Fluid flow control structure for a telescopic apparatus of a human powered vehicle

A fluid flow control structure is provided for a telescopic apparatus of a human powered vehicle. The fluid flow control structure basically comprises a first tube, a second tube and a positioning structure. The second tube is telescopically coupled to the first tube to move in an axial direction. The positioning structure includes first, second and third fluid chambers, and a valve that defines a port that is selectively opened and closed. The valve includes a valve body that is movable relative to a valve seat in the axial direction to change a valve state between a closed state and an open state. The valve body fluidly separates the first and second fluid chambers in the closed state and to fluidly connect the first and second fluid chambers in the open state. The third fluid chamber includes a compressible fluid.

BACKGROUND

Field of the Invention

This invention generally relates to a fluid flow control structure. More specifically, the present invention relates to a fluid flow control structure for a telescopic apparatus of a human powered vehicle such as a bicycle.

Background Information

Some human-powered vehicles, in particular bicycles, have been provided with a telescopic apparatus such as a seatpost. The seatpost adjustably supports a bicycle seat on a bicycle frame. Typically, the seatpost is telescopically disposed in a seat tube of the bicycle frame. The height of the bicycle seat with respect to the bicycle frame is typically adjusted by changing an insertion amount of the seatpost in the seat tube of the bicycle frame. The upper end of the seat tube is typically provided with a longitudinal slit and a clamping that adjusts the diameter of the upper end of the seat tube to squeeze the seatpost for securing the seatpost in a desired position with respect to the bicycle frame.

SUMMARY

Generally, the present disclosure is directed to various features of a fluid flow control structure for a telescopic apparatus of a human-powered vehicle. Human-powered vehicle vehicles as used here in refers to vehicles regardless of the number of their wheels, that are power by a human and not by a motor or engine.

In one feature, a fluid flow control structure is provided for a telescopic apparatus of a human-powered vehicle in which the fluid flow control structure can reduce an operating force for operating fluid flow control structure to change a dimension (e.g., a height) of the telescopic apparatus.

In view of the state of the known technology and in accordance with a first aspect of the present disclosure, a fluid flow control structure is provided for a telescopic apparatus of a human powered vehicle. The fluid flow control structure basically comprises a first tube, a second tube and a positioning structure. The first tube has a center axis. The second tube is telescopically coupled to the first tube to move in an axial direction of the center axis. The positioning structure includes a first fluid chamber, a second fluid chamber, a third fluid chamber, and a valve. The valve defines a port that is selectively opened and closed. The valve includes a valve body and a valve seat. The valve body is movable relative to the valve seat in the axial direction to change a valve state between a closed state and an open state. The valve body is configured to fluidly separate the first fluid chamber from the second fluid chamber in the closed state and to fluidly connect the first fluid chamber to the second fluid chamber in the open state. The third fluid chamber includes a compressible fluid. With the fluid flow control structure according to the first aspect, it is possible to reduce an operating force for operating fluid flow control structure to change a height of the telescopic apparatus.

In accordance with a second aspect of the present invention, the fluid flow control structure according to the first aspect is configured so that the third fluid chamber is configured such that the compressible fluid biases the valve body toward the valve seat in the open state. With the fluid flow control structure according to the second aspect, it is possible to improve the closing performance the valve body.

In accordance with a third aspect of the present invention, the fluid flow control structure according to the first or second aspect is configured so that the first fluid chamber and the valve body defines a first pressure-receiving dimension while the valve is in the closed state, and the third fluid chamber and the valve body defines a second pressure-receiving dimension while the valve is in the closed state. The second pressure-receiving dimension is smaller than the first pressure-receiving dimension. With the fluid flow control structure according to the third aspect, it is possible to reduce an operating force for operating fluid flow control structure to change a height of the telescopic apparatus.

In accordance with a fourth aspect of the present invention, the fluid flow control structure according to any one of the first to third aspects is configured so that the first and second fluid chambers include an incompressible fluid. With the fluid flow control structure according to the fourth aspect, it is possible to maintain a selected dimension (e.g., a height) of the telescopic apparatus.

In accordance with a fifth aspect of the present invention, the fluid flow control structure according to any one of the first to fourth aspects is configured so that the third fluid chamber is configured to increase in volume as the valve body is moved toward the valve seat, and is configured to decrease in volume as the valve body is moved away from the valve seat. With the fluid flow control structure according to the fifth aspect, it is possible to improve the closing and sealing performance the valve body with respect to the valve seat.

In accordance with a sixth aspect of the present invention, the fluid flow control structure according to any one of the first to fifth aspects is configured so that the third fluid chamber is defined between a dividing member and the valve. With the fluid flow control structure according to the sixth aspect, it is possible to easily define the third fluid chamber and set the pressure of the third fluid chamber to a desired pressure.

