JP2010185572A - Front fork - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of components contributing to weight reduction. <P>SOLUTION: This front fork includes a reservoir inside air chamber A having a boundary of a liquid face (O) within a fork body which can be extended/contracted by a vehicle body side tube 1 and a wheel side tube 2. The front fork includes a suppressing means (S) for providing a reaction force by filling air pressure equal to or more than an atmospheric pressure in the reservoir inside air chamber A when the fork body is in the most extended state and for suppressing a reaction force within a predetermined stroke region where the fork body is contracted from the most extended state. <P>COPYRIGHT: (C)2010,JPO&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 vibration that is input to a front wheel that is mounted on a front wheel side of a motorcycle and is suspended at a lower end portion. As shown, many front forks have a suspension spring consisting of a 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. ing.

  On the other hand, the front fork disclosed in Patent Document 1 has an inverted type damper having a cylinder body as an upper end side member in the fork body, and this damper is on the pressure side in the bottom end portion of the cylinder body. In addition to having a damping means, there is a free piston which is slidably disposed downstream of the pressure side damping means and defines a pressure receiving surface side oil chamber and a back side air chamber in the bottom end portion.

  In this damper, the back side air chamber defined by the free piston communicates with a reservoir in the fork main body outside the damper through a communication hole opened at the bottom end of the cylinder body. And a biasing spring comprising a coil spring that biases the free piston from the back side against the pressure in the damper.

  In addition, in this damper, the free piston is caused by the expansion of the working fluid due to the temperature rise of the working fluid in the damper, the working fluid outside the damper flowing into the damper during the operation of the damper, etc. When the working fluid in the damper exceeds a predetermined amount, the working fluid moves backward so as to rise above a predetermined stroke, and the surplus working fluid is returned to the reservoir through the open communication hole at the bottom end of the cylinder body. To release.

  Therefore, in the front fork disclosed in Patent Document 1, the fork main body is urged in the extending direction by the suspension spring, the amount of working fluid in the damper is stabilized, and the damper generates an excessive reaction force. Disappear.

Japanese Patent Laid-Open No. 6-109054 (see paragraphs 0022, 0024, 0044 to 0046, FIGS. 1 and 8 in the specification)

  However, in the proposal disclosed in Patent Document 1 described above, there is basically no problem in that the damper does not generate an excessive reaction force while the fork body is biased in the extension direction by the suspension spring. However, there is a possibility that it is pointed out that there is a slight defect in the implementation.

  That is, in many front forks proposed so far, including the proposal disclosed in Patent Document 1, the fork body has a suspension spring and is biased in the extending direction.

  Therefore, in the conventional front forks, there is a problem that it is difficult to reduce the number of parts and the preferable weight reduction effect cannot be obtained because of the suspension spring.

  The present invention was devised in view of such a current situation, and the object of the present invention is that the damper does not generate an excessive reaction force while being urged in the extending direction. It is possible to reduce the number of parts that contribute to reduction, and to provide a front fork that is optimal for expecting an improvement in versatility.

  In order to achieve the above-described object, the structure of the front fork according to the present invention is basically configured as a reservoir internal air chamber with a liquid level as a boundary in a fork body that can be expanded and contracted by a vehicle body side tube and a wheel side tube. In the front fork having the above-mentioned, when the fork main body is in the most extended state, the air pressure in the reservoir is sealed with a pressure higher than the atmospheric pressure and has a reaction force, and the fork main body is in the maximum extended state. It is assumed that there is a suppressing means for suppressing a reaction force in a predetermined stroke area that contracts from the position.

  Therefore, in the present invention, when the fork main body is in the most extended state, the air pressure in the reservoir is filled with a pressure higher than atmospheric pressure so as to have a reaction force, so that the inside of the fork main body can be maintained in a pressurized state. Therefore, when the fork body in the most extended state starts the contraction operation, the contraction operation stable from the beginning is enabled.

  In the present invention, when the fork main body is in the most extended state, the air pressure in the reservoir is filled with atmospheric pressure equal to or higher than the atmospheric pressure to provide a reaction force, so the fork main body is always urged in the extending direction. Therefore, the fork main body can be urged in the extending direction without having a suspension spring. As a result, the weight can be reduced and the number of parts can be reduced by the absence of the suspension spring. .

  Further, in the present invention, when the fork main body is in the maximum extension state, a pressure higher than the atmospheric pressure is sealed in the air chamber in the reservoir to provide a reaction force, while the fork main body contracts from the maximum extension state. Therefore, the reaction force during the contraction operation in the predetermined stroke region can be reduced from the maximum extension state.

It is a front view which fractures | ruptures the front fork by one Embodiment of this invention, and shows it partially in a cross section. FIG. 2 is a partial semi-longitudinal longitudinal sectional view showing an enlarged upper end side portion of the front fork of FIG. 1. It is a figure which shows the intermediate part in the front fork of FIG. 1 similarly to FIG. It is a figure which shows the intermediate part in the front fork by other Embodiment of this invention similarly to FIG. It is a figure which the lower end side part in the front fork by other embodiment of this invention partially fractures | ruptures and shows similarly to FIG. FIG. 4 is a partial view showing an enlarged arrangement state of a balance spring that constitutes the suppression means in FIG. 3 and a spring receiver that carries the base end of the balance spring. It is a figure which shows the arrangement | positioning state of the balance spring and spring receiver by other embodiment similarly to FIG. It is a figure which shows the arrangement | positioning state of the balance spring and spring receiver by other embodiment similarly to FIG. It is a figure which shows the arrangement | positioning state of the balance spring and spring receiver by other embodiment similarly to FIG. It is a figure which shows the arrangement | positioning state of the balance spring and spring receiver by other embodiment 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 and absorbs road surface vibrations inputted to the front wheel of the two-wheeled vehicle that is traveling. Functions as a shock absorber.

