JP2005351346A - Front fork of motorcycle or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front fork of a motorcycle or the like which prevents the interference of operability and vibration absorbency of a damper on a back side of a compression stroke. <P>SOLUTION: In a front fork 10 of a motorcycle or the like which includes a body side tube 11 and a wheel side tube 12 fitted to each other so as to be freely accommodated, a damper cylinder 21 mounted in the wheel side tube 12, an oil sump chamber 28 provided in an outer periphery of the damper cylinder 21 and a free piston 34 for hermetically partitioning a piston side oil chamber 27B with respect to the oil sump chamber 28 side, the oil sump chamber 28 is hermetically partitioned between the seal member 80 and the body side tube 11 while providing the seal member 80 to the side of the oil sump chamber 28 with respect to the free piston 34 and hermetically partitioning a gas chamber 81 between the seal member 80 and the free piston 34. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a front fork such as a motorcycle.

  The front fork described in Patent Literature 1 includes a damper cylinder and a piston rod that slides inside a vehicle body side tube 11 and an axle side tube 12 via a piston provided in the tip of the damper cylinder. The damper cylinder is erected in the axle side tube, and the piston rod is fixed to the vehicle body side tube.

In the damper cylinder, two oil chambers are defined on both sides of the piston, and these oil chambers are provided at the upper end of the damper cylinder 21, and a seal member 25 </ b> A that closely contacts the outer periphery of the piston rod 24, and the damper cylinder 21. Is sealed with a free piston that is slidably interposed between the outer periphery of the lower end of the cylinder and the inner periphery of the intermediate cylinder 31 that is provided upright around the damper cylinder. An oil reservoir chamber including an oil chamber and an upper gas chamber is provided on the outer periphery of the damper cylinder, and the free piston hermetically partitions the oil chamber and the oil reservoir chamber in the damper cylinder.
JP2004-19693

  In the front fork of Patent Document 1, the gas chamber at the upper part of the oil reservoir chamber is compressed when the front fork is compressed. The back pressure of the oil reservoir against the piston increases. As a result, the operation of the free piston during compression is hindered, and the vibration absorption of the damper on the back side of the compression stroke is deteriorated.

  An object of the present invention is to provide a front fork of a motorcycle or the like in which the operability and vibration absorption of the damper on the back side of the compression stroke are not hindered.

  In the first aspect of the invention, the vehicle body side tube and the wheel side tube are slidably fitted, a damper cylinder is mounted in the wheel side tube, and a piston that slides in the damper cylinder is attached to the vehicle body side tube. A piston rod side oil chamber that accommodates the piston rod in the damper cylinder and a piston oil chamber that does not accommodate the piston rod and a piston side oil chamber that does not accommodate the piston rod are provided between the vehicle body side tube side and the wheel side tube side. A suspension spring is interposed, and an oil reservoir chamber consisting of an oil chamber and an upper gas chamber is provided on the outer periphery of the damper cylinder, and the oil chamber in the damper cylinder is sealed between the piston rod and the opening of the damper cylinder. In a front fork such as a motorcycle provided with an oil seal and a movable partition member that seals and separates the piston side oil chamber from the oil reservoir chamber side, A seal member is provided on the oil reservoir chamber side with respect to the movable partition member, a gas chamber is hermetically defined between the seal member and the movable partition member, and the oil is interposed between the seal member and the vehicle body side tube. The reservoir chamber is sealed.

  In the invention of claim 2, the vehicle body side tube and the wheel side tube are slidably fitted, a damper cylinder is mounted in the wheel side tube, and a piston sliding in the damper cylinder is attached to the vehicle body side tube. Install the provided piston rod, and provide a piston rod side oil chamber that accommodates the piston rod in the damper cylinder and a piston side oil chamber that does not accommodate the piston rod, between the vehicle body side tube side and the wheel side tube side. A suspension spring is interposed, an oil reservoir chamber consisting of an oil chamber and an upper gas chamber is provided on the outer periphery of the damper cylinder, and the oil chamber in the damper cylinder is sealed between the piston rod and the opening of the damper cylinder. A motorcycle or the like provided with an oil seal and a free piston that seals the piston-side oil chamber against the oil reservoir chamber on the outer periphery of the damper cylinder. In the front fork, a seal member is provided on the oil reservoir chamber side with respect to the free piston and between the inner periphery of the wheel side tube and the outer periphery of the damper cylinder, and the seal member and the free piston The gas chamber is hermetically partitioned and the oil reservoir chamber is hermetically partitioned between the seal member and the vehicle body side tube.

  The invention of claim 3 further supports the lower end of the suspension spring by the seal member in the invention of claim 1 or 2.

(Claim 1)
(a) Since the oil chamber of the damper cylinder is hermetically partitioned by the oil seal provided at the opening of the damper cylinder and the movable partition member, it is possible to prevent the damping characteristics from being deteriorated due to air bubbles entering the damper cylinder.

