JP2009264489A - Front fork - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front fork enabling to operate damping means as set by hardly developing a low pressure phenomenon in a cylinder body during the operation of a damper and quickly cancelling the low pressure phenomenon if developed. <P>SOLUTION: The front fork comprises a reservoir chamber R formed inside a fork body consisting of a vehicle body side tube 1 and a wheel side tube 2, a check valve 7 provided in a cylinder body 3 between an upper chamber R1 and the reservoir chamber R, and a throttle. A control valve 6 is arranged in a bypass line which bypasses damping means 5a, 5b of a piston body 5 to permit the communication of the upper chamber R1 with a lower chamber R2. It controls the flow amount of operating oil passing into the bypass line L through a shaft core portion of an upper rod body 42 with the operation of an adjuster 9 from the outside of the fork body. On the other hand, the throttle is formed between the upper rod body 42 and a control rod 61 so that one end is communicated with the inside of the cylinder body 3 and the other end is communicated with the reservoir chamber R. <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 functions as a hydraulic shock absorber that is mounted on a front wheel side of a two-wheeled vehicle and absorbs road surface vibration that is input to the front wheel while incorporating a double rod type damper.

  There have been various proposals for a front fork that functions as a hydraulic shock absorber that is built on the front wheel side of a two-wheeled vehicle and absorbs road surface vibration that is input to the front wheel while incorporating a double rod type damper. Thus, for example, in the proposal disclosed in Patent Document 1, a double rod type damper is provided together with a suspension spring in a fork body composed of a vehicle body side tube and a wheel side tube.

  The double rod type damper has an upper chamber and a lower chamber defined in the cylinder body by a piston body slidably accommodated in the cylinder body, and an upper rod body and a lower chamber inserted through the upper chamber. The diameter of the lower rod body through which is inserted is made the same.

  Therefore, in the front fork disclosed in the above literature, when the fork main body is extended and contracted, the damper has a low pressure side when the upper chamber is on the high pressure side, and the low pressure is low in the high speed state of the extension operation. The side becomes negative pressure, so that fine bubbles remaining in the hydraulic oil expand.

  This expanded bubble contracts when the lower chamber turns to the high pressure side, but due to the contraction of the expanded bubble, the attenuation effect by the attenuation means decreases, and a phenomenon called “damping force sabotage” occurs. This “damping force sabotage” phenomenon is aggravated and makes the riding feeling of a motorcycle worse.

  Therefore, although not shown in the drawings, the applicant of the present application first proposes that the diameters of the two rod bodies are different when the damper in the fork main body is a double rod type. It is assumed that the head end portion of the cylinder body through which the rod body passes has a pressurizing means for pressurizing the cylinder body and a check valve in parallel therewith.

  Therefore, according to the previous proposal, when the damper that the upper chamber through which the small-diameter rod body is inserted contracts and the lower chamber through which the large-diameter rod body is inserted expands is operated, the excess oil based on the diameter difference in the cylinder body Is discharged to the reservoir chamber via the pressurizing means, so that the inside of the cylinder is pressurized and the pressure inside the cylinder is prevented from being lowered.

  Conversely, when the lower chamber contracts and the upper chamber expands, the lower chamber is not only pressurized, but hydraulic oil flows from the outside of the cylinder body through the check valve. Thus, the upper chamber is not reduced in pressure, and pressure reduction in the cylinder body is similarly prevented.

Therefore, the “damping force sag” phenomenon due to the damping means that appears between the time when the fine bubbles remaining in the hydraulic oil in the cylinder expands at low pressure and the expanded bubbles contract at the time of high pressure after dripping. Can be avoided.
Japanese Patent No. 3873192 (Claims, paragraphs 0021, 0033, 0037 to 0039 in the specification, see FIG. 1)

  However, the above-described front fork previously disclosed by the applicant of the present application is not basically problematic in that it can avoid the problem that fine bubbles remaining in the hydraulic oil in the cylinder body expand and contract. However, depending on the difference in diameter between the two rod bodies, it may be pointed out that a favorable damping effect cannot be obtained.