  By the way, 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 expression, 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 car.

  The front fork includes a fork main body that has a top end coupled to a handle (not shown) in a two-wheeled vehicle and suspends a front wheel (not shown) in the two-wheeled vehicle at a lower end, and is housed in the fork main body. And a damper that expands and contracts in synchronism with the expansion and contraction of the fork main body and has a predetermined damping action.

  As shown in FIG. 1, the fork main body has a vehicle body side tube 1 composed of a large-diameter outer tube whose upper end side is coupled to the handle side, and a lower end while the upper end side is inserted into the lower end side of the vehicle body side tube 1 so as to be able to protrude and retract. The wheel-side tube 2 formed of a small-diameter inner tube that suspends the front wheel at the portion is an inverted type, and is formed into a telescopic type that can be expanded and contracted.

  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 reservoir R that is inside and outside the damper, as shown in the figure, and this reservoir R is a reservoir that is bordered by an oil surface O that is a liquid surface in the working oil that is a working fluid. It has an inside air chamber A.

  Incidentally, in the present invention, the air pressure A which is equal to or higher than the atmospheric pressure when the fork main body is in the fully extended state is sealed in the air chamber A in the reservoir. This will be described in detail later.

  As for the height position of the oil level O in the reservoir R, as shown in the figure, when the fork main body is in the most extended state, the wheel side tube 2 is pierced and between the vehicle body side tube 1. It is positioned so as to have a communication hole 2a in the lower oil that allows the hydraulic oil to flow into the emerging lubricating gap (not shown).

  As shown, the damper is set upside down with the cylinder body 3 as an upper end side member and the rod body 4 as a lower end side member. Basically, the cylinder body 3 is coupled to the vehicle body side tube 1. Then, it is suspended from the shaft core portion of the vehicle body side tube 1, and the rod body 4 is coupled to the wheel side tube 2 and stands on the shaft core portion of the wheel side tube 2.

  In the damper, as shown in the drawing, specifically, the cylinder body 3 integrally has a bottom end portion 31 that is an upper end portion in the figure. Is formed by housing a compression side damping means 6 and a free piston 7 which will be described later, while being suspended from the shaft core portion of the vehicle body side tube 1.

  That is, as shown in FIG. 3, the damper has a piston body 5 that is slidably received in the cylinder body 3 while being held at the tip portion that is the upper end portion of the rod body 4 in the figure. The piston body 5 includes an extension side damping means that defines a rod side chamber R1 and a piston side chamber R2 in the cylinder body 3 and allows mutual communication between the rod side chamber R1 and the piston side chamber R2. The means includes an extension side damping valve 51 and an extension side check valve 52, and realizes a predetermined extension side damping action when hydraulic fluid passes through the extension side damping valve 51.

  Note that any configuration may be employed for the above-described damping means. For example, the above-described extension side check valve 52 may be replaced with a suction valve or a pressure side damping valve. May be.

  And, as with many dampers of almost all kinds, even in this damper, the extension spring 53 for absorbing the acting force at the time of the maximum extension operation of the fork body, that is, the maximum extension operation of the damper is provided. Have.

  Note that the illustrated front fork has an oil lock mechanism that absorbs the acting force at the time of the most contraction operation, and this oil lock mechanism is oil retained on the outer periphery of the head end portion of the cylinder body 3 in the damper. The lock piece 33 has an oil lock case 21 disposed in the bottom end portion of the wheel side tube 2, and the oil lock piece 33 is operated at the time of the most contraction operation in which the rod body 4 is immersed in the cylinder body 3 with a large stroke. It is inserted into the oil lock case 21 to absorb the acting force at the time of the most contraction operation.

  On the other hand, in this damper, during the contraction operation in which the rod body 4 is immersed in the cylinder body 3, an amount of hydraulic oil corresponding to the rod intrusion integral that becomes redundant in the piston side chamber R <b> 2 passes through the compression side damping means 6. It flows out to the free piston 7 side.

  In this damper, contrary to the above, when the rod body 4 protrudes from the cylinder body 3 during the extension operation, the amount of hydraulic oil corresponding to the rod withdrawal volume integral deficient in the piston side chamber R2 is reduced. It is replenished via the compression side damping means 6 from the side.

  By the way, in this damper, as shown in FIG. 2, the cylinder body 3 includes a pressure side damping means 6 corresponding to a damping means provided in a base valve portion in a so-called hydraulic shock absorber in the bottom end portion 31, and this A free piston 7 positioned downstream of the compression side damping means 6.

  Here, the bottom end portion 31 in the cylinder body 3 will be described a little. As shown in FIG. 2, the bottom end portion 31 is formed in a cylindrical shape having a larger diameter than the cylinder body 3, and the lower end connecting portion 31a. Is screwed to the outer periphery of the open end 3 a of the cylinder body 3 using the lock nut 32.

  The bottom end portion 31 is configured such that the upper end connecting portion 31 b is screwed to the inner periphery of the upper end portion of the vehicle body side tube 1, and the bottom end portion 31 is disposed on the shaft core portion of the vehicle body side tube 1.

  The bottom end portion 31 includes a main body portion 31c that houses the compression-side damping means 6 and slidably mounts the free piston 7, and a diameter-enlarged portion that is continuous with the main body portion 31c via a tapered portion 31d. 31e, and the enlarged diameter portion 31e has a communication hole 31f that allows communication between the inside and outside of the bottom end portion 31.