  (b) A seal member is provided on the oil reservoir chamber side with respect to the movable partition member, and the gas chamber is hermetically sealed between the seal member and the movable partition member, and the oil reservoir chamber is sealed between the seal member and the vehicle body side tube. Since it is partitioned, the operation of the movable partition member is not affected even if the pressure in the gas chamber above the oil reservoir chamber becomes high due to the compression of the front fork. That is, the back pressure of the oil reservoir chamber with respect to the movable partition member does not change. As a result, the operation of the movable partition member during compression is hindered, and the operability and vibration absorption of the damper on the back side of the compression stroke do not deteriorate.

  (c) Since the gas chamber is provided between the movable partition member and the seal member, the hydraulic oil corresponding to the volume of the gas chamber can be reduced, and the weight and the cost are reduced.

(Claim 2)
(d) Since the oil chamber of the damper cylinder is hermetically partitioned by the oil seal provided at the opening of the damper cylinder and the free piston, it is possible to prevent the damping characteristics from being deteriorated due to air bubbles entering the damper cylinder.

  (e) A seal member is provided on the oil reservoir chamber side with respect to the free piston, and the gas chamber is hermetically partitioned between the seal member and the free piston, and the oil reservoir chamber is hermetically sealed between the seal member and the vehicle body side tube. Therefore, even if the pressure of the gas chamber above the oil reservoir chamber is increased due to the compression of the front fork, the operation of the free piston is not affected. That is, the back pressure of the oil reservoir chamber with respect to the free piston does not change. As a result, the operation of the free piston during compression is hindered, and the operability and vibration absorption of the damper on the back side of the compression stroke do not deteriorate.

  (f) Since the gas chamber is provided between the free piston and the seal member, the hydraulic oil corresponding to the volume of the gas chamber can be reduced, and the weight is reduced and the cost is reduced.

  (g) A seal member was provided between the inner periphery of the wheel side tube and the outer periphery of the damper cylinder, and a gas chamber was provided between the seal member and the free piston. Therefore, the gas chamber on the outer periphery of the damper cylinder becomes an air cooling chamber for the hydraulic oil inside the damper cylinder, and the heat dissipation of the damper cylinder is improved.

(Claim 3)
(h) Since the seal member serves as a lower end support member of the suspension spring and the suspension spring serves as an axial fixing member for the seal member, a separate fixing member for the seal member is not required.

  1 is a cross-sectional view of the entire front fork, FIG. 2 is a cross-sectional view of the lower part of FIG. 1, FIG. 3 is an enlarged view of the main part of FIG. 6 is an enlarged view of the main part of FIG. 5, FIG. 7 is a cross-sectional view showing a sealing member, FIG. 8 is a cross-sectional view showing a spherical plain bearing, and FIG. 9 is a cross-sectional view showing a ball holding part of a control rod. 10 and 10 are cross-sectional views showing a modification of the seal member.

  The front fork 10 (hydraulic shock absorber) is used as a front fork of a motorcycle. As shown in FIGS. 1, 2, and 5, the vehicle body side outer tube 11 and the wheel side inner tube 12 are slid in a liquid-tight manner. It is configured to fit freely. A bush 13 is provided on the inner periphery of the lower end of the vehicle body side outer tube 11, and a bush 14 is provided on the inner periphery of the upper end side of the vehicle body side outer tube 11.

  The vehicle body side outer tube 11 is provided with a cap 16 (cap bolt) detachably in a liquid-tight manner at the opening 15 at the upper end portion, and the vehicle body side outer tube 11 is provided with a vehicle body side mounting portion. The wheel side inner tube 12 has a bottom bracket 18 fixed in a liquid-tight manner at a lower end portion, and an axle side mounting portion 19 is provided on the bottom bracket 18.

  The front fork 10 accommodates a damper cylinder 21 and a piston rod 24 that constitute a damper 20 inside a vehicle body side outer tube 11 and a wheel side inner tube 12. That is, the front fork 10 has a damper cylinder 21 fixed inside the bottom bracket 18 erected inside the wheel-side inner tube 12. The damper cylinder 21 is screwed to the inner periphery of the bottom piece 22 that is fixed by a center bolt 18 </ b> A inserted into the bottom of the bottom bracket 18. The front fork 10 has a spring load adjustment rod 23 attached to the center of the cap 16 in a fluid-tight manner, and a hollow piston rod 24 is fixed to the lower end of the spring load adjustment rod 23 inserted into the vehicle body outer tube 11. Support. The piston rod 24 slidably passes through a rod guide 25 provided at the upper end of the damper cylinder 21 and is inserted into an oil chamber 27 inside the damper cylinder 21, and is connected to a piston bolt 24 </ b> A provided at the insertion tip of the piston rod 24. 26. The piston 26 slides up and down on the inner surface of the damper cylinder 21. The oil chamber 27 is partitioned by the piston 26 into a piston rod side oil chamber 27A on the side where the piston rod 24 is inserted and a piston side oil chamber 27B on the side where the piston rod 24 is not inserted.

