JP4579844B2 - Front fork - Google Patents

Description

  The present invention relates to a front fork, and more particularly, to an improvement in a front fork that is mounted on a front wheel side of a two-wheeled bicycle and functions as a hydraulic shock absorber.

  In the case of a bicycle as a recent motorcycle, for example, from the viewpoint of advantageous long-time driving and off-road driving, or from reducing the burden during handling such as parking and transportation, as much as possible The company intends to reduce the weight of its body.

  Especially for off-road bicycles, in order to improve riding comfort, not only are cushion units such as dampers and springs mounted on the rear wheels, but they also function as hydraulic shock absorbers on the front wheels. The front fork is supposed to be mounted.

  By the way, about mounting this front fork, the front fork developed for the same motorcycle, which is a motorcycle, is simply reduced in size, and it is mounted on a bicycle that has a significantly smaller body weight than a motorcycle. When doing so, it may be pointed out that it does not necessarily contribute to weight reduction in a bicycle.

  Therefore, for example, as disclosed in Patent Document 1, each tube is a carbon fiber reinforced plastic (hereinafter abbreviated as CFRP) for the purpose of reducing the weight of the vehicle body side tube and the wheel side tube which are components in the front fork. ) Proposals have been made to consist of pipes.

Therefore, according to the inner tube disclosed in Patent Document 1, it should be understood that the inner tube has the necessary strength as a component constituting the front fork. For example, a metal portion for ensuring slidability This will contribute to a reduction in the weight of the front fork while guaranteeing the machining of the front fork.
Japanese Patent Publication No. 7-106712 (Claims Claim 1, Description (2) page, left column 2nd to 13th line, specification (2) page right column 10th to 13th page) Row, Fig. 1 and Fig. 2)

  However, in the inner tube disclosed in the above-mentioned Patent Document 1, for example, workability for ensuring slidability is ensured, but the contribution to weight reduction in the front fork is as follows. , It may be pointed out that there is a minor bug.

  That is, the inner tube is formed such that the outer peripheral portion is cut while leaving a part of the metal pipe serving as a base material, and the cut portion is provided with a CFRP pipe.

  Therefore, in this inner tube, it is possible to process the inner peripheral part which is a metal part and the remaining part which does not have a CFRP pipe while having the strength required as a component constituting the front fork. Since the remainder that does not include the pipe is made of only a metal material, weight reduction in the inner tube is not completely achieved.

  And when the front fork constructed using this inner tube is mounted on the front wheel side of the bicycle, the front fork developed for motorcycles is not simply miniaturized and mounted. If not, it will not fully contribute to weight reduction in the bicycle.

  The present invention was devised in view of such a current situation, and the object of the present invention is to form a metal pipe to ensure slidability when forming the outer tube as a component part with a CFRP pipe. Even if it is prepared for the inner circumference, it does not cause an increase in mischievous weight, and as a result, it can be expected to improve its versatility, that is, as a hydraulic shock absorber mounted on the front wheel side of the bicycle It is to provide a front fork that is optimal for use.

  In order to achieve the above object, the structure of the front fork according to the present invention is basically an outer tube in which a metal pipe is continuously provided on the inner periphery of a carbon fiber reinforced plastic pipe, and the outer tube can appear and disappear. In the front fork having the inner tube inserted into the outer tube, the end of the metal pipe is positioned inside the end of the outer tube on the side where the inner tube is not inserted, and the inner tube is inserted into the outer tube of the inner tube. A cylindrical body is connected to the end on the side, and a bush member interposed on the outer periphery of the cylindrical body is slidably contacted with the inner periphery of the metal pipe in the outer tube, so that the inner tube protrudes most from the outer tube. The other end of the metal pipe in the outer tube is the outer Bush member and not extend to the open end for inserting the inner tube is to become is determined positions within the range of sliding in the tube.

  Therefore, in the present invention, in the front fork in which the inner tube is inserted into the outer tube so as to be retractable, the outer tube is formed by connecting a metal pipe to the inner periphery of the carbon fiber reinforced plastic pipe. Therefore, at least as compared with the case where the outer tube is made of only a metal material, the weight of the front fork is reduced.