  Incidentally, the bottom end portion 31 is formed to have a larger diameter than the cylinder body 3 as shown in the figure, in order to increase the so-called pressure receiving area. Therefore, when a sufficient pressure receiving area can be secured, The cylinder body 3 may have the same diameter, that is, the cylinder body 3 and the same diameter.

  When the bottom end portion 31 of the cylinder body 3 is formed as described above, the compression side damping means 6 includes the inside of the bottom end portion 31 inside the cylinder body 3, that is, the piston side chamber R2 side, While defining on the reservoir R side, that is, on the free piston 7 side, mutual communication between the piston side chamber R2 side and the free piston 7 side is allowed.

  The pressure-side damping means 6 has, for example, a pressure-side damping valve 61 and a pressure-side check valve 62 in parallel therewith, and particularly when the piston-side chamber R2 side is communicated with the free piston 7 side. A predetermined pressure side damping action is realized by the valve 61.

  Incidentally, the compression side attenuating means 6 is, as shown in the figure, a front end portion facing the piston side chamber R2 in the cylinder body 3 which is the lower end portion in the figure in the center rod 8 suspended from the shaft core portion of the vehicle body side tube 1. Retained.

  The center rod 8 is basically suspended from the shaft core portion of the cap member 11 that closes the upper end opening of the vehicle body side tube 1 and is present at the shaft core portion of the bottom end portion 31. In this case, the cap member 11 is screwed onto the inner periphery of the upper end connecting portion 31b in the bottom end portion 31 described above, and the cap member 11 is configured to allow the gas pressure in the reservoir inner air chamber A to be optimized. It has an air valve V that enables supply and discharge.

  On the other hand, in this damper, a free piston is accommodated in the bottom end portion 31, in particular, in the main body portion 31 c at the bottom end portion 31 so as to be in series with the downstream side of the compression side damping means 6. 7 is slidable. The free piston 7 includes a pressure receiving surface side oil chamber R3 which is the main body portion 71 and the pressure side damping means 6 side in the bottom end portion 31 and an air spring force. The back side air chamber A1 is defined.

  The free piston 7 is in sliding contact with the inner periphery of the main body 31c while having the seal 72 and the bush 73 on the outer periphery of the main body 71, and has the check seal 74 on the inner periphery of the center rod 8 described above. It is slidably arranged on the outer periphery, that is, slidably disposed.

  Further, the free piston 7 moves backward in the bottom end portion 31 so as to rise in the drawing, and particularly when the lower end of the main body portion 71 reaches the inside of the tapered portion 31d, the free piston 7 A gap appears between the outer periphery and the inner periphery of the taper portion 31d, and the communication with the reservoir R through the communication hole 31f inside the main body portion 31c is allowed by using this gap.

  Therefore, in this free piston 7, when the amount of hydraulic oil in the damper is at a predetermined amount, the reaction force in the back side air chamber A1 defined behind the free piston 7, that is, the air chamber A in the reservoir Regardless of the pressure, the inside of the cylinder body 3 is pressurized by the air spring force in the back side air chamber A1 to maintain the pressure increasing tendency.

  In the free piston 7, for example, the hydraulic oil expands due to an oil temperature rise in the damper or the hydraulic oil from the reservoir R outside the cylinder body 3 flows into the damper during the operation of the damper. For example, when the hydraulic oil in the damper exceeds a predetermined amount, it is retracted so as to rise above a predetermined stroke, and the bottom end portion 31 of the cylinder body 3 is used by using the open communication hole 31f. Excess hydraulic fluid is released back to the reservoir R.

  As described above, when the compression side damping means 6 is held at the tip of the center rod 8 connected to the cap member 11 that closes the upper end opening of the vehicle body side tube 1, the center rod 8 is provided with the free piston 7. Therefore, the compression side damping means 6 and the free piston 7 can be assembled together with the cap member 11 so as to be advantageous in improving the assembly of the front fork.

  By the way, in this invention, the back side air chamber A1 defined in the closed space having the air spring force by the free piston 7 has a booster spring 75 as an urging spring, and the damper is in the fully extended state. At a certain time, the free piston 7 is lowered in the bottom end portion 31, that is, moved forward to maintain the cylinder body 3, that is, the damper in a pressure-increasing tendency, and the damper in the most extended state is contracted. This makes it possible to realize a stable compression-side damping action from the beginning of the operation.

  By the way, in the present invention, the fork main body that is in the most extended state is filled with an atmospheric pressure that is equal to or higher than the atmospheric pressure to provide a reaction force, so that the fork main body is attached in the extending direction without a suspension spring. Therefore, from this, it can be said that the above-described booster spring 75 is not necessarily accommodated in the back side air chamber A1.

  That is, in the fork main body that encloses atmospheric pressure that is equal to or higher than atmospheric pressure in the maximum extension state, it is expected that the inside of the damper is gradually increased during the contraction operation, but the air spring force caused by the back side air chamber A1 is increased. When the provided free piston 7 functions to release the boosted amount to the reservoir R, the boosting spring 75 is not necessary.

  Therefore, the damper housed in the fork main body according to the present invention does not need to have the booster spring 75 that urges the free piston 7 from the back side. Because it does not have, it can reduce the weight and the number of parts.

  As disclosed in the above-mentioned Patent Document 1 and as disclosed in Japanese Patent Application Laid-Open No. 2005-30534, this type of free piston has a coil spring as a biasing means behind. It is normal to have a booster spring (20a or 4) as an urging spring.

