JP4514640B2 - Front fork - Google Patents

Description

  The present invention relates to an improvement in a front fork as a hydraulic shock absorber mounted on the front wheel side of a motorcycle.

  There have been various proposals for a front fork that is a hydraulic shock absorber mounted on the front wheel side of a two-wheeled vehicle. Among them, for example, in the front fork disclosed in Patent Document 1, the front fork is in a telescopic operation. Air is prevented from being mixed into the hydraulic oil so that the generated damping force is stabilized.

  That is, the front fork disclosed in Patent Document 1 has a damper in a fork main body formed by an outer tube and an inner tube, and a reservoir outside the damper inside the fork main body. Is divided into so-called upper and lower portions by a float member to prevent the air from the upper side of the float member from mixing into the hydraulic fluid below the float member.

  Incidentally, in many cases, the damper is inserted into the cylinder body so that the rod body can protrude and retract, and the damper is slidably installed in the cylinder body while being held by the rod body. It has a piston body that defines a chamber and a piston-side oil chamber.

  In this damper, when the rod body comes out of the cylinder body during the extension operation, the hydraulic oil in the rod side oil chamber is connected to the piston side via the extension side damping valve disposed in the piston body. The oil flows out into the oil chamber, and at this time, a predetermined extension side damping force is generated by the extension side damping valve.

  Further, in this damper, the pressure side damping valve in the base valve portion in which the hydraulic oil in the piston side oil chamber is disposed at the bottom portion of the cylinder body during the contraction operation in which the rod body becomes immersed in the cylinder body It flows out to the lower side of the float member serving as a reservoir, and at this time, a predetermined compression side damping force is generated by the compression side damping valve.

  The hydraulic oil that has flowed out to the lower side of the float member when the damper is contracted is returned to the piston-side oil chamber when the damper is extended.

Therefore, in the front fork disclosed in Patent Document 1, since the hydraulic oil is sealed between the inside of the damper and the lower side of the float member in the reservoir, the operation in the damper is particularly important. There is no need to worry about the air being mixed into the oil. Therefore, it is possible to expect the generation of damping force as set during the expansion / contraction operation of the damper accompanying the expansion / contraction operation of the fork body.
Japanese Patent Laid-Open No. 10-132009 (Claims Claims 1, Paragraphs 0025, 0031, 0038, FIG. 1)

  However, in the front fork disclosed in Patent Document 1 described above, since the reservoir is provided outside the damper in the fork main body, there is a tendency that the amount of hydraulic oil increases. As the amount of oil increases, for example, it may be pointed out that weight reduction cannot be expected.

  Therefore, although not disclosed by illustration or the like, it is assumed that the damper disposed in the shaft core portion of the fork main body is formed in a single cylinder shape, that is, the cylinder body forming the damper is defined by a free piston body. By having a gas chamber, that is, an air spring, it is possible to make a proposal for reducing the amount of hydraulic oil so that the hydraulic oil does not exist outside the damper.

  However, in the proposal that this damper is formed in a single cylinder type, it is easy to generate a predetermined extension side damping force with the extension side damping valve arranged in the piston body in the cylinder body, but the same piston It is not easy to arrange a compression-side damping valve on the body and generate a predetermined compression-side damping force with this compression-side damping valve. is there.

  The present invention was devised in view of such a current situation, and the object of the invention is to reduce the amount of hydraulic oil as well as to realize a preferable damping force generation state. Therefore, it is possible to provide a front fork that can contribute to weight reduction and is optimally expected to improve its versatility.