  Then, one end which is the base end of the metal pipe is positioned inside the end portion of the outer tube where the inner tube is not inserted, and a cylindrical body made of a metal material is connected to the end portion where the inner tube is not inserted. Therefore, the cylindrical body can be processed, and the cylindrical body can form a connection portion of an upper bracket that is a bracket for gripping the upper end side of the front fork.

  In addition, a cylindrical body is connected to an end portion of the inner tube that is inserted into the outer tube, and a bush member interposed on the outer periphery of the cylindrical body connected to the inner tube passes through the inner tube of the outer tube. In this case, in the inner periphery of the outer tube to which the bush member is slidably contacted, the end of the metal pipe is located at the inner side of the end portion of the bush member. Since the tube is positioned so as to be closer to the end portion of the tube that is not inserted into the outer tube, the metal pipe can be provided only in the sliding range of the bush member, and the metal pipe is continued longer than necessary. This eliminates the need to install and prevents the cost of parts in the outer tube from increasing.

  As a result, according to the present invention, when the outer tube as the component is formed of the CFRP pipe, even if the metal pipe is continuously provided on the inner periphery to ensure the slidability, the increase in the mischievous weight and the mischief Therefore, it is possible to provide a front fork suitable for use as a hydraulic shock absorber mounted on the front wheel side of a bicycle without causing a significant increase in the cost of parts.

  Hereinafter, the present invention will be described based on the illustrated embodiment. A front fork according to the present invention is input to the front wheel of a traveling bicycle while being paired on the front wheel side of the two-wheeled bicycle and mounted on the left and right. It functions as a hydraulic shock absorber that absorbs road surface vibration.

  FIG. 1 and FIG. 2 show one of a pair of left and right, and an axial core portion of a fork main body that is inserted through the outer tube 1 so that the inner tube 2 can protrude and retract. The damper has a damper, and when the fork body extends and contracts, the damper expands and contracts to exhibit a damping function.

  The other front fork in the case of a pair on the left and right is not shown, but the fork body is inserted through the outer tube so that the inner tube can be retracted, but this fork has no damper. It has a spring element that urges the main body in the extending direction, that is, a suspension spring.

  In this way, when one of the front forks that are paired on the left and right and is mounted on the front wheel side of the bicycle exhibits a damping function, and the other is set to act as a spring, Since it is not necessary to use it, it contributes to reducing the product cost of the bicycle as well as to reducing the weight of the bicycle.

  By the way, in the front fork shown in FIG. 1, the fork main body comprising the outer tube 1 and the inner tube 2 is set in a so-called inverted type, that is, the vehicle body in which the outer tube 1 is connected to the handle side of the bicycle. An inner tube inserted into the outer tube 1 so as to be able to appear and retract is used as a lower side member which is a wheel side member for connecting a wheel in a bicycle. Since the weight of the fork main body is reduced by reducing the weight in the tube 1, the fork main body is set to a so-called upright type in which the outer tube 1 is a lower end side member and the inner tube is an upper end side member. It goes without saying that it may be done.

  Incidentally, as shown in the figure, when the front fork is set upside down, the mass at the lower end side of the front fork is made smaller than when the front fork is set upside down. It is possible to reduce the unsprung load caused by the above, which is advantageous in improving the operability of the steering wheel in the bicycle.

  Next, the outer tube 1 constituting the fork main body which is a front fork in the present invention is configured such that a metal pipe 12 is connected to the inner periphery of a carbon fiber reinforced plastic pipe, that is, a CFRP pipe 11.

  At this time, when the thickness of the CFRP pipe 11 forming the outer tube 1 is compared with the thickness of the metal pipe 12, the thickness of the CFRP pipe 11 is reduced from the viewpoint of reducing the weight of the outer tube 1 as much as possible. Is set to be larger than the thickness of the metal pipe 12.

  As for the thickness of the CFRP pipe 11, as shown in the figure, a cylindrical bracket 14 described later is provided on the outer periphery of the fork main body so that the fork main body can be connected to the handle side of the bicycle. The thickness of the portion where the bracket 14 is arranged is maximized, and the thickness is gradually reduced from there to the upper end side and the lower end side in the figure. At this time, the CFRP pipe 11 The outer peripheral side surface is finished to be a tapered surface.