  Therefore, even in the present invention, the booster spring 75 made of a coil spring may be provided behind the free piston 7, but the coil spring is generally attached to the biased member adjacent to the tip. It is difficult to apply the force evenly in the circumferential direction that is the winding direction of the coil spring, and when the biased member is the free piston 7, there is a problem that the free piston 7 is liable to develop a phenomenon.

  Therefore, when the free piston 7 is urged from behind, the reaction force in the back side air chamber A1, that is, the air spring force, is utilized without using the booster spring 75 as in the present invention, and at least In addition, it is preferable to prevent the occurrence of the wobbling phenomenon in the free piston 7 by using the booster spring 75 in advance.

  When air spring force is used, the occurrence of a sag phenomenon in the free piston 7 can be prevented. Therefore, in order to stabilize the slidability of the free piston 7, as shown in FIG. Although not shown in the figure, it is possible to prevent an unreasonable increase in weight by reducing the dimension of the free piston 7 in the sliding direction.

  In the front fork formed as described above, the fork main body in the fully extended state is filled with a pressure higher than the atmospheric pressure so as to have a reaction force. Thus, it is assumed that a stable contraction operation can be realized from the beginning when the fork body in the most extended state starts the contraction operation.

  That is, in the front fork according to the present invention, the pressure of the gas sealed in the reservoir air chamber A defined by the oil level O in the fork main body is as follows. It is said that the pressure is at least atmospheric pressure, for example, 0.3 MPa or more.

  Therefore, in this front fork, for example, the inside of the fork can be maintained at a high pressure tendency because the fork has a reaction force by enclosing an atmospheric pressure higher than atmospheric pressure of 0.3 MPa or more, When the fork main body in the most extended state starts the contraction operation, that is, the contraction operation stable from the beginning of the contraction operation is enabled.

  And, in the illustrated front fork, it becomes possible to maintain the internal pressure in the damper of the storage in the fork main body in a high-pressure tendency, and therefore, when the damper in the most extended state starts a contraction operation, A stable damping action can be realized from the beginning of the contraction operation.

  In the illustrated front fork, the fork main body is constantly energized in the extending direction because the fork main body is filled with, for example, an atmospheric pressure equal to or higher than 0.3 MPa to provide a reaction force. The fork main body can be urged in the extending direction without having a suspension spring. As long as the suspension spring is not provided, the weight can be reduced and the number of parts can be reduced.

  The applicant confirmed that when the fork main body having the inner diameter of the cylinder body 3 of approximately 25 mm and the length of 300 mm is in the most extended state, the reservoir air chamber A has an atmospheric pressure of about 0.3 MPa or more. When the gas is sealed, the internal pressure of the fork main body in the most contracted state becomes approximately 1.5 MPa, and therefore the fork main body can be urged in the extending direction without having a suspension spring.

  Incidentally, although no literature is shown, there has been a proposal of a front fork that urges the fork main body in the extending direction at an atmospheric 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.

  Therefore, in this embodiment, not only the atmospheric pressure of atmospheric pressure or higher, for example, 0.3 MPa or higher is enclosed in the fork main body, but also the atmospheric pressure of atmospheric pressure or higher in the fork main body as described later. The fork main body has a peculiarity having suppression means for suppressing a reaction force in a predetermined stroke region in which the fork main body contracts from the maximum extension state while enclosing the atmospheric pressure to provide a reaction force.

  That is, the front fork of this embodiment has a reaction force due to the atmospheric pressure at which the fork main body in the most extended state is enclosed. Therefore, when the contraction operation is started from the maximum extended state, the enclosed fork is enclosed. Compared to the case where there is no reaction force due to atmospheric pressure, for example, there is a risk that the rider in a motorcycle will give the impression that the front fork is hard, but the reaction force due to the atmospheric pressure enclosed in this most extended state is By suppressing, it is possible to avoid giving the rider in the motorcycle the impression that the front fork is hard.

  The predetermined stroke region is a region of a contraction stroke that starts from the most extended state, and is preferably a stroke region that is approximately 1/3 of the entire stroke from the most extended state to the most contracted state. This is not an absolute one, and even if there are some differences, the intention of the suppression means in the present invention is not different.

  In addition, as shown in the figure, this restraining means has a balance spring S made of a coil spring, and this balance spring S is between the wheel side tube 2 constituting the fork main body and the cylinder body 3 constituting the damper. The fork main body is biased in the contraction direction with a spring force that suppresses the reaction force in the fork main body.

  In view of biasing the fork main body in the contracting direction, that is, having a spring force for suppressing the reaction force in the fork main body, the balance spring S is provided with an extension spring 53 (see FIG. 1) in the damper. And there is room for the same spring as that shown in FIG.

  However, from the viewpoint of canceling out the so-called initial reaction force of the fork body in the most extended state, the balance spring S functions differently from the extension spring 53 that absorbs the acting force during the maximum extension operation of the damper. To do.

  By the way, as shown in FIG. 3, the balance spring S described above is supported by a spring receiver 9 whose base end, which is the lower end in the drawing, is held on the outer periphery of the cylinder body 3, and the tip which is the upper end in the drawing is the wheel. The fork main body is biased in the contracting direction with a spring force that suppresses a reaction force in the fork main body in a state of being locked to a cylindrically formed spacer 10 connected to the upper end portion of the side tube 2.