In order to achieve the above object, the means of the present invention includes a fork main body and a damper disposed in the fork main body and having a damping action during extension operation. The fork main body includes an outer tube and an outer tube. An inner tube that is slidably fitted to the tube, and the damper is a cylinder body, a rod body that is inserted into the cylinder body through a piston body so as to be retractable, and the cylinder body includes the above-described cylinder body. In a front fork comprising a rod-side oil chamber and a piston-side chamber defined by a piston body, and an extension-side damping valve that is disposed in the piston body and communicates the rod-side oil chamber with the piston-side chamber during an extension operation. A free piston body facing the piston body is inserted while sandwiching the piston side chamber in the cylinder body, and the free piston body is further inserted into the free piston body. A rod portion extending in the opposite direction to the piston body is projected, and a cylindrical oil chamber is defined between the outer periphery of the rod body and the inner periphery of the cylinder body. A pressure-side damping valve that communicates the oil chamber with the cylindrical oil chamber is provided, and a biasing spring is interposed between the rod portion and the fork main body to bias the free piston body toward the piston body. It is characterized by that.

  Therefore, according to the present invention, the hydraulic oil is accommodated in the rod side oil chamber and the piston side oil chamber defined in the cylinder body forming the damper disposed in the fork main body, and the free piston body. Since it is only accommodated in a cylindrical oil chamber defined between the rod portion and the cylinder body, for example, compared to the case where hydraulic oil is also stored in a reservoir outside the damper, the amount of hydraulic oil is reduced. It becomes possible to reduce.

  At this time, since the oil chamber portion defined on the back side of the free piston body is formed in a cylindrical shape, the amount of hydraulic oil stored in the damper can be prevented from being unnecessarily increased.

  In the present invention, when the damper disposed in the fork main body expands / contracts due to the expansion / contraction operation of the fork main body, the expansion side damping valve disposed in the piston body in the cylinder body forming the damper performs a predetermined expansion. While the side damping force is generated, a predetermined compression side damping force is generated by the compression side damping valve disposed in the free piston body disposed in the cylinder body.

  That is, when the damper is contracted by the contraction operation of the fork main body, the piston is relatively viewed by the immersion of the rod body that is the vehicle body side member into the cylinder body that is the wheel side member. The body is lowered into the cylinder body. At this time, the rod-side oil chamber defined by the piston expands in the cylinder body, and the hydraulic oil that is insufficient in the rod-side oil chamber is discharged from the piston-side oil chamber. Inflow and replenishment.

  On the other hand, when the damper is contracted, the fork main body contracts and, for example, the inner tube, which is the wheel side tube, is immersed in the outer tube, which is the vehicle body side tube. The cylinder body, which is a wheel side member in the damper, is integrally connected. For example, when viewed relatively, the cylinder body rises with respect to the descending piston body, and the rod portion of the free piston body A cylindrical oil chamber defined between the cylinder body and the hydraulic oil from the cylinder oil chamber is contracted between the cylinder body and the hydraulic oil from the cylinder oil chamber flows out into the piston side oil chamber in the cylinder body through a compression side damping valve disposed in the free piston body. At this time, a predetermined compression side damping force is generated.

  By the way, when the fork main body reverses from the contraction operation and extends, the piston body rises in the cylinder body, and the hydraulic oil in the rod side oil chamber is extended to the piston body. As the cylinder body flows into the piston side oil chamber via the damping valve and the cylinder body tends to descend with respect to the piston body, the cylindrical oil chamber defined between the rod portion of the free piston body and the cylinder body At this time, since the free piston body is urged so as to approach the piston body by the spring force of the urging spring, the vacuum phenomenon does not appear in the cylindrical oil chamber.

  As a result, according to the present invention, it is possible to reduce the amount of hydraulic oil and contribute to weight reduction as well as to realize a preferable state of generation of damping force.

Hereinafter, the present invention will be described on the basis of the illustrated embodiment. A front fork according to the present invention includes a hydraulic shock absorber that is mounted on the front wheel side of a two-wheeled vehicle and attenuates vibration that moves up and down and is input to the front wheel. intended to be, basically, for example, as shown in FIG. 2 serving principle diagram serving FIGS. 1 and specifically Figure, to the fork main body F, the damping action during extended operation is Zaisa distribution in the fork body F And a damper D.
The fork main body F includes, for example, an outer tube 1 that is a vehicle body side member, and an inner tube 2 that is a wheel side member that is slidably fitted to the outer tube 1.