  That is, in the above-described proposed front fork, in the damper, the larger the difference in diameter between the two rod bodies, the greater the amount of hydraulic oil flowing in and out between the cylinder body and the reservoir chamber. .

  For this reason, the amount of hydraulic oil flowing into the upper chamber through which the small-diameter rod body is inserted via the check valve increases, but the hydraulic oil flowing into the upper chamber via the check valve is increased in the reservoir chamber having an air chamber above. Since it is hydraulic oil, it becomes easy to entrain air in hydraulic oil.

  When this air flows into the cylinder through the check valve, the damping effect by the damping means is reduced.

  Therefore, when differentiating the diameter difference between the two rod bodies in a double rod type damper, the amount of hydraulic oil flowing into the upper chamber through which the small diameter rod body is inserted via the check valve is reduced. From the viewpoint of making it difficult to entrain, it can be said that it is better to reduce the difference in diameter between the two rod bodies.

  However, when reducing the difference in diameter between the two rod bodies, the upper chamber through which the small-diameter rod body is inserted contracts, and the lower chamber through which the large-diameter rod body is inserted expands from the cylinder body during operation of the damper. The amount of surplus oil discharged to the reservoir chamber via the pressure means is reduced, so that pressurization in the cylinder body is not effectively realized, and there is a concern that the “damping force sagging” phenomenon will occur due to the above-described damping means.

  The present invention was devised in view of the above-described circumstances, and an object of the present invention is to enable pressurization in a cylinder body in a double rod type damper having two rod bodies that reduce the diameter difference. Thus, it is to provide a front fork that is optimal for guaranteeing the damping effect by the damping means and expecting to improve its versatility.

  In order to achieve the above-described object, the structure of the front fork according to the present invention basically includes a suspension spring having a fork body composed of a vehicle body side tube and a wheel side tube as a reservoir chamber, and is also of a double rod type. A cylinder body having a damper, the rod-type damper being disposed in the wheel-side tube and defined as a reservoir chamber, and a rod that is suspended in the body-side tube and is inserted into the cylinder body so as to be able to appear and retract. And a piston body that is slidably housed in the cylinder body and allows communication between the upper chamber and the lower chamber through the damping means while defining an upper chamber and a lower chamber in the cylinder body, An upper rod body that connects the base end to the piston body in the cylinder body while the rod body is connected to the vehicle body side tube, and a base end that penetrates the bottom end portion of the cylinder body through the bottom end of the cylinder body It consists of two lower rod bodies to be connected to the piston body in the cylinder body, and one of the upper rod body and the lower rod body is formed with a smaller diameter than the other rod body, and the rod body formed with this smaller diameter is In a front fork provided with a check valve between an upper chamber or a lower chamber to be inserted and a reservoir chamber, and having a throttle parallel to the check valve, the one chamber and the other chamber bypass the piston body damping means. While the control valve located in the bypass passage allowing the communication of the rod passes through the shaft core portion of the rod body and controls the flow rate of hydraulic oil through the bypass passage by operating the adjuster from the outside of the fork body, It is assumed that the control rod serves as a throttle that communicates one end with the cylinder body and communicates the other end with the reservoir chamber.

  In the double rod type damper accommodated in the fork main body, a throttle parallel to the check valve is provided between the upper chamber or the lower chamber and the reservoir chamber in the cylinder body through which the rod body having a small diameter is inserted. Since the sliding gap between the rod body and the control rod is used as a throttle, it is not necessary to provide a member that constitutes the diaphragm.

  In addition, since the hydraulic oil that has passed through the throttle does not directly blow up the oil level in the reservoir chamber, it is difficult for aeration to occur in the hydraulic fluid in the reservoir chamber, and the hydraulic oil that flows into the cylinder body through the check valve Reduce air contamination.

