JP5281328B2 - Front fork - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform a predetermined damping action by a damper as set beforehand by reducing the sliding resistance of a free piston in a volume compensation chamber of the built-in damper. <P>SOLUTION: The free piston P which is moved backward by a hydraulic action from the inside of a cylinder body 3 forming the damper D to release hydraulic pressure in the cylinder body 3 includes a pair of left and right sides. The upper end of free piston is joined to the handle side, and the lower end thereof is located outside a fork body F for suspending a front wheel, and slidably stored in a housing H which is a part of a flow passage L communicating with the inside of the cylinder body 3 and a gas chamber A in the fork body F. An oil chamber R3 communicating with the inside of the cylinder body 3 and a rear side gas chamber A1 communicating with the gas chamber A are demarcated in the housing H. The hydraulic pressure from the inside of the cylinder body 3 is released to the rear side gas chamber A1 when the free piston P is moved backward a predetermined stroke by the hydraulic action from the inside of the cylinder body 3. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

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 the front wheel side of a two-wheeled vehicle and absorbs road surface vibrations that are input to the front wheel of the two-wheeled vehicle that is running.

  Conventionally, various proposals have been made 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 that are input to the front wheel of a traveling two-wheeled vehicle.

  For example, Patent Document 1 discloses a proposal in which a damper is provided in a fork main body that is urged in an extension direction by a suspension spring while a vehicle body side tube and a wheel side tube are connected in a retractable manner.

  In this proposal, the damper has compression side damping means that enables generation of compression side damping force during compression operation in the upper end portion of the cylinder body coupled to the upper end portion of the vehicle body side tube, and downstream of the compression side damping means. A volume compensation chamber having an air chamber defined by a free piston is provided above the side.

  This volume compensation chamber operates in the damper by, for example, expansion of the hydraulic oil due to an increase in the oil temperature in the damper, or when the hydraulic oil from the reservoir outside the cylinder body flows into the damper during the operation of the damper. When the amount of oil exceeds a predetermined amount, the above-mentioned free piston is raised so as to be retracted beyond a predetermined stroke, and the cylinder body is released so as to return surplus working oil to the reservoir through the open communication hole.

Therefore, in this damper, when the amount of hydraulic oil in the damper is a predetermined amount, the inside of the cylinder tends to be pressurized by the urging force of the pressure spring adjacent to the back surface of the free piston and the reaction force of the air chamber. Maintained.
JP-A-6-147248 (see abstract, claim 1, claim 2 and FIG. 2)

  In the front fork disclosed in the above document, the free piston in the volume compensation chamber of the damper is slidably accommodated in the upper end portion of the cylinder body coupled to the upper end portion of the vehicle body side tube under the arrangement of the seal member. On the other hand, a guide rod that is suspended from the upper end portion of the vehicle body side tube and holds the partition body having the compression side damping means is passed through the shaft core portion under the seal member.

  Therefore, the free piston causes the seal member to slide in contact with the outside and the inside of the free piston, increasing the sliding resistance, and not expecting smooth operation in the fork body, that is, the front fork. Make it worse.

  The present invention has been developed in view of such a current situation, and an object of the present invention is to reduce a sliding resistance of a free piston in a volume compensation chamber of a built-in damper, thereby reducing a predetermined amount by the damper. It is possible to provide a front fork that is optimal for expecting an improvement in its versatility.

In order to achieve the above-described object, the configuration of the front fork according to the present invention includes a fork main body in which the upper end is coupled to the handle side and the front wheel is suspended at the lower end, and the fork main body is accommodated in the fork main body. a damper for a predetermined damping action during stretching operation, the front fork for chromatic and volume compensation chamber which is to be compensated by expansion and contraction of the back-side air chamber defining behind the free piston the oil volume changes in the damper The fork main body is a pair of left and right, each reservoir chamber has an air chamber with an oil surface as a boundary, and the damper is inserted into the cylinder body, a rod body that is removably inserted into the cylinder body, and the rod body And a piston body that is slidably received in the cylinder body and defines a compression side chamber in the cylinder body, and the volume compensation chamber is A housing provided outside the ark body and provided in a flow path in which the pressure side chamber in one damper communicates with the air chamber of the other fork main body, and a free slidably received in the housing A piston, an oil chamber defined in the housing by the free piston, and the rear air chamber; the oil chamber communicates with the pressure side chamber of one damper and the pressure side chamber of the other damper The rear air chamber communicates with the air chamber of one fork main body and the air chamber of the other fork main body, and the housing expands the inner diameter of the rear air chamber to increase the inner diameter. It is assumed that a hydraulic pressure release path communicating with the air chamber is provided, and that the hydraulic pressure in the oil chamber can be released via the hydraulic pressure release path when the free piston moves backward .

