JP4921415B2 - Front fork - Google Patents

Description

  The present invention relates to a front fork, and more particularly, to an improvement in a front fork that is a hydraulic shock absorber that is mounted on a front wheel side of a two-wheeled vehicle and absorbs road surface vibration that is input to the front wheel.

  There have been various proposals for a front fork that is a hydraulic shock absorber that is mounted on the front wheel side of a two-wheeled vehicle and absorbs road surface vibrations input to the front wheel. A damper is built in as disclosed in FIG.

  That is, in the front fork disclosed in this document, an upright damper is housed together with a suspension spring in a fork body composed of a vehicle body side tube and a wheel side tube, and the inside of the fork body outside the damper is used as a reservoir chamber. ing.

  The reservoir chamber contains a sufficient amount of hydraulic oil to put the most extended damper in an oil-immersed state, and has an air chamber with the oil surface as a boundary. Demonstrates air spring force due to expansion and contraction of the air chamber.

  The suspension spring is disposed between the vehicle body side tube and the wheel side tube, and urges the fork main body in the extending direction by the spring force together with the air chamber.

  The damper is inserted into the cylinder body standing in the wheel side tube so that the rod body suspended in the vehicle body side tube can be projected and retracted. The damper is slidably mounted in the cylinder body and connected to the rod body. The piston side chamber defines the rod side chamber and the piston side chamber.

  In this damper, the rod side chamber and the piston side chamber in the cylinder body can communicate with each other via the damping means disposed in the piston body, and the damping means has a predetermined damping when the hydraulic oil passes through. Generate power.

  When the piston body descends in the cylinder body and the piston side chamber contracts, excess hydraulic oil in the piston side chamber flows out into the reservoir chamber, and conversely, the piston body rises in the cylinder body and the piston side chamber When expanding, the hydraulic fluid that is insufficient in the piston side chamber is replenished from the reservoir chamber.

Therefore, according to the front fork disclosed in this document, when the fork main body expands and contracts, the dampers expand and contract in synchronism to absorb road vibrations input to the front wheels of the two-wheeled vehicle with a predetermined damping action.
Japanese Patent Laid-Open No. 2002-181106 (see FIG. 1)

  However, the front fork disclosed in the above-mentioned literature is not basically problematic in that it can realize a predetermined damping action, but there is a minor problem in its implementation. May be pointed out.

  That is, in the above proposal, the lower end of the damper is coupled to the inner bottom of the wheel side tube, and the oil level position of the reservoir chamber is set from the relationship of the air spring when the fork body is extended and contracted, so that the damper stroke is small. When the damper is housed in the fork main body, the hydraulic oil is stored in an amount that is more than the amount that guarantees the operation of the damper.

  As a result, when viewed as a front fork as a whole, the amount of hydraulic oil stored in the fork main body is increased, which is disadvantageous in terms of weight and easily incurs disadvantages in terms of product cost.

  The present invention was devised in view of such a current situation, and an object of the present invention is to reduce the weight by making the amount of hydraulic oil accommodated in the inside necessary for the operation of the damper. It is to provide a front fork that is optimal for reducing product costs and expecting improved versatility.

  In order to achieve the above-described object, the front fork according to the present invention basically has a fork main body composed of a vehicle body side tube and a wheel side tube accommodated in a reservoir chamber while accommodating a damper. The cylinder body is arranged in the wheel side tube, and the rod body that is inserted into the cylinder body so as to be able to protrude and retract while forming the damper is also suspended in the body side tube, and is slidably accommodated in the cylinder body. The piston body connected to the rod body defines a rod side chamber and a piston side chamber in the cylinder body, and the rod side chamber and the piston side chamber communicate with each other via a damping means disposed in the piston body. The bottom end portion that closes the lower end opening has a base valve portion, and the piston side chamber in the cylinder body is communicated with the reservoir chamber via the base valve portion. In the front fork, and air chamber which is isolated from the reservoir chamber below the bottom end for closing the lower end opening of the cylinder body is being defined.