  In the front fork 10, an oil seal 25 </ b> A that is in close contact with the outer periphery of the piston rod 24 is provided on a rod guide 25 provided at the upper end of the damper cylinder 21, and the piston rod side oil chamber 27 </ b> A of the damper cylinder 21 is sealed.

  The front fork 10 has a space between the outer cylinder 11 on the vehicle body side and the inner tube 12 on the wheel side, and the space around the damper cylinder 21 serves as an oil reservoir chamber 28. The oil reservoir chamber 28 has a gas chamber (air chamber) above the oil chamber 28A. 29). Reference numeral 29A denotes an air valve provided on a damping force adjusting control rod 54 described later.

  The front fork 10 is erected by screwing an intermediate cylinder 31 to the outer periphery of the bottom piece 22 to which the damper cylinder 21 is screwed through a gap that forms an annular shape with the inner periphery of the wheel-side inner tube 12. doing. The intermediate cylinder 31 is seated on a stepped seating portion provided on the bottom piece 22 at the base end. The wheel side inner tube 12 and the bottom piece 22 screwed to the bottom bracket 18 are seated on the seal plate 32 on the wheel side inner bracket 12. An O-ring 33 A is provided between the wheel side inner tube 12 and the bottom bracket 18, an O-ring 33 B is provided between the wheel side inner tube 12, the intermediate cylinder 31 and the seal plate 32, and between the intermediate cylinder 31 and the bottom piece 22. An O-ring 33C is provided.

  An annular free piston 34 is slidably provided between the inner periphery of the intermediate cylinder 31 and the outer periphery of the damper cylinder 21 (34A is a bush), and the oil path 22A of the bottom piece 22 and the bottom bracket 18 are provided below the free piston 34. An annular oil chamber 35 communicating with the piston side oil chamber 27B via the oil passages 44A and 45A and the oil chambers 44 and 45 of the sub tank 43 is partitioned.

  The free piston 34 is fitted with an O-ring 36 in the outer ring groove and an O-ring 37 in the inner ring groove. The free piston 34 is a ring between the intermediate cylinder 31 and the damper cylinder 21 from the lowest end position shown in FIGS. 1 to 3, which is attached to the upper end surface of the bottom piece 22 located on the inner periphery of the lower end side of the intermediate cylinder 31. The oil chamber 35 is moved upward, and the O-ring 36 is slidably contacted with the inner periphery of the intermediate cylinder 31 in the entire movement range, and the O-ring 37 is slidably contacted with the outer periphery of the damper cylinder 21 in the entire movement range. The free piston 34 seals the piston-side oil chamber 27B with respect to the oil reservoir chamber 28 via the annular oil chamber 35 in the above-described movement range.

  The front fork 10 places the free piston 34 between an annular oil chamber between a spring seat 41 backed up by a retaining ring 41A attached to the outer periphery of the damper cylinder 21 and a spring seat 38 provided at the upper end of the free piston 34. A coil spring 42 that presses the oil chamber 27 of the damper cylinder 21 and biases it toward the side of the damper cylinder 21 is interposed.

  In the front fork 10, the sub tank 43 is connected to the aforementioned bottom bracket 18 fixed to the lower end of the wheel side inner tube 12, and the piston side oil chamber 27B of the damper cylinder 21 and the lower oil chamber 44 of the sub tank 43 are connected to the center bolt 18A. The oil passage 22A provided in the bottom bracket 18 communicates with the oil passage 44A provided in the bottom bracket 18, and the annular oil chamber 35 below the free piston 34 and the upper oil chamber 45 in the sub tank 43 communicate with each other via the oil passage 45A provided in the bottom bracket 18. doing.

  The front fork 10 has a spring collar 47 formed by coupling a plurality of members that are screwed up and down by the spring load adjusting rod 23 provided on the cap 16, and an upper spring seat 48 </ b> A backed up by the spring collar 47. A suspension spring 49 is interposed between the damper cylinder 21 and a lower spring seat 48B formed of a seal member 80 attached as will be described later.

  The front fork 10 buffers the impact force received from the road surface when the vehicle travels by the spring reaction force of the suspension spring 49 and the spring reaction force of the air spring of the air chamber 29.

  The front fork 10 suppresses the expansion and contraction vibrations of the suspension spring 49 and the air spring of the air chamber 29, so that a piston valve device (extension-side damping force generation device) 50 and a bottom valve device (pressure-side damping force generation device) 60 are used. have.

  The piston valve device 50 includes an extension side flow channel 51 and a pressure side flow channel 52 (not shown) that allow the piston rod side oil chamber 27A and the piston side oil chamber 27B to communicate with the piston 26 that is in sliding contact with the inner surface of the damper cylinder 21. The extension side channel 51 can be opened and closed by the extension side damping valve 51A, and the pressure side channel 52 can be opened and closed by the compression side damping valve 52A. The compression side damping valve 52A is backed up and supported by a valve spring 52C locked to the piston rod 24 via a spring receiver 52B. The piston valve device 50 has a bypass passage 53 that bypasses the piston 26 and allows the piston rod side oil chamber 27A and the piston side oil chamber 27B to communicate with each other. The bypass passage 53 can be opened and closed by the needle valve 53A. And At this time, the damping force adjusting control rod 54 is screwed into the center of the spring load adjusting rod 23 provided on the cap 16, and the damping force adjusting rod 54 is inserted into the hollow portion of the piston rod 24 so as to be able to advance and retract. The needle valve 53A described above is provided.