  Since a check valve is provided between the upper chamber or lower chamber in the cylinder body through which the rod body having a small diameter is inserted and the reservoir chamber, when the difference in diameter between the two rod bodies is reduced, the upper chamber or the lower chamber described above is used. The amount of hydraulic fluid that flows into the chamber from the reservoir chamber via the check valve is reduced, and there is no concern about air entrainment in the cylinder body.

  Further, since the throttle is provided in parallel with the check valve between the upper chamber or the lower chamber and the reservoir chamber, surplus oil in the cylinder body is discharged to the reservoir chamber through the throttle when the damper is operated, and the cylinder body Is pressurized, and negative pressure in the cylinder body is prevented.

  As a result, the expansion phenomenon of the fine bubbles remaining in the hydraulic oil due to the negative pressure in the cylinder body is not expressed, the occurrence of the “sag of the damping force” phenomenon by the damping means can be avoided, and the predetermined damping effect by the damping means is achieved. can get.

  Hereinafter, the present invention will be described based on the illustrated embodiment. The front fork according to the present invention is a hydraulic shock absorber that is mounted on the front wheel side of a two-wheeled vehicle and absorbs road surface vibrations input to the front wheel. As shown in FIG. 1, a fork body composed of a vehicle body side tube 1 and a wheel side tube 2 has a double rod type damper at an axial center portion while being urged in an extending direction by a suspension spring S.

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

  The vehicle body side tube 1 is connected to an upper bracket and an under bracket (not shown), the upper bracket connects the handle, and the wheel side tube 2 suspends the front wheel at the lower end portion. Through which the front wheels are turned.

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

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

  As shown in FIG. 2, the suspension spring S accommodated in the fork main body is supported on the head end portion 3a of the cylinder body 3 constituting the damper, as shown in FIG. The cap member 11 that closes the upper end opening of the tube 1 is locked via a spacer 12 and a push member 13.

  The damper has a cylinder body 3 defined with the reservoir chamber R, and a rod body 4 connected to the cylinder body 3 so as to be able to project and retract, and the cylinder body 3 is disposed on the shaft core portion of the wheel side tube 2. The rod body 4 is connected to a holder member 14 whose upper end is screwed to the cap member 11 described above, and is suspended from the shaft core portion of the vehicle body side tube 1 while being coupled with a lock nut 41.

  As shown, the cylinder body 3 is connected to the inner bottom of the bottom member 21 that closes the lower end opening of the wheel-side tube 2 via a sub-cylinder body 31 connected to the bottom end portion 3b, and stands up. The outer periphery of the portion 3a is separated from the inner periphery of the wheel-side tube 2, and the reservoir chamber R portion above the head end portion 3a communicates with the reservoir chamber R portion outside the cylinder body 3 below the head end portion 3a. (See FIG. 1).

  The bottom end portion 3b of the cylinder body 3 has an outer periphery adjacent to the inner periphery of the wheel side tube 2 and stabilizes the upper end of the sub cylinder body 31 connected to the bottom end portion 3b. The reservoir chamber R portion above the bottom end portion 3b communicates with the reservoir chamber R portion outside the sub-cylinder body 31 below the bottom end portion 3b (see FIG. 1).

  Although not shown, a communication hole is opened at the lower end of the sub-cylinder body 31 and allows communication between the inside and outside of the sub-cylinder body 31 through the communication hole. A damping force adjusting portion may be provided in a passage communicating the inside of the body 31 and the reservoir chamber R portion outside the sub-cylinder body 31.

  In the illustrated case, the cylinder body 3 is coupled to the wheel side tube 2 via the sub cylinder body 31, but instead of this, the head end 3a of the cylinder body 3 is connected to the wheel side tube, although not shown. The arrangement of the sub-cylinder body 31 may be omitted by being coupled to the upper end portion of the two. In this case, it is advantageous in that the influence on the bending action generated in the fork body is reduced.

