Adjustment device for bicycle seat

[0001] The present invention relates to an adjustment device, and more particularly, to an adjustment device for adjustment of height of bicycle seat by the use of hydraulic power.

[0002] A bicycle includes a seat post which is connected with a seat on a top end thereof and the seat post is inserted into the seat tube of the bicycle frame. The seat post can be adjusted along longitudinal axis of the seat tube to set the seat at desired height to meet needs of different users. The adjustment for the seat can be made in two different ways, one of which is to adjust the inclination of the seat relative to the horizontal plane and the other is to adjust the height of the seat relative to the ground. The present invention is developed to the adjustment device for adjustment the height of the bicycle seat.

[0003] The conventional methods for adjustment of the seat can be made by mechanical method and by hydraulic method. The mechanical method includes a lever which controls a control unit and the seat post can be adjusted relative to the seat tube by operation of the control unit.

[0004] The hydraulic method includes an adjustment unit which includes an adjustment member which is connected to the top end of the seat tube and has an adjustment tube which is connected to the seat tube so as to form an inner space and an outer space between the seat tube and the adjustment member. A path is defined between the adjustment member and the adjustment tube so as to communicate with the inner and outer spaces. An adjustment valve rod movably extends through the path so as to open or close the passages of the adjustment unit. By operation of the adjustment valve rod, the seat post can be set to a desired height.

[0005] However, the mechanical method can only provide two-position adjustment to the seat and this may not able to meet requirements for different users. The hydraulic method can set the seat at different heights by adjust the hydraulic fluid between the inner and outer spaces. However, the seat tube and the seat post both require a larger space to accommodate the inner and outer spaces, and the air room and fluid room. The wider and larger seat post and seat tube make the bicycle to be bulky and heavy.

[0006] The present invention intends to provide a seat adjustment device which includes a balance unit which is mounted to the seat post and the balance unit provide the device necessary space for the hydraulic fluid and air so that the sizes of the seat post and seat tube do not change.

[0007] The present invention relates to an adjustment device for bicycle seat and the adjustment device comprises a seat tube and a seat post is movably inserted into the seat tube. The seat post includes a connection portion located close to a top of the seat post and at least one through hole is defined through a wall of the connection portion. A seat connector is connected to the top of the seat post to be connected with a seat. An adjustment device is located between the seat connector and the seat post so as to control movement between the seat post relative to the seat tube. The adjustment device includes an adjustment path which is controlled to be in communication with the at least one through hole or to be isolated from the at least one through hole. A balance unit is connected to the connection portion and includes a cylinder with a piston ring movably received therein which defines an inner space of the cylinder into a liquid space and an air space. The cylinder includes a supply path which communicates with the liquid space and the at least one through hole.

[0008] The primary object of the present invention is to provide an adjustment device which includes an exterior balance unit which provides spaces for hydraulic liquid and air so that the size for the seat tube and seat post can be maintained the same.

[0009] Another object of the present invention is to provide an adjustment device which can adjust the seat post with longer travel distance when compared with the conventional adjustment device.

[0010] Yet another object of the present invention is to provide an adjustment device which can adjust the seat to any desired position to meet requirements of different users.

[0011] The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.

[0030] Referring to FIGS. 1 to 7, the adjustable bicycle seat includes a seat tube 10 and a seat post 20 which has a lower end movably inserted into the seat tube 10 and a seat connector 30 is connected to a top of the seat post 20 so as to be connected with a bicycle seat which is not shown. The seat post 20 includes a connection portion 21 located close to a top of the seat post 20 and the connection portion 21 includes stepped outer surface and four through holes 22 are defined through the wall of the connection portion 21 and located at the narrowest portion of the stepped outer surface,

[0031] An adjustment device 40 includes a control unit 50 and an adjustment unit 60. The control unit 50 is located between the seat connector 30 and the seat post 20 so as to control movement between the seat post 20 relative to the seat tube 10. The control unit 50 includes an adjustment path 51 which is controlled to be in communication with the through holes 22 or to be isolated from the through holes 22. The control unit 50 further includes an adjustment member 52 which is connected to the top of the seat post 20 and a central passage 53 is defined centrally through the adjustment member 52. The adjustment path 51 is defined between the adjustment member 52 and the central passage 53 so as to communicate with the at least one through hole 22 and the liquid room 62 which will be described later. A cap 55 is movably inserted in the seat connector 30 and located above a valve rod 54 which movably extends through the central passage 53 from the lower end of the adjustment member 52 and controls communication of the adjustment path 51. A spring 56 is located between the adjustment member 52 and the cap 55 so as to provide an upward force to the cap 55. A lever 57 is pivotably connected to the seat connector 30 and has a push end 571 which contacts the top of the cap 55.

