JP5324496B2 - Front fork - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the reduction of a parts count which contributes to the reduction of weight. <P>SOLUTION: A fork body, whose telescopic motion is enabled by a vehicle-body-side tube 1 and a wheel-side tube 2, has a damper which uses the inside of the fork body as a reservoir R. The damper has a cylinder body 3 used as a lower end side member and a rod body 4 used as an upper end side member. An air chamber A in the reservoir R is filled with an air pressure equal to or more than the atmospheric pressure in a most extended state of the fork body and a restraining means is provided that urges the fork body in the contracting direction by being brought into a most contracted state at the time of the most extended state of the fork body. The restraining means has a balance spring structured with a coil spring. The balance spring has a reaction force, which urges the fork body in the extending direction by being most contracted through the most extended state during the contraction at the time of the most contracted state of the fork body. <P>COPYRIGHT: (C)2011,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 shock absorber that absorbs road vibration input to a front wheel that is mounted on a front wheel side of a two-wheeled vehicle and is suspended at a lower end portion.

  There have been various proposals for a front fork as a shock absorber that absorbs road surface vibrations that are input to a front wheel that is mounted on the front wheel side of a motorcycle and is suspended at a lower end portion. In the case of a front fork, the coil spring that urges the fork body in the extension direction within the fork body that can be expanded and contracted by the vehicle body side tube and the wheel side tube, as is the case with almost all kinds of front forks. A suspension spring consisting of

  Therefore, in the front fork disclosed in Patent Document 1, in view of the disadvantage that a preferable weight reduction effect cannot be obtained because the suspension spring is provided, the applicant of this application first, The front fork shown in FIG. 10 was proposed.

  That is, the front fork shown in FIG. 10 is in an inverted fork main body that can be expanded and contracted by a vehicle body side tube 1 made of a large diameter outer tube and a wheel side tube 2 made of a thin inner tube. Similarly, it has a damper set upside down.

  At this time, the damper includes a cylinder body 3 that is suspended from the shaft core portion of the vehicle body side tube 1 and a wheel side tube 2 that is inserted into the cylinder body 3 so that the tip side that is the upper end side in the figure can be projected and retracted. And a rod body 4 standing on the shaft core portion.

  The front fork is defined in the air chamber A in the reservoir R in the fork main body, that is, in the reservoir R at the boundary between the working fluid and the liquid level O when the fork main body shown in FIG. The air chamber A has a reaction force that encloses atmospheric pressure equal to or higher than atmospheric pressure and urges the fork main body in the extending direction.

  Therefore, in this front fork, even when the fork main body is in the maximum extension state, it has a reaction force in the extension direction and is biased in the extension direction without having a suspension spring. Since there is no spring, the weight of the front fork can be reduced.

  In addition, in this front fork, even when the damper is in the fully extended state, the inside of the cylinder body 3 is made to be pressurized, and bubbles are introduced into the working fluid due to the negative pressure in the cylinder body 3. Effectively prevent the occurrence.

  Therefore, the damping action is not realized from the beginning when the damper in the most extended state starts the contraction operation until the bubbles in the working fluid are crushed in the compression side damping means disposed in the cylinder body 3, for example. A predetermined compression-side damping action can be realized without causing the “damping phenomenon of damping action”.

  On the other hand, in the illustrated front fork, there is a suppressing means for suppressing a reaction force in the extending direction within a predetermined stroke region in which the fork main body contracts from the most extended state.

  That is, in the illustrated front fork, when the fork main body is in the most extended state, air pressure equal to or higher than atmospheric pressure is sealed in the air chamber A. Therefore, there is a possibility that a rider who rides on a two-wheeled vehicle that mounts the front fork on the front wheel side may have an impression that the front fork is stiff from the beginning when the contraction operation starts from the fully extended state.

  Therefore, in the illustrated front fork, when it is in the most extended state, it is between the head end 3a in the cylinder body 3 that is disposed downward and the opening end 2a in the wheel side tube 2 that is disposed upward. It has a balance spring S composed of a coil spring that constitutes the suppression means that is sandwiched and contracts.

  Therefore, in this front fork, the balance spring S that constitutes the restraining means when the fork main body is in its maximum extension state has an extension force, that is, a reaction force that causes the fork main body to contract, Thus, it is possible to prevent the rider from having an impression that the fork main body is stiff from the time when the fork body starts its contraction operation until the predetermined stroke is reached.

Japanese Patent Laid-Open No. 6-109054 (see paragraphs 0021 to 0023 in the specification, see FIG. 1)

  However, in the proposal disclosed in FIG. 10 described above, the front fork that seals the atmospheric pressure that is equal to or higher than the atmospheric pressure in the maximum extension state has the suppression means, so that the two-wheeled vehicle that mounts the front fork on the front wheel side is provided. There is basically no problem in that it does not give the rider the impression that it is hard from the beginning of the contraction operation from the maximum extension state to the predetermined stroke, but it is not a problem. It may be pointed out that there is a minor defect.

  That is, including the front fork disclosed in Patent Document 1 described above, in the front fork shown in FIG. 10 described above, the damper is set in an inverted type with the cylinder body 3 as an upper member. Compared to the case where the cylinder body 3 is set as an upright type with the lower member as the lower member, it is not easy to ensure the liquid tightness in the cylinder body 3 to ensure the operability of the damper.

  Although not shown, the liquid-tightness is largely due to the liquid-tightness of the sealing member disposed in the sliding portion. However, the damper is sufficient to improve the sealing performance in the sliding portion. As is well known, the slidability of the sheet is easily lowered.

  Accordingly, the present invention has been made in view of the above-described circumstances, and the object of the invention is a front fork having a suppressing means while enclosing an atmospheric pressure that is equal to or higher than the atmospheric pressure in the most extended state. An object is to provide a front fork that can improve the slidability by setting the damper in an upright type and provide a proposal that can guarantee the operation of the restraining means and that can be expected to improve its versatility.