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

  As shown in FIG. 2, the rod body 4 includes an upper rod body 42 having a small diameter and a lower rod body 43 having a large diameter, as described above. The distal end is connected to the vehicle body side tube 1 under the intervention of the lock nut 41, the holder member 14 and the cap member 11 and is suspended from the shaft core portion of the vehicle body side tube 1 (see FIG. 3). The lower rod body 43 is connected to the piston body 5 so as to be slidable in the cylinder body 3 through the head end portion 3a. The end is connected to said piston body 5 (refer FIG. 1).

  A bearing 3d is disposed at the head end portion 3a of the cylinder body 3, and the upper rod body 42 passes through the bearing 3d, and the bottom end portion 3b has a bearing (not shown). The lower rod body 43 penetrates (see FIG. 1).

  As shown in FIG. 2, the piston body 5 defines an upper chamber R1 and a lower chamber R2 in the cylinder body 3, and the upper chamber R1 and the lower chamber R2 are damping means arranged in the piston body 5. The expansion side damping valve 5a and the compression side damping valve 5b can communicate with each other, and each damping valve 5a, 5b generates a predetermined damping force when hydraulic fluid passes through.

  Each of the damping valves 5a and 5b has an annular leaf valve, and generates a predetermined damping force when the outer peripheral side end of the annular leaf valve is bent. In particular, in the compression side damping valve 5b, The setting of the initial load is changed to enable the adjustment of the generated damping force.

  That is, a valve stopper 51 is brought into contact with the outer peripheral end of the annular leaf valve constituting the compression side damping valve 5b, and this valve stopper 51 is moved upward by an external force action while being fitted on the outer periphery of the upper rod body 42. The rod body 42 moves back and forth in the axial direction.

  Then, a tongue piece member 53 for raising and lowering the base end of the urging spring 52 that urges the valve stopper 51 from the back in the axial direction of the rod body 4 is inserted into the shaft core portion of the upper rod body 42 so as to be movable up and down. The control rod 54 made of a pipe body is advanced and retracted in the axial direction of the upper rod body 42.

  Since the control rod 54 is inserted through the shaft core portion of the upper rod body 42 so as to be movable up and down, a sliding gap is formed between them. In the damper of the present invention, this sliding gap A choke passage C which will be described later is used, and a throttle which is in parallel with a check valve 7 which will be described later is used.

  Therefore, in the present invention, when providing a throttle parallel to the check valve 7 described later, a dedicated part that functions only as a throttle is not prepared, and the number of mischievous parts is not increased.

  In addition, the sliding gap is narrower than the conventional structure of this type so that a predetermined choke effect can be obtained. Since hydraulic oil flows through the choke passage C, the lubrication between the two can be ensured.

  In addition, the control rod 61 is inserted through the shaft core portion of the control rod 54 made of a pipe body so as to be movable up and down, and thus a choke passage C1 is formed between both of them. This will also be described later. .

  On the other hand, the damper of the present invention has a bypass path L that bypasses the damping means including the damping valves 5a and 5b and allows the upper chamber R1 and the lower chamber R2 to communicate with each other. It has a control valve 6 inside.

  That is, as shown in FIG. 2, the damper has a bypass path L that bypasses the damping means of the piston body 5 and allows the upper chamber R1 and the lower chamber R2 to communicate with each other. L has a control valve 6 composed of a needle valve body, and this control valve 6 is operated by a control rod 61 that passes through the shaft core portion of the upper rod body 42.

  Since the control rod 61 is slidable at the shaft core portion of the control rod 54 described above, the control rod 61 has a sliding gap with the control rod 54, and this sliding gap has a restriction formed by the choke passage C1. Has been.

  Note that the control valve 6 is always urged in the backward direction by the return spring 62 and the rear end abuts against the front end of the inner control rod 61, and even if the hydraulic pressure from the upper chamber R1 acts when the fork body is extended, The bypass path L is not closed by the spring force of the return spring 62.

