓋閉塞時，緩衝器D與以往構造的緩衝器同樣地，僅在伸長作動時產生抑振力，在收縮作動時不產生抑振力。藉由如此般閥單元V的裝設，雖緩衝器D可以在伸長作動時和收縮作動時的雙方發揮抑振力，但將閥單元V從緩衝器D拆卸時成為僅在伸長作動時產生抑振力的緩衝器。
以上，本實施方式的緩衝器D，具備：缸1；活塞2，可移動地插入缸1內以將缸1內區隔成填充有液體的伸側室R1和壓側室R2；活塞桿3，可移動地插入缸1內並且連結於活塞2；槽4，用於儲存液體；第1通路P1及第2通路P2，分別並列且將伸側室R1和壓側室R2連通；第3通路P3，將壓側室R2和槽4連通；伸側抑振閥5，設置於第1通路P1並對於從伸側室R1朝向壓側室R2的液體流動給予阻力；壓側止回閥6，設置於第2通路P2並僅容許從壓側室R2朝向伸側室R1的液體流動；以及閥單元V，可拆卸地設置於第3通路P3的途中，閥單元V，具備：壓側抑振閥V1，對於從壓側室R2朝向槽4的液體流動給予阻力；壓側釋壓閥V2，並列配置於壓側抑振閥V1且在閉閥時阻斷壓側室R2和槽4的連通，並且當壓側室R2的壓力和槽4的壓力的差壓達到開閥壓時開閥，容許從壓側室R2朝向槽4的液體流動；以及伸側止回閥V3，並列置於壓側抑振閥V1而僅容許從槽4朝向壓側室R2的液體流動。
在如此般構成的緩衝器D中，由於並列具備壓側抑振閥V1、壓側釋壓閥V2及伸側止回閥V3的閥單元V可拆卸地設置於將壓側室R2和槽4連通的第3通路P3的途中，因而只靠裝設閥單元V就可以將僅在伸長作動時發揮抑振力的緩衝器作為不僅伸長作動時甚至在收縮作動時也發揮抑振力的緩衝器來發揮功能。另外，將閥單元V拆下的話，可以將緩衝器D作為僅在伸長作動時發揮抑振力的緩衝器利用。
藉由閥單元V的有無，可以將緩衝器D，設定成在伸長作動時和收縮作動時的雙方產生抑振力的緩衝器、以及僅在伸長作動時產生抑振力的緩衝器的任一個。緩衝器D的製造者，可以將閥單元V以外的緩衝器D以相同的零件在相同的生產線來組裝，且可以依據使用者的要求而決定閥單元V的有無來製造緩衝器D。因而，製造者可以減少緩衝器D的製造成本。
所以，依據如前述般構成的緩衝器D，可以將在收縮作動時能夠發揮抑振力的功能簡單地附加於不具備壓側抑振閥的緩衝器上。另外，緩衝器D的製造者，由於可以將閥單元V以外的緩衝器D以相同的零件在相同的生產線來組裝，因而也可以減少製造者之緩衝器D的製造成本。
並且，依據如前述般構成的緩衝器D，由於閥單元V具備壓側釋壓閥V2，因而在緩衝器D的收縮作動時即使緩衝器D的收縮速度成為高速仍可以防止缸1內的壓力成為過大的情形。
另外，本實施方式的緩衝器D，具備殼體11，該殼體將缸1和槽4連結並且具有第3通路P3和設置於第3通路P3之途中的閥孔h，閥單元V收容於閥孔h內。依據如此般構成的緩衝器D，由於在將缸1和槽4連結的殼體11的閥孔h收容閥單元V，因而可以抑制將閥單元V配置於缸1的側方而造成緩衝器D的全長變長的情形。此外，在閥孔h由沿著缸1的徑向配置的筒部11b形成，並且開口端朝向反缸側的情況下，閥單元V的裝卸也容易從緩衝器D的側方進行。
並且，由於在本實施方式的緩衝器D中，具備閥單元V並列配置於壓側抑振閥V1而對於從壓側室R2朝向槽4的液體流動給予阻力並且可調整流路面積的針閥V4，因而也能夠調整收縮作動時的抑振力。
另外，在本實施方式的緩衝器D中，針閥V4，具有：環狀閥座33、以及可對於環狀閥座33遠離或接近的針22，壓側釋壓閥V2收容於針22內。依據如此般構成的緩衝器D，壓側釋壓閥V2收容於針22內所以可以將閥單元V的整體小型化。此外，由於壓側釋壓閥V2收容於針22內，因而不論針22的位置都可以將壓側釋壓閥V2的開閥壓固定。
並且，在本實施方式的緩衝器D中，針22，具有：頭部22a，具有：呈現筒狀且設置於前端外周並可插入環狀閥座33之內側的針部22a1、以及設置於外周的中間部且可離開或就座於環狀閥座33的凸緣22a2；操作筒22b，連結於頭部22a的後方，具備：呈現有底筒狀且可進行來自形成於底部22b2的外部之操作的凹槽(操作部)22b3、以及連通內外的通孔22b4，壓側釋壓閥V2，具有：閥體30，將頭部22a之環狀的後端22a3作為環狀的釋壓閥閥座36，可離開或就座於釋壓閥閥座36且收容於操作筒22b內；以及彈簧31，介設於閥體30和操作筒22b之間，並且收容於操作筒內22b而將閥體30朝向釋壓閥閥座36彈壓，當閥體30從釋壓閥閥座36離開時，使頭部22a內和通孔22b4成為連通。
依據如此般構成的緩衝器D，在針22設置將閥體30和彈簧31收容於頭部22a和操作筒22b內的空間，藉著以構成針22的頭部22a作為釋壓閥閥座36使用，可以合理地將壓側釋壓閥V2收容於針22內。所以，依據如此般構成的緩衝器D，可以將壓側釋壓閥V2和針22更為小型化。
此外，本實施方式的緩衝器D，具備滑接於活塞桿3的外周而將活塞桿3的外周密封的密封構件8，壓側釋壓閥V2的開閥壓被設定為未達密封構件8可承受的最大壓力。依據如此般構成的緩衝器D，由於將密封構件8可承受的最大壓力不超過缸1內的壓力，因而可以保護密封構件8和防止來自於活塞桿3和密封構件8之間的液體的洩漏。
以上，雖然詳細說明本發明的較佳的實施方式，但只要不偏離專利申請的範圍，仍可進行改造、變形、及變更。
Hereinafter, the present invention will be described based on the embodiment shown in the drawings. As shown in FIGS. 1 and 2 , a buffer D according to one embodiment is composed of a cylinder 1 and a piston 2 that is movably inserted into the cylinder 1 to divide the cylinder 1 into an extension chamber R1 filled with liquid. and the pressure side chamber R2; the piston rod 3 is movably inserted into the cylinder 1 and connected to the piston 2; the groove 4 is used to store liquid; the first passage P1 and the second passage P2 are respectively parallel and connect the extension side chamber R1 and the pressure side chamber R2 is connected; the third passage P3 communicates the compression side chamber R2 and the groove 4; the extension side vibration suppression valve 5 is provided in the first passage P1 and provides resistance to the liquid flow from the extension side chamber R1 to the compression side chamber R2; the compression side check The valve 6 is provided in the second passage P2 and allows only the flow of liquid from the pressure side chamber R2 toward the expansion side chamber R1; and the valve unit V is detachably provided in the middle of the third passage P3. In the case of this shock absorber D, it is used interposed between the vehicle body and wheels of a vehicle (not shown) to suppress vibrations of the vehicle body and wheels. Each component of the buffer D will be described in detail below. As shown in FIG. 1 , an annular cover 10 , an annular sealing member 8 and an annular rod guide 7 are stacked on the inner periphery of the lower end of the cylinder 1 in order from the outside of the cylinder. insert. The rod guide 7 is fixed in the cylinder 1 by the fastening part 1a on the outer periphery of the cylinder 1. Furthermore, the cover 10 and the sealing member 8 are sandwiched between the rod guide 7 and the fastening portion 1 b at the lower end of the cylinder 1 , and are fixed to the cylinder 1 . In addition, the design of the means for fixing the cover 10, the sealing member 8 and the rod guide 7 to the cylinder 1 can be arbitrarily changed. In addition, a housing 11 is installed at the upper end of the cylinder 1 in FIG. 1 . The housing 11 blocks the upper end of the cylinder 1 , connects the cylinder 1 and the tank 4 , and accommodates the valve unit V. Furthermore, the piston rod 3 with the piston 2 installed at the front end is movably inserted into the cylinder 1 . The piston rod 3 is slidably inserted through the inner circumference of the sealing member 8 and the inner circumference of the rod guide 7 and inserted into the cylinder 1 , and is guided by the rod guide 7 to move in the axial direction. The sealing member 8 is in sliding contact with the outer periphery of the piston rod 3 and seals the outer periphery of the piston rod 3 to seal the inside of the cylinder 1 . In addition, the cylinder 1 is partitioned by the piston 2 into an extension side chamber R1 and a pressure side chamber R2 filled with liquid. In addition, in this embodiment, the liquid is hydraulic oil, but liquids other than hydraulic oil, such as water and aqueous solutions, may be used. The piston 2 is connected to the front end of the piston rod 3 which is the upper end in FIG. 1 . In addition, the lower end of the piston rod 3 in FIG. 1 is equipped with a bracket B1 that can be connected to a member for holding a vehicle wheel (not shown), and a cylindrical flange cushion 14 is installed on the outer periphery near the lower end in FIG. 1 . When the flange cushion pad 14 contacts and compresses the cover 10 fixed on the inner periphery of the lower end of the cylinder 1 when the shock absorber D is most contracted, the flange cushion pad 14 exerts a rebound force to alleviate the impact of the most contracted shock absorber D. The piston 2 is provided with a first passage P1 and a second passage P2 which are arranged in parallel and communicate with the expansion side chamber R1 and the pressure side chamber R2. Furthermore, the piston 2 is provided with an extension-side vibration suppressor valve 5 that opens and closes the first passage P1 and provides resistance to the flow of liquid from the extension-side chamber R1 toward the compression-side chamber R2, and a compression-side check valve 6 that switches the second The passage P2 is opened and closed to allow only the flow of liquid from the compression side chamber R2 toward the expansion side chamber R1. In addition, since the first passage P1 and the second passage P2 only need to communicate with the expansion side chamber R1 and the pressure side chamber R2, they may be provided outside the piston 2. For example, an outer cylinder (not shown) may be provided on the outer periphery of the cylinder 1. It is formed by utilizing the gap between the cylinder 1 and the outer cylinder. In addition, since the extension side vibration suppressor valve 5 is provided in the first passage P1 and the compression side check valve 6 is provided in the second passage P2, the expansion side vibration suppressor valve 5 and the pressure side check valve 6 are The installation location may be determined based on the installation pattern of the first path P1 and the second path P2. The extension