  In order to achieve the above-described object, the configuration of the front fork according to the present invention basically includes a fork main body that can be expanded and contracted by a vehicle body side tube and a wheel side tube. A cylinder body that has a damper that serves as a reservoir, and a cylinder body that stands on the shaft core portion of the wheel side tube, and a rod that is suspended from the shaft core portion of the vehicle body side tube so that the tip end is inserted into the cylinder body. The fork main body is in the reservoir in the fully extended state and has a reaction force in the extending direction by sealing the air pressure above the atmospheric pressure in the air chamber bordering the working fluid and the liquid level, The fork main body has a restraining means that is brought into a most contracted state when the fork main body is in the most extended state and urges the fork main body in the contracting direction. In a front fork that suppresses the reaction force in the extension direction in the rooke region, the balance is such that the suppression means is made of a coil spring and is in the most contracted state when the fork main body is fully extended to urge the fork main body in the contracting direction. It is assumed that the balance spring has a reaction force that is most contracted when the fork main body is in the most contracted state and biases the fork main body in the extending direction while being held by the holding means.

  Therefore, in the present invention, since the damper housed in the fork main body is set upright, it is absolutely necessary to ensure liquid tightness as compared with the case where the damper is set upside down. It is not a condition, and it is easy to ensure the slidability of the damper.

  In the present invention, when the fork main body is in the maximum extension state, the atmospheric pressure that is equal to or higher than the atmospheric pressure is sealed to have a reaction force in the extension direction, while the fork main body is contracted from the maximum extension state. Since there is a restraining means that suppresses the reaction force in the extension direction in the stroke region, that is, a balance spring made of a coil spring, the reaction force in the extension direction during the contraction operation of the predetermined stroke region is reduced from the maximum extension state. Is possible.

  Further, in the present invention, the balance spring that constitutes the suppression means is in the most contracted state when the fork main body is in the most contracted state, and the reaction force when the fork main body is in the second contracted state is increased. Of course, the balance spring can be used effectively, and the impact when the fork main body is in the most contracted state can be effectively mitigated.

  Furthermore, in the present invention, since the balance spring that constitutes the suppression means is held by the holding means, one end that is the free end does not move when the balance spring is in the most extended state, and is caused by the movement. Noise generation can be avoided and the occurrence of the buckling phenomenon in the most contracted state can be prevented.

  Even in the present invention, when the fork main body is in the most extended state, the fork main body is sealed without a suspension spring because it has a reaction force in the extension direction by sealing atmospheric pressure above atmospheric pressure. As long as it can be urged in the extension direction, the weight can be reduced and the number of parts can be reduced as long as there is no suspension spring.

  In addition, even in the present invention, when the fork main body is in the most extended state, the atmospheric pressure equal to or higher than the atmospheric pressure is sealed to have a reaction force in the extending direction, so that the inside of the fork main body can be maintained in a pressure increasing tendency, When the fork body in the extended state starts the contraction operation, the contraction operation can be stably performed from the beginning.

It is a figure which shows in principle the front fork by this invention. FIG. 3 is a half-longitudinal longitudinal cross-sectional view showing a partially forked front fork according to an embodiment of the present invention. It is a figure which shows the most contracted state of the front fork of FIG. 2 similarly to FIG. It is a partial semi-longitudinal longitudinal cross-sectional view which expands and shows the state which became the most contracted state, while the balance spring which comprises the suppression means was hold | maintained at the holding means. FIG. 5 is a view similar to FIG. 4 showing a state where the balance spring of FIG. 4 is in the most extended state while being held by the holding means. FIG. 6 is a view similar to FIG. 4 showing a state in which the balance spring of FIG. 5 is in the most contracted state again while being held by the holding means. It is a figure which shows the state which the holding means by other embodiment hold | maintains the balance spring which comprises a suppression means in the most contracted state similarly to FIG. It is a figure which shows the state which the holding means of FIG. 7 hold | maintains the balance spring of the most extended state similarly to FIG. FIG. 9 is a view similar to FIG. 7 showing a state in which the balance spring of FIG. 8 is in the most contracted state again while being held by the holding means. It is a figure which shows the front fork as a prior art example similarly to FIG.

  Hereinafter, the present invention will be described based on the illustrated embodiment. A front fork according to the present invention is mounted on the front wheel side of a two-wheeled vehicle (not shown), and the front wheel (not shown) of the two-wheeled vehicle running. It functions as a hydraulic shock absorber that absorbs road vibrations input to the motor.

  Incidentally, the front fork of the present invention is said to be mounted on the front wheel side of the two-wheeled vehicle, but the two-wheeled vehicle is a problem in terms of language, and may be mounted on the front wheel side of the three-wheeled vehicle, Of course, it may be mounted on the front wheel side of a four-wheeled vehicle such as a buggy.

  The front fork is housed in a fork main body (not shown) that suspends the front wheel at the lower end while the upper end is coupled to the handle (not shown) that is the vehicle body side of the motorcycle. It has a damper (not shown) that expands and contracts in synchronization with the expansion and contraction of the fork main body and has a predetermined damping action.

  Incidentally, the front fork is mounted on the front wheel side of the two-wheeled vehicle, although not shown, the upper end sides of the two front forks on the left and right are integrated in advance by a bridge mechanism, and the lower end of each front fork is connected to the front axle. It is connected to and suspended so as to sandwich the front wheel.

  Although not shown, the bridge mechanism has an upper bracket connected to the upper side of the upper end of the vehicle body side tube constituting the front fork, and an under bracket connected to the lower side. The upper end portion of the vehicle body side tube is inserted into the mounting hole formed in the portion and is gripped integrally.

  Although not shown, this bridge mechanism has a single steering shaft that integrally connects the upper bracket and the under bracket at the center of the two, and this steering shaft constitutes the front end of the vehicle body in the motorcycle. The head pipe is turnably connected to the head pipe, whereby the front wheel can be steered in the left-right direction via the two front forks by operating the handle.