  Therefore, in the present invention, when providing a throttle parallel to the check valve 7 described later, a dedicated part that functions only as a throttle is not prepared, and the number of mischievous parts is not increased.

  Further, even when the control rod 54 is provided in the control rod 61 and the sliding gap between the two is made a throttle, the hydraulic oil flows through the choke passage C1 as the throttle, as described above. Lubrication between the two is guaranteed.

  Therefore, in this damper, during the extension operation in which the piston body 5 rises in the cylinder body 3, the hydraulic oil in the upper chamber R1 flows into the lower chamber R2 via the extension-side damping valve 5a. When the piston body 5 moves down in the cylinder body 3, the hydraulic oil in the lower chamber R2 flows into the upper chamber R1 via the compression side damping valve 5b, and damping force of a predetermined magnitude by the damping valves 5a and 5b, respectively. Is generated.

  On the other hand, when the control valve 6 made of a needle valve body advances and retreats in the bypass path L that bypasses the damping means and changes the flow rate in the bypass path L, the damping force generated by the extension operation and the contraction operation is increased. It is changed at the same time.

  Therefore, when the opening area of the bypass L is adjusted by the control valve 6, the damping force of the extension operation and the contraction operation of the front fork is adjusted.

  On the other hand, when the initial load in the pressure side damping valve 5b is changed by raising and lowering the valve stopper 51, if the influence of the bypass path L is ignored, only the characteristics of the pressure side damping valve 5b are changed and the front fork is contracted. Adjust the damping force.

  By the way, in the present invention, the damper has a check valve 7 (see FIG. 2) between the upper chamber R1 and the reservoir chamber R through which the upper rod body 42 having a small diameter is inserted. It has an aperture in parallel.

  The check valve 7 prevents the hydraulic pressure in the upper chamber R1 from escaping to the reservoir chamber R outside the cylinder body 3 when the upper chamber R1 is contracted by the movement of the piston body 5 in the cylinder body 3. When R1 expands, the hydraulic oil from the reservoir chamber R outside the cylinder body 3 is allowed to flow into the upper chamber R1.

  Therefore, the check valve 7 may be configured in an arbitrary structure, but in the illustrated example, the check valve 7 includes an annular leaf valve 71 and a biasing spring 72 that biases the valve from the rear side.

  The annular leaf valve 71 is opened in the head end portion 3b and closes the downstream end of the port 3e allowing the communication between the upper and lower portions of the head end portion 3a so as to be openable. Is supported on a spring receiver 73 that is sandwiched between the upper end head end portion 3 a and the upper end of the cylinder body 3.

  The restrictor generates a differential pressure between the cylinder body 3 communicated by the restrictor and the reservoir chamber R outside the cylinder body 3, and is composed of choke passages C and C1 in the drawing.

  Since the throttle generates the differential pressure, the throttle resistance in the throttle is set larger than the throttle resistance in the damping means of the piston body 5 described above.

  Note that the choke passages C and C1, which are shown in the drawing, are connected to the reservoir chamber R through one end at the upper end in the drawing through the holder member 14 and the other end at the lower end in the drawing. Communicates with the inside of the cylinder body 3 via the bypass L.

  By the way, in the front fork according to the present invention, the adjustment of the passage flow rate in the bypass passage L depends on the advance / retreat of the control rod 61, and the adjustment of the initial load in the compression side damping valve 5b depends on the advance / retreat of the control rod 54. Although it depends, the advance and retreat of any control rod is realized by a rotation operation to the adjuster from the outside.

  As shown in FIG. 3, in the front fork according to the present invention, the cap member 11 that closes the upper end opening of the vehicle body side tube 1 has an adjuster 8 at the shaft core portion, and the adjuster 8 includes a first adjuster 9 and The second adjusters 10 are arranged in parallel.

  The adjuster 8 raises and lowers the upper end of the spacer 12 that engages the upper end of the suspension spring S by raising and lowering the push member 13 that is screwed onto the outer periphery during rotation by an external hand.

