JP4181948B2 - Front fork - Google Patents

Description

  The present invention relates to a front fork that serves as both a fork and a shock absorber that is interposed between a vehicle body side and an axle side of a motorcycle and attenuates vibration from a road surface. It relates to an improved inverted front fork.

  As this type of front fork, a built-in damper type upright or inverted front fork in which an inner tube is slidably inserted into the outer tube and a damper is provided between the outer tube and the inner tube is known. ing.

  Then, an oil lock case is erected at the lower part of the outer tube or inner tube as the wheel side tube, and an oil lock piece facing the oil lock case is provided on the damper cylinder side, and the oil lock piece enters the oil lock case at the time of maximum compression. By making the oil lock work, sudden bottom-out is prevented.

  For example, an oil lock mechanism disclosed in Patent Document 1 has been developed as an oil lock mechanism for preventing bottom thrust of this type of inverted front fork, and this oil lock mechanism has an elastic body at the center of the lower end of the inner tube as a wheel side tube. A spring receiving cylinder is also raised from the lower part of the inner tube, and an oil lock member is vertically movable inside the upper part of the spring receiving cylinder, and the elastic body and the oil lock member are opposed to the lower part of the damper cylinder. An oil lock piece is provided.

Then, the compression speed is reduced by inserting the oil lock piece into the oil lock member in the middle stroke area during compression and increasing the damping force by utilizing the gap between the oil lock piece and the oil lock member. At the time of the maximum compression, the oil lock piece is brought into contact with the elastic body to prevent a sudden bottom thrust.
JP-A-9-177863 (FIG. 1)

  However, the front fork configured as described above is not particularly functionally defective, but improvement of the following problems is desired.

  First, in the conventional front fork, the oil lock piece abuts against the elastic body while compressing it at the time of the most compression, so the oil lock piece receives the reaction force due to the restoring force of the elastic body when switching to the extension operation. There is a problem that the vehicle body is lifted up due to the impact and the ride comfort is deteriorated.

  Secondly, the conventional front fork requires a spring receiving tube, an oil lock member, and an elastic body, so that the number of parts is large, the structure is complicated, and it is disadvantageous in workability and economy.

  Accordingly, an object of the present invention is to provide a front fork which is not subjected to a sudden reaction force when switched from the most compressed state to an extension operation, has a small number of parts, and has a compact structure.

To achieve the object, means of the present invention, the vehicle body side outer wheel side inner tube into the tube is inserted slidably, and a damper and the reservoir provided on the vehicle body side outer tube and the axle-side inner inside tube, The damper cylinder is hanged downward from the upper center of the vehicle body side tube, the piston rod rises from the center of the wheel side tube and is inserted into the damper cylinder via the piston , and the oil lock case in the wheel side inner tube the provided, in the front fork is provided with the oil lock piece that faces in the oil lock case to the lower end of the damper cylinder, standing the oil lock case under end in the wheel-side inner tube, further above the oil lock case to carry the suspension spring as well as standing along the inner tube The cylindrical collar also serves as a spring receiving cylinder is coupled while being opposed to the oil lock piece, the inner diameter of the collar so as to form larger than the inner diameter of the oil lock case, it is reduced in diameter toward the top to the bottom It is characterized by.

  In this case, it is preferable that the base end of the collar is coupled to the outer periphery of the oil lock case via a joint or a screw.

Similarly, it is preferable that the oil lock case is formed of aluminum or other metal material, and the collar is formed of a synthetic resin material.

  According to the present invention, the following effects can be obtained.

According to the invention of each claim, in the intermediate stroke region during the compression operation, the oil lock piece enters the inner periphery of the collar, and the damping force can be increased by the oil flow resistance caused by the gap between the two. Further, near the time of recompression, the oil lock piece enters the oil lock case to prevent sudden bottom-out due to the oil lock. Moreover, even when switching from recompression to extension operation, a sudden reaction force is not received from the oil lock case side, so that no impact is input to the vehicle body side and riding comfort can be improved.
In particular, since the inner circumference of the collar is formed as a tapered surface that gradually decreases in diameter from the top to the bottom, the damping force generated by the oil lock piece entering the inner circumference of the collar is applied to the compression stroke. The riding comfort can be increased in order to further improve riding comfort.
Further, since the collar also serves as a spring receiving cylinder for supporting the suspension spring, an extra spring receiving member is not required, the structure can be simplified, and the economy is excellent.

  Similarly, as the oil lock mechanism, there are only an oil lock case and a collar coupled thereto, and these stand up in series along the inner tube, so the number of parts is small, the structure is compact, workability, Excellent assembly and economy.

  According to the invention of claim 2, since the collar is coupled to the outer periphery of the oil lock case, the inner diameter of the collar is necessarily larger than the inner diameter of the oil lock case, and the damping force is sequentially increased depending on the compression stroke position. The oil lock piece can be fitted into the oil lock case 7 at the time of the most compression, and an oil lock effect can be achieved, thereby preventing a sudden bottom butt.