  FIG. 1 shows in principle a front fork according to the present invention. In FIG. 1, the fork main body comprises a vehicle body side tube 1 composed of a large-diameter outer tube whose upper end side is coupled to the handle side, and the vehicle body. The telescopic tube is formed into a telescopic type and can be expanded and contracted with a wheel-side tube 2 formed of a small-diameter inner tube that suspends the front wheel at the lower end while the upper end side is inserted into the lower end side of the side tube 1 so as to protrude and retract.

  Incidentally, in the figure, the fork main body is set to be an inverted type in which the large-diameter outer tube is the vehicle body side tube 1, but from the viewpoint of realizing the present invention, the fork main body has a large-diameter outer tube. The wheel side tube 2 may be set upright.

  The fork main body has a damper that is formed in a cylindrical shape at the shaft core portion and is set upright. A reservoir R is an inner side that is outside the damper, and the reservoir R is a hydraulic fluid that is a working fluid. And an air chamber A having an oil level O as a liquid level of the hydraulic oil as a boundary.

  Further, in the present invention, the air chamber A in the fork main body is filled with an atmospheric pressure that is equal to or higher than the atmospheric pressure when the fork main body is in the most extended state. This will be described in detail later.

  The damper has a cylinder body 3 and a rod body 4 that is inserted into the cylinder body 3 so that the tip side, which is the lower end side in the figure, can be projected and retracted. In the drawing, the cylinder body 3 is used as a lower end side member. And the rod body 4 is set upright with the upper end side member, the cylinder body 3 is erected on the shaft core portion of the wheel side tube 2 and the rod body 4 is suspended from the shaft core portion of the vehicle body side tube 1. Being done.

  In the drawing, the height position of the oil level O in the reservoir R when the fork main body is in a so-called neutral state is shown. However, it is preferable that the head end portion 3a which is the upper end portion of the cylinder body 3 in the damper is in the hydraulic oil so that the hydraulic oil can be easily filled into the cylinder body 3.

  On the other hand, the damper has a piston body 5 that is slidably received in the cylinder body 3 while being connected to the tip of the rod body 4. The piston body 5 is disposed in the cylinder body 3. The rod-side chamber R1 that is above and the piston-side chamber R2 that is below the piston body 5 are defined. The rod-side chamber R1 has extension-side damping means that allows the rod-side chamber R1 to communicate with the piston-side chamber R2. The expansion-side damping valve 5a and the expansion-side check valve 5b parallel to the expansion-side damping valve 5a have a predetermined expansion-side damping action when hydraulic fluid passes through the expansion-side damping valve 5a.

  In the extension side damping means, the extension side check valve 5b may be of any configuration as long as it fulfills a predetermined check valve function. For example, the extension side check valve 5b may be a suction valve. It may be a valve.

  Further, in this damper, the base valve portion 6 provided at the bottom end portion 3b of the cylinder body 3 has a pressure side damping means, and this pressure side damping means is a pressure side check valve in parallel with the pressure side damping valve 6a. And a predetermined pressure side damping action when the hydraulic fluid in the piston side chamber R2 passes through the pressure side damping valve 6a and flows out to the reservoir R outside the cylinder body 3.

  Therefore, in the damper formed as described above, during the contraction operation in which the rod body 4 is immersed in the cylinder body 3, the hydraulic oil in the piston side chamber R2 passes through the expansion side check valve 5b and the rod side chamber R1. Flow into.

  At this time, an amount of hydraulic oil corresponding to the rod intrusion integral that becomes surplus in the piston side chamber R2 passes through the pressure side damping valve 6a in the pressure side damping means 6 and flows out to the reservoir R, and the pressure side damping valve 6a passes through the hydraulic oil. A predetermined compression-side damping action is realized by passing.

  On the other hand, in this damper, contrary to the above, when the rod body 4 protrudes from the cylinder body 3, the hydraulic oil in the rod side chamber R1 passes through the extension side damping valve 5a and flows out to the piston side chamber R2. Then, a predetermined extension side damping action is realized by the hydraulic oil passing through the extension side damping valve 5a.

  At this time, an amount of hydraulic oil corresponding to the rod withdrawal volume integral which is insufficient in the piston side chamber R2 passes through the pressure side check valve 6b in the pressure side damping means 6 and is replenished from the reservoir R.

  Incidentally, as described above, in the present invention, the damper is set upright, and the cylinder body 3 is always positioned below the oil level O. As a result, it is possible to realize the damping action on each side by the extension side damping means and the compression side damping means as set.

  In the front fork of the present invention in which the damper is formed as described above, as described above, it is defined in the fork main body in the most extended state, that is, in the reservoir R with the oil level O as a boundary. In the air chamber A, a pressure higher than the atmospheric pressure is enclosed, and a suppression means (not shown) is provided in the fork main body in order to eliminate the negative effects associated with the enclosure of the atmospheric pressure higher than the atmospheric pressure. .

  Explaining briefly, in the front fork according to the present invention, the air chamber A defined by the oil level O is enclosed in the fork body which is in the most extended state, and the extension direction is obtained by enclosing the atmospheric pressure above atmospheric pressure. Have a reaction force of.

  That is, according to the applicant's confirmation, when the fork main body in which the outer diameter of the wheel side tube 2 is approximately 48 mm and the contraction stroke length is approximately 300 mm is in the most extended state, the air pressure in the air chamber A becomes equal to or higher than atmospheric pressure. When a gas of approximately 0.3 MPa is sealed, the internal pressure of the fork main body in the most contracted state is approximately 1.5 MPa.

  For this reason, in this front fork, when the fork main body is in the fully extended state, the inside of the fork main body can be maintained at a high pressure tendency by sealing the atmospheric pressure that is equal to or higher than the atmospheric pressure inside the fork main body. When the fork body starts the contraction operation, that is, the contraction operation is stabilized from the beginning of the contraction operation.