In accordance with a seventh aspect of the present invention, the fluid flow control structure according to the sixth aspect is configured so that the dividing member is configured to receive an end portion of the valve body. With the fluid flow control structure according to the seventh aspect, it is possible for the fluid of the third fluid chamber to directly apply a force on the valve body.

In accordance with an eighth aspect of the present invention, the fluid flow control structure according to any one of the first to seventh aspects is configured so that the second tube has a distal end disposed closer to a bicycle seat mounting end and a proximal end opposite to the distal end in the axial direction, and the third fluid chamber is configured to be disposed closer to the distal end of the second tube than the first fluid chamber. With the fluid flow control structure according to the eighth aspect, it is possible to use the fluid flow control structure to support a bicycle seat such that the height of the bicycle seat is adjustable.

In accordance with a ninth aspect of the present invention, the fluid flow control structure according to any one of the first to eighth aspects is configured so that the valve seat includes a first tapered surface that contacts the valve body in the closed state. With the fluid flow control structure according to the ninth aspect, it is possible to improve the sealing performance between the valve body and the valve seat in the closed state.

In accordance with a tenth aspect of the present invention, the fluid flow control structure according to the ninth aspect is configured so that the first tapered surface has a first axial end and a second axial end. The first tapered surface is configured such that a diameter of the first tapered surface decreases from the first axial end toward the second axial end. The first axial end is disposed closer to the third fluid chamber than is the second axial end. With the fluid flow control structure according to the tenth aspect, it is possible to improve the sealing performance between the valve body and the valve seat in the closed state.

In accordance with an eleventh aspect of the present invention, the fluid flow control structure according to the ninth or tenth aspect is configured so that the valve body includes a second tapered surface configured to contact the valve seat. With the fluid flow control structure according to the eleventh aspect, it is possible to improve the sealing performance between the valve body and the valve seat in the closed state.

In accordance with a twelfth aspect of the present invention, the fluid flow control structure according to the eleventh aspect is configured so that at least part of the second tapered surface includes a partial spherical surface. With the fluid flow control structure according to the twelfth aspect, it is possible to improve the sealing performance between the valve body and the valve seat in the closed state.

In accordance with a thirteenth aspect of the present invention, the fluid flow control structure according to any one of the first to twelfth aspects is configured so that the positioning structure further includes a fourth fluid chamber having a compressible fluid, and a movable piston disposed between the first and fourth fluid chambers to change a volume ratio between the first and fourth fluid chambers. The compressible fluid in the fourth fluid chamber biases the movable piston toward the first fluid chamber. With the fluid flow control structure according to the thirteenth aspect, it is possible to bias the first and second tubes apart from each other.

In accordance with a fourteenth aspect of the present invention, the fluid flow control structure according to the thirteenth aspect is configured so that the positioning structure further includes a check valve disposed in a fluid passage of the first fluid chamber to block incompressible fluid in the first fluid chamber from flowing away from the valve body towards the movable piston while the valve body is in the closed state. With the fluid flow control structure according to the fourteenth aspect, it is possible to appropriately control the pressure in the first fluid chamber while the valve body is in the closed state.

In accordance with a fifteenth aspect of the present invention, the fluid flow control structure according to any one of the first to fourteenth aspects is configured so that the valve body includes a first portion that contacts the valve seat, a second portion that extends from the first portion, and a third portion coupled to the second portion at an opposite end of the second portion from the first portion. The first fluid chamber and the first portion of the valve body defines a first pressure-receiving dimension while the valve body is in the closed state. The third fluid chamber and the first portion of the valve body defines a second pressure-receiving dimension while the valve body is in the closed state. The second pressure-receiving dimension is smaller than the first pressure-receiving dimension. The first fluid chamber and the third portion of the valve body defines a third pressure-receiving dimension while the valve body is in the closed state. The second and third pressure-receiving dimensions are equal. With the fluid flow control structure according to the fifteenth aspect, it is possible to reduce an operating force for operating fluid flow control structure to change a height of the telescopic apparatus.

In accordance with a sixteenth aspect of the present invention, the fluid flow control structure according to any one of the first to fifteenth aspects further comprises an actuator configured to move the valve body to change the valve state from one of the closed state and the open state to the other of the closed state and the open state. With the fluid flow control structure according to the sixteenth aspect, it is possible to easily operate the valve body.

In accordance with a seventeenth aspect of the present invention, a height adjustable seatpost assembly as the telescopic apparatus comprising the fluid flow control structure according to any one of the first to fifteenth aspects, and further comprises an actuator configured to move the valve body to change the valve state from one of the closed state and the open state to the other of the closed state and the open state. With the fluid flow control structure according to the seventeenth aspect, it is possible use the telescopic apparatus as a height adjustable seatpost assembly for adjusting a height of a seat.