side vibration suppression valve 5 may be a valve that provides resistance to the flow of hydraulic oil from the extension side chamber R1 to the pressure side chamber R2 and can exert a vibration suppression force that hinders the expansion of the shock absorber D when the shock absorber D is extended. . Furthermore, specifically, the extension side vibration suppressor valve 5 is configured, for example, by laminating a plurality of annular plates on the upper end of the piston 2 in FIG. 1 and is set to open the first passage P1 when the pressure of the extension side chamber R1 bends. Laminated valves, etc. are sufficient. In addition, the pressure side check valve 6 may be a valve that allows the hydraulic oil to flow only from the pressure side chamber R2 toward the extension side chamber R1 during the contraction operation of the shock absorber D without providing too much resistance. Furthermore, specifically, the pressure side check valve 6 is configured, for example, by an annular plate that overlaps the lower end of the piston 2 in FIG. 1 and a spring with a small spring constant that presses the annular plate. A valve or the like that opens the second passage P2 based on the pressure of the pressure side chamber R2 may be used. In this embodiment, the housing 11 is provided with: an upper cover 11a, which is installed on the upper end of the cylinder 1 in FIG. h; and a cylindrical sleeve 11c, which is connected to the lower end of the cylindrical portion 11b in Figure 1 and holds the groove 4. In addition, the upper cover 11a is coupled to the upper end of the cylinder 1 in FIG. 1 to block the upper end of the cylinder 1, and is provided with a bracket B2 on the upper side in FIG. 1 that can be connected to the body of a vehicle (not shown). In the shock absorber D of this embodiment, as shown in FIGS. 1 and 2 , one end of the cylindrical portion 11 b is integrated with the side of the upper cover 11 a and extends in the horizontal direction, and a threaded portion 11 b 1 is provided on the inner periphery of the open end. Furthermore, the inside of the cylindrical portion 11b forms a valve hole h, and the valve unit V is accommodated in the valve hole h. In addition, the inside of the cylindrical portion 11b is connected to the pressure side chamber R2 in the cylinder 1 through the port 11a1 formed in the upper cover 11a. Furthermore, the port 11a1 leads to the deepest part of the valve hole h. The sleeve 11c is annular and the upper end is the side part of the barrel part 11b. In Figure 1, it is integrally connected to the lower part and extends vertically downward. The sleeve 11c is provided with a threaded part 11c1 on the outer periphery of the lower end. Furthermore, the cylindrical groove 4 is screwed to the threaded portion 11c1 on the outer periphery of the lower end of the sleeve 11c. The inside of the sleeve 11c leads to the inside of the cylindrical part 11b via the port 11b2 which opens toward the side part of the cylindrical part 11b. The deepest part of the valve hole h is connected to the pressure side chamber R2 via the port 11a1, and the middle part is connected to the sleeve 11c via the port 11b2. In this embodiment, the groove 4 is cylindrical and is screwed to the sleeve 11c. Furthermore, the diaphragm 12 is inserted into the tank 4, and the tank 4 is divided into a liquid chamber L filled with liquid and a gas chamber G filled with gas by the diaphragm 12. In addition, gas is enclosed in the air chamber G so that at least the pressure in the air chamber G becomes equal to or higher than the atmospheric pressure when the shock absorber D is most extended. In addition, in addition to using the diaphragm 12, a free piston, an air bag, etc. may also be used to divide the liquid chamber L and the air chamber G in the tank 4. The liquid chamber L of the tank 4 is connected to the pressure side chamber R2 via the port 11b2 opened into the sleeve 11c, the valve hole h, and the port 11a1. In this way, in the buffer D of this embodiment, the third passage P3 is formed by the port 11b2, the valve hole h, and the port 11a1. In this way, the casing 11 connects the cylinder 1 and the tank 4, and is provided with the third passage P3 that communicates the pressure side chamber R2 and the tank 4, and the valve hole h that accommodates the valve unit V in the middle of the third passage P3. The casing 11 further includes a cylindrical portion 11b forming a valve hole h on the side of the upper cover 11a that blocks the upper end of the cylinder 1, and a sleeve 11c for mounting the groove 4 below the cylindrical portion 11b. Therefore, arranging the valve unit V on the side of the cylinder 1 can suppress the overall length of the shock absorber D from being increased. In addition, the valve hole h is formed by the cylindrical portion 11b arranged in the radial direction with respect to the cylinder 1, and since the opening end faces the opposite cylinder side, the valve unit V can be easily attached and detached from the side of the shock absorber D. Next, the valve unit V is accommodated in the valve hole h forming part of the third passage P3 of the housing 11 and is provided in the middle of the third passage P3. In addition, the valve unit V is detachably accommodated in the cylindrical portion 11 b forming the valve hole h of the housing 11 . The valve unit V is provided with: a pressure-side vibration suppression passage PV1, a pressure-side pressure relief passage PV2, a suction passage PV3 and a vibration suppression force adjustment passage PV4, which are connected in parallel to the middle of the third passage P3; the pressure-side vibration suppression valve V1 is provided The pressure-side vibration suppression passage PV1 provides resistance to the liquid flow from the pressure-side chamber R2 toward the tank 4; the pressure-side pressure relief valve V2 is provided in the pressure-side pressure relief passage PV2 and is arranged in parallel with the pressure-side vibration suppression valve V1. The valve blocks the communication between the pressure side chamber R2 and the groove 4, and when the difference between the pressure of the pressure side chamber R2 and the pressure of the groove 4 reaches the valve opening pressure, the valve opens to allow the liquid from the pressure side chamber R2 to flow toward the groove 4; The side check valve V3 is provided in the suction passage PV3 and is arranged in parallel with the pressure-side vibration suppressor valve V1 to allow only the flow of liquid from the groove 4 to the pressure side chamber R2; and the needle valve V4 is provided in the vibration suppression force adjustment passage PV4 and is arranged in parallel. It is arranged in the pressure side vibration suppressor valve V1 to provide resistance to the liquid flow between the tank 4 and the pressure side chamber R2, and the resistance can be adjusted by external operation. Specifically, the valve unit V is equipped with: a cylindrical valve holding shaft 21 inserted into the valve hole h of the housing 11; a needle 22 inserted into the valve holding shaft 21; and a valve disc 23 installed on the valve holding shaft. The outer periphery of 21; the collar 24 is installed on the outer periphery of the valve holding shaft 21; the annular spacer 25, the annular plate 26 and the annular plate 27 are axially movably fitted to the outer periphery of the collar 24; the disk The spring 28 is also