  In this front fork, since the atmospheric pressure above atmospheric pressure is sealed in the fork main body to provide a reaction force in the extension direction, the fork main body is always urged in the extension direction and does not have a suspension spring. As a result, the fork body can be urged in the extension direction, and as long as there is no suspension spring, the volume for distributing the suspension spring can be reduced, and the weight and the number of parts can be reduced. Enable.

  As described above, in the front fork according to the present invention, the fork body that is in the most extended state is filled with an atmospheric pressure that is equal to or higher than the atmospheric pressure so as to have a reaction force in the extension direction, thereby providing a suspension spring. Without forcing the fork body in the direction of extension.

  On the other hand, although no literature is shown, there has been a proposal of a front fork that urges the fork main body in the extending direction only at the air pressure enclosed without a suspension spring, that is, only with an air spring.

  It is also well known that when assembling the front fork, it becomes more difficult to assemble the front fork unless the atmospheric pressure enclosed in the fork main body is higher than atmospheric pressure.

  In view of this, in the present invention, there is room for not having any specificity for enclosing an atmospheric pressure in the fork main body that is equal to or higher than atmospheric pressure, for example, approximately 0.3 MPa or higher.

  However, in the present invention, the fork main body has a suppressing means as a removal of the harmful effects by enclosing the atmospheric pressure higher than the atmospheric pressure and having a reaction force in the extension direction, that is, the fork main body is the most extended. There is peculiarity by having suppression means for suppressing the reaction force in the extending direction within a predetermined stroke region that contracts from the state.

  That is, the front fork of the present invention has a reaction force in the extension direction caused by the atmospheric pressure at which the fork main body in the most extended state is enclosed. Compared to the case where there is no reaction force in the extension direction due to the generated atmospheric pressure, for example, a rider who rides a motorcycle that mounts the front fork on the front wheel side has an impression that the front fork is hard. Although it may be held, by suppressing the reaction force in the extending direction caused by the atmospheric pressure enclosed in the most extended state, the rider riding on the motorcycle does not have the impression that the front fork is hard.

  The predetermined stroke area is a contraction stroke area starting from the maximum extension state, and preferably a stroke area of approximately 1/3 of the front side of all strokes from the maximum extension state to the maximum contraction state. However, this is not absolute, and even if there are some differences, the intention of the suppression means in the present invention is not different.

  In addition, this restraining means, as shown, has a balance spring S made of a coil spring, and this balance spring S is disposed outside the cylinder body 3 and exerts an extension force when it enters a contracted state. The fork main body is urged in a contracting direction in a direction in which the rod body 4 is immersed in the cylinder body 3.

  From the viewpoint of energizing the fork body in the contracting direction, the balance spring S is a spring similar to the extension spring 53 (see FIGS. 2 and 3) housed in a damper of the kind, that is, the next spring. There is room for it to be called an extended spring.

  However, this balance spring S is different from the extension spring 53 that absorbs the acting force during the maximum extension operation of the damper from the viewpoint of canceling out the so-called initial reaction force in the extension direction of the fork body in the maximum extension state. Work.

  By the way, this balance spring S is disposed outside the cylinder body 3 in the damper, that is, when it is wound around the outer periphery of the cylinder body 3 and the damper is in the neutral state shown in the figure, The rod which is in the most extended state and is supported on the lower end portion of the cylindrical portion 71 of the case body 7 formed in a headed cylindrical shape connected to the rod body 4, and the upper end constitutes the head end portion 3 a of the cylinder body 3. The guide 23 (see FIGS. 2 and 3) is locked to a flange portion 23a (see FIGS. 2 and 3).

  In the balance spring S, although not shown, when the damper is in the fully extended state, the lower end portion of the cylindrical portion 71 is raised while the upper end is locked to the flange portion 23a. By doing so, it is in the most contracted state, and has a force that it tries to expand, that is, a reaction force that tries to contract the damper.

  The balance spring S is configured to urge the damper, that is, the fork main body in the contracting direction by the extension force when contracting, and the stroke region starts from the front before the fork main body is extended and fully extended. Therefore, the balance spring S contracts and tends to suppress the movement of the extending fork main body. In particular, the reaction force in the extending direction of the fork main body in the most extended state is reduced to zero.

  As a result, it is possible to prevent the rider who rides the motorcycle mounted with the front fork on the front wheel side from giving the impression that the front fork starting the contraction operation from the fully extended state is hard.

  And in said balance spring S, since this is wound by the outer periphery of the cylinder body 3, expression of the buckling phenomenon when it will be in the most contracted state is blocked | prevented beforehand.

  In this embodiment, the balance spring S is disposed outside the cylinder body 3 and is not disposed inside the cylinder body 3, so that the balance spring S can be easily disposed. This is advantageous in that the inner circumference of the body 3 is not damaged.

  Further, in the case of this embodiment, when the balance spring S is disposed, so-called component processing is not required for the vehicle body side tube 1 and the wheel side tube 2 constituting the fork main body, and can be embodied in an existing front fork. This is advantageous.

  As for the case body 7 described above, the main point is that the head 72 is integrally connected to the rod body 4, and the inside of the cylindrical portion 71 is opened upward by the formation of the head 72. Therefore, a plurality of communication holes 71 a (see FIGS. 2 and 3) are provided in the cylinder portion 71 in the vertical direction, or a throttle 72 a is provided in the head 72, so that the inside of the cylinder portion 71 serves as the reservoir R. It is good to make it communicate and to stabilize the position of the oil level O.

  Further, in the case body 7 described above, the flange portion 23a of the rod guide 23 constituting the head end portion 3a of the cylinder body 3 moves up and down inside the cylindrical portion 71 as viewed relatively. When the flange portion 23a is lifted, a damping action by the hydraulic oil passing through an annular gap that appears between the outer periphery of the flange portion 23a and the inner periphery of the cylindrical portion 71 may be embodied.