  As described above, the balance spring S tends to be contracted in the above-described stroke region starting from the front where the fork main body is extended to reach the maximum extended state, and tends to suppress the movement of the fork main body in the extending direction. In particular, the reaction force in the extension direction of the fork main body in the most extended state is set to zero to avoid giving the rider in the motorcycle the impression that the front fork is stiff when starting the contraction operation from the maximum extended state. .

  And when the balance spring S which comprises this suppression means is arrange | positioned outside a damper, the change of the setting of the spring force in this balance spring S becomes easy, and what is called maintenance property is also improved.

  However, from the viewpoint of the function of the suppression means, the balance spring S may be disposed inside the damper (not shown) instead of being disposed outside the damper as described above. In such a case, it is possible to reduce the number of related parts as compared with the case where the balance spring S is disposed outside the damper, as well as not hindering the damper from being made into a cartridge.

  FIGS. 4 and 5 show a front fork according to another embodiment of the present invention, which will be described below. The structure of the front fork is shown in FIGS. Parts that are the same as those shown in FIGS. 1 to 3 are given the same reference numerals in each figure, and detailed descriptions thereof are omitted unless necessary.

  4 and 5, the fork main body is set to be an upright type in which the wheel side tube 2 is made of a large diameter outer tube and the vehicle body side tube 1 is made of a small diameter inner tube.

  Moreover, in the place shown in FIG. 4, the damper is set to the upright type which makes the cylinder body 3 a lower end side member and makes the rod body 4 an upper end side member.

  To explain a little, in the case of FIG. 4, the fork main body seals the air pressure in the reservoir R in the reservoir internal air chamber (not shown) of the atmospheric pressure higher than the atmospheric pressure. Have.

  4 has a piston body 5 that is slidably accommodated in the cylinder body 3, and this piston body 5 defines a rod side chamber R1 and a piston side chamber R2 in the cylinder body 3. The extension side damping means includes an extension side damping valve 51 and an extension side check valve 52 in parallel therewith, and the hydraulic oil in the rod side chamber R1 is supplied to the extension side damping valve 51. When the flow passes through and flows out into the piston side chamber R2, a predetermined extension side damping action is realized.

  The damper shown in the figure is in the fully extended state, and in this fully extended state, the lower end is carried by the seat portion 4a adjacent to the piston body 5 that is held at the tip portion that is the lower end portion in the drawing of the rod body 4. At the same time, the upper end constitutes a head end portion of the cylinder body 3 and the rod body 4 passes through the shaft core portion, and is locked to the rod guide 34 that closes the opening end of the cylinder body 3 under the arrangement of the spring seat 53a. The extension spring 53 contracts and absorbs the action force of the damper with the maximum extension.

  The rod guide 34 slides the outer periphery of the upper end portion into the inner periphery of the vehicle body side tube 1 to prevent the upper end side of the cylinder body 3 from falling down. A communication hole 34a that allows communication is provided.

  As described above, when the damper is set to the upright type, the cylinder body 3 is always positioned in the hydraulic oil as compared with the case where the damper is set to the inverted type. It is easy to maintain the state filled with hydraulic oil, and therefore it is easy to ensure the operation of the damper.

  As a result, in the front fork having the upright damper, the arrangement of the seal member for improving the liquid tightness in the damper can be omitted, or the sliding resistance in the seal can be reduced. This is advantageous in that the operability can be improved.

  On the other hand, the balance spring S is disposed in a state of being wound around the outer periphery of the cylinder body 3, and the upper end is suspended by the stopper 22 held on the outer periphery of the cylinder body 3, and the lower end of the fork main body shown in the figure. It is carried by the carrying ring 12 held on the inner periphery of the lower end portion of the vehicle body side tube 1 in the most extended state, and reaches the most contracted state and urges the fork main body in the most extended state in the contracting direction.

  Incidentally, the stopper 22 is connected to a stop ring 23 fitted in an annular groove 3b formed on the outer periphery of the cylinder body 3, and the carrier ring 12 is formed in an annular groove (not shown) formed on the inner periphery of the lower end portion of the vehicle body side tube 1. ) And the lower end of the vehicle body side tube 1 is held by being bent inward.

  The balance spring S functions in the same manner as the balance spring S shown in FIGS. 1 and 3 described above.

  The front fork shown in FIG. 5 implements a predetermined damping action without the fork main body comprising the vehicle body side tube 1 and the wheel side tube 2 having a damper, that is, the cylinder body 3 and the rod body 4. And has a balance spring S constituting the suppression means.

  That is, the front fork erects the seat pipe 24 at the axial center portion of the wheel side tube 2 and the lower end portion of the vehicle body side tube 1 inserted into the wheel side tube 2 serves as a piston portion (not shown). Then, the inner periphery is made to face the outer periphery of the seat pipe 24.

  On the other hand, the upper end portion of the seat pipe 24 has a check valve 25 slidably in contact with the inner periphery of the vehicle body side tube 1 on the outer periphery, and this check valve 25 moves downward to the lower side of the hydraulic oil from the upper side. Is allowed to flow, but when it rises, it prevents the hydraulic oil from flowing downward from the upper side.

  From the above-described check valve 25, the lower piston portion of the vehicle body side tube 1 is in sliding contact with the outer periphery of the seat pipe 24, and when it rises, the hydraulic oil from the lower side moves upward. However, it has a check valve 13 that prevents the hydraulic oil from flowing upward from the upper side when it descends.