  Further, the end portion of the inner tube 2 on the side inserted into the outer tube 1 which is the upper end portion in the drawing, that is, the opening end portion 2a is connected to the outer tube 1 with the cylindrical body 21 and the bush member 22 interposed therebetween. Since the sliding contact is made with the inner periphery of the metal pipe 12 that can be placed, the sliding of the bush member 22 is ensured.

  In addition, the metal pipe 12 is formed of a material that is advantageous for contributing to the weight reduction of the outer tube 1. In the illustrated case, the metal pipe 12 is formed of an aluminum material.

  Therefore, in this outer tube 1, when it is used as a component of the front fork, it will of course have the necessary mechanical strength, but at least when it is made of only a metal material. In comparison, this contributes to weight reduction in the front fork.

  Further, in the outer tube 1, for example, the metal pipe 12 can be processed to ensure the slidability of the bush member 22, and at least this includes only the CFRP pipe 11. Compared to the case, it is advantageous to be a component of the front fork.

  On the other hand, the inner tube 2 that forms the fork main body together with the outer tube 1 described above is not limited to a special material in the present invention, but in the illustrated case, it contributes to the weight reduction of the fork main body. And CFRP pipe.

  At this time, the inner tube 2 is not connected to a metal pipe on the inner periphery like the outer tube 1 in the drawing, but the inner tube 2 is connected to the inner periphery, for example, a free piston or a bush member. Of course, in the case of the setting for sliding contact with each other, a metal pipe may be provided continuously on the inner periphery of the CFRP pipe, similarly to the outer tube 1.

  Note that the end of the inner tube 2 that is not inserted into the outer tube 1, which is not illustrated, is called a “bottom end”. In many cases, an axle bracket made of a metal material is externally mounted. In addition to the suspension of the front wheel in the bicycle through the bracket, it is possible to hold the brake mechanism, for example, using this axle bracket.

  The fork main body having the outer tube 1 and the inner tube 2 formed as described above has a damper at its axial center in the drawing, but this damper is shown in the drawing. By the way, it is said that it is set upright.

  That is, the damper is erected on the axial core portion of the inner tube 2 while the lower end is connected to the inner tube 2 which is a lower end side member of the fork main body, and the damper 3 A rod body 4 that is also a component that can be inserted and retracted is suspended from an axial core portion of the outer tube 1 while being connected to an outer tube 1 that is an upper end side member in the fork main body.

  Therefore, the damper is expanded and contracted when the fork main body is expanded and contracted. At this time, for example, the piston connected to the rod body 4 and accommodated in the cylinder body 3 is connected to the damping portion. Therefore, a desired attenuation function can be exhibited.

  Incidentally, the front fork shown in the drawing is provided with a damper in the shaft core portion of the fork body, but this damper itself is not required to have a special configuration. A well-known configuration may be arbitrarily adopted.

  As described above, in the front fork of the present invention having the outer tube 1 in which the metal pipe 12 is continuously provided on the inner periphery of the CFRP pipe 11, the following consideration is given.

  That is, first, in the outer tube 1, one end which is the base end of the metal pipe 12 is positioned inside the end portion 1 a on the side where the inner tube 2 in the outer tube 1 which is the upper end portion in the drawing is not inserted, and this The cylindrical body 13 made of a metal material is connected to the end 1a under the use of an adhesive material made of, for example, an epoxy resin.

  At this time, one end of the metal pipe 12 is connected to the inner periphery of the cylindrical body 13 so as to exceed the one end of the CFRP pipe 11 as shown in the figure. Therefore, one end of the CFRP pipe 11 is compared. In other words, it will be placed in a position to be protected by being surrounded by metal parts that are resistant to wear.

  And this cylindrical body 13 shall have the skirt part 13a suspended so that the edge part 1a in the outer tube 1 may be covered from an outer peripheral side, and this edge part 1a in the outer tube 1 by this skirt part 13a. In addition, the upper end of the CFRP pipe 11 forming the upper end 1a, that is, the upper end of the CFRP pipe 11 is protected from flying stones from the outside.