  In addition, the case body 7 is connected to the rod body 4 in the drawing, but the point is that it is sufficient to move up and down in synchronization with the rod body 4, that is, the vehicle body side tube 1. For example, although not shown, for example, the cap member 14 (see FIGS. 2 and 3) that closes the upper end opening of the vehicle body side tube 1 may be connected.

  FIGS. 2 to 5 show specific embodiments of the front fork according to the present invention, which will be described below, but this front fork is also not shown but has a fork main body. The fork main body accommodates hydraulic oil as a working fluid and houses a damper. Further, the fork main body is filled with atmospheric pressure equal to or higher than atmospheric pressure, and has a suppression means.

  Incidentally, in the following description, in FIGS. 2 to 5, where the configuration is the same as that shown in FIG. 1 described above, only the same reference numerals are given in the drawing, except where necessary. Detailed description thereof is omitted.

  First, as shown in FIGS. 2 and 3, in the front fork, the fork main body is formed in a telescopic type in which the wheel side tube 2 can protrude and retract with respect to the inside of the vehicle body side tube 1 and can be extended and contracted. Is done.

  At this time, the fork main body has an upper bearing 21 and a lower bearing 11 which are vertically spaced between the vehicle body side tube 1 and the wheel side tube 2 and are spaced apart from each other. The upper and lower bearings 21 and 11 ensure the slidability to be concentric between the vehicle body side tube 1 and the wheel side tube 2.

  Further, in the fork main body, a lubricating gap (not shown) appears between the vehicle body side tube 1 and the wheel side tube 2 between the upper bearing 21 and the lower bearing 11 that are spaced apart from each other. The hydraulic fluid inside the wheel side tube 2 is caused to flow through the communicating hole 2a (see FIG. 3) opened in the wheel side tube 2 into the lubrication gap, and this hydraulic oil is used as the lubricating oil. The lubrication with the wheel side tube 2 is ensured.

  Further, this fork main body has an oil seal 12 and a dust seal 13 in series with the lower bearing 11 on the inner periphery of the opening end portion which is the lower end portion of the vehicle body side tube 1. The fork main body is made into a sealed space, and the dust seal 13 is disposed to scrape dust such as fine sand particles adhering to the outer periphery of the wheel side tube 2 to prevent the dust from entering the oil seal 12 side. The sealing function of the oil seal 12 is ensured.

  Further, in the fork main body, the upper end opening of the vehicle body side tube 1 is closed by screwing of the cap member 14, and the cap member 14 has an air valve V, and the air valve V is connected to the fork main body. Enables atmospheric pressure encapsulation and change adjustment of enclosed atmospheric pressure.

  And in this fork main body, as shown in FIG. 3, in order to prevent the further contraction at the time of the most contraction operation in which the wheel side tube 2 is immersed in the vehicle body side tube 1 with a large stroke, as shown in FIG. 2 is brought into contact with the lower end side of the cap member 14.

  Although the fork body has an oil lock mechanism (not shown), the oil lock mechanism exerts a cushion effect during the most contraction operation to slow down the fork body contraction speed, and also exhibits an oil lock effect. The impact at the time of the most contraction operation of the fork main body may be reduced.

  Furthermore, as for the fork main body, in the illustrated case, the large-diameter outer tube is set as the vehicle body side tube 1 and the small-diameter inner tube is set as an inverted type in which the wheel-side tube 2 is used. From the point of view of the present invention, instead of this, although not shown, the outer tube may be set to the wheel side tube 2 and the inner tube may be set to the upright type in which the vehicle body side tube 2 is used.

  However, in the present invention, the damper described later is intended to be set upside down, so that even if the fork body is set upright, the damper is not changed from upright to upside down.

  On the other hand, this fork main body accommodates hydraulic oil inside the reservoir R and has a damper. The damper has a lower end portion coupled to the bottom member 22 of the inner tube 1 and a shaft of the wheel side tube 2. A cylinder body 3 that stands on the core and serves as a lower end member, and a rod body 4 that is inserted into the cylinder body 3 so that the lower end side can be projected and retracted and is used as an upper end side member are set upright. Is done.

  The rod body 4 is coupled to a cap member 14 that closes the upper end opening of the vehicle body side tube 1 under the arrangement of the lock nut 41, and is suspended from the shaft core portion of the vehicle body side tube 1.

  In this damper, the piston body 5 is slidably accommodated in the cylinder body 3 filled with hydraulic oil, and the piston body 5 has a tip end portion serving as a lower end portion in the drawing. Are concatenated.

  The piston body 5 defines a rod-side chamber R1 above the piston body 5 and a piston-side chamber R2 below the piston body 5 in the cylinder body 3, and also connects the rod-side chamber R1 to the piston-side chamber R2. There is an extension-side damping means that allows communication.

  The extension side damping means includes an extension side damping valve 51 that allows the hydraulic oil in the rod side chamber R1 to pass to the piston side chamber R2, and the hydraulic oil from the piston side chamber R2 in parallel with the extension side damping valve 51. And an extension side check valve 52 that allows inflow into the rod side chamber R1.

  On the other hand, the cylinder body 3 closes the opening end taken at the upper end in the figure by screwing the rod guide 23, and the head end portion 3a (see FIG. 1) which is the upper end portion of the cylinder body 3 by the arrangement of the rod guide 23. Is forming.

  The spring 53 extends between the lower end portion of the rod guide 23 forming the head end portion 3a and the seat portion 4a adjacent to the piston body 5 in the rod body 4 penetrating the shaft core portion of the rod guide 23. As shown in FIG. 2, the extension spring 53 is sandwiched between the lower end portion of the rod guide 23 and the seat portion 4 a and contracted most when the damper is in the maximum extension state. Absorbs the acting force when the damper is fully extended.