  The push member 13 includes a cylindrical portion 13a and a leg portion 13b formed in a bifurcated shape, and can be moved up and down in a hol member 14 formed in a bottomed cylindrical shape that is screwed into the cap member 11. It is disguised.

  Then, the inner periphery of the cylindrical portion 13a is screwed to the outer periphery of the adjuster 8, and the leg portion 13b formed in a bifurcated shape penetrates the hole 14a in the bottom portion of the holder 14 and the lower end is set to the upper end of the spacer 12 while the rotation is restricted. It is in contact.

  Therefore, the push member 13 moves up and down by the rotation operation of the adjuster 8 and adjusts the strength of the suspension spring S via the spacer 12.

  Also, the adjuster 8 allows the lower adjuster side to be an empty portion and allows the distribution of related mechanisms of the first adjuster 9 and the second adjuster 10 described later. The first adjuster 9 and the second adjuster 10 Like 8, it is moved forward and backward by a manual turning operation from the outside, and both the forward and backward directions are the axial direction of the rod body 4.

  In terms of appearance, the main body portion 9 a of the first adjuster 9 and the main body portion 10 a of the second adjuster 10 are formed in the same structure, and the shaft portion 9 b of the first adjuster 9 is more than the shaft portion 10 b of the second adjuster 10. It is short.

  The shaft portion 9 b of the first adjuster 9 is in contact with a plate 63 placed on the upper end of the control rod 61, and the shaft portion 10 b of the second adjuster 10 is a plate placed on the upper end of the control rod 54. 55 abuts.

  The plates 63 and 55 are housed in the lower half of the adjuster 8 so that they can be raised and lowered. In particular, the upper plate 73 allows the second adjuster 10 shaft portion 10b to pass therethrough. The lower plate 55 allows the control rod rod 61 to pass therethrough.

  Therefore, in the adjuster 8, it is possible to raise and lower the upper end position of the suspension spring S by the turning operation, and as a result, the vehicle height on the front wheel side in the two-wheeled vehicle can be raised or lowered.

  In the first adjuster 9 described above, the control rod 61 can be moved up and down by its turning operation, and as described above, the passing flow through the bypass path L can be controlled and the damping force generated by the damping means can be raised or lowered.

  In the second adjuster 10 described above, the control rod 54 can be moved up and down by its turning operation, and the initial load in the compression side damping valve 5b is controlled as described above, and the damping generated in the compression side damping valve 5b. The power can be raised or lowered.

  Further, since the first adjuster 9 and the second adjuster 10 are arranged in parallel with the adjuster 8, the second adjuster 10 as the other cannot rotate together during the rotation operation of the first adjuster 9 as one. A configuration for blocking is not required, so that the component structure is not complicated, and the number of assembling steps and the product cost are not increased.

  In addition, as shown in the figure, the first adjuster 9 and the second adjuster 10 are arranged in parallel with the adjuster 8 that enables adjustment of the spring force of the suspension spring S. Compared to the case where the adjuster is provided with a double-structure adjuster at the shaft core portion, the adjuster is not made into a triple structure. Therefore, in this case, the above-mentioned co-rotation prevention and simplification of the parts structure are further improved. This makes it difficult and does not lead to a significant increase in the structure of the parts, an increase in the number of assembly steps, and an increase in product cost.

  As described above, in the above-described damper, the upper rod body 42 is formed with a small diameter with respect to the lower rod body 43, and naturally, the lower rod body 43 has a large diameter with respect to the upper rod body 42. Since the respective base ends are connected to the piston body 5 accommodated in the cylinder body 3, the pressure receiving area at the end surface facing the upper chamber R <b> 1 of the piston body 5 faces the lower chamber R <b> 2 of the piston body 5. It becomes larger than the pressure receiving area at the end face.