  Incidentally, the check valve 25 is accommodated in an annular groove (not shown) formed by bending the upper end portion of the seat pipe 24 so as to be movable up and down, and the check valve 13 is provided on the vehicle body side tube 1. An annular hollow portion that appears between the collar member 14 that is fitted to the inner periphery of the lower end portion and constitutes the piston portion and that constitutes the oil lock case and the case body 15 that is placed on the upper end of the collar member 14 ( (Not shown) so that it can move up and down.

  The collar member 14 has a communication hole 14a that allows communication between the inner and outer circumferences, and in particular, the hydraulic oil on the inner circumference side passes through the communication hole 14a and the communication hole 1a that opens in the vehicle body side tube 1 is provided. Is allowed to flow in as a lubricating oil into a lubricating gap (not shown) appearing between the vehicle body side tube 1 and the wheel side tube 2.

  In the front fork, the inside of the seat pipe 24 communicates with the reservoir R that is above the check valve 25, and the lower end side of the seat pipe 24 is opened through a communicating hole 24a. It communicates with the piston side chamber R2 below the piston portion.

  Incidentally, in correspondence with the lower part of the piston part being the piston side chamber R2, the upper part of the piston part is a piston upper chamber (not shown), and a balance spring S that constitutes a suppression means described later in this piston upper chamber. Is disposed.

  On the other hand, the seat pipe 24 has an orifice 24b on the upper end side, and this orifice 24b allows communication between the inside of the seat pipe 24 and the piston upper chamber when the above-described piston portion is in a normal operation region. However, when the fork main body reaches the maximum extension state, the fork body is closed by the check valve 13 to prevent communication between the inside of the seat pipe 24 and the piston upper chamber, and a reservoir of hydraulic oil from the piston upper chamber. The so-called omission toward R is prevented.

  The collar member 14 constitutes an oil lock case. The oil lock piece fitted to the oil lock case is an oil hole 16 and is wound around the outer periphery of the lower end portion of the seat pipe 24. The

  Incidentally, the balance spring S constituting the suppressing means is disposed between the upper end portion of the seat pipe 24 and the case body 15 constituting the piston portion, and the vehicle body side tube from the wheel side tube 2. When 1 protrudes most, that is, when the fork main body is in its maximum extension state, it is contracted most between the upper end portion of the seat pipe 24 and the case body 15 and urges the fork main body in a contracting direction.

  The balance spring S functions in the same manner as the balance spring S shown in FIGS. 1 and 3 described above.

  Therefore, in this front fork, when the vehicle body side tube 1 is retracted into the wheel side tube 2, the piston side chamber R2 is contracted by the lowering of the piston portion which is the lower end portion of the vehicle body side tube 1, The hydraulic oil from the side chamber R <b> 2 passes through the communication hole 24 a and flows out to the reservoir R that is inside the seat pipe 24.

  In this front fork, during the extension operation in which the vehicle body side tube 1 protrudes from the wheel side tube 2, the hydraulic oil from the piston upper chamber above the piston portion which is the lower end portion of the vehicle body side tube 1 is transferred to the seat pipe. A predetermined extension side damping action is realized by passing through the orifice 24b opened at 24 and flowing out to the reservoir R which is the inside of the seat pipe 24, and the working oil passes through the orifice 24b.

  By the way, as for the restraining means, as shown in FIG. 3, as long as the balance spring S is provided, the spring receiver 9 carrying the base end which is the lower end in the figure of the balance spring S can be freely configured. Therefore, in the following, a representative configuration will be described a little.

  6 and 7 and the subsequent drawings, the description of the wheel side tube 1 is omitted, and the shape of the balance spring S is except for the case shown in FIG. 3, that is, FIG. 6 and FIG. 8 (A). 7, FIG. 8 (B) and FIG. 9 and subsequent figures, the base end portion as the lower end portion in the drawing may be formed in a straight shape without being reduced in diameter.

  Each of the following embodiments is a so-called example, and therefore, each embodiment is not an absolute one that cannot be changed, and it goes without saying that each configuration may be used together or mixed. is there.

  First, as shown in FIG. 6, that is, as shown in FIG. 3 described above, the spring receiver 9 that supports the lower end of the balance spring S is configured so that the outer periphery does not slide in contact with the inner periphery of the wheel side tube 2.

  The spring receiver 9 supports the base end of the balance spring S with a support portion 91a integrally formed in a flange shape on the outer periphery while the main body portion 91 is formed in a cylindrical shape and is wound around the outer periphery of the cylinder body 3. To do.

  In the spring receiver 9, the lower end of the main body 91 is only supported by the stop ring 92 fitted in the annular groove 3 b formed on the outer periphery of the cylinder body 3. This can be said to be sufficient, considering where it works.

  That is, as described above, the balance spring S is set to have an urging force for contracting the fork body when the fork body is in the fully extended state, so that the spring receiver 9 is stopped by the urging force. It functions to press against the ring 92, and from this, the spring receiver 9 is fixed to a predetermined position.

  Therefore, in this embodiment, since the configuration of the restraining means, in particular, the configuration of the spring receiver 9 is simplified and the minimum component configuration, the weight of the mischief in the front fork by having the restraining means is reduced. This is advantageous in that increase and cost increase can be avoided.

  In addition, in the case of this embodiment, since the base end side of the balance spring S does not interfere with the wheel side tube 2 and does not generate sliding contact resistance, it can be made to be a free end side. Is advantageous in that it can be used without waste.

  In the embodiment shown in FIG. 7, the main body portion 91 constituting the spring receiver 9 is formed in a substantially funnel shape, and the outer periphery is brought into sliding contact with the inner periphery of the wheel side tube 2 under the bushing 93. Accordingly, the main body 91 can be made larger in diameter compared to the embodiment shown in FIG. 4, and therefore, it is advantageous in that the lower end of the balance spring S does not need to be reduced in diameter.

