JP2009264488A - Front fork - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress expansion of fine bubbles mixed in hydraulic oil when a damper is operated, and to operate a damping valve as set.
A cylinder body constituting a damper in a front fork having a double rod type damper in a fork main body having a vehicle body side tube 1 and a wheel side tube 2 under the distribution of a suspension spring S. 3 has pressure means 6 at the head end portion 3a and the bottom end portion 3b, respectively, through which the rod body 4 that also constitutes a damper passes, and this pressure means 6 is directed from the inside of the cylinder body 3 to the outside of the cylinder body 3. It prevents the passage of all hydraulic pressure.
[Selection] Figure 1

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.

  As a front fork that functions as a hydraulic shock absorber that is mounted on the front wheel side of a two-wheeled vehicle and absorbs road surface vibrations that are input to the front wheel while incorporating a double rod type damper, there is a proposal disclosed in Patent Document 1, for example. .

  The front fork disclosed in this document has a double rod type damper in a fork main body which is connected to a vehicle body side tube so that the wheel side tube can be projected and retracted in the presence of a suspension spring. A cylinder body disposed in the side tube, a rod body which is suspended in the vehicle body side tube and is slidably inserted into the cylinder body, and is slidably received in the cylinder body and is disposed in the upper chamber in the cylinder body. And a piston body that allows communication between the upper chamber and the lower chamber through a damping valve while defining the lower chamber.

  The cylinder body is erected in the wheel side tube via a sub cylinder body continuously provided at the bottom end portion, and the rod body is suspended in the vehicle body side tube with the tip connected to the vehicle body side tube. An upper rod that connects the end of the cylinder body to the piston body in the cylinder body and a lower rod that connects the base end to the piston body in the cylinder body while passing the bottom end of the cylinder body through the bottom end of the cylinder body The two are the same diameter of the body.

  The piston body is slidably accommodated in the cylinder body, and defines an upper chamber and a lower chamber in the cylinder body. The upper chamber and the lower chamber communicate with each other via a damping valve disposed in the piston body. A predetermined damping force is generated when hydraulic fluid passes through the damping valve.

Therefore, in the front fork disclosed in the above literature, since the damper is a double rod type, there is no flow of hydraulic oil between the cylinder body and the reservoir chamber when the fork main body is extended and retracted. Damping force is stable without any trouble of expecting air in the body.
Japanese Patent No. 3873192 (Claims, paragraphs 0021, 0033, 0037 to 0039 in the specification, see FIG. 1)

  However, the front fork disclosed in the above document is not basically problematic, but there is a possibility that it is pointed out that there is a slight problem in actual use.

  That is, in the above-mentioned front fork, the hydraulic oil injected into the fork main body after being assembled can be filled into the cylinder body by a pumping operation which is an expansion / contraction operation of the fork main body.

  For this reason, the damper has a check valve that allows the hydraulic oil to flow into the cylinder body at the bottom end of the cylinder body, and does not prevent the hydraulic oil from being filled into the cylinder body using this check valve. A small hole provided in the cylinder body or a gap in the sliding portion of the rod body is used as an air vent passage.

  Therefore, the hydraulic oil can be filled in the cylinder body of the damper by the pumping operation after assembling, and the operation of the damping valve of the piston body after the start can be enabled.

  However, even if the air before filling the cylinder body with hydraulic fluid is released to the outside of the cylinder body, even fine bubbles remaining in the hydraulic oil cannot be released, so the piston body slides when the damper operates. Thus, when the upper chamber or the lower chamber in the cylinder body is selectively reduced in pressure, the fine bubbles expand, and when reversed and the pressure is increased, the fine bubbles contract.

  As a result, when the upper chamber or the lower chamber in the cylinder body is reversed from the low pressure side to the high pressure side, the damping valve cannot operate as set until the bubbles on the high pressure side that have expanded so far contract. A phenomenon called “damping force sag” is developed, and this “damping force sag” phenomenon deteriorates the riding feeling in a motorcycle.