Also, other objects, features, aspects and advantages of the disclosed fluid flow control structure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the fluid flow control structure.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring initially toFIG. 1, a human powered vehicle1is illustrated that is equipped with a height adjustable seatpost assembly10in accordance with a first embodiment. The height adjustable seatpost assembly10is one example of a telescopic apparatus of the present invention. The telescopic apparatus of the present invention can be adapted to other components such as a suspension. In other words, a height adjustable seatpost assembly is a telescopic apparatus of the present invention. The height adjustable seatpost assembly10can also be called a bicycle seatpost assembly.

Here, in the illustrated embodiment, for example, the human powered vehicle1is a bicycle. The height adjustable seatpost assembly10is configured to selectively adjust a seat height of a bicycle seat S relative to a bicycle frame F. Here, in the illustrated embodiment, the height adjustable seatpost assembly10is mechanically actuated by a rider. Alternatively, the height adjustable seatpost assembly10can be modified to be automatically operated via an electronic controller.

In the illustrated embodiment, the height adjustable seatpost assembly10is a separate unit that is mounted in a seat tube ST of the bicycle frame F. In particular, the upper end of the seat tube ST is provided with a longitudinal slit such that a clamping device adjusts the diameter of the upper end of the seat tube ST to squeeze the upper end of the seat tube ST around the height adjustable seatpost assembly10. When the height adjustable seatpost assembly10is mounted to the seat tube ST, the height adjustable seatpost assembly10adjusts a seat height of the bicycle seat S with respect to the seat tube ST.

As seen inFIG. 2, the height adjustable seatpost assembly10basically comprises a fluid flow control structure12and an actuator14. As seen inFIG. 2, the height adjustable seatpost assembly10further comprises a user operable input device16that is operatively coupled to the actuator14to operate the fluid flow control structure12via the actuator14. Specifically, the user operable input device16is operatively coupled to the actuator14via a control cable18such as a Bowden cable. The control cable18has an inner wire18aand an outer casing18b. The inner wire18ais slidably disposed in the outer casing18b. The actuator14is provided in and/or on the first tube20and/or the second tube22. In other words, while the actuator14is mainly disposed outside of the first tube20, the actuator14can be mounted in other positions in and/or on the first tube20and/or the second tube22. In any case, the actuator14receives an operation force (e.g., pulling force) applied from the user operable input device16via the control cable18. As a result, the actuator14is operated to control the fluid flow control structure12. However, the actuator14is not limited to this embodiment. The actuator14can include an electric motor, an electric solenoid, or any other electrical actuator. In a case where the actuator14includes an electric motor, the actuator can further include a speed reducer to convert rotation of the motor into linear motion/axial movement of the connecting rod56. In a case where the actuator14includes an electric solenoid, the solenoid is preferably configured to move the connecting rod56in the telescopic movement direction.

As shown inFIGS. 2 and 3, the actuator14is configured to actuate the fluid flow control structure12in response to operation of the user operable input device16. The user operable input device16is configured to operate the control cable18. For example, the user operable input device16is mounted on the bicycle handlebar H. The user operable input device16includes an operated part16aand a mounting base16b. The operated part16ais configured to be pivotal arranged relative to the mounting base16bfrom a rest position P0to an operated position P1about a pivot axis CA. Each of the rest position P0and the operated position P1is defined based on the pivot axis CA of the operated part16a. The term “rest position” as used herein refers to a state in which the part (e.g., the operated part16a) remains stationary without the need of a user holding the part in that state corresponding to the rest position. The term “operated position” as used herein refers to a state in which the part (e.g., the operated part16a) is temporarily held by an external force (e.g., a user holding the part in a state corresponding to the operated position). The control cable18is pulled by pivoting the operated part16arelative to the mounting base16bfrom the rest position P0to the operated position P1. The actuator14actuates the fluid flow control structure12, when the control cable18is pulled by pivoting the operated part16ato the operated position P1.