  Although not shown, a base valve portion (see reference numeral 6 in FIG. 1) having a compression side damping means is disposed inside the bottom end portion (not shown) which is the lower end portion of the cylinder body 3, and this base The valve portion has a pressure side damping valve (see reference numeral 6a in FIG. 1) constituting a pressure side damping means, and a pressure side check valve (see reference numeral 6b in FIG. 1) in parallel with the pressure side damping valve. .

  By the way, in the front fork according to the present invention, when the fork main body is in the most extended state, the fork main body encloses atmospheric pressure that is equal to or higher than atmospheric pressure, and therefore has a reaction force in the extending direction, and the suspension spring is not disposed. And biased in the extending direction.

  That is, in this fork main body, the air chamber A bordering on the oil level O in the inner reservoir R is basically inflated and contracted when the fork main body expands and contracts, and is predetermined when the fork main body expands and contracts. The air spring force, that is, the tube reaction force is generated. In the present invention, at the time of the maximum extension operation of the fork main body, an atmospheric pressure that is equal to or higher than atmospheric pressure, for example, approximately 0.3 MPa is enclosed.

  Therefore, in the front fork, it is possible to maintain the inside of the damper in a pressure-increasing tendency even in the maximum extension state, and the pressure in the cylinder body 3 in the damper is increased.

  Therefore, in the damper, when the damper is extended, the negative pressure phenomenon is not generated in the piston-side chamber R2, and the generation of bubbles in the hydraulic oil is prevented. When the contraction operation is started after reversing, it is possible to prevent the occurrence of the “damping action sabbath” phenomenon in which the predetermined pressure side damping action cannot be expected until the bubbles in the hydraulic oil are crushed in the piston side chamber R2. .

  On the other hand, in this front fork, when the fork main body is in the maximum extension state, the atmospheric pressure that is equal to or higher than the atmospheric pressure is enclosed. Therefore, in the conventional front fork disclosed in Patent Document 1, it is possible to omit the provision of the suspension spring housed in the fork main body.

  By the way, in the front fork of the present invention, when the fork main body is in the most extended state, the air pressure A that is equal to or higher than the atmospheric pressure is sealed in the air chamber A in the reservoir R. For example, in the case of a rider who rides a two-wheeled vehicle that mounts the front fork on the front wheel side compared to the case where there is no reaction force in the extending direction due to the enclosed atmospheric pressure when starting the contraction operation, The front fork may be stiff.

  Therefore, as described above, in the present invention, a rider who rides a two-wheeled vehicle can suppress the reaction force in the extending direction caused by the atmospheric pressure enclosed in the most extended state by the suppressing means. Don't let the impression that the fork is stiff.

  And the area | region which a suppression means suppresses is the area | region of the contraction stroke started from the maximum extension state, Preferably, it is the stroke area of about 1/3 of the front side of all the strokes from the maximum extension state to the maximum contraction state. Although this is a predetermined stroke area, this is not absolute, and even if there are some differences, the intention of the suppression means in the present invention is not different.

  In addition, this suppression means has a balance spring S made up of a coil spring, as shown in the figure, and this balance spring S is disposed outside the cylinder body 3 and is extended by the extension force in the contracted state. The fork main body is urged in the contracting direction in the direction in which the rod body 4 is immersed.

  On the other hand, this balance spring S is shown in the figure, is wound around the outer periphery of the cylinder body 3 and is carried by the lower end portion 71 a of the cylindrical portion 71 in the case body 7 whose lower end is connected to the rod body 4. .

  In the balance spring S, when the fork main body shown in FIG. 2 is fully extended, the upper end of the balance spring S is engaged with the flange portion 23a of the rod guide 23 that forms the head end portion 3a of the cylinder body 3. It becomes a state.

  In the balance spring S, the upper end of the balance spring S is separated from the flange portion 23a of the rod guide 23 and becomes a so-called free end when the fork main body is retracted as shown in FIG.

  In the case body 7 described above, the head 72 is integrally connected to the rod body 4 by an appropriate means. At this time, the head 72 communicates with the reservoir R inside the cylindrical portion 71. In order to eliminate the adverse effect that hydraulic oil accumulates inside the cylinder portion 71, the cylinder portion 71 is provided with a plurality of communication holes 71a in the vertical direction, or the head 72 is provided with a throttle 72a. Thus, the inside of the cylindrical portion 71 is preferably communicated with the reservoir R.

  In this case, the position of the oil surface O in the cylinder portion 71 is stabilized, and the hydraulic oil passes through the throttle 72a opened in the head 72. When the flange portion 23a of the rod guide 23 rises in the cylindrical portion 71, an annular gap appears between the inner periphery of the cylindrical portion 71 and the outer periphery of the flange portion 23a. By passing, it becomes possible to realize the damping action by the diaphragm effect.

  As described above, in the balance spring S which is the restraining means in the present invention, since it is wound around the outer periphery of the cylinder body 3, the occurrence of the buckling phenomenon when it is most contracted is prevented, and as set. The expansion and contraction of is realized.

  When the balance spring S is in the most contracted state, the balance spring S urges the fork main body in the maximum extension state in the contraction direction by a reaction force in the extension direction. Since the reaction force is reduced to zero, the rider who rides on the two-wheeled vehicle with the front fork mounted on the front wheel side does not have the impression that the front fork in the most extended state is hard.

  4 to 6 and 7 to 9, for example, as shown in FIG. 3 described above, when the balance spring S is in the most extended state, the upper end is detached from the flange portion 23a of the rod guide 23. Alternatively, although not shown, holding means for preventing the lower end from separating from the spring receiving portion 71c as the lower end portion of the case body 7 to become a so-called free end is shown.

  That is, the holding means basically prevents the expression of the free state at the upper end or the lower end of the balance spring S in the most extended state, so-called the outer periphery of the cylinder body 3 or the rod body 4 of the balance spring S. Effectively prevents noise generation due to idle movement.

  On the other hand, the holding means shown in the figure enables the balance spring S once extended to be contracted again when the fork main body is reversed from the most extended state to the contracted state and the fork main body is continuously contracted. To do.