  The present invention was devised in view of such a current situation, and an object of the present invention is to suppress the expansion of fine bubbles in the hydraulic oil in the cylinder as much as possible when the damper is operated, When the upper chamber or the lower chamber of the engine is reversed from the low pressure side to the high pressure side, the damping valve can operate as set, and a front fork that is optimal for expecting an improvement in versatility is provided. .

  In order to achieve the above-described object, the structure of the front fork according to the present invention is basically a double-rod type in a fork main body having a vehicle body side tube and a wheel side tube under the presence of a suspension spring. A cylinder body in which the rod-type damper is disposed in the wheel-side tube, a rod body that is suspended in the vehicle body-side tube and is slidably inserted into the cylinder body, and a slide in the cylinder body. A piston body that is movably accommodated and defines an upper chamber and a lower chamber in the cylinder body and allows communication between the upper chamber and the lower chamber via a damping valve, and the rod body has a tip on the vehicle body side tube An upper rod body that connects the base end to the piston body in the cylinder body while being suspended in the vehicle body side tube, and a base end that is connected to the bottom end portion of the cylinder body through the bottom end of the cylinder body. In the front fork that has the same diameter as the lower rod body connected to the piston body in the cylinder body, the cylinder body has a head end portion that penetrates the upper rod body and a bottom end portion that penetrates the lower rod body, respectively. It is assumed that a pressurizing means is provided and the pressurizing means prevents passage of hydraulic pressure from the cylinder body toward the outside of the cylinder body.

  Therefore, in the present invention, in the damper in the fork main body, the cylinder body has pressurizing means at the head end portion through which the upper rod body penetrates and the bottom end portion through which the lower rod body penetrates, respectively. Since the pressure means prevents the passage of hydraulic pressure from the cylinder body to the outside of the cylinder body, the cylinder body is maintained at a high pressure tendency, so that fine bubbles mixed in the hydraulic oil in the cylinder body are reduced by the low pressure in the cylinder body. The opportunity for expansion is greatly reduced, and as a result, the above-mentioned bubbles do not expand when the pressure in the cylinder body is reduced, and therefore, when the upper chamber or lower chamber in the cylinder body is reversed from the low pressure side to the high pressure side. The phenomenon that the bubble that has been expanded until then contracts does not appear, and the damping valve operates as set.

  Hereinafter, the present invention will be described based on the illustrated embodiment. As shown in FIG. 1, the front fork according to the present invention is basically not shown in the same manner as the front fork disclosed in the above document. The hydraulic shock absorber is mounted on the front wheel side of the two-wheeled vehicle and absorbs road surface vibration, and the fork main body composed of the vehicle body side tube 1 and the wheel side tube 2 is urged in the extension direction by the suspension spring S while being attached to the shaft core portion. It has a double rod type damper.

  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.

  Although not shown, the wheel side tube 2 inserted into the lower end side of the vehicle body side tube 1 has a hole that allows internal and external communication, and the vehicle body side tube 1 and the wheel through this hole. Inflow of oil into the side tube 2 is allowed, 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 damper (described later) is in an oil-immersed state even when the fork main body is fully extended. The chamber A exhibits an air spring effect when the fork main body is extended and contracted.

  The suspension spring S accommodated in the fork main body is supported by a head end 3a which is the upper end of a cylinder body 3 which will be described later and forms a damper, and the upper end closes the upper end opening of the vehicle body side tube 1. It is locked to.

  The damper includes a cylinder body 3 and a rod body 4, and the cylinder body 3 is disposed on the shaft core portion of the wheel side tube 2, and the rod body 4 has an upper end portion coupled to the cap member 11 described above. It is suspended from the shaft core portion of the vehicle body side tube 1.