  As shown in FIG. 4, the bottom valve device 60 is built in the sub tank 43 installed as described above between the piston side oil chamber 27B of the damper cylinder 21 and the annular oil chamber 35 below the free piston 34. . In the bottom valve device 60, a cap 62 is screwed into the opening 61 of the sub tank 43, and a support bolt 63 is screwed to the upper end surface of the cap 62 facing the lower oil chamber 44 of the sub tank 43. A bypass bolt 64 is provided, and a bottom piece 65 is fixed to an intermediate portion of the bypass bolt 64. The bottom piece 65 partitions the lower oil chamber 44 and the upper oil chamber 45. The bottom piece 65 includes a pressure side channel 66 and an extension side channel 67 that allow the lower oil chamber 44 and the upper oil chamber 45 to communicate with each other. The pressure side channel 66 can be opened and closed by a pressure side damping valve 66A. The path 67 can be opened and closed by a check valve 67A. Further, the bottom valve device 60 has a bypass oil passage 68 in the bolts 63 and 64 that bypasses the bottom piece 65 and allows the lower oil chamber 44 and the upper oil chamber 45 to communicate with each other, and the bypass oil passage 68 is connected to the needle valve 68A. Can be opened and closed. At this time, the damping force adjusting rod 69 is screwed into the cap 62, the damping force adjusting rod 69 is inserted into the center of the cap 62, and the needle valve 68A is provided at the insertion end.

  The sub tank 43 has a hydraulic oil supply / discharge port 71 that opens into the upper oil chamber 45, and the supply / discharge port 71 can be opened and closed by a plug 72 screwed into a screw hole of the sub tank 43.

  The front fork 10 is buffered at the time of maximum extension by a rebound spring 55 interposed between the rod guide 25 and the piston bolt 24A inside the damper cylinder 21.

  Further, the front fork 10 provides a buffer at the time of maximum compression by abutting a stopper rubber 56 fixed to the outer periphery of the piston rod 24 with the rod guide 25 outside the damper cylinder 21.

Accordingly, the front fork 10 operates as follows.
(Compression process)
When the front fork 10 is compressed, one of the vehicle body side outer tube 11 and the wheel side inner tube 12 is compressed relative to the other, and the suspension spring 49 is compressed. Further, the piston rod 24 enters the damper cylinder 21, and the hydraulic oil in the piston side oil chamber 27B passes through the bypass flow path 53 of the piston 26 at low speed, and the pressure side damping valve of the pressure side flow path 52 of the piston 26 at medium and high speed. It flows through the piston rod side oil chamber 27A through 52A. In addition, the hydraulic oil corresponding to the volume of the piston rod 24 entering flows through the bypass flow path 68 that bypasses the bottom piece 65 at a low speed and flows into the lower oil chamber 35 of the free piston 34, and at the medium and high speed, the pressure side flow path of the bottom piece 65 It flows through the compression side damping valve 66A of 66 and flows into the lower oil chamber 35 of the free piston 34.

  During this compression, the free piston 34 moves upward and compresses the spring 42.

  Thus, at low speed, the oil in the piston-side oil chamber 27B flows through the bypass passage 53 of the piston 26 to the piston rod-side oil chamber 27A, and a compression-side damping force is obtained by the throttle resistance of the needle valve 53A during this time. At the same time, the oil corresponding to the volume of the piston rod 24 entering the damper cylinder 21 enters the lower oil chamber 44 of the sub tank 43 from the piston side oil chamber 27B, and further passes through the bypass passage 68 of the bottom piece 65 to the upper oil chamber 45. In the process of flowing, the compression side damping force is obtained by the throttle resistance of the needle valve 68A. Further, the oil in the piston side oil chamber 27B passes through the pressure side flow path 52 of the piston 26 and flows from the micro flow path formed by lifting up the pressure side damping valve 52A to the piston rod side oil chamber 27A. Get damping force. At medium and high speeds, the oil corresponding to the volume of the piston rod 24 entering the damper cylinder 21 enters the lower oil chamber 44 of the sub tank 43 from the piston side oil chamber 27B, and further passes through the pressure side flow channel 66 of the bottom piece 65 to the upper oil chamber. The pressure side damping force is obtained by the bending resistance of the pressure side damping valve 66A during this period. Further, the oil in the piston side oil chamber 27B passes through the pressure side flow path 52 of the piston 26 and flows into the piston rod side oil chamber 27A in a state in which the pressure side damping valve 52A is bent and deformed. Get damping force. The suspension spring 49 and the spring 42 buffer an impact during compression, and the compression side damping force controls the compression speed of the suspension spring 49 and the spring 42.