  When the fork body is in the most contracted state, the balance spring S that is contracted most has a reaction force in the extending direction, so that the reaction force in the extending direction is increased in the fork body that is in the most contracted state. It is possible to effectively realize shock absorption during contraction operation.

  Incidentally, when the balance spring S that is in the most contracted state when the fork main body is in the most extended state and urges the fork main body in the contracting direction is once extended and then continuously contracted, In order to effectively relieve the impact at the time of the most contraction operation in the main body, it is advantageous in that the air pressure enclosed in the fork main body does not need to be set extremely high.

  First, as shown in FIG. 4, when the fork main body is in the most contracted state, the balance spring S is also in the most contracted state, and in FIG. 5, the fork main body is reversed from the most contracted state to the extended state. Thus, the balance spring S is in the extended state, and the portion shown in FIG. 6 shows that the fork body is in the most extended state and the balance spring S is in the most contracted state again.

  The holding means for holding the balance spring S is shown in the figure, but in the illustrated case, the annular groove 71b formed on the inner periphery of the cylindrical portion 71 in the case body 7 integrally connected to the rod body 4, and the cylindrical portion as well. 71, a spring receiving portion 71c which is the lower end portion of 71, a stop ring 24 fitted in an annular groove 3c formed on the outer periphery of the cylinder body 3, and a flange portion 23a in the rod guide 23 constituting the head end portion 3a of the cylinder body 3. It consists of.

  That is, as shown in FIG. 5, the balance spring S is accommodated in an annular groove 71b formed on the inner periphery of the cylindrical portion 71 in the case body 7 as shown in FIG. In this state, the upper end is locked to the upper end portion of the annular groove 71b, and the lower end is carried by the spring receiving portion 71c. Therefore, so-called play at the upper and lower ends is prevented.

  When the balance spring S is in the most contracted state shown in FIG. 4, the upper end is locked to the upper end portion of the annular groove 71 b and the lower end is carried on the stop ring 24.

  When the balance spring S is in the most contracted state shown in FIG. 6, the upper end is engaged with the flange portion 23 a of the rod guide 23 and the lower end is carried by the stop ring 24.

  Incidentally, in the place shown in FIGS. 4 to 6, the balance spring S is wound around the outer periphery of the cylinder body 3, so that the occurrence of the buckling phenomenon at the time of the most contraction operation is effectively prevented.

  Therefore, in the holding means described above, when the balance spring S is in the fully extended state, the upper end or the lower end is prevented from freely moving and free from noise due to the movement.

  When this holding means is used, there is no need to perform so-called component processing on the vehicle body side tube 1 or the wheel side tube 2, which is advantageous in that an existing front fork can be used as it is.

  On the other hand, as described above, the balance spring S is in the most contracted state when the fork main body reaches the maximum extension state, and with the extension force, that is, the negative reaction force, the fork main body is moved in the contraction direction. Energize.

  Therefore, the fork body that is in the most extended state has the reaction force in the extending direction, which is essentially zero, in a rider who rides a motorcycle that mounts the front fork on the front wheel side, and is in the most extended state. The impression that the front fork is hard will not be held.

  In the balance spring S, when the fork main body starts to contract, for example, contracts in a stroke region of approximately 1/3 of the front of the entire stroke from the maximum extension state to the maximum contraction state, It becomes an extended state, that is, a so-called fully extended state, and has no negative biasing force.

  In the balance spring S, when the fork main body further continues to contract and further contracts, the balance spring S contracts again, so that it has a positive reaction force. When the main body is in the most contracted state, the main body is in the most contracted state, and the fork main body is urged in the extending direction.

  Incidentally, the region where the balance spring S starts to contract again from the most extended state may be, for example, a stroke region that is approximately 1/3 of the rear side of the entire stroke from the most contracted state to the maximum extended state. .

  As a result, when the fork main body in the most extended state contracts in the approximately 1/3 stroke area on the front side of the entire stroke, the balance spring S that is in the contracted state and has a negative reaction force is once in the maximum extended state. After becoming, it is contracted again and this time has a positive reaction force.

  That is, the balance spring S according to this embodiment has positive and negative reaction forces when the fork main body is extended and contracted, as compared with the balance spring S according to the embodiment shown in FIGS. As a result, the so-called full use is realized, and the expansion and contraction operation of the fork main body is effectively realized.

  7 to 9 show a holding means according to another embodiment in place of the holding means shown in FIGS. 4 to 6 described above, and this will be described below a little, but the effects thereof are as follows. 4 to 6 are not different from those shown in FIGS.

  That is, first, the place shown in FIG. 7 shows that the fork main body is in the most contracted state, and therefore the balance spring S is also in the most contracted state, and FIG. Therefore, the balance spring S is shown in the most extended state, and the portion shown in FIG. 9 shows that the fork body is in the most extended state, and therefore the balance spring S is in the most contracted state. .

  Even in this embodiment, the balance spring S is held by the holding means, and the holding means is disposed outside the rod body 4 so as to allow the rod body 4 to be inserted into the shaft core portion. An inner slider 8 that is formed in a substantially cylindrical shape that moves up and down on the side, and is arranged on the outer side of the inner slider 8 while being concentric with the inner slider 8 and vertically along the axial direction of the wheel side tube 2. A substantially cylindrical outer slider 9 that moves, an annular stopper 25 connected to the inner periphery of the upper end of the inner tube 1, and a stop ring 10 fitted in an annular groove 4 b formed on the outer periphery of the rod body 4. It has.

  The inner slider 8 has a spring receiving portion 8a formed in a flange shape at the lower end portion, and has an engaging portion 8b formed in a bent state at the upper end portion, and the outer slider 9 has a lower end portion. It has an annular step portion 9a formed so as to cut the inner peripheral portion of the side portion, a locking portion 9b formed on the flange at the lower end portion, and a balance spring on the spring receiving portion 8a of the inner slider 8 The lower end of S is carried, and the upper end of the balance spring S is engaged with the annular step portion 9a of the outer slider 9 so as to be sandwiched.