  Therefore, in the present invention, the free piston is provided outside the fork main body so as to be slidable in the housing which is a part of the flow path communicating with the cylinder inside the damper and the air chamber inside the fork main body. Since it is housed, the sliding resistance of the free piston is limited to that of the housing, and stable sliding of the free piston can be expected as compared to the case where other members are brought into sliding contact.

  Since the free piston is connected to the left and right fork main bodies with the flow paths constituting the housing for housing the left and right fork main bodies, it is possible to make the hydraulic action in the left and right fork main bodies the same. You can expect synchronized operation on the fork.

Hereinafter, the present invention will be described based on the illustrated embodiment. The front fork according to the present invention is paired on the left and right as shown in FIG. fork and fork body F for suspending a front wheel at the lower end, and the damper D which is housed in the fork main body F to a predetermined damping action during expansion and contraction operation of the fork main body F, the oil amount change in the damper D A volume compensation chamber T that compensates outside the main body F, and a change in the oil amount in the damper D is defined by a free piston P in a housing H that forms the volume compensation chamber T. Compensated by contraction .

  The fork main body F has a vehicle body side tube 1 coupled to a handle side of a two-wheeled vehicle via a fork bracket (not shown), and a wheel side tube 2 for suspending a front wheel of the two-wheeled vehicle at a lower end portion. The upper end side part of the wheel side tube 2 is connected to the side part so as to be retractable and extendable, and is set to an inverted type that is urged in the extension direction by the internal suspension spring S.

  From the point of realization of the present invention, the fork main body F may be set upright with the vehicle body side tube 1 inserted into the wheel side tube 2.

  The damper D accommodated in the fork main body F has a rod body 4 erected on the shaft core portion of the wheel side tube 2 in the lower end side portion of the cylinder body 3 suspended from the shaft core portion of the vehicle body side tube 1. It is set to an inverted type that allows the upper end side portion to be inserted and retracted.

  The suspension spring S has a lower end supported on the bottom portion 2 a of the wheel-side tube 2 and an upper end engaged with the lower end portion 3 a of the cylinder body 3.

  The damper D is slidably accommodated in the cylinder body 3 while being held at the upper end of the rod body 4, and defines an extension side chamber R1 and a pressure side chamber R2 in the cylinder body 3. It has the piston body 5 which does.

  In this damper D, the piston body 5 has extension side damping means 5a that allows the extension side chamber R1 and the compression side chamber R2 to communicate with each other. The extension side damping means 5a is an extension of the damper D. During operation, the extension side chamber R1 and the compression side chamber R2 are connected to generate a predetermined damping force.

  On the other hand, the damper D shown in the figure has a compression side damping means 6 for generating a compression side damping force in the upper end portion of the cylinder body 3 during the compression operation with respect to the expansion side damping means 5a of the piston body 5 described above. It becomes.

The compression side damping means 6 is pushed out from the compression side chamber R2 toward the volume compensation chamber T (described later) disposed outside the fork body F during the contraction operation of the fork body F in which the piston body 5 ascends in the cylinder body 3. A predetermined damping action is performed when the hydraulic oil passes.

The compression side damping means 6 is insufficient in the hydraulic fluid from the volume compensation chamber T outside the above , that is, in the compression side chamber R2 when the fork main body F is extended in the cylinder body 3 and the piston body 5 is lowered. The amount of hydraulic oil corresponding to the exit rod volume to be allowed is allowed to flow into the compression side chamber R2.

  By the way, the pressure side damping means 6 will be described based on a specific embodiment shown in FIG. 2. The pressure side damping means 6 forms the upper end portion of the cylinder body 3 while opening the upper end of the vehicle body side tube 1. It is accommodated in the cap member 11 formed in the cylindrical shape which closes up.

  The compression side attenuating means 6 has a partition wall body 61 that is fitted to the cap member 11 and divides the cap member 11 in the vertical direction, and the flow path 61a and the flow path 61b are opened in the partition wall body 61. It is worn.