  By the way, during the compression stroke of the front fork 10, the suspension spring 49 is compressed by an amount corresponding to the compression stroke of the vehicle body side outer tube 11 with respect to the wheel side inner tube 12. Further, since the piston rod 24 enters the damper cylinder 21, the hydraulic oil corresponding to the volume of the piston rod 24 that has entered flows into the lower oil chamber 35 of the free piston 34, causing the free piston 34 to move upward and the spring 42. Compress.

That is, at the time of compression, in addition to the suspension spring 49 being deflected to the contraction side, the spring 42 urging the free piston 34 is equivalent to the amount that the piston rod 24 enters the damper cylinder 21 and the free piston 34 moves upward. Bends to the shrink side. Thereby, the spring reaction force of the front fork 10 increases, and the sinking of the front fork 10 can be suppressed by a large spring reaction force during braking.

(Extension process)
When the front fork 10 extends, one of the vehicle body side outer tube 11 and the wheel side inner tube 12 extends relative to the other, and the suspension spring 49 extends. Further, the piston rod 24 retreats from the damper cylinder 21, and the hydraulic oil in the piston rod side oil chamber 27A passes through the bypass flow path 53 of the piston 26 at low speed, and passes through the expansion side flow path 51 of the piston 26 at medium speed. It flows into the piston-side oil chamber 27B through the expansion-side damping valve 51A. Further, the hydraulic oil corresponding to the volume that the piston rod 24 has retreated enters from the lower oil chamber 35 of the free piston 34 into the upper oil chamber 45 of the sub tank 43, and passes through the check valve 67 </ b> A of the extension side channel 67 of the bottom piece 65. Return to the piston side oil chamber 27B.

  The free piston 34 is moved downward by the urging force of the spring 42, and the spring 42 extends.

  Thereby, at low speed, the oil in the piston rod side oil chamber 27A flows into the piston side oil chamber 27B through the bypass flow path 53 of the piston 26, and the expansion side damping force is obtained by the throttle resistance of the needle valve 53A during this time. At medium and high speeds, the oil in the piston rod side oil chamber 27A flows into the piston side oil chamber 27B through the extension side flow passage 51 of the piston 26, and the extension side damping force is obtained by the bending resistance of the extension side damping valve 51A during this time. The extension side damping force prevents the suspension spring 49 and the spring 42 from resonating.

  (a) By the way, when moving from the compression stroke to the expansion stroke, the suspension spring 49 extends by the amount of stroke of the vehicle body side outer tube 11 relative to the wheel side inner tube 12. Further, since the piston rod 24 retreats from the damper cylinder 21, the lower oil chamber 35 of the free piston 34 is depressurized, and the free piston 34 is moved downward by the biasing force of the spring 42.

  That is, when moving from the compression stroke to the expansion stroke, in addition to the suspension spring 49 being deflected to the extension side, the piston rod 24 is retracted from the damper cylinder 21 and the free piston 34 is moved downward to bias the free piston 34. The spring 42 is bent to the extended side. As a result, the spring reaction force of the front fork 10 is reduced, and it is possible to prevent the front fork 10 from extending during cornering to prevent the front fork 10 from being understeered.

  (b) When the front fork 10 further expands, the free piston 34 bottoms on the upper end surface of the bottom piece 22 and no longer moves downward. From the time when the free piston 34 is bottomed out, only the spring reaction force of the suspension spring 49 is obtained, the spring reaction force of the front fork 10 is quickly reduced, and the suspension spring 49 returns to the maximum extension state.

(Seal member 80 of oil reservoir chamber 28) (FIGS. 2 and 7)
As shown in FIG. 2, the front fork 10 is provided with an annular seal member 80 on the oil reservoir chamber 28 side with respect to the free piston 34 and between the inner periphery of the wheel side inner tube 12 and the outer periphery of the damper cylinder 21. It was. Thereby, the gas chamber 81 was hermetically partitioned between the annular seal member 80 and the free piston 34, and the oil reservoir chamber 28 was hermetically partitioned between the seal member 80 and the vehicle body side outer tube 11.

  As shown in FIG. 7, the seal member 80 is fitted with an O-ring 82 in the outer ring groove and an O-ring 83 in the inner ring groove. The seal member 80 is loaded so as to be movable up and down between a lower retaining ring 84A and an upper retaining ring 84B engaged with the outer periphery of the damper cylinder 21. However, the seal member 80 also serves as a lower spring seat 48B that supports the lower end of the suspension spring 49, and is pressed and locked to the lower retaining ring 84A by the spring force of the suspension spring 49.

According to the present embodiment, the following operational effects can be obtained.
(a) Since the oil chamber 27 of the damper cylinder 21 is hermetically partitioned by the oil seal 25A provided in the opening of the damper cylinder 21 and the free piston 34, the damping characteristic is poor due to air bubbles entering the damper cylinder 21. Can be prevented.