According to the invention of claim 3 , since the oil lock case and the collar are formed of separate members, both can be formed of different materials. In particular, since the oil lock case is formed of a metal material, also act a large pressure in the oil lock pressure during most compression can be improved durability. In addition , a collar on which a pressure smaller than the above pressure is applied can be made of a synthetic resin so that durability, weight reduction and dimensional accuracy can be reduced, and the material cost of the collar can be saved to improve productivity.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1 to 3 show an inverted front fork according to an embodiment of the present invention. The tube 1 is used as a vehicle body side tube, and the inner tube 2 is used as a wheel side tube.

  In this front fork, the inner tube 2 is slidably inserted into the outer tube 1 and a damper cylinder 4 is provided from the outer tube 1 into the inner tube 2 as in the prior art. The piston rod 6 is movably inserted through the piston 5 toward the inside 4, an oil lock case 7 is provided in the inner tube 2, and an oil lock facing the oil lock case 7 is provided at the lower end of the damper cylinder 4. This is a front fork provided with a piece 8.

  In the present invention, the oil lock case 7 is further erected at the lower end of the inner tube 2, and a cylindrical collar 33 that is erected along the inner tube 2 above the oil lock case 7 is opposed to the oil lock piece 8. It is combined while letting.

  In this case, the base end of the collar 33 is coupled to the outer periphery of the oil lock case 7 via a joint 32 or a screw. Further, the collar 33 also serves as a spring receiving cylinder for supporting the suspension spring 34, and the inner diameter of the collar 33 is formed larger than the inner diameter of the oil lock case 7. In particular, the oil lock case 7 is formed of aluminum or other metal material, and the collar 33 is formed of a synthetic resin material.

  In more detail, a damper 3 and a reservoir R are provided in the outer tube 1 and the inner tube 2, an oil lock case 7 is erected at the inner end of the inner tube 2, and the oil is applied to the lower end small diameter portion of the damper cylinder 4. An oil lock piece 8 facing the inside of the lock case 7 is provided.

  The oil lock piece 8 includes a cylindrical body 8a that is movably inserted into the outer periphery of the small-diameter portion of the lower end of the damper cylinder 4, and a notch 8b formed at the end of the cylindrical body 8a. An oil suction passage 9 communicating with the reservoir R is formed between the lower end small diameter portion of the cylinder 4.

  Further, as will be described later, another oil suction passage 9 a is formed in parallel with the flow passage 9 in the small diameter portion of the lower end of the damper cylinder 4, and each suction passage 9, 9 a is connected to the oil lock piece 8. It can be selectively opened and closed by movement.

Lower small-diameter portion of the damper cylinder 4 may be formed by extending the dust emission path over the cylinder 4 itself downward, but may be formed by combining the cap 3a having a smaller diameter cylindrical portion 12.

  In the damper 3, the damper cylinder 4 is suspended downward from the upper center of the outer tube 1, and the piston rod 6 stands up from the center of the inner tube 2 and is inserted into the damper cylinder 4 via the piston 5. Yes.

  The damper 3 includes oil chambers 13 and 14 partitioned by a piston 5 and a valve mechanism provided in the piston 5. In this embodiment, a cylinder whose one end is opened to the reservoir R side of the damper cylinder 4 is provided. A cap 3 a provided with a portion 12 is provided, and this cap 3 a is configured as a small diameter portion at the lower end of the damper cylinder 4 and the oil chamber of the damper cylinder 4 is closed.

  In addition, the oil lock piece 8 is movably inserted into the outer periphery of the cylindrical portion 12, and the suction port 10 formed in the cylindrical portion 12 in the radial direction and a space 12 a along the inner periphery of the cylindrical portion 12 are used for other purposes. An oil suction passage 9a is formed.

  The port 10 joins the inlet of one suction flow path 9 and communicates with the reservoir R. In this case, if a trumpet-shaped taper surface 8c is formed at the inner peripheral end of the oil lock piece 8 as shown in the drawing, oil is sucked when the oil lock piece 8 opens the flow passages 9 and 9a. The flow rate can be increased.

  As shown in FIG. 2, in the damper cylinder 4, two upper and lower oil chambers 13, 14 defined by a piston 5 are defined, and the two oil chambers 13, 14 are two ports of extension and pressure provided in the piston 5. 15 and 16 and leaf valves 17 and 18 provided at the outlet ends of the ports 15 and 16, respectively.

  Further, the center rod 19 which is coupled to the piston rod 6 and holds the piston 5 is formed with vertical and horizontal ports 20, 21 to communicate the two oil chambers 13, 14. The damping force is adjusted by inserting 22 so as to be movable up and down.