As seen inFIG. 3, the fluid flow control structure16basically comprises a first tube20, a second tube22and a positioning structure24. The first and second tubes20and22form a telescoping seatpost26. The telescoping seatpost26adjustable supports the bicycle seat S with respect to the seat tube ST. The positioning structure24is operated between a closed state (seeFIGS. 4 and 6) and an adjustable state (seeFIG. 5) in response to the operation of the user operable input device16that is operatively coupled to the actuator14by the control cable18. The positioning structure24is in the locked state when the user operable input device16is in the rest position P0. Operation of the user operable input device16to the operated position P1pulls the inner wire18ato move the actuator14. This movement of the actuator14actuates the positioning structure24, which switches from the locked state (seeFIGS. 4 and 6) and the adjustable state (seeFIG. 5). Upon release of the user operable input device16, the operated part16apivots from the operated position P1back to the rest position P0by a return spring. Thus, the operated part16ais a trigger type member that return to the rest position when released from the operated position. The actuator14is not limited to being mechanically controlled (e.g., via the control cable18). Alternatively, the actuator14can be an electric actuator that is controlled by a control signal that can be transmitted via wireless or wired communication. The actuator14also can be disposed as a part of valve rod (e.g., linear actuator).

Here, the first tube20is an outer tube and the second tube22is an inner tube that is telescopically arranged inside of the first tube20. In general, the first and second tubes20and22are telescopically arranged, with an amount of insertion of the second tube22into the first tube20being adjustable between a plurality of seatpost positions. Thus, the fluid flow control structure16is a telescopic apparatus of the human powered vehicle1. The first tube20has a center axis A. The second tube22is telescopically coupled to the first tube20to move in an axial direction of the center axis A. Basically, the first and second tubes20and22have a common longitudinal center axis that corresponds to the center axis A of the first tube20.

As shown inFIG. 3, the second tube22is configured to be movable relative to the first tube20. Specifically, the second tube22is configured to be telescopically received in the first tube20. The second tube22moves relative to the first tube20in a first telescopic direction D1to increase an overall length of the telescoping seatpost26. The second tube22moves relative to the first tube20in a second telescopic direction D2to decrease an overall length of the telescoping seatpost26. The first and second telescopic directions D1and D2are parallel to the center axis A. The telescoping seatpost26has a minimum overall length L1and a maximum overall length L2. The overall length of the height adjustable seatpost assembly10is adjustable within an adjustable range AR defined as a difference between the maximum overall length L2and the minimum overall length L1.

As shown inFIG. 1, the first tube20is detachably attached to the seat tube ST of the bicycle frame F. For example, the first tube20is formed in a substantially cylindrical shape. The first tube20has a first or lower end portion20a, a second or upper end portion20band an interior bore20c. The interior bore20cextends longitudinally between the first and second end portions20aand20bof the first tube20. The first end portion20ais opposite to the second end portion20b. Here, for example, the actuator14is provided at the first end portion20aof the first tube20. The actuator14can be provided at other positions in or outside the height adjustable seatpost assembly10. For example, the actuator14can be mounted to the second tube22. The second end portion20bis an open end for receiving the second tube22into the interior bore20c.

As shown inFIG. 3, the second tube22is formed in a substantially cylindrical shape. The outer diameter of the second tube22is smaller than the inner diameter of the first tube20. The second tube22has a first or upper end portion22a, a second or lower end portion22band an interior bore22c. The interior bore22cextends longitudinally between the first and second end portions22aand22bof the second tube22. The first end portion22ais opposite to the second end portion22b. The first or upper end portion22ais provided with a bicycle seat mounting structure28. The first or upper end portion22acan also be considered a distal end of the second tube22with respect to the first tube20, while the second end portion22bcan also be considered a proximal end of the second tube22with respect to the first tube20. In this way, the second tube22has a distal end disposed closer to a bicycle seat mounting end and a proximal end opposite to the distal end in the axial direction. The actuator14is mounted to the first end portion20aof the first tube20by an end plug29.

The bicycle seat mounting structure28is configured to fixedly mount the bicycle seat S to the second tube22. For example, the bicycle seat S is a saddle. The bicycle seat mounting structure28is fixedly attached to the first end portion22aof the second tube22. The bicycle seat mounting structure28is provided with an air filling valve30. The positioning structure24is primarily provided in the second end portion22bof the second tube22.

As shown inFIGS. 4 to 6, the positioning structure24is configured to position the first tube20and the second tube22relative to each other. The positioning structure24is configured to be operated via the user operable input device16(seeFIGS. 2 and 3). As shown inFIGS. 4 to 6, the positioning structure24includes the locked state (seeFIGS. 4 and 6) and the adjustable state (seeFIG. 5). The positioning structure24changes a state of the height adjustable seatpost assembly10between the locked state and the adjustable state.