Further, the damper D includes a cylinder body 3, a rod body 4 inserted into the cylinder body 3 via a piston body 5 so as to be able to protrude and retract, and a rod side defined by the piston body 4 in the cylinder body 5. An oil chamber and R1 and a piston side chamber R2 are provided, and an extension side damping valve 5a that is disposed in the piston body 5 and communicates the rod side oil chamber R1 with the piston side chamber R2 during extension operation.
In the present invention, the free piston body 6 facing the piston body 5 is inserted into the cylinder body 5 with the piston side chamber R2 interposed therebetween.
Further, the free piston body 6 is provided with a rod portion 61 extending in the opposite direction to the piston body 5, and a cylindrical oil chamber R is formed between the outer periphery of the rod body 61 and the inner periphery of the cylinder body 5. It is defined.
The free piston body 6 is provided with a pressure-side damping valve 6a that connects the piston-side oil chamber R2 to the cylindrical oil chamber R, and a biasing spring is provided between the rod portion 61 and the fork main body F. 7, the free piston body 6 is urged toward the piston body 5.

  Incidentally, in the fork main body F, a suspension spring S is arranged between the outer tube 1 and the inner tube 2, and the inner tube 2 is detached from the outer tube 1 by the urging force of the suspension spring S. In other words, the fork main body F is biased in the extending direction.

  At this time, in the drawing, the fork main body F is urged in the extending direction by the urging force of the suspension spring S. For example, when the front fork is used for a bicycle instead of a motorcycle, Instead of the suspension spring S, the fork main body F may be urged in the extending direction by an urging force of an air spring.

  In the case where the fork main body F is biased in the extending direction by an air spring instead of the suspension spring S, for example, the opening 2a formed in the bottom portion of the inner tube 2 is not formed as shown in FIG. Thus, the inside of the fork main body F is preferably sealed.

  1 and 2, the outer tube 1 is a vehicle body side member and the inner tube 2 is a wheel side member. However, if the present invention is intended, As will be described later, which is the vehicle body side member or the wheel side member is arbitrary.

  This also applies to the damper D. In the place shown in FIGS. 1 and 2, the cylinder body 3 is a wheel side member and the rod body 4 is a vehicle body side member. However, from the point of view of the present invention, as will be described later, which is the vehicle body side member or the wheel side member is free.

  By the way, the damper D has a piston body 5 that is slidable in the cylinder body 3 while being held by the rod body 4. The piston side oil chamber R2 is defined.

  Further, the damper D is connected to the rod side oil chamber R1 via the extension side damping valve 5a (see FIG. 1) disposed in the piston body 5 during the extension operation in which the rod body 4 comes out from the cylinder body 3. The hydraulic oil is allowed to flow into the piston side oil chamber R2.

  Incidentally, the piston body 5 is provided with an extension side check valve 5b (see FIG. 1) in parallel with the extension side damping valve 5a, and the extension side check valve 5b is opened when the damper D is contracted. Insufficient inflow of hydraulic oil in the rod side oil chamber R <b> 1 that expands due to operation is prevented.

  Therefore, in the damper D, when the fork main body F is extended, the extension operation is performed in synchronization with this. At that time, a predetermined extension side damping force is generated by the extension side damping valve 5a. Will do.

  In the damper D, when the fork main body F contracts, it contracts in synchronism with this, and at this time, the rod-side oil chamber R1 that expands via the expansion check valve 5b The hydraulic oil from the piston side oil chamber R2 will flow in.

By the way, in the present invention, the damper D is mounted on the piston side oil chamber defined by the piston body in the cylinder body 3 so as to be slidable in the axial direction of the cylinder body 3. The free piston body 6 is formed so as to oppose the body 5 and cooperate with the piston body 5 to define the piston-side oil chamber R2.

  And this free piston body 6 is provided between the cylinder body 3 while projecting along the axial direction of the cylinder body 3 on the axial center portion of the back surface which is the lower surface in the figure not facing the piston body 5. It is assumed that a rod portion 61 that defines the cylindrical oil chamber R is provided.