  In addition, the cylindrical body 13 is made of an aluminum material, which is a metal material, as shown in the figure, and becomes a strength component against an external force acting on the outer tube 1 in the axial direction. The upper bracket, which is a bracket when connecting to the side, is allowed to be connected in a gripping posture.

  Incidentally, as shown in the figure, a cylindrical bracket 14 made of an aluminum material, which is a metal material, is attached to an outer periphery of a portion closer to the cylindrical body 13 above the intermediate portion of the outer tube 1 with an adhesive made of an epoxy resin or the like. It is assumed that the front fork is connected in a state of gripping the under bracket as a bracket when the front fork is connected to the handle side of the bicycle.

  Further, the cylindrical body 13 is formed by connecting the cap member 15 to the end of the cylindrical body 13 that is the upper end portion in the drawing, that is, the inner periphery of the opening end 13b. The upper end side of the outer tube 1 is closed by the cap member 15, and in the illustrated case, the cap member 15 connects the upper end of the rod body 4 in the damper to the shaft core portion. It is said.

  Next, in the inner tube 2, the cylindrical body 21 is connected to the end portion on the side inserted into the outer tube 1 serving as the upper end portion in the drawing, that is, the open end portion 2a. It is assumed that a bush member 22 is interposed on the outer periphery of the cylindrical body 21, and that the bush member 22 is in sliding contact with the inner periphery of the outer tube 1.

  At this time, the cylindrical body 21 is made of an aluminum material, which is a metal material, and the inner tube 2 is made of a CFRP pipe. It is assumed that it is connected to the outer periphery of 2a.

  Therefore, in the inner tube 2, the inner tube 2 is formed by sliding the interposed bush member 22 on the inner periphery of the outer tube 1 to the cylindrical body 21 connected to the opening end 2 a. However, it is not necessary to be concerned about the situation in which the outer wall 1 is inclined with respect to the outer tube 1, and the bush member 22 is in sliding contact with the inner periphery of the outer tube 1, that is, the inner periphery of the metal pipe 12. As a result, it is not necessary to unnecessarily cause a damage phenomenon on the inner periphery of the metal pipe 12.

  By the way, the cylindrical body 21 is made of an aluminum material, which is a metal material, and a shaft sealing member that closes the opening end 3a of the cylinder body 3 in the above-described damper under the insertion of the rod body 4. 31 is connected.

  Therefore, in the illustrated damper, the so-called head portion of the cylinder body 3 is integrally connected to the opening end portion 2a of the inner tube 2, and the vibration at the head portion of the cylinder body 3 can be prevented. Of course, the reservoir chamber R is defined between the cylinder body 3 and the inner tube 2, that is, the reservoir chamber R that has an air chamber with the oil surface as a boundary and communicates with the damper is defined. Can be achieved.

  By the way, as described above, in the present invention, the bush member 22 held in the open end 2a of the inner tube 2 under the intervention of the cylindrical body 21 is in sliding contact with the inner periphery of the outer tube 1. The metal pipe 12 forming the inner periphery of the outer tube 1 is naturally arranged so as to allow the sliding contact of the bush member 22, but on the other hand, it is arranged more than necessary, that is, so-called long. It can be said that there is no need to be present.

  Therefore, in the front fork according to the present invention, the other end which is the lower end in the figure of the metal pipe 12 on the inner periphery of the outer tube 1 when the inner tube 1 is fully extended from the outer tube 2 is the outer tube. It is assumed that the bush member 22 is positioned within a range in which the bush member 22 is slid without being extended to the open end 1b.

  That is, the outer tube 1 according to the present invention has a metal pipe 12 connected to the inner periphery of the CFRP pipe 11 so as to ensure so-called slidability. Therefore, it can be said that there is no need to cover the inner periphery of the CFRP pipe 11 with the metal pipe 12, and from this, the metal pipe 12 is provided continuously over the entire inner periphery of the CFRP pipe 11. Therefore, by setting as described above, it is possible to prevent the parts cost in the outer tube 1 from being unnecessarily increased.