In the locked state, as shown inFIGS. 4 and 6, the second tube22is fixed relative to the first tube20to prevent movement in the axial direction. Specifically, in the locked state, the overall length of the height adjustable seatpost assembly10is maintained at an adjusted overall length. In the locked state, the first tube20and the second tube22are fixedly positioned relative to each other in the telescopic directions D1and D2. In the adjustable state, as shown inFIG. 5, a position of the second tube22is adjustable relative to the first tube20in the telescopic directions D1and D2. Specifically, in the adjustable state, the overall length of the height adjustable seatpost assembly10is continuously adjustable within the adjustable range AR by operating the operated part16ato the operated position P1(seeFIG. 2). Namely, in the adjustable state, the positional relationship between the first tube20and the second tube22is continuously adjustable within the adjustable range AR. The adjustable state of the height adjustable seatpost assembly10is not limited to this embodiment. The total length of the height adjustable seatpost assembly10can be stepwise adjusted in the adjustable state. For example, the total length of the height adjustable seatpost assembly10can be stepwise adjusted at each of different lengths. Thus, the positioning structure24changes the state of the height adjustable seatpost assembly10between the locked state and the adjustable state. Specifically, the positioning structure24changes the state of the first tube20and the second tube22between the locked state and the adjustable state.

As shown inFIGS. 4 to 6, the positioning structure24includes a first fluid chamber31, a second fluid chamber32and a third fluid chamber33. Here, in the illustrated embodiment, the positioning structure24further includes a fourth fluid chamber34. The first and second fluid chambers31and32include an incompressible fluid35(shown as a non-shaded area for the sake of illustration). Specifically, the incompressible fluid35is filled in each of the first and second fluid chambers31and32. For example, the incompressible fluid35can be a hydraulic oil or any other suitable liquid.

As shown inFIGS. 4 to 6, the first chamber31is arranged downward from the second chamber32and on radially outside of the second chamber32. In this embodiment, the first chamber31is filled with oil as the incompressible fluid35.

As shown inFIGS. 4 to 6, the second chamber32is configured to be disposed closer to the first end portion22aof the second tube22than the first chamber31(seeFIGS. 4 to 6). The second chamber32is arranged outside the third fluid chamber33, for example, on the upper side of the third fluid chamber33.

As seenFIGS. 4 to 6, the third fluid chamber33is configured to expand as the valve body46is moved toward the valve seat48in the second telescopic direction D2, and is configured to shrink as the valve body46is moved away from the valve seat48in the first telescopic direction D1. The third fluid chamber33includes a compressible fluid36(shown as dots). The third fluid chamber33is arranged between the first chamber31and the second chamber32in the axial direction. In this embodiment, for example, the compressible fluid36can be air or any other suitable gas. Thus, the third fluid chamber33can be filled with air as the compressible fluid36.

As shown inFIG. 4, the fourth fluid chamber34is arranged on upper side of the first chamber31. The fourth fluid chamber34is arranged on radially outside of the second chamber32. Here, in the illustrated embodiment, the fourth fluid chamber34has a compressible fluid37(shown as dots). For example, the compressible fluid37can be air or any other suitable gas. In this embodiment, the compressible fluid such as air or gas is filled in the fourth fluid chamber34.

As shown inFIGS. 4 to 6, the positioning structure24further includes a movable piston40. The movable piston40is formed in a substantially cylindrical shape. The movable piston40is disposed between the first and fourth fluid chambers31and34to change a volume ratio between the first and fourth fluid chambers31and34. Specifically, the movable piston40is disposed in the space between the inner peripheral surface of the second tube22and the outer peripheral surface of the inner tube42in the radial direction. The movable piston40is configured to be movable between the second tube22and the inner tube42in the axial direction. In this way, the movable piston40is configured to be movable between the first chamber31and the fourth fluid chamber34in the axial direction. The compressible fluid37in the fourth fluid chamber34biases the movable piston40toward the first fluid chamber31.

As shown inFIGS. 4 to 6, the positioning structure24further comprises an inner tube42that is coaxially disposed inside the second tube22. As seen inFIG. 3, the inner tube42has an upper end42athat is coupled to the bottom of the air filling valve30. The fourth fluid chamber34is defined between the second tube22and the inner tube42with the air filling valve30in fluid communication with the fourth fluid chamber34for supplying the compressible fluid37therein. The movable piston40is slidably supported between the second tube22and the inner tube42.

As shown inFIGS. 4 to 6, the positioning structure24further includes a valve44. Basically, the valve44includes a valve body46and a valve seat48. The position of the valve body46is continuously adjustable relative to the valve seat48between the closed position and the open position. Here, the valve44also includes a biasing element50for biasing the valve body46towards the valve seat48. Thus, the biasing element50is configured to bias the valve body46toward the closed position. When the operated part16ais located at the rest position P0, the valve body46is in the closed position by the biasing force of the biasing element50. When the operated part16ais operated to the operated position P1, the actuator14transmits the operation force applied from the user operable input device16to the positioning structure24. Thereby, the valve body46moves relative to the support rod52from the closed position to the open position against a biasing force of the biasing element50. Here, the biasing element50is a coil compression spring that is disposed around the valve body46.