  At this time, this rod portion 61 is formed in a cylindrical shape, and thereby, compared with the case where this rod portion 61 is formed in a cylindrical shape, the mass in this rod portion 61 is not increased, It is supposed to contribute to preventing an increase in weight in the damper D.

  Moreover, since this rod part 61 is formed in a cylindrical shape, it becomes possible to divert the inner empty part to a tool insertion hole.

  That is, since the rod portion 61 is formed in a cylindrical shape, although not shown, for example, the free piston body 6 has a bypass path that bypasses a pressure side damping valve 6a described later, and the oil passing through the bypass path When a control valve capable of selecting a certain amount is provided, it is possible to use the inner space of the cylindrical portion as a hole for inserting a control rod or a tool for controlling the rotation of the control valve.

  The rod portion 61 formed as described above has a flange portion 61a at the lower end portion in the drawing, and this flange portion 61a is a base that becomes the lower end portion in the drawing of the cylinder body 3 by the biasing spring 7. It is supposed to be pressed toward the end 3a side.

  At this time, as shown in the figure, the flange portion 61a is separated from the base end portion 3a of the cylinder body 3, but by providing a so-called dead zone between the flange portion 61a and the base end portion 3a, If the place shown in FIG. 1 is in the vicinity of the fully extended state of the damper D, a further rise in the piston body 5 in the cylinder body 3 will cause a negative pressure in the piston-side oil chamber R2. Can be avoided in advance.

  By providing the so-called dead zone while making the volume in the cylindrical oil chamber R larger than the moving body integral of the rod body 4, even if the hydraulic oil in the damper D leaks to the outside, the so-called dead zone is caused by this leakage. It can be said that there is an advantage that the shortage of hydraulic oil can be compensated.

  Incidentally, as shown in FIG. 2, the base end portion 3 a of the cylinder body 3 is configured such that the liquid between the bearing member 3 b and the rod portion 61 that guarantees slidability between the inner periphery and the rod portion 61. It has a seal member 3c that ensures tightness.

  By the way, as long as the above-described cylindrical oil chamber R is formed between the rod portion 61 and the cylinder body 3, the base end portion 3a of the cylinder body 3 is on the flange portion 61a side of the rod portion 61 as described above. As shown in FIG. 3, it is directly supported by the bottom part of the inner tube 2 which is a wheel side member forming the fork main body F, and is connected to the bottom part. It will be good.

  Incidentally, at this time as well, although not shown in order to define the cylindrical oil chamber R, it goes without saying that slidability and liquid tightness between the cylinder body 3 and the rod portion 61 are guaranteed. It is.

  Thus, when the base end which is the lower end of the cylinder body 3 in the damper D is connected to the bottom portion of the inner tube 2, it is arranged in the fork main body in the existing multi-cylinder front fork. There is an advantage that the configuration of the damper can be the same as that of the damper D according to the present invention having the above-described free piston body 6.

  On the other hand, the free piston body 6 includes a pressure-side damping valve 6a (see FIG. 1) that allows the cylindrical oil chamber R to communicate with the piston-side oil chamber R2, and a pressure-side check valve 6b that is in parallel therewith. (See FIG. 1).

  Further, the free piston body 6 has the cylinder body 3 by the spring force of the biasing spring 7 whose top end is adjacent to the flange portion 61a which is the lower end portion in the drawing of the rod portion 61 in the drawing. It is supposed to be biased so as to approach the inner piston body 5.

  Incidentally, the rear end, which is the lower end of the biasing spring 7 in the figure, is assumed to be carried on the fork main body F side, that is, the bottom portion of the inner tube 2 which is a wheel side member in FIG.

  Further, the spring force of the urging spring 7 is set to a spring force smaller than the spring force of the suspension spring S in the fork main body F described above, and the free piston body 6 has a moving speed of the piston body 5. It is set to the spring force that can follow.

  Therefore, in the free piston body 6 formed as described above, the cylindrical oil chamber R contracts when the free piston body 6 descends in the cylinder body 3 when viewed relatively. Thus, the hydraulic oil from the cylindrical oil chamber R is allowed to flow out to the piston side oil chamber R2 via the damping valve 6a, and at this time, a predetermined compression side damping force is generated.