  Therefore, unlike the embodiment described above, the balance spring S is wound around the outside of the rod body 4, that is, outside the inner slider 8, and the free movement of the upper and lower ends in the fully extended state. It is effectively prevented and the occurrence of the buckling phenomenon in the most contracted state is effectively prevented.

  On the other hand, as the operation of the holding means, when the fork main body is retracted most when the wheel side tube 2 rises in the vehicle body side tube 1, the annular stopper portion 25 connected to the upper end portion of the wheel side tube 2 is provided in the vehicle body. It abuts on the lower end side of the cap member 14 that closes the open end of the side tube 1.

  At this time, the rod body 4 is immersed in the cylinder body 3. When viewed relatively, the head end portion 3 a of the cylinder body 3 rises, and the spring receiving portion 8 a serving as the lower end portion becomes the head end portion. The inner slider 8 carried by 3a is raised.

  Therefore, the lower end of the balance spring S is raised, the balance spring S is contracted, and the outer slider 9 is raised by the reaction force at that time. Is brought into contact with the annular stopper 25 to prevent the outer slider 9 from further rising.

  As a result, as shown in FIG. 7, the balance spring S is in the most contracted state and has a positive reaction force that urges the most contracted fork main body in the extending direction.

  When the fork main body is extended from the above state, the balance spring S can be extended. Therefore, the inner slider 8 is lowered on the outer periphery of the rod body 4 so as to respond to the extension operation of the balance spring S. As a result, the lowering of the inner slider 8 is prevented by contacting the stop ring 10 fitted in the annular groove 4b of the rod body 4 of the upper end locking bracket 8b of the inner slider.

  At this time, since the wheel side tube 2 descends in the vehicle body side tube 1, the annular stopper portion 25 connected to the upper end portion of the wheel side tube 2 descends in accordance with the cylinder body 3. The portion 25 is locked to the lower end locking portion 9b of the outer slider 9, and at this time, the balance spring S is in the most extended state (see FIG. 8).

  When the fork main body is further extended, the annular stopper 25 connected to the upper end of the wheel side tube 2 is further lowered while being engaged with the lower end engaging portion 9b of the outer slider 9. Therefore, the balance spring S whose upper end is locked to the step 9a of the outer slider 9 is contracted.

  Moreover, when the wheel side tube 2 is in the fully extended state in which it largely protrudes from the vehicle body side tube 1, further lowering of the outer slider 9 is stopped, and further contraction of the balance spring S is prevented.

  As described above, according to the present invention, since the balance spring S is held by the holding means, the freedom of the end portion of the balance spring S in the most extended state is restrained. Noise generation due to so-called floating is effectively prevented.

  In the above description, the fork main body does not have the suspension spring. However, in view of the function of the balance spring S as the restraining means in the present invention, the embodiment of the present invention is realized even if the fork main body has the suspension spring. Of course, there is no difference in the operational effects in that case.

  In the above description, the balance spring S constituting the suppressing means is disposed outside the damper. However, considering the function of the balance spring S, the balance spring S is placed in the cylinder body 3. It may be arranged.

  It is suitable for use as a shock absorber that absorbs road surface vibration that is input to the front wheel that is mounted on the front wheel side of the motorcycle and is suspended at the lower end.

DESCRIPTION OF SYMBOLS 1 Car body side tube 2 Wheel side tube 3 Cylinder body 4 Rod body 5 Piston body 6 Base valve part 7 Case body 8 Inner slider 9 Outer slider 10, 24 Stop ring 11, 21, Bearing 12 Oil seal 13 Dust seal 23 Rod guide 23a Flange part 71 Cylinder 71b Annular groove A Air chamber O Oil level R Reservoir S Balance spring

Claims (4)

  It has a fork main body that can be expanded and contracted by a vehicle body side tube and a wheel side tube, and a damper that uses the inside of the fork main body as a reservoir is provided in the fork main body, and the damper stands on the shaft core portion of the wheel side tube. And a rod body that is suspended from the shaft core portion of the vehicle body side tube and allows the distal end side to be inserted into the cylinder body. When the air pressure that exceeds the atmospheric pressure is sealed in the air chamber that forms the boundary, it has a reaction force in the extension direction, and when the fork main body reaches the maximum extension state, it is brought into the maximum contraction state and the fork main body is attached in the contraction direction. In the front fork, which has a restraining means for biasing, and restrains the reaction force in the extension direction in a predetermined stroke region in the fork main body that contracts from the most extended state, the restraining means It has a balance spring consisting of a coil spring, and this balance spring has a reaction force that is most contracted through the most extended state in the middle when the fork body is in the most contracted state and biases the fork body in the extending direction. A featured front fork.   The balance spring suppresses the reaction force in the extension direction of the fork body when the damper contracts approximately 1/3 or more of the front stroke in the entire stroke from the maximum extension state to the maximum contraction state. The front fork according to claim 1, wherein the front fork has a spring force.   The balance spring is held by holding means, and the holding means has a case body connected to the vehicle body side tube side, and the case body has a cylindrical portion disposed outside the cylinder body. The cylindrical portion has an annular groove formed on the inner periphery, and the balance spring is accommodated in the annular groove in the most extended state, and the upper end of the balance spring is locked to the upper end of the annular groove. The front fork according to claim 1 or 2, wherein a lower end is supported on a lower end portion of the cylindrical portion.   The balance spring is held by the holding means, the inner slider in which the holding means is slidably disposed on the rod body, the outer slider disposed concentrically with the inner slider, and a wheel An annular stopper connected to the upper end of the side tube, and a stop ring fitted to the outer periphery of the rod body, and the upper end while the balance spring is between the inner slider and the outer slider The front fork according to claim 1, wherein a front end of the outer slider is engaged with a step portion of the outer slider and a lower end thereof is supported by a spring receiving portion of the inner slider.

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