  Further, in positioning the end of the metal pipe 12, it is assumed that the end face of the end of the metal pipe 12 is a tapered surface, and bending stress is applied to the corresponding part of the CFRP pipe 11 where the end of the metal pipe 12 is positioned. It is supposed to avoid inviting concentrated bugs.

  In particular, as shown in the figure, in the outer tube 1, the corresponding part of the CFRP pipe 11 that positions the end of the metal pipe 12 is a part where the cylindrical bracket 14 located above the CFRP pipe 11 is located. The tapered surface is finished so as to make the thickness of the opening end 1b the thinnest while making the wall thickness the thickest, and even from this, the CFRP pipe 11 in which the end of the metal pipe 12 is positioned The inconvenience that the bending stress concentrates on the corresponding part of this is to avoid this absolutely.

  The fact that the concentration of bending stress can be avoided by finishing the end surface of the end of the metal pipe 12 to be a tapered surface means that the cylindrical body 21 connected to the open end portion 2a of the inner tube 2 described above is used. Since the same can be said for the end portion, it is preferable to finish the end portion of the cylindrical body 21 to a tapered surface as shown in the figure.

  Then, in the case where a measure for avoiding the concentration of bending stress by finishing the so-called end portion into a tapered surface is realized, for example, the tapered surface of the metal pipe 12 is directly spaced apart from the tapered surface of the CFRP pipe 11. It can be said that it is preferable not to be continuous.

It is a longitudinal cross-sectional view which partially cuts and shows the upper end side of the front fork by this invention. It is a figure which shows the center part of the front fork continuous with the place shown in FIG. 1 similarly to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer tube 1a End part 1b, 2a, 3a, 13b Open end part which is an end part 2 Inner tube 3 Cylinder body 4 Rod body 11 CFRP pipe 12 Metal pipe 13, 21 Cylindrical body 15 Cap member 22 Bush member 31 Shaft seal member

Claims (8)

In the front fork that has an outer tube with a metal pipe connected to the inner circumference of a carbon fiber reinforced plastic pipe and an inner tube that can be inserted into and retracted from the outer tube, the inner tube in the outer tube is inserted. One end of the metal pipe is positioned inside the end portion on the side that is not to be connected, and the cylindrical body is connected to the end portion of the inner tube that is inserted into the outer tube, and is interposed on the outer periphery of the cylindrical body. The bushing member is in sliding contact with the inner circumference of the metal pipe in the outer tube, and the other end of the metal pipe in the outer tube is inserted through the inner tube in the outer tube when the inner tube is fully extended from the outer tube. Bush part without extending to the part There front fork, characterized by comprising predetermined position within the slide. The front fork according to claim 1, wherein the outer tube is a vehicle body side member connected to a handle side of the bicycle, and the inner tube is a wheel side member connecting wheels of the bicycle. A cylindrical body is connected to an end portion of the outer tube on the side where the inner tube is not inserted, and an end portion of the cylindrical body that opens to the outside of the cylindrical body is closed with a cap member connected to the inner periphery. Item 2. The front fork according to item 1. The front fork according to claim 1, wherein the inner tube is made of a carbon fiber reinforced plastic pipe. The front fork according to claim 1, wherein the cylindrical body connected to the end portion of the inner tube that is inserted into the outer tube is made of a metal material. A damper is arranged on the shaft core portion of the fork main body composed of the outer tube and the inner tube, and the rod body is projected and retracted with respect to the cylinder body while the damper is inserted into the cylinder body so that the rod body can be projected and retracted. The front fork according to claim 1, wherein the front fork exhibits a damping function during expansion and contraction operation. 7. The front according to claim 6, wherein the damper is disposed on the shaft core portion of the inner tube while connecting the cylinder body to the inner tube, and is disposed on the shaft core portion of the outer tube while connecting the rod body to the outer tube. fork. A shaft seal member that closes the open end of the cylinder body in the damper under the insertion of the rod body is connected to the inner periphery of the cylindrical body connected to the end of the inner tube that is inserted into the outer tube. The front fork according to claim 6.

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