  Therefore, according to the present invention, an air chamber that is blocked from the reservoir chamber is defined below the bottom end portion that closes the lower end opening of the cylinder body. The amount corresponding to the volume of the chamber can be reduced, reducing the weight of the front fork and reducing the product cost.

  Hereinafter, the present invention will be described based on the illustrated embodiment. As shown in FIGS. 1 and 2, the front fork according to the present invention includes a fork main body including a vehicle body side tube 1 and a wheel side tube 2. The interior is a reservoir chamber R, and a damper is housed in the shaft core portion while being urged in the extending direction by a suspension spring S.

  The fork main body is set to an inverted type in which the upper end side of the wheel side tube 2 made of a small diameter inner tube is inserted into the lower end side of the vehicle body side tube 1 made of a large diameter outer tube so as to be able to protrude and retract.

  The vehicle body side tube 1 is connected to an upper bracket B1 (see FIG. 2) and an under bracket B2 (see FIG. 2). The upper bracket B1 connects a handle (not shown), and the wheel side tube 2 has a lower end portion. Thus, the front wheel (not shown) is suspended, and therefore the front wheel is turned through the fork body by turning the handle.

  On the upper end side of the wheel side tube 2 inserted through the lower end side of the vehicle body side tube 1, there are a plurality of holes 2a (see FIG. 2) that allow internal and external communication, and the vehicle body side tube through these holes 2a. Inflow of oil between 1 and the wheel side tube 2 is permitted, and lubrication between the two is ensured.

  The inside of the fork main body is a reservoir chamber R, and the oil level O is positioned so that a cylinder body 3 as a lower member of a damper, which will be described later, is in an oil-immersed state even when the fork main body is fully extended. This air chamber A exhibits an air spring effect when the fork body is extended and contracted.

  The suspension spring S accommodated in the fork main body is supported on the cap member 11 whose lower end is supported by the head end portion 3a of the cylinder body 3 constituting the damper, and whose upper end closes the upper end opening of the vehicle body side tube 1. 2) and the push member 13 (see FIG. 2).

  The damper is set to a single rod type, and is set to an upright type in which a rod body 4 that is an upper member is inserted into a cylinder body 3 that is defined as a lower member and is defined as a reservoir chamber R. Has been.

  The cylinder body 3 is disposed on the shaft core portion of the wheel-side tube 2, and the rod body 4 has a lock nut 41 (see FIG. 2) on a holder member 14 (see FIG. 2) whose upper end portion is screwed to the cap member 11 described above. 2) and suspended from the shaft core portion of the vehicle body side tube 1.

  The cylinder body 3 is coupled to the inner bottom of the bottom member 21 that closes the lower end opening of the wheel-side tube 2 via a sub-cylinder body 31 formed to have substantially the same diameter as the cylinder body 3 connected to the bottom end portion 3b. The outer periphery of the head end 3a is separated from the inner periphery of the wheel-side tube 2, and the reservoir chamber R portion above the head end 3a and the reservoir chamber R outside the cylinder body 3 below the head end 3a. It communicates with the part.

  The bottom end portion 3b of the cylinder body 3 has an outer periphery adjacent to the inner periphery of the wheel side tube 2 and stabilizes the upper end of the sub cylinder body 31 connected to the bottom end portion 3b. (See FIG. 2), the reservoir chamber R portion above the bottom end portion 3b communicates with the reservoir chamber R portion outside the sub-cylinder body 31 below the bottom end portion 3b.

  Although the sub cylinder body 31 is integrally connected to the cylinder body 3 via the bottom end portion 3b, the sub cylinder body 31 is integrally formed with the cylinder body 3, although not shown in the figure. The bottom end portion 3b may be inserted inside with a seal member interposed therebetween, and the bottom end portion 3b may be fixed by roll caulking on the outer periphery of the cylinder body 3 or the like.

