JP4703981B2 - Front fork - Google Patents

Description

  The present invention relates to a front fork that serves as both a shock absorber and a fork that are interposed between a vehicle body such as a motorcycle and an axle and attenuates vibrations from a road surface.

  As this type of front fork, for example, the one described in Patent Document 1 has been developed.

  As shown in FIG. 5, in the front fork, an inner tube 31 that is a vehicle body side tube is slidably inserted into an outer tube 1 that is a wheel side tube, and the hollow rod 2 rises from the center of the outer tube 1 The upper piston portion of the hollow rod 2 is in sliding contact with the inner periphery of the inner tube 31, and the lower oil chamber 5 of the outer tube 1 is further connected to the reservoir-side oil chamber 3 in the hollow rod 2 through the port 4 formed in the hollow rod 2. Communicated with

In the extending stroke in which the inner tube 31 is lifted, the hydraulic oil in the reservoir-side oil chamber 3 is sucked into the oil chamber 5 in the outer tube 2 via the port 4 and is compressed in the pressure stroke in which the inner tube 31 is lowered. The hydraulic oil in the oil chamber 5 in the outer tube 1 flows out to the oil chamber 3 on the reservoir side through the port 4, and at this time, the damping force on the pressure side is generated by the flow resistance by the port 4.
Japanese Patent No. 3511192 (FIG. 1, paragraphs 0016 and 0017)

  The conventional front fork is not particularly defective in function, but the following improvements are desired.

  That is, the port 4 formed in the hollow rod 2 is a common oil hole that is used as a passage for sucking hydraulic oil in the extension stroke and also used as an orifice for generating a damping force in the pressure stroke. If a small diameter is used to increase the compression side damping force, insufficient suction of hydraulic oil occurs during the extension stroke and negative pressure is generated. Conversely, if a large diameter is used to increase the suction amount, the damping force during the compression stroke is reduced. There may be a shortage.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a front fork that obtains a desired high compression-side damping force and secures a sufficient amount of hydraulic oil to be sucked during an extension stroke to prevent the generation of negative pressure.

To achieve the above object, one aspect of the present invention, the vehicle body side tube is slidably inserted into the wheel side in the tube, the hollow rod is erected in the center of the wheel side tube, an upper piston portion of the hollow rod Is in sliding contact with the inner periphery of the vehicle body side tube, and the oil chamber in the hollow rod communicates with the oil chamber in the wheel side tube through a port formed in the hollow rod. The oil lock collar is provided at the lower part of the vehicle body side tube, and the hydraulic oil in the wheel side tube flows out to the oil chamber in the hollow rod through the port during the pressure stroke. the damping force is generated, and in the front fork in which the oil lock collar to generate oil lock invade the outer periphery of the oil hole lever, provided to fix the valve holder into the lower inner circumference of the hollow rod, An oil passage that bypasses the port is formed by an annular groove formed on the outer periphery of the valve holder and a through-hole formed in the hollow rod, and a check valve that closes by a pressure stroke and opens by an extension stroke can be opened and closed in the annular groove. it is characterized in that provided in the.
Similarly, the other means is that the vehicle body side tube is slidably inserted into the wheel side tube, the hollow rod rises at the center of the wheel side tube, and the upper piston portion of the hollow rod slides on the inner periphery of the vehicle side tube. The oil chamber in the hollow rod communicates with the oil chamber in the wheel side tube through the port formed in the hollow rod, and the oil hole 桿 stands upside down on the outside of the base end of the hollow rod, An oil lock collar is provided at the lower part of the tube, and the hydraulic oil in the wheel side tube flows into the oil chamber in the hollow rod through the port in the pressure stroke to generate a pressure side damping force. In a front fork in which an oil lock collar enters the outer periphery of the oil hole 発 生 and generates an oil lock, a valve seat and a valve holder are fixed to the lower inner periphery of the hollow rod, and the valve seat An oil passage that bypasses the port is constituted by the inside, the chamber between the valve seat and the valve holder, and the through hole formed in the hollow rod, and is closed in the middle of the oil passage by a pressure stroke and opened by an extension stroke. A check valve is provided, and a valve body in which the check valve is movably inserted into the valve holder, and a spring that presses the valve body against the seat surface of the valve seat are configured.