  The cylinder body 3 is erected on the shaft core portion of the wheel side tube 2 via a sub cylinder body 31 connected to the bottom end portion 3b which is the lower end portion, and the sub cylinder body 31 opens the lower end opening of the wheel side tube 2. It stands on the inner bottom of the bottom member 21 to be closed.

  The rod body 4 is composed of an upper rod body 41 and a lower rod body 42 having the same diameter. The upper rod body 41 is suspended from the shaft core portion of the vehicle body side tube 1 with its tip connected to the vehicle body side tube 1. The bottom end of the lower rod 42 is connected to the bottom of the cylinder body 3 with the base end passing through the head end 3a of the cylinder body 3 and slidable in the cylinder body 3. The base end is connected to the piston body 5 while penetrating the end 3b.

  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 can communicate with each other via a damping valve 5a disposed in the piston body 5. The damping valve 5a generates a predetermined damping force when the hydraulic oil passes through.

  A communication hole 31 a is opened at the lower end portion of the sub cylinder body 31 where the tip of the lower rod body 42 is present, and the sub chamber R 3 in the sub cylinder body 31 and the sub cylinder body 31 are outside the sub cylinder body 31. Communication with the reservoir chamber R is allowed.

  As described above, in this damper, since both rod bodies 41 and 42 are formed to have the same diameter, the base ends of the rod bodies 41 and 42 are connected to the piston body 5 that is housed in the cylinder body 3. The pressure receiving areas at both ends of the body 5 are the same, so that it is possible to realize the generation of damping force having the same characteristics when the fork body is extended and contracted, and a damping valve is separately provided on the expansion side and the pressure side (in FIG. 2). The desired damping force generation state can be realized by making the characteristics of the damping valves different from each other.

  In this damper, since both chambers R1, R2 have the same cross-sectional area, the amount of hydraulic oil reciprocating between both chambers R1, R2 is the same. Although not necessary, since it has a hydraulic pressure holding means 7 to be described later together with a pressurizing means 6 to be described later, oil amount compensation and oil temperature compensation are possible.

  By the way, in the front fork according to the present invention, the cylinder body 3 in the damper has the pressure means 6 at the head end portion 3a through which the upper rod body 41 passes and the bottom end portion 3b through which the lower rod body 42 passes. It becomes.

  As shown in FIG. 2, the pressurizing means 6 is made of U-packing, and allows the hydraulic pressure outside the cylinder body 3 to pass into the cylinder body 3. It blocks from passing outside the body 3.

  Therefore, if the inside of the cylinder body 3 of this damper is not provided with the pressurizing means 6, the cylinder body 3 is not greatly restricted and communicates with the outside of the cylinder body 3. 3 cannot be easily communicated to the outside.

  As a result, comparing the case where the inside of the cylinder body 3 can communicate with the outside of the cylinder body 3 without restriction, and the case where the communication with the outside of the cylinder body 3 is restricted, the latter is more The cylinder body 3 is pressurized while maintaining a higher pressure tendency.

  Then, the cylinder body 3 is pressurized, so that the opportunity for the expansion and contraction of fine bubbles mixed in the hydraulic oil is reduced as compared with the case where there is no pressure, and the piston body slides in the cylinder body 3. The operation of the damping valve 5a of 5 is stabilized.

  In view of the above, the pressurizing means 6 may be of any configuration instead of the above-described U-packing. However, in the drawing, the head end portion 3a and the bottom end portion 3b of the cylinder body 3 are shown. Then, the bearing members B1 and B2 are connected in series to the U packing as the pressurizing means 6, and the rod bodies 41 and 42 are in sliding contact with the bearing members B1 and B2, so that the sliding contact force of the rod body 4 with respect to the U packing is circumferential. Prevents variation in direction.

  On the other hand, in the present invention, in order to make the function of the pressurizing means 6 effective, as shown in FIG. 2, the hydraulic pressure holding means 7 for holding the hydraulic pressure in the cylinder body 3 is a lower rod. The body 42 is provided.