The valve44is partial disposed in a lower end42bof the inner tube42, and is supported by the first tube20via a support rod52. Thus, the valve body46is movable relative to the support rod52and the first tube20in the axial direction. The support rod52is disposed at the lower end42bof the inner tube42, and supports the actuator14. The support rod52is a hollow tube that is centered on the center axis A. Thus, the second tube22and the inner tube42slide with respect to the valve44during adjustment of the length (i.e., the height in the case of a seatpost) of the telescoping seatpost26.

Here, the valve44also includes a valve seat support54that is attached to the upper end of the support rod52. The valve seat48is coupled to the valve seat support54, while the valve body46is movably disposed inside the support rod52. The valve body46is connected to the actuator14by a connecting rod56. The connecting rod56receives the lower end of the valve body46such that axial movement of the connecting rod56is transmitted to the valve body46. In this way, the valve body46is moved in the axial direction by the operation of the actuator14. In other words, the actuator14is configured to move the valve body46to change the valve state from one of the closed state and the open state to the other of the closed state and the open state. In particular, the connecting rod56is attached to the valve body46for moving the valve body46relative to the valve seat48in the axial direction in response to movement of the actuator14by the user operable input device16. While the connecting rod56is illustrated as being hollow, it will be apparent from this disclosure that the connecting rod56does not need to be hollow, and can be modified as needed and/or desired.

In the closed state, the incompressible fluid35is immovable between the first chamber31and the second chamber32, and the movable piston40is also substantially stable. In the closed state, the bicycle seat S is held at an adjusted height position where a bicycle user sets. In this case, the incompressible fluid35doesn't move between the first chamber31and the second chamber32, because the port60is closed by the positioning structure24.

In the open state, the incompressible fluid35moves between the first and second chambers31and32as the second tube22moves relative to the first tube20in the axial direction. Then, the movable piston40moves in the axial direction by the movement of the incompressible fluid35. For example, the movable piston40moves downward as the incompressible fluid35moves from the first chamber31to the second chamber32. In this case, the fourth fluid chamber34expands, the first chamber31shrinks, and the second chamber32expands. Thereby, the bicycle seat S moves upward. Also, for example, the movable piston40moves upward as the incompressible fluid35moves from the second chamber32to the first chamber31. In this case, the fourth fluid chamber34shrinks, the first chamber31expands, and the second chamber32shrinks. Thereby, the bicycle seat S moves downward.

Here, in the illustrated embodiment, the valve body46includes a first portion46a, a second portion46band a third portion46c. While the first portion46a, the second portion46band the third portion46care illustrated as a one-piece member, the first portion46a, the second portion46band the third portion46ccould be made of two or more pieces. The first portion46acontacts the valve seat48. The second portion46bextends from the first portion46a, while the third portion46cis coupled to the second portion46bat an opposite end of the second portion46bfrom the first portion46a.

Here, in the illustrated embodiment, the positioning structure24further includes a dividing member58. The dividing member58is configured to receive an end portion of the valve body46. In particular, the dividing member58slidably receive the first portion46aof the valve body46. In this way, in the illustrated embodiment, the third fluid chamber33is defined between the dividing member58and the valve44. The dividing member58is attached to the valve seat support54. Specifically, the dividing member58forms the third fluid chamber33with the valve body46. The dividing member58is disposed in the inner tube42. The third fluid chamber33is configured such that the compressible fluid36biases the valve body46toward the valve seat48in the open state. The third fluid chamber33is configured to increase in volume as the valve body46is moved toward the valve seat48, and is configured to decrease in volume as the valve body46is moved away from the valve seat48. In the illustrated embodiment, the third fluid chamber33is configured to be disposed closer to the distal end22aof the second tube22than the first fluid chamber31.

As best seen inFIG. 5, the valve44defines a port60that is selectively opened and closed. In particular, the valve body46and the valve seat48defines the port60that is selectively opened and closed by axial movement of the valve body46relative to the valve seat48. The port60fluidly connects the first chamber31and the second chamber32between the valve body46and the valve seat48. The valve body46is configured to fluidly separate the first fluid chamber31from the second fluid chamber32in the closed state and to fluidly connect the first fluid chamber31to the second fluid chamber32in the open state. In other words, the valve body46is movable relative to the valve seat48in the axial direction to change a valve state between a closed state and an open state. As shown inFIGS. 4 and 5, the valve body46is movable in the first and second telescopic directions D1and D2between the open position to open the port60and the closed position to close the port60. In this way, the positioning structure24is configured such that the incompressible fluid35moves between the first chamber31and the second chamber32.