  Accordingly, when the fork main body is extended so that the piston body 5 in the cylinder body 3 narrows the upper chamber R1 in the damper, the excess hydraulic oil in the upper chamber R1 is stored in the reservoir chamber outside the cylinder body 3 via the throttle. To R.

  At this time, the diaphragm resistance in the diaphragm is set to be larger than the diaphragm resistance in the damping means of the piston body 5, so that the upper chamber R1 becomes high pressure and the lower chamber R2 in the cylinder body 3 The hydraulic oil from the chamber R1 flows in via the damping means, but the inside of the cylinder body 3 is caused by the squeezing resistance when excess hydraulic oil in the upper chamber R1 flows out of the cylinder body 3 through the throttle. Not only does the oil pressure in the lower chamber R2 become insufficient, but also the expansion of fine bubbles remaining in the hydraulic oil in the lower chamber R2 is prevented.

  On the other hand, in the damper, when the fork main body contracts so that the piston body 5 in the cylinder body 3 narrows the lower chamber R2, the lower chamber R2 tends to have a high pressure, and the upper chamber R1 has a lower chamber. Since the hydraulic oil from R2 flows in, an insufficient amount of hydraulic oil caused by the pressure receiving area difference flows from the reservoir chamber R outside the cylinder body 3 via the check valve 7 to prevent the lower pressure in the upper chamber R1. The fine bubbles remaining in the hydraulic oil in the upper chamber R1 do not expand.

  Further, when the hydraulic oil flows from the reservoir chamber R into the upper chamber R1, when the diameter difference between the two rod bodies 42 and 43 becomes small, the amount of the hydraulic oil becomes small, and the air in the reservoir chamber R is entrained. There is no fault.

  Therefore, in the front fork of the present invention, in the built-in double rod type damper, the inside of the cylinder body 3 is added during operation as compared with the damper in which both the rod bodies are set to have the same diameter. Therefore, the pressure is not lowered and the hydraulic oil does not run short in the cylinder body 3.

  Therefore, the fine bubbles remaining in the hydraulic oil in the cylinder body 3 do not expand, and when the upper chamber R1 or the lower chamber R2 in the cylinder body 3 is reversed from the low pressure side to the high pressure side, it has expanded until then. The phenomenon that the bubble contracts is not expressed, and the damping means operates as set.

  In this regard, in the proposal of the above-described literature disclosure, since both rods in the damper have the same diameter, there is no change in the amount of hydraulic fluid flowing between the upper chamber R1 and the lower chamber R2 in the cylinder body 3. Since there is no pressurizing action on the inside of the cylinder body 3, there is a high possibility that fine bubbles mixed in the hydraulic oil will expand.

  In particular, when the fork main body expands and contracts at a high speed, a low pressure in the low pressure side chamber appears remarkably, and a phenomenon of expansion of fine bubbles mixed in the hydraulic oil appears remarkably.

  From this, when the throttle is provided as in the present invention, it is possible to pressurize the cylinder body 3 by the throttle, and the low pressure on the low pressure side is prevented, and the damping effect of the damping means is set as set. Can be realized to avoid "sag of damping force".

  In addition, the proposal disclosed in the literature has a small hole opened in the cylinder body together with the check valve. This hole allows air in the cylinder body to flow when the check valve is filled with hydraulic oil. It is a hole for discharging outside the cylinder body, and is different from the throttle of the present invention.

  As described above, the hydraulic oil also flows into the sub-cylinder body 31 connected to the cylinder body 3, but instead of this, the notch passage 3 c in the bottom end portion 3 b is abolished, and the bottom end A portion below the portion 3b may be an air chamber that is blocked from the reservoir chamber R, and a seal member is interposed between the outer periphery of the head end portion 3a and the inner periphery of the wheel side tube 2 to An air chamber that is cut off from the reservoir chamber R above the head end portion 3a may be provided below 3a.