  The hydraulic pressure holding means 7 is formed in an accumulator structure as shown in the figure, and has a volume chamber 72 defined by a free piston 71 as a partition wall in the lower rod body 42. It communicates with the lower chamber R2 in the cylinder body 3 through a hole 42a opened in the body 42.

  The free piston 71 which is a partition body is urged in the direction of narrowing the chamber 72 by a coil spring 73 which is an urging member disposed on the back side, and the coil spring 73 is a stop ring 74 fitted to the tip of the lower rod 42. It is carried on.

  Therefore, in the hydraulic pressure holding means 7, the pressure based on the biasing force of the coil spring 73 is applied to the lower chamber R <b> 2 in the cylinder body 3, so that the hydraulic pressure in the cylinder body 3 is held.

  Then, when the oil temperature in the hydraulic oil in the cylinder body 3 rises and the volume is expanded, the hydraulic pressure holding means 7 allows the expanded hydraulic oil to flow into the chamber 72 and the oil temperature. When compensation is performed and the oil temperature in the hydraulic oil in the cylinder body 3 is lowered and the volume is contracted, the amount of the contracted hydraulic oil is allowed to flow into the cylinder body 3 to compensate the oil amount.

  As described above, in the front fork according to the present invention, the cylinder body 3 in the built-in damper has the pressure means 6 at the head end portion 3a and the bottom end portion 3b. Care must be taken to fill the hydraulic fluid.

  That is, in the present invention, the cylinder body 3 has the check valve 8 and the relief valve 9, and the check valve 8 allows the hydraulic oil to flow into the cylinder body 3, and the hydraulic oil flows into the cylinder body 3. The relief valve 9 releases the air in the cylinder body 3 to the outside of the cylinder body 3 at the time of inflow.

  In FIG. 1, a check valve 8 is disposed at the bottom end 3 b of the cylinder body 3 and a relief valve 9 is disposed at the head end 3 a of the cylinder body 3. However, the check valve 8 may be disposed alone or together with the relief valve 9 at the head end portion 3a of the cylinder body 3, and the relief valve 9 is disposed alone or together with the check valve 8 at the bottom end portion 3b. May be.

  In particular, as shown in FIG. 1, a notch passage 3c is provided in the head end portion 3a of the cylinder body 3, and a portion between the reservoir chamber R portion above the head end portion 3a and the reservoir chamber R portion below the head end portion 3a. However, instead of this, the notch passage 3c is not provided, and therefore, the reservoir chamber R portion outside the cylinder body 3 below the head end portion 3a and the sub cylinder body 31 When the sub chamber R3 is not filled with hydraulic oil, a check valve 8 and a relief valve 9 are disposed at the head end 3a.

  The check valve 8 is a pumping operation that is an expansion / contraction operation in the fork main body, and allows the hydraulic oil in the sub chamber R3 in the sub cylinder body 31 to flow into the cylinder body 3, and the relief valve 9 is a check valve 8 As well as assisting the operation of the cylinder body, excessive hydraulic pressure in the cylinder body 3 is released to the outside of the cylinder body 3 to enable seal protection in the damper.

  By the way, the check valve 8 may be freely configured as long as it exhibits a predetermined function. However, as shown in FIG. 2, in the cylinder body 3, the bottom end portion 3 b connects the sub cylinder body 31. The diameter becomes smaller.

  Therefore, the configuration of the check valve 8 disposed at the bottom end portion 3b is likely to be limited. However, in the illustrated case, the annular leaf that closes the opening port 3d at the bottom end portion 3b so that it can be opened and closed. The valve 81 and the urging spring 82 that urges the annular leaf valve 81 from the back side are configured, and the flow path area is secured by using the bottom end portion 3b over the entire circumference.

  On the other hand, since the relief valve 9 is disposed at the head end 3a which has a larger diameter than the bottom end 3b, a freer configuration than the check valve 8 can be adopted. The head end 3a has a steel ball 91 facing the port 3e that is opened, and a coil spring 92 that urges the steel ball 91 from the rear side, and is assembled into the head end 3a. Has been.