arranged on the outer periphery of the collar 24 to urge the spacer 25, the annular plate 26 and the annular plate 27 toward the valve disc 23 side; the nut 29 fixes the valve disc 23 and the collar 24 to the valve retaining The shaft 21; the valve body 30 and the spring 31 are accommodated in the needle 22; and the cylindrical sleeve 32 is installed on the inner periphery of the base end opening of the valve holding shaft 21. As shown in FIG. 2 , the valve holding shaft 21 has a cylindrical shape, and has a large diameter part 21 a with the largest inner and outer diameter at the base end, and a small diameter part 21 b with the smallest inner and outer diameter at the front end. The large diameter part 21 a and the small diameter part 21 b A middle diameter portion 21c having an inner and outer diameter between the large diameter portion 21a and the small diameter portion 21b is provided therebetween. In addition, the valve holding shaft 21 is provided with a flange 21d formed on the outer periphery of the large diameter portion 21a and located in the middle of the axial direction, and a hole 21e that communicates the inside and outside of the medium diameter portion 21c. In addition, the valve holding shaft 21 is provided with an annular groove 21f and a threaded portion 21g on the outer periphery of the large-diameter portion 21a and on the front end side of the flange 21d. The threaded portion 21g is connected to the opening end of the cylindrical portion 11b of the housing 11. The peripheral thread portion 11b1 is threadedly engaged and fixed to the housing 11. The outer peripheral shape on the proximal side of the flange 21d of the large diameter portion 21a is formed into a shape that can be grasped with a tool such as a hexagon. The valve holding shaft 21 can be easily screwed to the cylindrical portion 11b by using the tool. In addition, a sealing ring 21i is installed on the outer periphery of the annular groove 21f of the large diameter portion 21a. When the valve holding shaft 21 is inserted into the cylindrical portion 11b, the sealing ring 21i comes into close contact with the inner periphery of the cylindrical portion 11b to seal the valve. between the shaft 21 and the cylindrical portion 11b. On the outer periphery of the small diameter portion 21b of the valve holding shaft 21, a valve disc 23 fitted to the inner periphery of the cylindrical portion 11b is installed. When the valve holding shaft 21 is inserted into the valve hole formed by the cylindrical portion 11b of the housing 11 h until the flange 21d abuts the end surface of the cylinder portion 11b, the valve hole h is divided by the valve disc 23 into a chamber A leading to the pressure side chamber R2 via the port 11a1, and a chamber A leading to the groove 4 via the port 11b2. Room B. The inside of the valve holding shaft 21 is connected to the pressure side chamber R2 via the chamber A and the port 11a1 in the valve hole h, and is connected to the liquid chamber L of the tank 4 via the hole 21e, chamber B and the port 11b2 in the valve hole h. Furthermore, the inner circumference of the large-diameter portion 21a of the valve holding shaft 21 is reduced in diameter on the front end side, and a threaded portion 21h is provided in the reduced-diameter inner circumference. The step portion is formed on the inner peripheral side of the valve holding shaft 21 at the boundary between the medium diameter portion 21 c and the small diameter portion 21 b. In this way, the aforementioned step portion formed on the inner circumference of the valve holding shaft 21 forms the annular valve seat 33 of the needle valve V4. The needle 22 has a head 22a and an operating cylinder 22b connected to the head 22a, and is inserted into the valve holding shaft 21 so as to be movable in the left-right direction in FIG. 2 which is the axial direction. The head 22a has a cylindrical shape, a needle portion 22a1 provided on the outer periphery of the front end that is the left end in FIG. 2 and can be inserted into the inside of the annular valve seat 33, and an intermediate portion provided on the outer periphery and can be separated from or seated on the annular valve seat 33. flange 22a2 of the valve seat 33. The needle portion 22a1 has a shape that becomes narrower toward the front end, and can be inserted into the small diameter portion 21b of the valve holding shaft 21. In addition, the outer diameter of the base end of the needle portion 22a1 is slightly smaller than the inner diameter of the annular valve seat 33. When the needle 22 moves in the axial direction within the valve holding shaft 21, the needle portion 22a1 and the annular valve seat can be separated. The size of the flow path area formed by the gap between the inner edges of 33 is adjusted. In this way, the needle 22 and the annular valve seat 33 form a needle valve V4 in the valve holding shaft 21 connecting the pressure side chamber R2 and the groove 4. The needle valve V4 can be adjusted by adjusting the axial position of the needle 22 relative to the valve holding shaft 21. The flow path area of the vibration suppression force adjustment path PV4 formed in the valve holding shaft 21 is adjusted in size. In addition, the flange 22a2 faces the annular valve seat 33 in the axial direction. When the needle 22 moves to the left side in FIG. 2 which is the front end side with respect to the valve holding shaft 21 and contacts the annular valve seat 33, the needle 22 can be moved to the annular valve seat 33. The valve holds the communication between the small diameter portion 21b and the medium diameter portion 21c of the shaft 21. On the contrary, the flange 22a2 connects the inside of the small diameter portion 21b and the inside of the medium diameter portion 21c of the valve holding shaft 21 in a state separated from the annular valve seat 33. The operating cylinder 22b is provided with a groove 22b3, which is a bottomed cylinder having a cylindrical portion 22b1 and a bottom portion 22b2 with an outer diameter larger than the cylindrical portion 22b1, as an operating portion that can be operated from the outside formed in the bottom portion 22b2; and a through hole. 22b4 is formed on the side part of the cylindrical part 22b1 and connects the inside and outside of the cylindrical part 22b1. Furthermore, the rear end 22a3 on the rear side of the flange 22a2 of the head 22a is press-fitted into the cylindrical portion 22b1 of the operating tube 22b, and the operating tube 22b and the head 22a are integrally connected. The bottom 22b2 of the operating cylinder 22b is provided with a pocket hole 22b5 that opens from the side, and a threaded portion 22b6 that is formed on the inner circumference of the large-diameter portion 21a of the valve holding shaft 21 on the outer periphery and further forward than the pocket hole 22b5. The part is screwed in 21h. In addition, the sealing ring 22b7 is installed on the outer periphery of the cylinder portion 22b1 of the operating cylinder 22b. And the needle 22 is inserted into the valve holding shaft 21, and the thread part 22b6 and the thread part 21h are screwed together, and is attached to the valve holding shaft 21. When the needle 22 is inserted into the valve holding shaft 21, the sealing ring 22b7 is in sliding contact with the inner circumference of the middle diameter portion 21c of the valve holding shaft 21, thereby sealing the gap between the needle 22 