  A laminated annular leaf valve 62 is provided at the upper opening of the flow path 61a, and the laminated annular leaf valve 62 generates a compression side damping force during the compression operation of the damper D.

  A check valve 63 is seated in the lower opening of the flow path 61b, and the check valve 63 is opened only when the damper D is extended to compensate for the shortage of hydraulic oil generated in the pressure side chamber R2.

  On the other hand, a connector 12 is integrally coupled to the cap member 11, and the connector 12 is connected to the pipes L1 and L2 (or the drawings) constituting the flow path L extending outside the fork main body F. 1 and L3 in L1 are connected.

  And this connector 12 connects the said pipe line L1, L3 to the downstream of the said compression side damping means 6, and the above-mentioned pipe line L2, L4 to the air chamber A in the fork main body F. And a passage 12b opened to the air chamber A side.

  The air chamber A is defined by the oil chamber O (see FIG. 1) as a boundary in a reservoir chamber R (see FIG. 1) defined in the fork main body F and outside the damper D. A predetermined air spring force is exhibited by expansion and contraction of the air chamber A.

Note that, as shown in the figure, the connector 12 includes an adjusting unit 13 that adjusts the level of the damping force generated by the compression side damping unit 6, and the adjustment unit 13 bypasses the compression side damping unit 6. The bypass passage that communicates the pressure side chamber R2 and the downstream side of the pressure side damping means 6 is widened and narrowed to control the passage flow rate in the bypass passage.

The free piston P in the volume compensation chamber T that receives the hydraulic oil from the cylinder body 3 in the damper D through the compression side damping means 6 formed as described above includes the compression side chamber R2 in each fork body F, It is slidably accommodated in a housing H that constitutes a part of a flow path L that communicates with the air chamber A in the fork main body F.

As shown in FIG. 1, the free piston P defines an oil chamber R3 and a back side air chamber A1 in a housing H, and an energizing spring S1 accommodated in the back side air chamber A1. It is urged to the left in the figure by the force.

Since the free piston P is urged to the rear side air chamber A1 by the energizing spring S1, the cylinder body 3 is pressurized in the damper D in each fork main body F, and the free piston P The inside of the cylinder body 3 is maintained in a high-pressure tendency as compared with the case where it is not biased by the biasing spring S1.

  In the present invention, by providing the volume compensation chamber T in the flow path L that communicates with each fork main body F outside, the damper D in the fork main body F is always maintained at a high pressure tendency, and the free piston P Since only the seal member P1 is provided on the outer periphery, the smooth and stable sliding of the free piston P can be ensured.

When the damper D expands and contracts, the free piston P moves in the left-right direction in the housing H in accordance with the change in the amount of hydraulic oil in the housing H due to the rod body 4 projecting and retracting relative to the cylinder body 3.

The housing H is moved from the inside of the cylinder body 3 when the free piston P moves backward in the drawing to the right in the figure by the expansion of the hydraulic oil in the damper D or the increase in the hydraulic oil amount. In order to release the hydraulic oil to the back side air chamber A1, the back side air chamber A1 has a hydraulic pressure release path H1.

  With respect to the hydraulic pressure release path H1, it is sufficient to relieve the hydraulic oil from the inside of the cylinder body 3, so as long as it is configured arbitrarily, it may be partially formed as shown in FIG. Instead, for example, as shown in FIG. 3, the inner diameter of the housing H may be expanded.

  As described above, the housing H may be arbitrarily formed as long as it has a free piston P urged from behind and exhibits a predetermined relief function.

  For example, as shown in FIG. 3, it may be preferable to have the compression side damping means 6 in combination.

As shown in FIG. 3, when the compression side damping means 6 is provided in the housing H, it is not necessary to provide the compression side damping means 6 in each fork main body F, which is advantageous in terms of reducing parts. As compared with the case where the compression side damping means 6 is provided in each fork main body F, not only the maintenance is facilitated, but also the damping action in each pair of fork main bodies F on the left and right is set to be the same. It is advantageous in terms of obtaining.

  Here, the portion shown in FIG. 3 will be described briefly. The compression side damping means 6 is housed in a bottomed cylindrical case portion H2 of the housing H that extends to the left side of the free piston P in the drawing. Has been.

  The inside of the case portion H2 communicates with the pipe lines L1 and L3 constituting the flow path L through the through hole H3, while in the oil chamber R3 on the left side of the free piston P in the drawing through the through hole H4. Communicate.