  A control rod 23 is inserted into the piston rod 6 so as to face the needle valve 22, and a lower portion of the control rod 23 is brought into contact with an adjuster 25 provided on a lower bottom 24 of the inner tube 2, and the adjuster 25 is rotated. By moving the control rod 23 up and down, the needle valve 22 is moved up and down to adjust the opening area of the ports 20 and 21.

  As described above, the hollow cap bush 3a is coupled to the lower portion of the damper cylinder 4 as the lower end small-diameter portion. Inside the cap 3a, a seal holder 26, an oil seal S, and a bush 28 are inserted. A spring guide 31 is inserted in the outer periphery of the cap 3a, and one or a plurality of grooves 31a along the axial direction are formed in the body portion.

  The cap 3a is composed of a main body and a cylindrical portion 12 integrally coupled to the main body. A lower portion of the space 12a of the cylindrical portion 12 opens into a reservoir R in the inner tube 2, and the suction port 10 is similarly reserved in the reservoir. -It communicates with the upper side of bar R.

  A spring seat 29 is provided on the upper portion of the seal holder 26, and a cushion spring 30 is seated on the spring seat 29 so that the cushion is effective near the maximum extension.

  A bottom 24 is screwed into the base portion 11a of the axle bracket 11, and a lower portion of the inner tube 2 is screwed into the inside of the tube portion 11b, so that the base portion 11a of the axle bracket 11 and the inner peripheral side of the tube portion 11b are engaged. The base end of the oil lock case 7 is held and stands upward.

  A flange is provided on the outer periphery of the lower portion of the oil lock case 7, and this flange is sandwiched between the lower end of the inner tube 2 and the upper end of the base portion 11a. However, the oil lock case 7 may be held by press-fitting or screw connection.

  A nut 38 is inserted and raised on the outer periphery of the base end of the piston rod 6, and this nut 38 faces the inside of the cylindrical portion 12 on the damper cylinder 4 side, and at the time of maximum compression, the nut 38 is in the space 12 a of the cylindrical portion 12. It is designed to be inserted.

  A base end of a hollow collar 33 is inserted between the outer periphery of the oil lock case 7 and the lower inner periphery of the inner tube 2, and the collar 33 is formed between the outer periphery of the oil lock case 7 and the inner periphery of the inner tube 2. It is held in the oil lock case 7 through a joint 32 that is fitted between them.

  The joint 32 is divided into a left and right pair and is formed in a half shape. The joint 32 is fitted to the collar 33 and the oil lock case 7 from both sides, and the outer periphery is constrained by the inner periphery of the inner tube 2 to be separated in the lateral direction. Is regulated.

  In this case, the joint 32 is provided with two upper and lower annular projections on the inner periphery, the lower projection is fitted in the outer annular groove on the oil lock case 7 side, and the upper projection is fitted in the outer annular groove on the collar 33 side. The collar 33 is coupled to the oil lock case 7.

  The collar 33 stands up along the inner tube 2, and the lower end of the suspension spring 34 is supported on the upper end of the collar 33, and the inner space 36 of the collar 33 is open to the reservoir R, and in the intermediate stroke area, The damping force can be increased by the flow resistance caused by the gap between the inner periphery and the oil lock piece 8.

In the present invention, in order to improve the riding comfort by sequentially increasing the damping force depending on the compression stroke, the inner periphery of the collar 33 is formed as a tapered surface that gradually decreases in diameter from the upper side to the lower side . .

  The upper end of the suspension spring 34 is held by a spring seat provided on the upper outer periphery of the damper cylinder 4 or the upper portion of the outer tube 1, whereby the suspension spring 34 constantly urges the outer tube 1 in the extending direction.

  A gap 35 that opens to the reservoir R is formed between the collar 33 and the inner tube 2, and this gap 35 is formed in the interior 36 of the collar 33 via an upper notch 37 formed in the collar 33 and a lower port 33 a. Communicate.

  A check valve 27 is inserted into an annular groove provided on the outer periphery of the collar 33 so as to be movable up and down, and this check valve 27 allows the oil above the gap 35 to flow only downward.

  Next, the operation will be described. When the front fork is extended, the outer tube 1 and the damper cylinder 4 are raised. At this time, the oil in the lower oil chamber 14 in the damper 3 flows into the port 15, the leaf valve 17, the port 21, The oil flows out into the upper oil chamber 13 through 20, and the expansion damping force is generated by the leaf valve 17 and the needle valve 22.

  On the contrary, during the compression operation, the damper cylinder 4 and the outer tube 1 are lowered, and at this time, the oil in the upper oil chamber 13 flows into the lower oil chamber 14 through the port 16, the leaf valve 18 and the ports 20 and 21, and the leaf valve 18 and the needle valve 22 generate a compression side damping force.