  In the spring receiver 9 of this embodiment, a spring sheet 94 is laid on the upper end of the main body 91, and the base end of the balance spring S is carried via the spring sheet 94.

  On the other hand, in the embodiment shown in FIG. 7, the reduced diameter base portion of the main body 91 wound around the outer periphery of the cylinder body 3 is held on the outer periphery of the cylinder body 3 in various modes.

  Incidentally, regarding the point that the lower end of the balance spring S does not need to be reduced in diameter and the point that the spring seat 94 is laid on the upper end of the main body 91, FIG. 9 and FIG. The same applies to each embodiment shown.

  That is, first, as shown in FIG. 7A, the upper and lower two-stage annular grooves 3b and 3c are formed on the outer periphery of the cylinder body 3, and the stop ring fitted into the annular grooves 3b and 3c. 92 clamps the base in the main body 91 of the spring receiver 9.

  Therefore, in the case of the embodiment shown in FIG. 7 (A), the main body is compared with the case where it is only carried by the lower stop ring 92 as in the case of the embodiment shown in FIG. Fixability of the portion 91 to the cylinder body 3 is improved.

  Next, as shown in FIG. 7B, the stop ring 92 fitted on the outer periphery of the cylinder body 3 is only the lower stop ring 92 as in the embodiment shown in FIG. However, the base of the main body 91 of the spring receiver 9 is crimped so as to wrap the stop ring 92.

  Therefore, in the case of the embodiment shown in FIG. 7B, the base portion needs to be crimped as compared with the case of the embodiment shown in FIG. The fixing property to the cylinder body 3 in the main body 91 is improved.

  Incidentally, in the case of the embodiment shown in FIG. 7B, the number of stop rings 92 is reduced, that is, the formation of the annular groove 3b on the outer periphery of the cylinder body 3 is made one. The annular groove formed on the outer periphery of the cylinder body is only required to be formed at one place. Therefore, it is advantageous in that the mechanical strength of the cylinder body 3 is hardly lowered.

  7 (C), the stop ring 92 fitted on the outer periphery of the cylinder body 3 is only the lower stage, and the above-described diagram is not necessary for the base part of the main body 91. The main body 91 shown in FIG.

  On the other hand, in this embodiment, the annular plug 95 interposed on the outer periphery of the cylinder body 3 is swaged and the main body portion 91 is pressed against the cylinder body 3, so that the main body portion 91 is against the cylinder body 3. Ensures fixability.

  Therefore, in the case of the embodiment shown in FIG. 7C, an annular plug 95 is required, but it is formed on the outer periphery of the cylinder body 3 as compared with the case of the embodiment shown in FIG. Since the number of annular grooves to be reduced is reduced, it is advantageous in that it is difficult to reduce the mechanical strength of the cylinder body 3.

  7D, a thread 3d is formed on the outer periphery of the cylinder body 3, and a thread 91a that is screwed into the thread 3d is formed at the base of the main body 91. By fixing the base portion to the outer periphery of the cylinder body 3, the fixing property of the main body portion 91 to the cylinder body 3 is ensured.

  Therefore, in the case of the embodiment shown in FIG. 7D, it takes time to form the respective threads 3d and 91a on both the outer periphery of the cylinder body 3 and the base portion of the main body 21, but the stop ring This is advantageous in that 92 parts are unnecessary and the number of parts is not increased accordingly.

  In the embodiment shown in FIG. 8, the main body 91 of the spring receiver 9 is formed in a shape substantially similar to the main body 91 of the spring receiver 9 in the embodiment shown in FIG. The outer periphery of the locking portion 91a is slidably contacted with the inner periphery of the wheel side tube 2 under the bushing 93 while the base end of the balance spring S is supported by the locking portion 91a that is integrally provided.

  Incidentally, in this embodiment, the main body portion 91 of the spring receiver 9 is in a state of being sandwiched between a pair of stop rings 92 that are fitted on the outer periphery of the cylinder body 3 so as to be in two upper and lower stages. Has been established.

  In this embodiment, the locking portion 91a has a hole 91b that allows communication between the upper and lower sides, and a predetermined damping action when hydraulic oil passes through the hole 91b, that is, a cylinder If the damping action embodied by the damping means of the piston body 5 (see FIG. 3) in the body 3 is called primary damping, it can be said that secondary damping can be realized.

  8A, the base end of the balance spring S is reduced in diameter, and the base end of the balance spring S is not reduced in diameter as shown in FIG. 8B. Is formed.

  Therefore, in the embodiment shown in FIG. 8, though the pressure is increased via the reservoir R, the pressure inside the damper is increased, and the expansion and contraction of the bubbles in the hydraulic oil and the disturbance of the damping action associated therewith are disturbed. Can be effectively prevented.

  The embodiment shown in FIG. 9 is an alternative to the embodiment shown in FIG. 7 described above, and enables secondary attenuation as in the case of the embodiment shown in FIG. In the illustrated embodiment, the body 91 of the spring receiver 9 has a plurality of holes 91c and 91d that embody secondary damping.

  By the way, the hole for secondary attenuation is a plurality of holes 91c and 91d as shown in the figure, and instead of making the diameters of the holes 91c and 91d different from each other, although not shown, It may be a long hole that extends or a wedge-shaped hole that converges upward in a front view.

  In the embodiment shown in FIG. 9B, secondary damping is performed between the outer periphery of the main body 91, that is, between the bush 93 and the wheel side tube 2 interposed on the outer periphery of the main body 91 in the drawing. It has a gap (not shown) that makes it possible.