  When viewed relatively in the same manner, the free piston body 6 that has been lowered in the cylinder body 3 is expanded in the cylindrical oil chamber R when it rises in the cylinder body 3, and the piston-side oil chamber is expanded. The hydraulic oil is allowed to flow from R2 into the cylindrical oil chamber R through the pressure side check valve 6b.

  At this time, the free piston body 6 is urged by the urging spring 7 from the so-called rear side, and tends to push in the direction of contracting the piston side oil chamber R2, so that it operates in the cylindrical oil chamber R. The vacuum phenomenon due to insufficient inhalation of oil is not expressed.

  From the above, in the front fork according to the present invention, a preferable damping action can be realized while reducing the amount of hydraulic oil. For this purpose, the following considerations are made. .

  That is, first, regarding the cylindrical oil chamber R defined between the rod portion 61 projecting from the back surface of the free piston body 6 and the cylinder body 3, the volume in the cylindrical oil chamber R is equal to the piston body. 5 is preferably set so as to be larger than the product of the cross-sectional area of the rod body 4 connected to 5 and the stroke length of the rod body 4.

  As a result, the amount of hydraulic oil when the piston body 5 strokes in the cylinder body 3 can be accommodated, and the sliding of the piston body 5 and the free piston 6 is ensured and the extension of the distribution of the piston body 5 is increased. The operation of the side damping valve 5a and the operation of the compression side damping valve 6a disposed in the free piston body 6 are ensured.

  And as described above, by making the volume in the cylindrical oil chamber R larger than the moving body integral of the rod body 4, even if the hydraulic oil in the damper D leaks outside for some reason, It is possible to compensate for the so-called lack of hydraulic fluid due to this leakage.

  Further, when the cylindrical oil chamber R is formed so as to increase the cross-sectional area of the cylindrical oil chamber R, the amount of movement of the free piston body 6 in the axial direction can be reduced. Only the length of the damper D can be reduced.

  In addition, in the above description, the volume in the cylindrical oil chamber R is made larger than the moving body integral of the rod body 4, but instead, the volume of the cylindrical oil chamber R is moved to the rod body 4. It can be said that the contraction operation of the piston body 5 in the cylinder body 3 can be hydraulically regulated by setting it smaller than the volume.

  Next, in the illustrated front fork, the upper end of the cylinder body 3 is connected to, that is, connected to, the upper end of the inner tube 2 that is a wheel side member that distributes the cylinder body 3 to the shaft core portion. .

  Thereby, when the fork main body F is expanded and contracted, the rod body 4 is immersed in the cylinder body 3 when the inner tube 2 is synchronized, that is, when the inner tube 2 is immersed in the outer tube 1. When the damper D contracts and the inner tube 2 comes out of the outer tube 1, the extension operation of the damper D is embodied such that the rod body 4 comes out of the cylinder body 3. It will be.

  However, when the upper end of the cylinder body 3 is connected to the upper end of the inner tube 2, the damper D is hardly affected by the bending action applied to the inner tube 2, and thus the expansion and contraction operability of the damper D is improved. There are benefits that you will get.

  Accordingly, if the upper end of the inner tube 2 is connected to the upper end of the cylinder body 3 via a so-called cap member 3d so as to be maintained in a sealed state (see FIG. 2), lubricating oil is placed above the cap member 3d. As a result, it is advantageous in that it is easy to ensure the slidability of the inner tube 2 with respect to the outer tube 1.

  In addition, as described above, regardless of whether or not the cap member 3d is kept in a sealed state by arranging the cap member 3d, in the present invention, the outside of the damper D is not set as a reservoir, that is, this Since the hydraulic oil is not stored in the portion corresponding to the reservoir, the weight can be easily reduced significantly.

  In view of the above, the front fork according to the present invention is configured as follows, that is, the fork main body F is set upright or inverted, and is disposed on the shaft core portion of the fork main body F. The damper D may be freely selected as to whether it is an upright type or an inverted type.