and the valve holding shaft 21. In addition, since the threaded portion 22b6 of the needle 22 is screwed to the threaded portion 21h, when a screwdriver (not shown) is inserted into the groove 22b3 at the rear end of the operating barrel 22b to rotate the needle 22, the needle 22 is inside the valve holding shaft 21. Move toward the axis direction that becomes the left-right direction in FIG. 2 . When the needle 22 is accommodated in the valve holding shaft 21 as described above, an annular gap is formed between the outer circumference of the bottom 22b2 of the operating cylinder 22b of the needle 22 and the inner circumference of the large diameter portion 21a of the valve holding shaft 21. Furthermore, after the needle 22 is inserted into the valve holding shaft 21, when the sleeve 32 is pressed into the inner circumference of the large diameter portion 21a of the valve holding shaft 21, the bottom 22b2 of the operating cylinder 22b and the large diameter of the valve holding shaft 21 The gap between the portions 21a is blocked. Since the sleeve 32 is cylindrical, it is allowed to be inserted through the rear end of the bottom 22b2 of the operating barrel 22b, thereby not causing an obstruction to the insertion of the screwdriver into the groove 22b3 of the operating barrel 22b, and also allows the needle 22 to be held relative to the valve holding shaft 21. movement in the axis direction. The sleeve 32 has grooves 32 a along the axial direction provided at equal intervals in the circumferential direction on the left end side in FIG. 2 which becomes the front end side of the inner periphery. When the sleeve 32 is pressed into and fixed to the large diameter portion 21a of the valve holding shaft 21, the aforementioned groove 32a faces the pocket hole 22b5 of the operating cylinder 22b. Into the bag hole 22b5, the ball 34 and the spring 35 which urges the ball 34 in the ejection direction from the bag hole 22b5 are inserted. The sleeve 32, the ball 34 and the spring 35 form a detent mechanism. As long as the needle 22 is not rotated with a torque greater than the detent torque when the ball 34 enters the groove 32a relatively, the movement of the needle 22 relative to the valve holding shaft 21 can be limited. Circumferential rotation. Since the positional relationship between the needle 22 and the annular valve seat 33 is maintained by the detent mechanism in this way, it is possible to prevent the flow path area of the needle valve V4 from changing arbitrarily while the straddle-type vehicle is traveling. In addition, the valve body 30 and the spring 31 are accommodated in the needle 22 . Specifically, the valve body 30 is formed as a sphere, and the annular rear end of the head 22a of the needle 22 is used as the pressure relief valve seat 36, which can be separated or moved away from the valve seat 36 by moving in the axial direction within the cylinder portion 22b1 of the operating cylinder 22b. Sitting on the pressure relief valve seat 36. In addition, a coil spring, that is, a spring 31 is interposed between the valve body 30 and the bottom 22b2 of the operating cylinder 22b to urge the valve body 30 toward the pressure relief valve seat 36. The diameter of the valve body 30 is formed to be larger than the inner circumferential diameter of the rear end of the head portion 22a. When seated on the pressure relief valve seat 36, the communication between the inside of the needle portion 22a1 and the inside of the operating cylinder 22b is blocked. When the pressure relief valve seat 36 is separated, the inside of the needle part 22a1 and the inside of the operating cylinder 22b are connected. Since the through hole 22b4 is provided in the barrel portion 22b1 of the operating barrel 22b of the needle 22, the inside of the operating barrel 22b communicates with the middle diameter portion 21c of the valve holding shaft 21 through the through hole 22b4. Since the inside of the middle diameter portion 21c of the valve holding shaft 21 communicates with the groove 4 via the hole 21e and the chamber B, the inside of the operating cylinder 22b communicates with the groove 4. In addition, the inside of the operating cylinder 22b passes through the head portion 22a of the needle 22 and leads to the small diameter portion 21b of the valve holding shaft 21. Since the inside of the small diameter portion 21b of the valve holding shaft 21 is connected to the pressure side chamber R2 via the chamber A and the port 11a1, the inside of the operating cylinder 22b is also connected to the pressure side chamber R2. In this way, the pressure-side pressure relief passage PV2 is formed in the needle 22 and is arranged in parallel with the vibration suppression force adjustment passage PV4 formed in the valve holding shaft 21. The pressure-side pressure relief passage PV2 is provided with the valve body 30 and the spring. 31 and the pressure relief valve seat 36 constitute the pressure side pressure relief valve V2. In the pressure-side pressure relief valve V2, until the difference between the pressure in the pressure-side chamber R2 and the pressure in the tank 4 reaches the valve opening pressure, the valve body 30 is maintained in contact with the pressure relief valve seat 36 by the spring 31. Closed valve state. In addition, in the pressure-side pressure relief valve V2, when the difference between the pressure in the pressure-side chamber R2 and the pressure in the tank 4 becomes the valve opening pressure, the valve body 30 is pressed by the pressure in the pressure-side chamber R2, compressing the spring 31 and It is separated from the pressure relief valve seat 36 to open the pressure side pressure relief passage PV2. The valve opening pressure at which the pressure-side pressure relief valve V2 opens is set to a pressure lower than the maximum pressure that the sealing member 8 that seals the outer periphery of the piston rod 3 can withstand. In addition, when the needle valve V4 is eliminated, the needle 22 is replaced with a cover, the rear end of the valve holding shaft 21 is blocked, and the valve body 30 and the spring 31 arranged between the valve body 30 and the cover are accommodated in the valve holding body. In the shaft 21, it is sufficient to configure the pressure-side pressure relief valve V2 by using the step portion at the boundary between the small diameter portion 21b and the medium diameter portion 21c as a pressure relief valve seat. On the outer periphery of the small diameter portion 21b of the valve holding shaft 21, the valve disc 23 and the collar 24 are connected by the step portion of the outer periphery between the small diameter portion 21b and the middle diameter portion 21c and by screwing the front end of the small diameter portion 21b. The outer nut 29 is clamped and fixed. In addition, the annular spacer 25 , the annular plate 26 , the annular plate 27 and the annular disk spring 28 are fitted to the outer periphery of the collar 24 . The valve disc 23 is provided with: a plurality of annular ports 23a, which are arranged on the same circumference and penetrate the thick part of the valve disc 23 in the axial direction; an annular window 23b is provided at the left end in Figure 2 and is connected to each port. The annular recess of the port 23a is formed; the annular valve seat 23c protrudes from the left end in the axial direction in Figure 2 to surround the outlet end of each port 23a, that