  As described above, the rod body 4 is connected to the vehicle body side tube 1 under the intervention of the lock nut 41, the holder member 14, and the cap member 11 and is suspended from the shaft core portion of the vehicle body side tube 1. The base end passes through the head end 3 a of the cylinder body 3 and is connected to the receiving piston body 5 so as to be slidable in the cylinder body 3.

  A bearing 3d is disposed at the head end 3a of the cylinder body 3, and the rod body 4 passes through the bearing 3d (see FIG. 2).

  The piston body 5 defines a rod-side chamber R1 and a piston-side chamber R2 in the cylinder body 3, and the rod-side chamber R1 and the piston-side chamber R2 are arranged in parallel with a damping valve 5a serving as a damping means arranged in the piston body 5. The check valve 5b can communicate with each other, and the damping valve 5a generates a predetermined damping force when the hydraulic oil passes through.

  In the above description, the damping means is composed of the damping valve 5a. However, this is for convenience of explanation, and in the specific embodiment shown in FIG. 2, the damping means is the damping valve. A damping valve may be provided in addition to 5a, and the other damping valve may function as the check valve 5b.

  On the other hand, the damper shown in the figure has a base valve portion 6 at the bottom end portion 3b that closes the lower end opening of the cylinder body 3, and the piston side chamber R2 in the cylinder body 3 is connected to the reservoir via the base valve portion 6. It communicates with chamber R.

  The base valve section 6 has a damping valve 6a and a check valve 6b in parallel with the damping valve 6a (see FIG. 1), and when hydraulic fluid from the piston side chamber R2 flows into the reservoir chamber R. When the hydraulic oil from the reservoir chamber R flows into the piston side chamber R2 through the damping valve, it passes through the check valve 6b.

  Therefore, in the damper formed as described above, when the fork main body expands and contracts, the rod body 4 protrudes and retracts in synchronization with the cylinder body 3 and expands and contracts to perform a predetermined damping action. To do.

  That is, in the damper, for example, when the piston body 5 moves up in the cylinder body 3, the hydraulic oil from the rod side chamber R <b> 1 passes through the damping valve 5 a serving as damping means disposed in the piston body 5. At this time, a predetermined damping force is generated by the damping valve 5a.

  Further, in the damper, contrary to the above, when the piston body 5 is contracted to descend in the cylinder body 3, the hydraulic oil from the piston side chamber R <b> 2 is inserted into the rod via the check valve 5 b disposed in the piston body 5. It flows into the side chamber R1.

  Then, an insufficient amount of hydraulic oil in the piston side chamber R2 during the extension operation is replenished from the reservoir chamber R via the check valve 6b in the base valve portion 6, and an excess amount of hydraulic oil in the piston side chamber R2 during the contraction operation of the damper. Flows out into the reservoir chamber R through the damping valve 6a in the base valve portion 6, and a predetermined damping force is generated in the damping valve 6a.

  By the way, in the front fork of the present invention, the air chamber A1 is defined below the damper in the fork main body, and the amount of hydraulic oil stored in the fork main body is reduced by defining the air chamber A1. In addition, the weight can be reduced and the product cost can be reduced.

  That is, in the above-described FIGS. 1 and 2, the bottom end portion 3 b that closes the lower end opening of the cylinder body 3 has the base valve portion 6, and the upper end portion of the sub-cylinder body 31 is connected under an airtight structure. At the same time, the lower end portion of the sub-cylinder body 31 is coupled to the inner bottom portion of the wheel side tube 2 under an airtight structure, and the sub-cylinder body 31 below the bottom end portion 3b is an air chamber that is blocked from the reservoir chamber R. Yes.

  Therefore, according to this embodiment, the amount of hydraulic oil stored in the fork main body is reduced as well as the air chamber A1 is defined, and the sub cylinder body 31 and the wheel side tube 2 The hydraulic oil flows into the gap between them, and therefore the hydraulic oil flowing into the gap is cooled at the atmospheric temperature.