  Further, in the embodiment shown in FIG. 9C, a check valve 96 is provided between the main body 91 and the spring seat 94 in the spring receiver 9, and the check valve 96 is hydraulic oil from the reservoir R. Is allowed to flow into the inside of the main body 21, but the reverse flow is prevented.

  In this embodiment, when the hydraulic oil from the reservoir R flows into the inside of the main body 21 via the check valve 96, secondary damping is realized.

  Incidentally, even in the embodiment shown in FIG. 9, the main body portion 91 of the spring receiver 9 is in a state of being sandwiched between a pair of stop rings 92 that are fitted on the outer periphery of the cylinder body 3 in two upper and lower stages. The cylinder body 3 is fixed.

  Therefore, according to the embodiment shown in FIG. 9, as in the case of the above-described embodiment shown in FIG. It is possible to effectively prevent the expansion and contraction of bubbles and the disturbance of the damping action associated therewith.

  In the embodiment shown in FIG. 10, the outer periphery of the main body 91 in the spring receiver 9 is in sliding contact with the inner periphery of the wheel side tube 2 under the bushing 93, and the fixing manner to the cylinder body 3 at the base of the main body 91. There is a difference.

  That is, first, in the embodiment shown in FIG. 10A, it is assumed that the base portion of the main body 91 is sandwiched between the main body of the cylinder body 3 and the head end portion of the cylinder body 3, In other words, the use of a plurality of stopper rings 92 is avoided while the spring receiver 9 is fixedly fixed to the outer periphery of the cylinder body 3.

  In the embodiment shown in FIG. 10B, the inner diameter of the main body 91 of the spring receiver 9 is made smaller than the inner diameter of the balance spring S, thereby forming the outer periphery of the cylinder body 3 and the inner periphery of the main body 91. The gap 9a is reduced, and this gap 9a has the same effect as the hole 91b.

  That is, the above-described secondary damping is realized by the hydraulic oil passing through the gap 9a.

  In addition, the part which makes the internal diameter of the main-body part 91 smaller than the internal diameter of the balance spring S is shown in FIG. 10 (B). Also good.

  Further, in the embodiment shown in FIG. 10C, the base portion of the main body portion 91 of the spring receiver 9, that is, the upper end portion in the figure, is crimped and fitted to the outer periphery of the cylinder body 3. Fix to the stop ring 92.

  Therefore, in the embodiment shown in FIG. 10C, the base end of the balance spring S is positioned below the stop ring fitted on the outer periphery of the cylinder body 3, so that the base end of the balance spring S is Compared with the case where is positioned above the stop ring, the total length of the balance spring S can be increased.

  In the above description, the case where the front fork turns the fork body upside down and the damper is turned upside down, or when the fork body is turned upright and the damper is also upside down has been described as an example. In view of the intention of the present invention, particularly when the damper is set to be upright, the fork body may be set to be upright or may be set to be inverted. Of course.

  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 6 Pressure side damping means 7 Free piston 9 Spring receiver 31 Bottom end A Reservoir air chamber A1 Back side air chamber O Oil surface R3 Pressure side oil chamber S Suppressing means Constructing balance spring

Claims (7)

  In a front fork having a reservoir internal air chamber with a liquid level as a boundary in a fork main body that can be expanded and contracted by a vehicle body side tube and a wheel side tube, when the fork main body is in a fully extended state, In addition to having a reaction force by enclosing an air pressure higher than atmospheric pressure in the air chamber in the reservoir, the fork main body has a suppression means for suppressing the reaction force in a predetermined stroke region where the fork main body contracts from the most extended state. A featured front fork.   The fork main body has a damper that can be expanded and contracted between the cylinder body and the rod body, and the damper is set to an inverted type having the cylinder body as an upper end side member and the rod body as a lower end side member, or The front fork according to claim 1, wherein the front fork is set upright with the cylinder body as a lower end side member and the rod body as an upper end side member.   The fork main body has a damping force generating portion comprising a seat pipe standing on the shaft core portion of the wheel side tube and a piston portion which is composed of a lower end portion of the vehicle body side tube and is positioned outward of the seat pipe. The front fork according to claim 1 formed.   The fork main body has a damper that can be expanded and contracted between the cylinder body and the rod body, and the damper is set to an inverted type in which the cylinder body is an upper end side member and the rod body is a lower end side member. A free piston having a cylinder body having pressure side damping means in the bottom end portion and slidably disposed downstream of the pressure side damping means to define a pressure receiving surface side oil chamber and a back side air chamber in the bottom end portion. The pressure side oil chamber communicates with the reservoir air chamber when the free piston moves back a predetermined stroke while the back side air chamber is blocked from the reservoir air chamber. The front fork according to claim 1, wherein the suppression means is disposed between the wheel-side tube and the cylinder body.   The suppression means has a balance spring made up of a coil spring, and the balance is reduced when the fork main body contracts a stroke of approximately 1/3 or more of the total stroke from the maximum extension state to the maximum contraction state. 5. The front fork according to claim 1, wherein the spring has a spring force for suppressing a reaction force in the fork main body.   The said restraining means has a balance spring which consists of a coil spring, and a spring receiver which carries the base end of this balance spring, and this spring receiver is hold | maintained on the outer periphery of the said cylinder body. The front fork according to claim 2, claim 3, claim 4 or claim 5.   The front fork according to claim 6, wherein the spring receiver has a damping means for performing a predetermined damping action when the hydraulic oil passes.

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