  Further, as shown in FIG. 3A, a suction valve structure having an annular leaf valve 92 which closes the opening port 3e at the head end 3a so as to be openable and closable is formed. In comparison, the configuration is simplified.

  As shown in FIG. 3B, the relief valve 9 has a chamber 94 communicating with the opening port 3e at the head end 3a, and a free piston 95 is accommodated in the chamber 94. The free piston 95 is urged by a coil spring 96 as an urging member disposed on the rear side.

  Therefore, the relief valve 9 can increase or decrease the volume of the capacity chamber 94 by advancing and retreating the free piston 95, and therefore performs the same function as the hydraulic pressure holding means 7 shown in FIG. 2, and therefore FIG. When the relief valve 9 structure is employed, the arrangement of the hydraulic pressure holding means 7 on the rod body 4 can be omitted.

  In the above description, it has been described that the cylinder body 3 has the pressurizing means 6 in the damper built in the front fork according to the present invention. Although the configuration of the piston body 5 and the configuration around the piston body 5 are not described in detail, it is sufficient if a well-known configuration is adopted.

  In the above description, the sub-cylinder body 31 is integrally connected to the cylinder body 3 of the damper via the bottom member 3b. However, from the point of view of the present invention, the cylinder body 3 is not shown. And the sub-cylinder body 31 may be integrally formed, and the bottom member 3b may be inserted inside with the seal member interposed therebetween, and the bottom member 3b may be fixed by roll caulking or the like with respect to the outer periphery of the cylinder body 3.

  And 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, although not shown, 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 and effects in that case are not different. Of course.

It is a figure which shows in principle the front fork which incorporates the double rod type damper by this invention. FIG. 3 is a half vertical cross-sectional view specifically showing a main part of a damper in the front fork according to the present invention with a part broken away. FIG. 5 is a semi-longitudinal longitudinal sectional view further partially showing another embodiment of the present 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 6 Pressurizing means 7 Hydraulic pressure holding means 8 Check valve 9 Relief valve 41 Upper rod body 42 Lower rod body B1, B2 Bearing member R1 Upper chamber R2 Lower chamber S Suspension spring

Claims (5)

A cylinder body in which a double rod type damper is provided in a fork body having a vehicle body side tube and a wheel side tube under the suspension spring, and the double rod type damper is disposed in the wheel side tube; A rod body that is suspended in the vehicle body side tube and is slidably inserted into the cylinder body, and is slidably received in the cylinder body and defines an upper chamber and a lower chamber in the cylinder body through a damping valve. A piston body that allows communication between the upper chamber and the lower chamber, and the rod body is connected to the piston body in the cylinder body while the distal end is connected to the vehicle body side tube and is suspended in the vehicle body side tube. The front rod is formed of two rods having the same diameter as the lower rod body that connects the base end to the piston body in the cylinder body while penetrating the upper rod body and the distal end side through the bottom end portion of the cylinder body. The cylinder body has pressurizing means at the head end portion through which the upper rod body passes and the bottom end portion through which the lower rod body penetrates, respectively, and the pressurizing means has a hydraulic pressure from the cylinder body toward the outside of the cylinder body. Front fork characterized by blocking the passage of 2. The front fork according to claim 1, wherein a hydraulic pressure holding means for holding the hydraulic pressure in the cylinder body is provided in the rod body. The front fork according to claim 1, wherein the pressurizing means allows passage of hydraulic pressure from outside the cylinder body toward the inside of the cylinder body. The rod body is in sliding contact with the pressurizing means at the head end portion and the bottom end portion of the cylinder body, and a bearing member is connected in series with the pressurizing means, and the rod body is in sliding contact with the bearing member. The described front fork. The front fork according to claim 1, wherein a check valve and a relief valve are provided alone or in combination in a head end portion or a bottom end portion of the cylinder body.

Images