  (b) A seal member 80 is provided on the oil reservoir chamber 28 side with respect to the free piston 34, and the gas chamber 81 is hermetically defined between the seal member 80 and the free piston 34, and the seal member 80 and the vehicle body side outer tube 11 Since the oil reservoir chamber 28 is hermetically sealed in the middle, even if the pressure of the gas chamber 29 above the oil reservoir chamber 28 increases due to the compression of the front fork 10, the operation of the free piston 34 is not affected. That is, the back pressure of the oil reservoir chamber 28 with respect to the free piston 34 does not change. As a result, the operation of the free piston 34 at the time of compression is inhibited, and the operability and vibration absorption of the damper 20 on the back side of the compression stroke are not deteriorated.

  (c) Since the gas chamber 81 is provided between the free piston 34 and the seal member 80, the hydraulic oil corresponding to the volume of the gas chamber 81 can be reduced, and the weight and cost are reduced.

  (d) A seal member 80 is provided between the inner periphery of the wheel side inner tube 12 and the outer periphery of the damper cylinder 21, and a gas chamber 81 is provided between the seal member 80 and the free piston 34. Therefore, the gas chamber 81 on the outer periphery of the damper cylinder 21 becomes an air cooling chamber for the hydraulic oil inside the damper cylinder 21, and the heat dissipation of the damper cylinder 21 is improved.

  (e) Since the seal member 80 becomes a lower end supporting member of the suspension spring 49 and the suspension spring 49 becomes an axial fixing member for the sealing member 80, a separate fixing member for the sealing member 80 is not required. .

  In this embodiment, the free piston 34 may be composed of another movable partition member such as a diaphragm.

(Divided structure of piston rod 24) (FIGS. 1, 2, 5, 6, and 8)
In the front fork 10, as shown in FIGS. 5 and 6, the piston rod 24 is composed of a proximal end side piston rod member 91, a distal end side piston rod member 92, and a spherical plain bearing unit 93.

  The proximal end side piston rod member 91 includes a spring load adjusting rod 23 that is rotatably attached to the cap 16 of the vehicle body side outer tube 11. The front end side piston rod member 92 slidably passes through the rod guide 25 of the damper cylinder 21 and is inserted into the damper cylinder 21, and a piston bolt 24 </ b> A is screwed to the insertion front end portion. The proximal-side piston rod member 91 and the distal-side piston rod member 92 are connected to each other so as to be capable of relative tilting (bending) in all directions by a spherical plain bearing unit 93 (spherical plain bearing 96).

  The spherical plain bearing unit 93 is an assembly in which a spherical plain bearing 96 is sandwiched between an inner joint pipe 94 and an outer joint pipe 95 outside the inner joint pipe 94. In this embodiment, the base end side piston rod is used. The upper end portion of the outer joint pipe 95 is screwed to the outer periphery of the lower end portion of the member 91, and the lower end portion of the inner joint pipe 94 is screwed to the outer periphery of the upper end portion of the front end side piston rod member 92. As shown in FIG. 8, the spherical plain bearing 96 has an outer ring 96B brought into spherical contact with the outer periphery of the inner ring 96A through a lubrication liner. The inner ring 96A is attached to the outer periphery of the inner joint pipe 94 with a nut 97. The outer ring 96 </ b> B is attached to the inner periphery of the outer joint pipe 95 with a retaining ring 98.

According to the present embodiment, the following operational effects can be obtained.
(a) Since the piston rod 24 is divided into the proximal end side piston rod member 91 and the distal end side piston rod member 92, it is possible to prevent the piston rod 24 from being bent or twisted.

  (b) In order to prevent unreasonable bending of the piston rod 24, the proximal end side piston rod member 91 and the distal end side piston rod member 92 are connected via the spherical plain bearing 96, so that compared with the case where they are connected by an elastic body. The piston rod 24 is not contracted or stretched in the axial direction. As a result, the damping force is not reduced when the stroke is switched, and the responsiveness is improved.

  (c) The spherical plain bearing 96 for preventing excessive bending of the piston rod 24 does not have a radial clearance. Therefore, the spherical plain bearing 96 is smoothly tilted with low friction in all directions without causing play in the gap in the radial direction, and no abnormal noise is generated.

  (d) The proximal end side piston rod member 91 also serves as the spring load adjusting rod 23. Since the rotation of the spring load adjusting rod 23 is not transmitted to the front end side piston rod member 92 due to the presence of the spherical plain bearing 96, the rotation operation force is small.

  (e) Since the base end side piston rod member 91 and the front end side piston rod member 92 are connected via the spherical plain bearing unit 93, the two piston rod members 91 and 92 can be easily connected.

(Divided structure of damping rod control rod 54) (FIGS. 1, 2, 5, 6, and 9)
The front fork 10 divides the piston rod 24 into the base end side piston rod member 91 and the front end side piston rod member 92 as described above, and the base end side piston rod member 91 and the front end side piston rod member 92 are divided into spherical plain bearing units. As shown in FIGS. 5 and 6, the control rod 54 for adjusting the damping force in the piston rod 24 is connected to the base end side piston rod member 91 and the front end side piston rod member in addition to being connected to each other via the lever 93. The upper control rod member 101 and the lower control rod member 102 are divided at the connecting portion 92 (position of the spherical plain bearing 96 of the spherical plain bearing unit 93), and the upper and lower control rod members 101 and 102 are relatively tilted in all directions ( It was connected to bendable. It is preferable that the spherical center of the spherical plain bearing 96, which is the center of tilt of the two piston rod members 91, 92, and the center of tilt of the two control rod members 101, 102 coincide.