  That is, in the front fork shown in FIG. 4, the fork main body F is set upright with the vehicle body side member as the inner tube 2 and the wheel side member as the outer tube 1, and the damper D is a cylinder body. 3 is set upright with the wheel side member and the rod body 4 as the vehicle body side member.

  At this time, in the damper D, the lower end of the cylinder body 3 is connected to the bottom portion of the outer tube 1, that is, fixedly connected.

  In the front fork shown in FIG. 5, the fork main body F is set upside down with the vehicle body side member as the outer tube 1 and the wheel side member as the inner tube 2, and the damper D connects the cylinder body 3 to the vehicle body side. It is supposed that it is set to the inverted type which uses the rod body 4 as a member and the wheel side member.

  At this time, in the damper D, the upper end of the cylinder body 3 is connected to the upper end of the outer tube 1, that is, fixedly connected.

  Further, in the front fork shown in FIG. 6, the fork main body F is set in an inverted type with the outer tube 1 as a vehicle body side member and the inner tube 2 as a wheel side member, and the damper D is a cylinder body. It is assumed that the cylinder body 3 in the damper D is composed of the inner tube 2 in the fork main body F.

  Therefore, in the embodiment shown in FIG. 6, there is no need to stand the cylinder body 3 on the shaft core portion of the inner tube 2, so that the number of parts can be reduced and the weight of the front fork can be reduced. This is advantageous in that it can contribute to reduction and cost reduction.

It is a longitudinal cross-sectional view which shows in principle the front fork by this invention. It is a fragmentary longitudinal cross-section which shows more specifically the front fork shown in FIG. It is a figure which shows the front fork by other embodiment similarly to FIG. It is a figure which shows the front fork by other embodiment similarly to FIG. It is a figure which shows the front fork by other embodiment similarly to FIG. It is a figure which shows the front fork by other embodiment similarly to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer tube 2 Inner tube 3 Cylinder body 4 Rod body 5 Piston body 5a Extension side damping valve 6 Free piston body 6a Pressure side damping valve 7 Energizing spring 61 Rod part D Damper F Fork main body R Cylindrical oil chamber R1 Rod side oil chamber R2 piston side-side oil chamber

Claims (5)

A fork main body and a damper disposed in the fork main body and having a damping action during extension operation. The fork main body is an outer tube and an inner tube that is slidably fitted to the outer tube. The damper includes a cylinder body, a rod body inserted into the cylinder body through a piston body so as to be able to protrude and retract, and a rod side oil chamber and a piston side chamber defined by the piston body in the cylinder body. A front fork provided with an extension-side damping valve that is disposed in the piston body and communicates the rod-side oil chamber with the piston-side chamber during extension operation, and faces the piston body while sandwiching the piston-side chamber in the cylinder body The free piston body is inserted, and the free piston body has a rod portion extending in the opposite direction to the piston body. A cylindrical oil chamber is defined between the outer periphery of the rod body and the inner periphery of the cylinder body, and the piston-side oil chamber communicates with the cylindrical oil chamber in the free piston body. the compression side damping valve is provided, also a front fork, characterized in that by interposing a biasing spring between the rod portion and the fork bodies are energized the free piston member to the piston body direction.   In the fork main body, the outer tube is a vehicle body side member and the inner tube is a wheel side member. In the damper, the cylinder body is a wheel side member and the rod body is a vehicle body side member. The front fork according to claim 1, wherein the upper end is connected to the upper end of the inner tube.   In the fork main body, the outer tube is a vehicle body side member and the inner tube is a wheel side member. In the damper, the cylinder body is a wheel side member and the rod body is a vehicle body side member. The front fork according to claim 1, wherein the lower end is connected to the lower end of the inner tube.   In the fork main body, the outer tube is a vehicle body side member, the inner tube is a wheel side member, the cylinder body is a wheel side member in the damper, the rod body is a vehicle body side member, and the cylinder body in the damper is The front fork according to claim 1, comprising an inner tube in the fork main body.   The front fork according to claim 1, wherein the volume in the cylindrical oil chamber is set to be larger than the moving volume integral of the rod body.

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