is, the annular window 23b; and the sealing ring 23e is installed on the in the outer annular groove 23d. As described above, when the valve disc 23 is mounted on the outer periphery of the small diameter portion 21b of the valve holding shaft 21 and inserted into the valve hole h, it is fitted into the inner periphery of the cylindrical portion 11b to partition the inside of the valve hole h into the chamber A. Japanese Room B. The sealing ring 23e provided on the outer periphery of the valve disc 23 is in close contact with the inner periphery of the cylindrical portion 11b to seal between the valve disc 23 and the cylindrical portion 11b, and prevents chamber A and chamber B from passing between the valve disc 23 and the cylindrical portion 11b. Connected. The port 23a communicates the chamber A leading to the pressure side chamber R2 and the chamber B leading to the groove 4, and functions as the pressure side vibration suppression passage PV1 and the suction passage PV3 in the shock absorber D of this embodiment. The collar 24 is provided with: a fitting cylindrical portion 24a, which is cylindrical for fitting the spacer 25, the annular plate 26, the annular plate 27 and the annular disc spring 28 on the outer periphery; and a flange 24b, which is provided on The left end in FIG. 2 of the fitting cylindrical part 24a is caused to make the right end in FIG. 2 of the fitting cylindrical part 24a contact the inner periphery of the left end in FIG. 2 of the valve disc 23 so as to overlap the valve disc 23 . The valve disc 23 and the collar 24 are sandwiched between the stepped portion of the outer periphery of the valve holding shaft 21 and the nut 29 in an overlapping state as described above, and are immovably fixed to the valve holding shaft 21 . The spacer 25 is an annular plate with a small diameter and is slidably fitted on the outer periphery of the fitting cylinder portion 24 a of the collar 24 . Far away or close. In addition, the outer diameter of the spacer 25 is formed into a small diameter so as not to block the port 23a. The annular plate 26 is an annular plate that is slidably fitted to the outer periphery of the fitting cylinder portion 24a of the collar 24 and overlaps the anti-valve disk side of the spacer 25, and can be axially oriented relative to the valve disk 23. direction, and can move away from or approach the valve disc 23. In addition, the outer diameter of the annular plate 26 is formed to be smaller than the inner diameter of the valve seat 23c, and since the annular window 23b is provided in the valve disc 23, bending toward the valve disc 23 side of the outer circumference is allowed. The annular plate 27 is an annular plate that is slidably fitted to the outer periphery of the fitting cylinder portion 24a of the collar 24 and overlaps the anti-valve disk side of the annular plate 26, and can be directed toward the valve disk 23. It moves in the axial direction and can move away from or approach the valve disc 23 . The outer diameter of the annular plate 27 is slightly larger than the outer diameter of the valve seat 23c so that the valve seat 23c can be separated from or seated on the valve disc 23. In addition, the annular plate 27 is provided with a plurality of holes 27 a arranged on the same circumference and penetrating the annular plate 27 in the axial direction. The diameter of the circumscribed circle of each hole 27a is less than the diameter of the annular plate 26. When the annular plate 26 is in contact with the annular plate 27, the hole 27a of the annular plate 27 is blocked. When the annular plate 26 When the outer periphery of the valve disc is bent toward the valve disc 23 side and separated from the annular plate 27, the hole 27a is opened. Therefore, when the annular plate 26 is in contact with the annular plate 27 and the annular plate 27 is seated on the valve seat 23c, the port 23a is blocked and the communication between the chamber A and the chamber B is blocked. The shaped plate 27 is seated on the valve seat 23c, and the annular plate 26 is still bent toward the valve disc 23 side and separated from the annular plate 27 so that the hole 27a is opened so that the chamber A and the chamber B are connected. Then, when the outer periphery of the annular plate 27 is curved toward the anti-valve disk side, or when the annular plate 27 moves in the direction away from the valve disk 23 on the collar 24, the port 23a is opened and the chamber A and the chamber B are connected. The disk spring 28 is fitted to the outer periphery of the fitting cylinder portion 24a of the collar 24, and is interposed between the flange 24b and the annular plate 27 in a state of initial bending, so that the spacer 25 and the annular plate are always connected. 26 and annular plate 27 are urged toward the valve disc 23 side. For the liquid flow from the pressure side chamber R2 to the groove 4 through the port 23a, the annular plate 27 bears the pressure of the pressure side chamber R2 and the elastic force of the disk spring 28 to sit on the valve seat 23c and block the port 23a. However, the annular plate 27 26 receives the pressure of the pressure side chamber R2 through the hole 27a and bends with the outer edge of the spacer 25 as a fulcrum to leave the annular plate 27 and open the port 23a, allowing the liquid to flow from the pressure side chamber R2 toward the groove 4, and for this liquid flow Give resistance. In addition, the spacer 25 determines the fulcrum of the bending of the annular plate 26, and the resistance provided by the annular plate 26 to the liquid flow can be adjusted by setting the outer diameter of the spacer 25. In this way, the annular plate 26 functions as the valve body of the pressure-side vibration suppressor valve V1, the annular plate 27 functions as a valve seat, and the annular plate 26 and the annular plate 27 form the pressure-side vibration suppressor valve V1. In addition, when the inner periphery of the annular plate 26 is directly supported by the valve disc 23, the spacer 25 may be omitted, or a plurality of annular plates may be laminated to form the valve body of the pressure-side vibration suppression valve V1. On the other hand, for the liquid flow from the groove 4 to the pressure side chamber R2 through the port 23a, the annular plate 27 receives the pressure of the groove 4 and bends away from the valve seat 23c, or compresses the disk spring 28 and separates from the valve disc 23 The port 23a is opened to allow the flow of the liquid from the tank 4 to the pressure side chamber R2 without giving too much resistance to the flow of the liquid. In this case, the annular plate 26 receives pressure from the groove 4 side and comes into contact with the annular plate 27 and bends together with the annular plate 27 , or moves on the collar 24 and moves away from the valve disc 23 . In this way, the annular plate 26 and the annular plate 27 function as the valve body of the extension side check valve V3, and the valve disc 23 functions as the valve seat of the extension side check valve V3. Through the valve disc 23 and the annular plate 26. The annular plate 27, the disc spring 28 and the collar 24 form the extension side check valve V3. In addition, in the present embodiment, the pressure-side vibration suppression valve V1 and the extension-side check valve V3 are arranged in parallel at the port 23a of the valve plate 23, and the port 23a serves