As shown inFIGS. 4 to 6, in the illustrated embodiment, the first chamber31is primarily defined by the second tube22, the movable piston40, the inner tube42, the valve body46and the support rod52. The second chamber32is primarily defined by the mounting structure28, the inner tube42and the dividing member58. The third fluid chamber33is primarily defined by the valve body46and the dividing member58. The fourth fluid chamber34is primarily defined by the second tube22, the mounting structure28, the movable piston40and the inner tube42.

As seen inFIG. 7, the valve seat48is disposed in the valve seat support54. Specifically, the valve seat48is disposed in a concave portion22cof the valve seat support54. For example, the valve seat48is formed in a substantially annular shape. The valve seat48includes a first tapered surface48athat contacts the valve body46in the closed state. The first tapered surface48ais formed on an inner peripheral portion of the valve seat48. Preferably, as in the illustrated embodiment, the valve body46includes a second tapered surface46a1configured to contact the valve seat48. As shown inFIG. 4, the valve body46is arranged in the valve seat48so as to contact the first tapered surface48aof the valve seat48when the valve44is in the closed state. Thus, the first tapered surface48aof the valve seat48is configured to contact the second tapered surface46a1of the valve body46while the valve44is in the closed state where the port60is closed. As shown inFIG. 5, the valve body46is arranged in the valve seat48so as to be spaced apart from the first tapered surface48aof the valve seat48when the valve44is in the open state.

A contact or sealing line is defined where the second tapered surface46a1of the valve body46contacts the first tapered surface48aof the valve seat48. For example, the contact line is formed in a substantially annular shape. The contact or sealing line can be zonal area with a prescribed axial width.

Also, preferably, as in the illustrated embodiment, at least part of the second tapered surface46a1includes a partial spherical surface. The first tapered surface48ahas a first axial end48a1and a second axial end48a2. The first tapered surface48ais configured such that a diameter of the first tapered surface48adecreases from the first axial end48a1toward the second axial end48a2. The first axial end48a1is disposed closer to the third fluid chamber33than is the second axial end48a2.

As seen inFIG. 7, the first fluid chamber31and the valve body46defines a first pressure-receiving dimension “a” while the valve40is in the closed state. More specifically, the first fluid chamber31and the first portion46aof the valve body46defines the first pressure-receiving dimension “a” while the valve body46is in the closed state. The first pressure-receiving dimension “a” is defined along an outer diameter of the first portion46aof the valve body46that is located in the third fluid chamber33. The first pressure-receiving dimension “a” is also defined by an inner diameter of the dividing member58. The third fluid chamber33and the valve body46defines a second pressure-receiving dimension “b” while the valve40is in the closed state. More specifically, the third fluid chamber33and the first portion46aof the valve body46defines the second pressure-receiving dimension “b” while the valve body46is in the closed state. The pressure-receiving dimension “b” is defined along the contact or sealing line that is defined where the second tapered surface46a1of the valve body46contacts the first tapered surface48aof the valve seat48. The second pressure-receiving dimension “b” is smaller than the first pressure-receiving dimension “a”. Since the second pressure-receiving dimension “b” is smaller than the first pressure-receiving dimension “a”, the downward load pressure acting on the first portion46aof the valve body46from the incompressible fluid35in the second chamber32is equal to the pressure receiving area defined by the second pressure-receiving dimension “b” minus the pressure receiving area defined by the second pressure-receiving the first pressure-receiving dimension “a”. As a result, the sealing performance of the valve44can be improved while still providing a light operating force to open the valve44using the operated part16a.

The first fluid chamber31and the third portion46cof the valve body46defines a third pressure-receiving dimension “c” while the valve body46is in the closed state. The second and third pressure-receiving dimensions “b” and “c” are equal. In the illustrated embodiment, these pressure-receiving dimensions “a”, b” and “c” refer to surface areas of the valve body46that receive a pressure in the axial direction. With this arrangement, adjustment of the length (i.e., the height in the case of a seatpost) of the telescoping seatpost26can be improved by providing a light operating force to open the valve44using the operated part16aat all times while suppressing a change in the operating force derived from the seating load.

As best seen inFIGS. 8 and 9, the positioning structure24further includes a check valve62that is disposed in a fluid passage64of the first fluid chamber31. The check valve62divides the first fluid chamber31into a first space S1and a second space S2. The check valve62is normally biased towards an open position as seen inFIG. 8so that the incompressible fluid35can freely flow between the first and second spaces S1and S2. When the valve44of the positioning structure24is in a closed position, as seen inFIG. 9, the incompressible fluid35is prevented from flow between the first and second spaces S1and S2.