  3 and 4 show a front fork according to another embodiment of the present invention. In each embodiment, there is a feature in the structure forming the air chamber A1, and the other structure is shown in FIG. 1 described above. The same is true.

  Therefore, in the description based on FIG. 3 and FIG. 4, where the configuration is the same as that shown in FIG. .

  3, a seal member 7 is disposed between the upper end portion of the sub-cylinder body 31 and the wheel side tube 2, and a reservoir chamber above the seal member 7 is disposed below the seal member 7. The air chamber A1 is cut off from the R, and the air chamber A1 is formed so as to extend inside and outside the sub cylinder body 31 through a communication hole 31a opened in the sub cylinder body 31.

  Therefore, according to the embodiment shown in FIG. 3, the amount of hydraulic oil stored in the fork main body is reduced by the amount of the air chamber A1, and the sub cylinder body 31 is connected to the communication hole. Since it has 31a, the weight in the subcylinder body 31 can be reduced accordingly.

  4, the bottom end 3b that closes the lower end opening of the cylinder body 3 is connected to the wheel side tube 2 under the seal member 7, and the reservoir chamber R and the bottom end 3b are located below the bottom end 3b. The air chamber A1 to be blocked is defined.

  Therefore, in the case of the embodiment shown in FIG. 4, the amount of hydraulic oil stored in the fork main body is reduced as much as the air chamber A1 is defined. Since the sub cylinder body 31 is not necessary, the weight can be further reduced.

  As described above, the fork main body is set upside down. However, from the point of view of the present invention, the fork main body may be set upright. The effect is not different.

1 is a longitudinal sectional view showing in principle a front fork according to an embodiment of the present invention. FIG. 2 is a half-longitudinal longitudinal front view specifically showing the front fork of FIG. 1. It is a figure which shows the front fork by other Embodiment of this invention similarly to FIG. It is a figure which shows the front fork by other embodiment similarly to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body side tube 2 Wheel side tube 3 Cylinder body 3b Bottom end part 4 Rod body 5 Piston body 5a Damping means 6 Base valve part 7 Seal member A, A1 Air chamber R Reservoir chamber R1 Rod side chamber R2 Piston side chamber

Claims (4)

A fork body consisting of a vehicle body side tube and a wheel side tube accommodates a damper while making the inside a reservoir chamber, and a cylinder body constituting the damper is disposed in the wheel side tube. A rod body that can be inserted and retracted is suspended in the vehicle body side tube, and a piston body that is slidably received in the cylinder body and connected to the rod body defines a rod side chamber and a piston side chamber in the cylinder body. The rod side chamber and the piston side chamber are communicated with each other through a damping means disposed in the piston body, and the bottom end portion that closes the lower end opening of the cylinder body has a base valve portion. In the front fork in which the piston side chamber in the cylinder body communicates with the reservoir chamber, a reserve is provided below the bottom end portion that closes the lower end opening of the cylinder body. Front fork air chamber is blocked and the chamber is characterized by comprising defined. The bottom end part which closes the lower end opening of a cylinder body is connected to the wheel side tube under arrangement | positioning of the sealing member, and the air chamber which is interrupted | blocked with a reservoir chamber under the bottom end part is defined. Front fork. The bottom end that closes the bottom opening of the cylinder body is connected to the top end of the sub-cylinder body that has the same diameter as the cylinder body under an airtight structure, and the bottom end of the sub-cylinder body is airtight to the inner bottom of the wheel side tube. The front fork according to claim 1, wherein an air chamber is formed in the sub-cylinder body and is cut off from the reservoir chamber. A seal member is arranged between the upper end portion of the sub cylinder body and the wheel side tube so that the lower portion of the seal member is blocked from the reservoir chamber above the seal member and a communication hole is opened in the sub cylinder body. The front fork according to claim 3, wherein the inner and outer sides of the sub-cylinder body are air chambers that are blocked from the reservoir chamber.

Images