as a pressure-side vibration suppression passage that allows the liquid to flow from the pressure side chamber R2 toward the tank 4. PV1 and the suction passage PV3 that allow the liquid to flow from the groove 4 toward the pressure side chamber R2 function. In addition, the valve plate 23 may be provided with a port corresponding to the pressure-side vibration suppression passage PV1, a port corresponding to the suction passage PV3, and a pressure-side vibration suppression valve V1 that opens and closes the port corresponding to the pressure-side vibration suppression passage PV1. , an extension check valve V3 is provided that opens and closes the port corresponding to the suction passage PV3. In addition, although the pressure-side vibration suppressor valve V1 is configured as described above, it only needs to be a valve that can provide resistance to the flow of liquid from the pressure-side chamber R2 toward the groove 4 and generate a vibration suppression force during the contraction operation of the shock absorber D. Therefore, appropriate design changes can be made to the valve structure within its limits. In addition, although the extension side check valve V3 is configured as described above, it only needs to be a valve that allows only the flow of liquid from the tank 4 to the pressure side chamber R2. Therefore, the structure of the valve can be appropriately designed and changed within its limits. . In addition, valves having the same configuration as the pressure-side vibration suppressor valve V1 and the expansion-side check valve V3 may be used as the extension-side vibration suppressor valve 5 and the pressure-side check valve 6 of the piston 2 . The valve unit V is specifically configured to include: a pressure-side vibration suppression passage PV1, a pressure-side pressure relief passage PV2, a suction passage PV3, and a vibration suppression force adjustment passage PV4, which are parallel to each other, and the pressure-side vibration suppression valve V1 and the pressure-side relief passage are combined. The pressure valve V2, extension side check valve V3 and needle valve V4 are arranged in parallel. Therefore, when the valve unit V is inserted into the valve hole h of the housing 11, the pressure-side vibration suppression valve V1, pressure-side pressure relief valve V2, extension-side check valve V3 and The needle valves V4 are arranged side by side. Furthermore, an example of an assembly method of the valve unit V configured as described above will be described below. First, on the outer periphery of the fitting cylinder portion 24a of the collar 24, the disk spring 28, the annular plate 27, the annular plate 26, and the spacer 25 are arranged in this order. The plate 26 and the spacer 25 are fitted and combined. Next, the valve disc 23 and the collar 24 in which the disc spring 28, the annular plate 27, the annular plate 26 and the spacer 25 are assembled are sequentially fitted on the outer periphery of the small diameter portion 21b of the valve holding shaft 21. After assembly, the nut 29 is screwed onto the outer periphery of the front end of the small diameter portion 21b. Then, the valve disc 23 and the collar 24 in which the disc spring 28, the annular plate 27, the annular plate 26 and the spacer 25 are assembled are fixed to the outer periphery of the small diameter portion 21b of the valve holding shaft 21 through the nut 29. . Then, insert the spring 31 and the valve body 30 into the operating barrel 22b of the needle 22 in sequence, press the rear end 22a3 of the head 22a into the open end of the operating barrel 22b, and combine the head 22a with the operating barrel 22b. Assemble the pressure side pressure relief valve V2 and needle 22. Next, the spring 35 and the ball 34 are sequentially inserted into the pocket hole 22b5 that opens to the side of the bottom 22b2 of the operating cylinder 22b of the needle 22, and then the needle 22 is inserted into the valve holding shaft 21, and the bottom 22b2 is The outer peripheral threaded portion 22b6 is threaded into the threaded portion 21h of the valve holding shaft 21. After the needle 22 is screwed and accommodated in the valve holding shaft 21, the groove 32a side is directed toward the valve holding shaft in the annular gap between the inner circumference of the large diameter portion 21a of the valve holding shaft 21 and the outer circumference of the operating cylinder 22b. 21 while inserting the sleeve 32, and the sleeve 32 is press-fitted into the inner periphery of the large diameter portion 21a. Then, the sleeve 32 is fixed to the valve holding shaft 21 and prevents the needle 22 from coming off the valve holding shaft 21 . In this way, the valve disc 23, the collar 24, the spacer 25, the annular plate 26, the annular plate 27, the disk spring 28, the needle 22 and the sleeve 32 that accommodate the pressure side pressure relief valve V2 are assembled on the valve holding shaft. After 21, the assembly of the valve unit V is completed. The completed valve unit V is a single unit including the pressure-side vibration suppressor valve V1, the pressure-side pressure relief valve V2, the extension-side check valve V3, and the needle valve V4. Furthermore, the valve unit V is inserted into the cylindrical portion 11b of the housing 11, and is accommodated in the valve hole h by screwing the threaded portion 11b1 with the threaded portion 21g on the outer periphery of the large-diameter portion 21a of the valve holding shaft 21. fixed to the housing 11. Since the valve unit V is fastened to the housing 11 with screws, it can be easily installed and removed from the housing 11 . In addition, as long as the valve unit V is detachable from the housing 11, fastening means other than screw fixing may be used. The buffer D is configured as described above, and its operation will be described below. During the expansion stroke of the shock absorber D in which the piston 2 moves downward relative to the cylinder 1 in FIG. 1 , the liquid moves from the expansion side chamber R1 compressed by the piston 2 to the pressure side chamber R2 via the first passage P1. During the extension stroke of the shock absorber D, the extension-side vibration suppression valve 5 provides resistance to the liquid flow passing through the first passage P1 and generates an extension-side vibration suppression force that hinders the extension. In addition, during the extension stroke of the buffer D, since the piston rod 3 withdraws from the cylinder 1, the volume of liquid in the pressure side chamber R2 that the piston rod 3 withdraws from the cylinder 1 is insufficient. However, this insufficient amount of liquid causes the diaphragm 12 to expand. The gas chamber G expands and the liquid chamber L of the tank 4 is supplied to the pressure side chamber R2 via the extension side check valve V3. Specifically, since the annular plate 27 receives the pressure of the groove 4 and is separated from the valve seat 23c and the expansion side check valve V3 opens, the liquid moves from the groove 4 to the pressure side chamber R2 through the port 23a. On the other hand, during the contraction stroke of the shock absorber D in which the piston 2 moves upward relative to the cylinder 1 in FIG. 1 , the liquid in the pressure side chamber R2 compressed by the piston 2 causes the pressure side check valve 6 to open and pass through. The second passage P2 moves toward the extension side chamber R1. In addition, during the contraction stroke of the shock absorber D, since the piston rod 3 intrudes into the cylinder 1, there is excess liquid in the cylinder 1 by the volume of the piston rod 3 intruding into the cylinder 1. However, this excess amount of liquid is eliminated through the pressure side suppression. The vibration valve V1 discharges the liquid chamber L in the tank 4, and the diaphragm 12 contracts to shrink the air chamber G. During the contraction stroke of the shock absorber D in this manner, the pressure-side vibration suppressor valve V1 and the needle valve V4 provide resistance to the flow of liquid from the pressure-side chamber R2 toward the groove 4 . Therefore, during the contraction stroke of the shock absorber D, since the second passage P2 is open, the extension side chamber R1 and the pressure side chamber R2 in the cylinder 1 are in a communication state, and the pressure side vibration suppressor valve V1 and the needle valve V4 are in a state from the pressure side chamber R2 toward the groove. 