When the valve44of the positioning structure24is switched from the closed state to the open state, the incompressible fluid35flows from the second fluid chamber32to the first fluid chamber31via the port60. Since the incompressible fluid35in the second fluid chamber32has a higher fluid pressure than the incompressible fluid35, a volume change occurs during the switching operation of the valve44of the positioning structure24. The third fluid chamber33with the compressible fluid36compensates for this volume change that occurs during the switching operation of the valve44of the positioning structure24. With this arrangement, the volume change does not affect the check valve62, so that the check valve62do not becoming stuck during the switching operation of the valve44of the positioning structure24.

In the illustrated embodiment, the check valve62includes a valve body66and a biasing member68. An end plug70is fixed to the second end portion22bof the second tube22, and supports the check valve62on the second tube22so that the check valve62moves with the second tube22as the second tube22moves axially relative to the first tube20. The valve body66is a substantially annular member that is slidable disposed around the support rod52for movement in the axial direction. The biasing element68is a coil compression spring that is disposed around the support rod52. The end plug70acts as an abutment for the biasing element68, and also aids in supporting the support rod52. The biasing element68applies a biasing force on the valve body66to urge the valve body66towards the open position as seen inFIG. 8.

With the valve44is in the open state, the bicycle seat S and the second tube22moves upward with respect to the first tube20due to the force of the compressible fluid37applying a force on the movable piston40in a downward direction which causes the incompressible fluid35to flow from the first fluid chamber31to the second fluid chamber32via the fluid passage64and the port60. More specifically, with the check valve62in the open position, the incompressible fluid35is forced upward through the fluid passage64by the downward movement of the movable piston40. Then, with the valve44is in the open state, the incompressible fluid35is forced upward through the port60from the first fluid chamber31to the second fluid chamber32to force the bicycle seat S and the second tube22moves upward with respect to the first tube20. When the incompressible fluid35is forced upward through the port60, the valve body66is pressed upward by flow of the incompressible fluid35and the compressible fluid36in the third chamber33is compressed.

However, in case that the bicycle seat S is pushed down with the valve44is in the open state, the valve body66moves upward with respect to the sealing plug36by the sliding resistance between the valve body66and the second support member22b. In this case, the incompressible fluid35moves from the second fluid chamber32to the first fluid chamber31via the port60. Also, the incompressible fluid35passes through the fluid passage64towards the movable piston40, since the check valve62is held in the open position by the biasing element68.

In case that the bicycle seat S is pulled up with the valve44is in the closed state, the valve body66moves downward with respect to the end plug70is fixed to the second end portion22bof the second tube22against the force of the biasing element68as seen inFIG. 9. Specifically, the pressure of the incompressible fluid35increases in space between the port60and the valve body66to move the valve body66downward overpowering the force of the biasing element68. Thus, the valve body66is pressed downward by the incompressible fluid35abut against the end plug70to close an annular gap72between the end plug70and the support rod52. In this way, the valve body66prevents the incompressible fluid35in the first fluid chamber31from flowing from the second space S2towards toward the first space S1. Thereby, the incompressible fluid35in the first fluid chamber31is substantially stable by the check valve62, even if the bicycle seat S is manually pulled up while the valve44is in the closed state.

As used herein, the following directional terms “frame facing side”, “non-frame facing side”, “forward”, “rearward”, “front”, “rear”, “up”, “down”, “above”, “below”, “upward”, “downward”, “top”, “bottom”, “side”, “vertical”, “horizontal”, “perpendicular” and “transverse” as well as any other similar directional terms refer to those directions of a bicycle in an upright, riding position and equipped with the fluid flow control structure. In other words, directions terms are determined based a rider who sits on a bicycle seat of a bicycle with facing a bicycle handlebar. Similarly, the terms “left” and “right” are used to indicate the “right” when referencing from the right side as viewed from the rear of the bicycle, and the “left” when referencing from the left side as viewed from the rear of the bicycle.

Also, it will be understood that although the terms “first” and “second” may be used herein to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, for example, a first component discussed above could be termed a second component and vice versa without departing from the teachings of the present invention. The term “attached” or “attaching”, as used herein, encompasses configurations in which an element is directly secured to another element by affixing the element directly to the other element; configurations in which the element is indirectly secured to the other element by affixing the element to the intermediate member(s) which in turn are affixed to the other element; and configurations in which one element is integral with another element, i.e. one element is essentially part of the other element. This definition also applies to words of similar meaning, for example, “joined”, “connected”, “coupled”, “mounted”, “bonded”, “fixed” and their derivatives. Finally, terms of degree such as “substantially”, “about” and “approximately” as used herein mean an amount of deviation of the modified term such that the end result is not significantly changed.