[0032] The adjustment unit 60 includes a guide rod 61 which is inserted into the seat post 20 and a lower end of the guide rod 61 is fixed to the seat tube 10. The liquid room 62 is defined between a top end of the guide rod 61 and the seat post 20. A collar 63 is located in the lower end of the seat post 20 and the guide rod 61 extends through the collar 63. A positioning member 64 is connected in the lower end of the seat tube 10 and a lower end of the guide rod 61 is fixed to the positioning member 64. An air room 65 is defined between the collar 63, the positioning member 64 and an inner periphery of the seat tube 10.

[0033] A balance unit 70 is connected to the connection portion 21 and includes a cylinder 71 and a piston ring 72 is movably received in the cylinder 71. The piston ring 72 defines an inner space of the cylinder 71 into a liquid space 711 and an air space 712. The balance unit 70 includes a mounting ring 73 which is integral to the cylinder and mounted to the connection portion 21. The cylinder 71 includes a supply path 74 which communicates with the liquid space 711, the inner periphery of the mounting ring 73 and the through holes 22. A seal member 75 is used to seal the air space 712 and an air valve 76 is connected to the seal member 75 so that air is introduced into the air space 712. An inlet 713 is defined through a wall of the cylinder 71 and communicates with the liquid space 711 so that hydraulic fluid can be supplied to the fluid room via the inlet 713. A seal piece 77 seals the inlet 713.

[0034] The hydraulic fluid is supplied via the inlet 713 and fills the liquid room 62, the adjustment path 51, the central passage 53, the through holes 22, the supply path 74 and the liquid space 711 when the adjustment path 51 is not sealed. The adjustment path 51 communicates all of the paths and passages of the adjustment device, such as the liquid room 62, the adjustment path 51, the central passage 53, the through holes 22, the supply path 74 and the liquid space 711.

[0035] As shown in FIGS. 8 to 12, when pivoting the lever 57 upward, the push end 571 pushes the cap 55 downward and the valve rod 54 is lowered so that the lower end of the valve rod 54 does not seal the adjustment member 52, the hydraulic in the liquid room 62 flows to the central passage 53 and the through holes 22, this means that the adjustment path 51 is in an opened status so that the seat post 20 can be moved relative to the seat tube 10.

[0036] When the seat post 20 is adjusted to a lower position, the hydraulic fluid in the liquid room 62 flows into the liquid space 711 in the cylinder 71 via the adjustment path 51. The piston ring 72 moves toward the air space 712 to compress the air space 712 as shown FIGS. 9 and 10. As shown in FIGS. 9 and 11, when adjusting the seat at a higher position, the pressure in the air space 712 in the cylinder 71 of the balance unit 70 pushes the piston ring 72 toward the liquid space 711 so that the hydraulic liquid in the liquid space 711 is supplied to the liquid room 62 via the adjustment path 51. The piston ring 72 moves to a position where the pressures on two sides of the piston ring 72 obtain a new balance.

[0037] As shown in FIGS. 13 and 14, when the seat is adjusted to a desired position, the lever 57 is released and the spring 56 pushes the cap 55 upward and pivots the lever 57 downward. On the other hand, the pressure in the liquid room 62 pushes the valve rod 54 upward to seal the adjustment member 52 so that the adjustment path 51 is closed and the seat is set at the position.

[0038] The balance unit 70 is connected exteriorly to the seat post 20 and provides sufficient hydraulic fluid to the seat post 20 so that the seat tube 10 and the seat post 20 do not need to change. The volume of the cylinder 71 of the balance unit 70 can be adjusted to meet the need of the travel distance of the seat post 20. The bicycle frame does not need to make any amendment and only the balance unit 70 should be changed. The seat can be adjusted to any desired position.

[0039] It is noted that the pressure of air in the air space 712 can be adjusted via the air valve 76 and the volume of the hydraulic fluid can be adjusted via the inlet 713. The guide rod 61 is located within the seat post 20 so that the seat post 20 can move along the guide rod 61 without worry of shaking.

[0040] FIGS. 15 to 18 show another embodiment, wherein the connection portion 21 includes a protrusion and the through holes 22 are defined through the protrusion. A tube unit 80 is connected between the connection portion 21 and the balance unit 70 so as to communicate the at least one through hole 22 and the supply path 74. The tube unit 80 includes two connection members 81 with a tube 82 connected therebetween, the two connection members 81 are respectively connected to the through holes 22 and the supply path 74.

[0041] The balance unit 70 can be installed on any desired portion of the bicycle frame and is connected the adjustment device 40 by the tube unit 80. As shown in FIG. 17, when the seat post 20 is adjusted to a lower position, the hydraulic fluid flows through the through holes 22, the supply path 74, the connection member 81, the tube 82, the other connection member 81 and enters into the liquid space 711. When the seat post 20 is adjusted to a higher position, as shown in FIG. 18, the hydraulic fluid flows from the liquid space 711, the connection member 81, the tube 82, the other the connection member 81, the supply path 74, through the through holes 22, and enters into the liquid room 62.

[0042] The adjustment device of the present invention can be applied to most of the conventional bicycles without too much change in their structure. The seat tube 10 and the seat post 20 can be maintained the same, and the operation is easy. The seat can be adjusted to any desired position.

[0043] While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.