4 gives resistance to liquid flow. Therefore, during the contraction stroke of the shock absorber D, the pressures in both the expansion side chamber R1 and the pressure side chamber R2 rise and become substantially the same pressure. In the shock absorber D of this embodiment, the area of the piston 2 facing the expansion side chamber R1 is reduced by only the area of the piston rod 3 compared with the area of the piston 2 facing the pressure side chamber R2. Therefore, the shock absorber D that is contracted will The vibration suppressing force, which is the value of the pressure in the cylinder 1 multiplied by the area of the piston rod 3, acts in a direction that hinders the aforementioned contraction operation. In other words, when the single-rod type shock absorber D is configured such that the piston rod 3 is present only on one side of the piston 2, a vibration suppressing force is generated in proportion to the cross-sectional area of the piston rod 3 during the contraction operation. In addition, since the valve unit V in the buffer D of this embodiment is equipped with the needle valve V4, the resistance given by the needle valve V4 to the liquid flow can be changed by adjusting the flow path area of the needle valve V4, so the buffer D can adjust the pressure. side vibration suppression force. In addition, during the contraction stroke of the buffer D, when the difference between the pressure in the pressure side chamber R2 and the pressure in the tank 4 reaches the valve opening pressure of the pressure side pressure relief valve V2, the ball 34 moves from the pressure relief valve seat 36 When the pressure side pressure relief valve V2 is moved backward and the pressure side pressure relief valve V2 is opened, the pressure side pressure relief passage PV2 communicates with the pressure side chamber R2 and the tank 4 . By opening the pressure side pressure relief passage PV2, the liquid in the cylinder 1 is discharged to the tank 4, and the pressure in the cylinder 1 is adjusted so that the pressure in the cylinder 1 does not exceed the valve opening pressure of the pressure side pressure relief valve V2. Here, in a shock absorber used in a relatively lightweight straddle-type vehicle, in order to reduce the weight of the shock absorber without any problem in terms of strength, the outer diameter of the piston rod may be reduced. The vibration suppressing force generated by the shock absorber during the contraction operation is proportional to the cross-sectional area of the piston rod 3 as mentioned above. Therefore, when using such a buffer to reduce the outer diameter of the piston rod and at the same time exerting a large vibration suppressing force during the contraction operation, it is necessary to increase the pressure in the cylinder to a high pressure. To make the pressure in the cylinder become high during the contraction operation, the pressure-side vibration suppressor valve V1 can increase the resistance to the liquid flow. However, when the shock absorber D is contracting at a high speed, there is a pressure in the cylinder. The pressure becomes too great and exceeds the pressure resistance of the sealing member that seals the outer periphery of the piston rod. However, in the shock absorber D of the present embodiment, as described above, the valve unit V includes the pressure-side pressure relief valve V2 arranged in parallel with the pressure-side vibration suppressor valve V1. Therefore, even if the contraction speed of the shock absorber D becomes high during the contraction operation of the shock absorber D, it is possible to prevent the pressure side pressure relief valve V2 from opening and causing the pressure in the cylinder 1 to become excessively high, thereby protecting the outer periphery of the piston rod 3 The sealing member 8 is sealed and prevents liquid leakage from between the piston rod 3 and the sealing member 8 . In addition, when the valve unit V is removed from the casing 11 and the opening of the cylindrical portion 11b is closed with a cover (not shown), the shock absorber D generates a vibration suppression force only during the extension operation, just like the shock absorber of the conventional structure. , no vibration suppression force is generated during contraction. By installing the valve unit V in this way, the shock absorber D can exert a vibration suppressing force during both expansion and contraction operations. However, when the valve unit V is removed from the shock absorber D, the shock absorbing force is exerted only during the expansion operation. Vibration buffer. As mentioned above, the shock absorber D of this embodiment is equipped with: a cylinder 1; a piston 2, which is movably inserted into the cylinder 1 to partition the cylinder 1 into an extension side chamber R1 and a pressure side chamber R2 filled with liquid; and a piston rod 3, which can It is movably inserted into the cylinder 1 and connected to the piston 2; the groove 4 is used to store liquid; the first passage P1 and the second passage P2 are respectively parallel and communicate the extension side chamber R1 and the pressure side chamber R2; the third passage P3 is used to store the pressure side chamber R1 and the pressure side chamber R2. The side chamber R2 communicates with the tank 4; the extension side vibration suppressor valve 5 is provided in the first passage P1 and provides resistance to the liquid flow from the extension side chamber R1 toward the compression side chamber R2; the compression side check valve 6 is provided in the second passage P2 and Only the liquid flow from the pressure side chamber R2 to the extension side chamber R1 is allowed; and the valve unit V is detachably installed in the middle of the third passage P3. The valve unit V is equipped with: a pressure side vibration suppression valve V1, which is used for liquid flow from the pressure side chamber R2 to the expansion side chamber R1. The liquid flow in tank 4 provides resistance; the pressure side pressure relief valve V2 is arranged in parallel with the pressure side vibration suppression valve V1 and blocks the communication between the pressure side chamber R2 and tank 4 when the valve is closed, and when the pressure of the pressure side chamber R2 and tank 4 The valve opens when the pressure difference reaches the valve opening pressure, allowing