  The upper control rod member 101 is screwed to the cap 16 by engaging the rod portion 101A in a rotational direction with a rod portion 101A attached to the center of the spring load adjusting rod 23 provided on the cap 16 in a rotational direction. The rod portion 101B includes a rod portion 101B that is guided by the outer joint pipe 95 of the piston rod 24 so as to move up and down and abuts against the rod portion 101B in the axial direction. The lower control rod member 102 includes a rod portion 102A that is guided by the inner joint pipe 94 of the piston rod 24 so as to move up and down, and a rod portion 102B that is axially abutted against the rod portion 102A and includes a needle valve 53A. . The needle valve 53A is fluid-tightly inserted into the piston bolt 24A and is urged upward (in the valve opening direction) by a spring 53B interposed between the needle bolt 53A and the piston bolt 24A. The upper control rod member 101 and the lower control rod member 102 can relatively tilt the rod portion 101C and the rod portion 102A at the connecting portion (spherical plain bearing 96) of the proximal end side piston rod member 91 and the distal end side piston rod member 92. To do.

  As shown in FIG. 6, the upper control rod member 101 (rod portion 101C) and the lower control rod member 102 (rod portion 102A) are connecting portions of the base end side piston rod member 91 and the front end side piston rod member 92, and the ball 103 It is connected via. In this embodiment, as shown in FIG. 9, the ball 103 is rotatably held by a ball holding portion 103A provided at the upper end portion of the lower control rod member 102 (rod portion 102A), and the lower end surface of the upper control rod member 101 is Abut against the ball 103. The center of tilting of the base end side piston rod member 91 and the tip end side piston rod member 92 is the center of the spherical surface of the spherical plain bearing 96, and the centers of tilting of the upper control rod member 101 and the lower control rod member 102 are the upper control rod member. 101 is a contact surface between the lower end surface of 101 and the ball 103 on the lower control rod member 102 side.

According to the present embodiment, the following effects can be obtained.
(a) The control rod 54 for adjusting the damping force is divided into an upper control rod member 101 and a lower control rod member 102 at the connecting portion of the proximal end side piston rod member 91 and the distal end side piston rod member 92, and the upper and lower control rods are controlled. Since the rod members 101 and 102 are connected so as to be relatively tiltable, the operability of the control rod 54 inserted into the piston rod 24 can be improved in the front fork 10 in which the piston rod 24 is divided.

  (b) Since the control rod 54 is not subjected to an excessive bending load, the axial displacement of the damping force adjusting portion (needle valve 53A) at the tip of the control rod 54 is reduced, the change in damping force adjustment is reduced, and the damping force To stabilize.

  (c) In order to prevent unreasonable bending of the piston rod 24, the proximal end side piston rod member 91 and the distal end side piston rod member 92 are connected via the spherical plain bearing 96, so that compared to the case where they are connected by an elastic body. The piston rod 24 is not contracted or stretched in the axial direction. As a result, the damping force is not reduced when the stroke is switched, and the responsiveness is improved.

  (d) The spherical plain bearing 96 for preventing excessive bending of the piston rod 24 does not have a radial clearance. Therefore, the spherical plain bearing 96 is smoothly tilted with low friction in all directions without causing play in the gap in the radial direction, and no abnormal noise is generated.

  (e) Since the base end side piston rod member 91 and the front end side piston rod member 92 are connected by the spherical plain bearing 96 and are not misaligned with each other, the upper and lower control rod members inserted into the piston rod members 91 and 92 are inserted. The operation of 101 and 102 becomes smooth.

  (f) Since the two control rod members 101 and 102 are connected via the ball 103, the control rod members 101 and 102 can be tilted in all directions, and the friction at the connecting portion of both the control rod members 101 and 102 is reduced. It becomes easy.

  (g) Only the end surface of the other control rod member 101 is brought into contact with the ball 103 rotatably held at the end portion of one control rod member 102, which is easy to manufacture.

  The ball 103 is fixed to the lower end portion of the upper control rod member 101 (rod portion 101C) (or a ball portion is formed), and the ball 103 is rotatable on the upper end portion of the lower control rod member 102 (rod portion 102A). You may hold it. At this time, the center of tilting of the base end side piston rod member 91 and the tip end side piston rod member 92 is the center of the spherical surface of the spherical plain bearing 96, and the centers of tilting of the upper control rod member 101 and the lower control rod member 102 are the balls 103. The center of tilting of the base end side piston rod member 91 and the tip end side piston rod member 92 and the center of tilting of the upper control rod member 101 and the lower control rod member 102 are preferably coincident with each other. According to this, the ball 103 fixed to the end of one control rod member 101 is rotatably held by the other control rod member 102, and the two control rod members 101, 102 are integrally connected. Therefore, the axial displacement of the damping force adjusting portion (needle valve 53A) at the tip of the control rod 54 is made smaller, the change in damping force adjustment is made smaller, and the damping force is made more stable.