  When the air chamber is defined, the amount of hydraulic oil stored in the fork main body is greatly reduced, which is advantageous in reducing the weight of the front fork. However, the cylinder body facing the reservoir chamber R is advantageous. 3, a check valve 7 and a throttle are disposed on the head end 3a side, and a seal member is interposed in a sliding portion of the lower rod body 42 with the bottom end 3b.

  On the other hand, when allowing the hydraulic oil to flow into the sub-cylinder body 31 connected to the cylinder body 3, a small-diameter rod body is inserted through the lower chamber R2 in place of the illustrated embodiment, A rod body having a diameter may be inserted through the upper chamber R <b> 1, and the check valve 6 and the throttle may be disposed at the bottom end 3 b of the cylinder body 3.

  In the above description, the piston body 5 is accommodated in the cylinder body 3 disposed in the shaft core portion of the wheel side tube. The arrangement may be omitted, and the wheel side tube 2 may be replaced with a cylinder body.

  Furthermore, as described above, the fork main body constituting the front fork according to the present invention is set to an inverted type in which the vehicle body side tube 1 is a large diameter outer tube and the wheel side tube 2 is a small diameter inner tube. From the point of view of the present invention, the vehicle body side tube 1 may be set as an inner tube, and the wheel side tube 2 may be set as an upright type, and the operation effect in that case is not different. is there.

It is a partial front longitudinal cross-sectional view which shows the front fork by this invention partially fractured | ruptured. FIG. 3 is a half vertical cross-sectional view showing a main part of a damper in the front fork according to the present invention. It is a longitudinal cross-sectional view which shows the upper end part of the front fork by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body side tube 2 Wheel side tube 3 Cylinder body 3a Head end part 3b Bottom end part 4 Rod body 5 Piston body 5a Extension side damping valve 5b as damping means 5b Pressure side damping valve as damping means 6 Control valve 7 Check valve 8 Adjuster 9 First One adjuster 10 Second adjuster 11 Cap member 42 Upper rod body 43 Lower rod body 61 Control rods C and C1 Choke passage to be throttled L Bypass passage R Reservoir chamber R1 Upper chamber R2 Lower chamber S Suspension spring

Claims (4)

A fork body consisting of a vehicle body side tube and a wheel side tube is used as a reservoir chamber and has a suspension spring and a double rod type damper, and the double rod type damper is disposed in the wheel side tube, A cylinder body that is defined, a rod body that is suspended in the body-side tube and is slidably inserted into the cylinder body, and is slidably housed in the cylinder body so that an upper chamber and a lower chamber are provided in the cylinder body. A piston body that allows communication between the upper chamber and the lower chamber through the damping means while defining the rod body, and the base end is connected to the piston body in the cylinder body while the tip end is connected to the vehicle body side tube. The upper rod body and the lower rod body are connected to the piston body in the cylinder body while penetrating the bottom end portion of the cylinder body through the upper rod body. One of the lower rod bodies is formed with a smaller diameter than the other rod body, and a check valve is provided between the upper chamber or lower chamber through which the rod body formed with this smaller diameter is inserted and the reservoir chamber. In a front fork having a throttle in parallel with the valve, a control valve disposed in a bypass passage that bypasses the damping means of the piston body and allows communication between the one chamber and the other chamber is provided on the axis of the rod body. While controlling the flow rate of hydraulic oil passing through the bypass passage by operating an adjuster from the outside of the fork body while passing through the section, one end communicates with the cylinder body between the rod body and the control rod, and the other end enters the reservoir chamber. A front fork characterized by a diaphragm that communicates. The front fork according to claim 1, wherein the diaphragm resistance in the diaphragm is set to be larger than the diaphragm resistance in the damping means of the piston body. The front fork according to claim 1, wherein the check valve is disposed at a head end portion or a bottom end portion of a cylinder body through which a rod body having a small diameter passes. The front fork according to claim 1, wherein the adjuster is disposed on a cap member that connects the upper end portion of the rod body while closing the upper end opening of the vehicle body side tube.

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