the liquid from the pressure side chamber R2 to flow toward the groove 4; and the extension side check valve V3 is placed side by side with the pressure side vibration suppressor valve V1 and only allows the flow from the pressure side chamber R2 toward the pressure side chamber R2. Liquid flow in side chamber R2. In the shock absorber D configured in this way, the valve unit V including the compression side vibration suppressing valve V1, the compression side pressure relief valve V2, and the expansion side check valve V3 is detachably provided to communicate the pressure side chamber R2 and the tank 4. In the middle of the third passage P3, therefore, by simply installing the valve unit V, the shock absorber that exerts the vibration suppressing force only during the extension operation can be used as a shock absorber that exerts the vibration suppressing force not only during the extension operation but also during the contraction operation. Function. In addition, by detaching the valve unit V, the shock absorber D can be used as a shock absorber that exerts a vibration suppressing force only during the extension operation. Depending on the presence or absence of the valve unit V, the shock absorber D can be set to either a shock absorber that generates a vibration suppressing force during both extension and contraction operations, or a shock absorber that generates a vibration suppressing force only during the extension operation. . The manufacturer of the shock absorber D can assemble the shock absorbers D other than the valve unit V with the same parts on the same production line, and can manufacture the shock absorber D with or without the valve unit V according to the user's requirements. Therefore, the manufacturer can reduce the manufacturing cost of the buffer D. Therefore, according to the shock absorber D configured as described above, the function of exerting a vibration suppressing force during contraction operation can be easily added to the shock absorber without the compression side vibration suppressing valve. In addition, since the manufacturer of the shock absorber D can assemble the shock absorbers D other than the valve unit V using the same parts on the same production line, the manufacturer can also reduce the manufacturing cost of the shock absorber D. Furthermore, according to the shock absorber D configured as described above, since the valve unit V is provided with the pressure-side pressure relief valve V2, during the contraction operation of the shock absorber D, even if the contraction speed of the shock absorber D becomes high, the pressure in the cylinder 1 can be prevented from being increased. becomes an oversized situation. In addition, the shock absorber D of this embodiment is provided with a casing 11 that connects the cylinder 1 and the tank 4 and has a third passage P3 and a valve hole h provided in the middle of the third passage P3. The valve unit V is accommodated in Inside the valve hole h. According to the shock absorber D configured in this way, since the valve unit V is accommodated in the valve hole h of the casing 11 that connects the cylinder 1 and the tank 4, it can be suppressed that the valve unit V is arranged to the side of the cylinder 1 and the shock absorber D is damaged. The full length of the object becomes longer. In addition, when the valve hole h is formed by the cylindrical portion 11 b arranged along the radial direction of the cylinder 1 and the opening end faces the opposite cylinder side, the valve unit V can be easily attached and detached from the side of the shock absorber D. In addition, in the shock absorber D of the present embodiment, the valve unit V is arranged in parallel with the pressure-side vibration suppressor valve V1 to provide resistance to the flow of liquid from the pressure-side chamber R2 to the tank 4 and to adjust the flow path area of the needle valve V4. , so it is also possible to adjust the vibration suppression force during contraction. In addition, in the shock absorber D of this embodiment, the needle valve V4 has an annular valve seat 33 and a needle 22 that can move away from or approach the annular valve seat 33, and the pressure-side pressure relief valve V2 is accommodated in the needle 22. . According to the shock absorber D configured in this way, the pressure side pressure relief valve V2 is accommodated in the needle 22, so the entire valve unit V can be downsized. In addition, since the pressure-side pressure relief valve V2 is accommodated in the needle 22, the valve opening pressure of the pressure-side pressure relief valve V2 can be fixed regardless of the position of the needle 22. Furthermore, in the shock absorber D of this embodiment, the needle 22 has a head 22a, a cylindrical needle portion 22a1 provided on the outer periphery of the front end and insertable into the annular valve seat 33, and a needle portion 22a1 provided on the outer periphery. The middle part of the valve seat 33 can be separated from or seated on the flange 22a2 of the annular valve seat 33; the operating cylinder 22b, connected to the rear of the head 22a, has a bottomed cylinder shape and can be operated from the outside formed on the bottom 22b2 The operating groove (operating part) 22b3 and the through hole 22b4 communicating the inside and outside, the pressure side pressure relief valve V2 has a valve body 30, and the annular rear end 22a3 of the head 22a serves as an annular pressure relief valve. The seat 36 can leave or sit on the pressure relief valve seat 36 and is contained in the operating cylinder 22b; and the spring 31 is interposed between the valve body 30 and the operating cylinder 22b and is contained in the operating cylinder 22b to move the valve. The body 30 is biased toward the pressure relief valve seat 36. When the valve body 30 is separated from the pressure relief valve seat 36, the inside of the head 22a and the through hole 22b4 are connected. According to the shock absorber D configured in this way, the needle 22 is provided with a space for accommodating the valve body 30 and the spring 31 in the head 22a and the operating cylinder 22b, and the head 22a constituting the needle 22 serves as the pressure relief valve seat 36. By using the pressure-side pressure relief valve V2, the pressure side pressure relief valve V2 can be reasonably accommodated in the needle 22. Therefore, according to the shock absorber D configured in this way, the pressure side pressure relief valve V2 and the needle 22 can be further miniaturized. In addition, the shock absorber D of this embodiment is provided with a sealing member 8 that is slidably connected to the outer periphery of the piston rod 3 to seal the outer periphery of the piston rod 3. The valve opening pressure of the pressure-side pressure relief valve V2 is set to be less than the sealing member 8. Maximum pressure that can be tolerated. According to the shock absorber D configured in this way, since the maximum pressure that the sealing member 8 can withstand does not exceed the pressure in the cylinder 1, the sealing member 8 can be protected and the leakage of the liquid from between the piston rod 3 and the sealing member 8 can be prevented. . Although the preferred embodiments of the present invention have been described in detail above, modifications, transformations, and changes can be made without departing from the scope of the patent application.