  FIG. 10 shows a modification of the seal member 80 for the oil reservoir chamber 28. This seal member 80 has a small-diameter outer peripheral portion 80A on the upper end side, an upper end surface on the outer peripheral side as a step surface 80B, and a right triangle that forms a lower spring seat 48B in an annular step portion formed by the small-diameter outer peripheral portion 80A and the step surface 80B An annular ring 85 having a cross section is fitted, and an O-ring 82 sandwiched between the outer peripheral slope of the annular ring 85 and the stepped surface 80B of the seal member 80 is expanded by the spring force of the suspension spring 49, and the wheel-side inner tube 12 is expanded. It is press-contacted to the inner periphery of the.

  The front fork 10 is an inverted type in which the vehicle body side tube 11 is an outer tube and the wheel side tube 12 is an inner tube inserted into the vehicle body side tube 11. However, in the front fork 10 of the present invention, it may be an upright type in which the vehicle body side tube 11 is an inner tube and the wheel side tube is an outer tube.

  In the front fork 10, the damper cylinder 21 is fixed to the wheel side tube 12 side, and the piston rod 24 is fixed to the vehicle body side tube 11 side. However, in the front fork 10 of the present invention, the damper cylinder 21 may be fixed to the vehicle body side tube 11 side, and the piston rod 24 may be fixed to the wheel side tube 12 side.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

FIG. 1 is a sectional view showing the entire front fork. FIG. 2 is a lower cross-sectional view of FIG. FIG. 3 is an enlarged view of a main part of FIG. FIG. 4 is a cross-sectional view showing the compression-side damping force generator. FIG. 5 is a top sectional view of FIG. 6 is an enlarged view of a main part of FIG. FIG. 7 is a cross-sectional view showing the seal member. FIG. 8 is a sectional view showing a spherical plain bearing. FIG. 9 is a cross-sectional view showing the ball holding portion of the control rod. FIG. 10 is a cross-sectional view showing a modification of the seal member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Front fork 11 Car body side outer tube 12 Wheel side inner tube 21 Damper cylinder 24 Piston rod 25A Oil seal 26 Piston 27A Piston rod side oil chamber 27B Piston side oil chamber 28 Oil reservoir chamber 28A Oil chamber 29 Gas chamber 34 Free piston (movable) Bulkhead member)
48B Lower spring seat 49 Suspension spring 80 Seal member 81 Gas chamber

Claims (3)

Fit the body side tube and wheel side tube slidably,
A damper cylinder is installed in the wheel side tube, and a piston rod provided at the tip of the piston that slides in the damper cylinder is attached to the vehicle body side tube.
A piston rod side oil chamber that houses the piston rod and a piston side oil chamber that does not contain the piston rod are provided in the damper cylinder,
A suspension spring is interposed between the vehicle body side tube side and the wheel side tube side,
An oil reservoir chamber consisting of an oil chamber and an upper gas chamber is provided on the outer periphery of the damper cylinder
Between the piston rod and the opening of the damper cylinder is provided an oil seal that seals the oil chamber in the damper cylinder,
In a front fork such as a motorcycle provided with a movable partition member that hermetically partitions the piston side oil chamber with respect to the oil reservoir chamber side,
A seal member is provided on the oil reservoir chamber side with respect to the movable partition member, a gas chamber is hermetically defined between the seal member and the movable partition member, and the gas chamber is disposed between the seal member and the vehicle body side tube. A front fork for a motorcycle or the like, characterized in that the oil reservoir is sealed off. Fit the body side tube and wheel side tube slidably,
A damper cylinder is installed in the wheel side tube, and a piston rod provided at the tip of the piston that slides in the damper cylinder is attached to the vehicle body side tube.
A piston rod side oil chamber that accommodates the piston rod in the damper cylinder and a piston side oil chamber that does not accommodate the piston rod are provided.
A suspension spring is interposed between the vehicle body side tube side and the wheel side tube side,
An oil reservoir chamber consisting of an oil chamber and an upper gas chamber is provided on the outer periphery of the damper cylinder
Between the piston rod and the opening of the damper cylinder is provided an oil seal that seals the oil chamber in the damper cylinder,
In a front fork such as a motorcycle provided with a free piston that seals the piston-side oil chamber with respect to the oil reservoir chamber on the outer periphery of the damper cylinder,
A seal member is provided on the oil reservoir chamber side with respect to the free piston and between the inner periphery of the wheel side tube and the outer periphery of the damper cylinder, and a gas chamber is provided between the seal member and the free piston. A front fork for a motorcycle or the like, wherein the oil reservoir chamber is hermetically sealed between the seal member and the vehicle body side tube.   The front fork of a motorcycle or the like according to claim 1 or 2, wherein a lower end of the suspension spring is supported by the seal member.

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