Then, the compression side damping means 6, like the compression side damping means 6 shown in FIG. 2 described above, has a partition wall body 61 to divide the casing portion H2 vertically is fitted to the case portion H2, A channel 61 a and a channel 61 b are opened in the partition wall 61.

  A laminated annular leaf valve 62 is provided at the upper opening of the flow path 61a, and the laminated annular leaf valve 62 generates a compression side damping force during the compression operation of the damper D.

  A check valve 63 is seated in the lower opening of the flow path 61b, and the check valve 63 is opened only when the damper D is extended to compensate for the shortage of hydraulic oil generated in the pressure side chamber R2.

  The rear air chamber A1 defined by the free piston P in the housing H can be adjusted to adjust the air spring force in the free piston P by adjusting the air pressure in the rear air chamber A1. It becomes possible, and the pressure in the cylinder body 3 can be ensured appropriately.

Therefore, even in the embodiment shown in FIG. 3, the free piston P is provided outside the fork main body F, and the damper D has a pressure side chamber R2 in the cylinder body 3 and an air chamber A in the fork main body F in the damper D. Since it is slidably housed in the housing H that is a part of the communicating flow path L, the sliding resistance of the free piston P is limited to that of the housing H, compared with the case where other members are slidably contacted. Thus, stable sliding of the free piston P can be expected.

  And, since the flow path constituting the housing H for housing the free piston P is connected to each fork body F that is paired on the left and right, it is possible to make the hydraulic action in the left and right fork bodies F the same. The synchronized operation of the left and right front forks P can be expected.

  Further, when the amount of hydraulic oil in the cylinder body 3 increases due to repeated expansion and contraction operations in the damper D and the hydraulic oil in the cylinder body 3 increases to a predetermined amount or more, the free piston P is shown in the figure. A predetermined amount or more is moved in the right direction, and the high pressure from the cylinder body 3 on the left side of the free piston P is defined in the air chamber A in the fork main body F, that is, in the reservoir chamber with the oil level O as a boundary. By releasing to the air chamber A, high pressure in the cylinder body 3 can be avoided.

1 is a front view showing a front fork partially broken according to an embodiment of the present invention. FIG. 2 is a partial half-longitudinal longitudinal sectional view showing an upper end side portion of the front fork of FIG. It is a figure which shows the intermediate part in the front fork of FIG. 1 similarly to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body side tube 2 Wheel side tube 3 Cylinder body 4 Rod body 6 Pressure side damping means A Air chamber A1 Back side air chamber D Damper F Fork main body H Housing L Flow path L1, L2, L3, L4 Pipe line P Free piston R3 Oil Chamber S Suspension spring S1 Energizing spring T Volume compensation chamber

Claims (3)

A fork main body that suspends the front wheel at the lower end while the upper end side is coupled to the handle side, a damper that is housed in the fork main body and has a predetermined damping action when the fork main body is extended and contracted, and an oil amount in the damper in a front fork for chromatic and volume compensation chamber which is adapted to compensate for changes in expansion and contraction behind side air chamber defining behind the free piston,
The fork main body is a pair of left and right, and each reservoir chamber has an air chamber with the oil level as a boundary,
The damper is a cylinder body, a rod body that is slidably inserted into the cylinder body, and is held by the rod body so as to be slidable and defines a pressure side chamber in the cylinder body. A piston body,
A housing in which the volume compensation chamber is provided outside the fork main body and the pressure side chamber in one damper is provided in a flow path communicating with the air chamber of the other fork main body, and is slidable in the housing A free piston accommodated in the housing, an oil chamber defined in the housing by the free piston, and the back side air chamber,
The oil chamber communicates with the pressure side chamber of one damper and communicates with the pressure side chamber of the other damper;
The back side air chamber communicates with the air chamber of one fork main body and communicates with the air chamber of the other fork main body,
The housing has a hydraulic pressure release passage communicating with the air chamber by expanding the inner diameter of the rear air chamber;
A front fork capable of releasing hydraulic pressure in the oil chamber through the hydraulic pressure release passage when the free piston moves backward . Front fork according to claim 1 in which the free piston is biased in the forward direction by biasing spring Haizai to the rear side air chamber be within the housing. It said housing front fork according to claim 1 or claim 2, have a compression side damping means for allowing communication to the oil chamber of the pressure side room.

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