Further, in the compression operation, when the oil lock piece 8 enters the collar 33, the oil lock piece 8 moves upward due to the pressure increase in the collar 33, and closes the upper inlet of each of the suction flow paths 9, 9a. In this case through the gap between the inner periphery of the outer peripheral and collar 33 of the oil lock piece 8 flows into the reservoir R oil above the inside 36 of the collar 33, Ri by the tapered inner circumferential surface of the collar 33 The damping force increases sequentially, a position-dependent damping force characteristic is obtained, and the compression speed is reduced.

  When the compression operation is further deepened, the oil lock piece 8 enters the oil lock case 7, and the flow resistance is increased because the fitting gap between the two is small, and the bottom bottom of the damper cylinder 4 is prevented.

  When the damper cylinder 3 is moved up from this state and the damper cylinder 3 is raised, the chamber below the oil lock case 7 becomes negative pressure, the oil lock piece 12 is lowered, and the suction channels 9 and 9a are opened to the reservoir R.

  For this reason, the oil of the reservoir R is sucked into the suction passages 9 and 9a from the taper surface 8c, and this oil flows out from the suction passage 9 directly into the lower part of the oil lock case 7 and a part thereof. The oil flows out into the lower part of the oil lock case 7 through the suction port 10 and the inner space 12a of the cylindrical portion 12, thereby preventing negative pressure and allowing the damper cylinder 4 to rise smoothly.

  That is, in addition to the suction flow path 9, another flow path 9 a is formed in parallel with the suction port 10 and the space 12 a inside the oil lock piece 8. The supply of oil is sufficient, the shortage of oil suction is prevented, and a smooth elongation operation is achieved. Further, since the trumpet type taper surface 8c is expanded in diameter upward to make the inlet of the flow path large, the oil suction is good.

  Further, even while the oil lock piece 8 is raised in the collar 33, the check valve 27 is lowered, and the oil in the gap 35 passes through the check valve 27 and is supplied from the port 33a to the inside 33a of the collar 33. Therefore, the generation of negative pressure can be prevented, and the damper cylinder 4 can rise smoothly and extend. Although it can be used without the notch 37, when the gap 35 is closed by the upper end flange of the suspension spring 34 or the collar 33, it is effective to improve oil suction.

  As described above, the oil lock piece 8 and the oil lock case 7 can be oil-locked in the stroke near the most compression, but in the intermediate stroke area where the oil lock piece 8 moves up and down in the collar 33, the collar 33 and the oil lock The damping force can be increased by the oil flow resistance caused by the gap between the pieces 8.

  Moreover, since the oil is supplied to the inside of the collar 33 through the notch 37, the check valve 27, and the port 36 when the compression stroke is switched to the extension stroke in this intermediate stroke region, the oil is insufficiently sucked even in this intermediate region. Is prevented, and a smooth extension operation is achieved.

  At this time, when the collar 33 is formed of a synthetic resin material and the oil lock case 7 is divided and formed of a metal material such as aluminum, the shape of the oil lock case 7 changes even if the internal pressure rises during oil lock. Can be prevented and its durability can be improved. Further, the collar 33 can reduce dimensional accuracy, improve productivity, and save material costs.

It is a partially cut longitudinal front view of a front fork according to an embodiment of the present invention. FIG. 2 is a partially enlarged front view of FIG. 1. FIG. 2 is a partially enlarged front view of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer tube 2 Inner tube 4 Damper cylinder 5 Piston 6 Piston rod 7 Oil lock case 8 Oil lock piece 8a Cylindrical body 8b Notch 8c Tape surface 9, 9a Suction flow path 10 Suction port 12 Cylindrical part 12a space 3a Cap 32 Fitting 33 color

Claims (3)

A wheel side inner tube is slidably inserted in the vehicle body side outer tube, a damper and a reservoir are provided in the vehicle body side outer tube and the axle side inner tube, and the damper cylinder faces downward from the upper center of the vehicle body side tube. The piston rod rises from the center in the wheel side tube and is inserted into the damper cylinder via the piston. An oil lock case is provided in the wheel side inner tube, and the oil lock case is installed at the lower end of the damper cylinder. in the front fork is provided with the opposing oil lock piece, standing the oil lock case under end in the wheel-side inner tube, further carries a suspension spring as well as standing along the inner tube above the oil lock case the o a cylindrical collar serving as a spring receiving cylinder Coupled while facing the Le locking piece, a front fork that the inner diameter of the collar so as to form larger than the inner diameter of the oil lock case, characterized in that it is reduced in diameter toward the top to the bottom. The front fork according to claim 1, wherein the base end of the collar is coupled to the outer periphery of the oil lock case via a joint or a screw. The front fork according to claim 1 or 2 , wherein the oil lock case is formed of aluminum or another metal material, and the collar is formed of a synthetic resin material .

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