  According to the present invention, an oil passage that bypasses the port is provided, and a check valve that is closed during the pressure stroke and opened during the extension stroke is provided in the middle of the oil passage, so that a desired high compression side damping force is generated by the port during the pressure stroke. In the extension stroke, sufficient hydraulic fluid can be sucked from the reservoir-side oil chamber through the port and the oil passage, and the generation of negative pressure can be prevented.

An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1, 3, and 5, the front fork of the present invention basically has a vehicle body side tube in an outer tube 1 as a wheel side tube. The inner tube 31 is slidably inserted, the hollow rod 2 rises at the center of the outer tube 1, the upper piston portion of the hollow rod 2 is in sliding contact with the inner periphery of the inner tube 31, and the reservoir side in the hollow rod 2 The oil chamber 3 communicates with the lower oil chamber 5 of the outer tube 1 through the port 4 formed in the hollow rod 2, and the oil hole 8 stands upright on the outer side of the base end portion of the hollow rod 2 so as to move up and down. An oil lock collar 32 is provided at a lower portion of 31, and hydraulic oil in the outer tube 1 flows out to the oil chamber 3 in the hollow rod 2 through the port 4 in the pressure stroke and is attenuated on the pressure side. Is generated, also, the oil lock collar 32 is shall generate an oil lock invade the outer periphery of the oil Ana桿8.
In the embodiment of FIG. 1, the valve holder 11 is fixedly provided on the lower inner periphery of the hollow rod 2, and the annular grooves 12 and 13 formed on the outer periphery of the valve holder 11 and the hollow rod 2 are formed. An oil passage A that bypasses the port 4 is constituted by the through hole 14, and a check valve B that is closed by a pressure stroke and opened by an extension stroke is provided in the annular groove 12 so as to be freely opened and closed.
On the other hand, in the embodiment of FIG. 3, the valve seat 15 and the valve holder 16 are fixedly provided on the lower inner periphery of the hollow rod 2, and the inside of the valve seat 15 and between the valve seat 15 and the valve holder 16 are provided. The chamber 17 and the through hole 18 formed in the hollow rod 2 constitute an oil passage A that bypasses the port 4, and a check valve B1 that is closed in the pressure stroke and opened in the extension stroke is provided in the oil passage A. The check valve B1 is composed of a valve body 19 that is movably inserted into the valve holder 16 and a spring 20 that presses the valve body 19 against the seat surface of the valve seat 15. .
This will be described in detail below.

  In the present invention, as shown in the embodiments of FIGS. 1 and 3, the oil passage A that communicates the oil chamber 3 in the hollow rod 2 and the oil chamber 5 in the wheel side tube is connected to the port 4 as described above. The check valves B and B1 are provided in a detour, closed in the pressure stroke in the middle of the oil passage A, and opened in the extension stroke, respectively.

  1 and 2 show an embodiment of an oil passage A and a check valve B, and FIGS. 3 and 4 show another embodiment.

  1 and 3 differ in the configuration of the oil passage A and the check valves B and B1, but the rest is common, so the structure will be described first.

  That is, a bolt 6 is inserted from the center of the bottom 1A of the outer tube 1 to the lower part of the hollow rod 2, and the hollow rod 2 is attracted by screwing the bolt 6 to the inner periphery of the base end 3A of the hollow rod 2. It stands on the bottom 1A.

  The base end portion 3A side of the hollow rod 2 is bent to have a small diameter, and an oil hole rod 8 in which a collar 7 is press-fitted outside the base end portion 3A is erected in a vertically movable manner. Is urged to the bottom 1A side via a return spring 9 carried by the. In the pressure stroke, an oil lock collar 32 provided at the lower portion of the inner tube 31 enters the outer periphery of the oil hole 8 to form an oil lock chamber, and an oil lock is generated by a gap between them.

  Then, the hydraulic oil in the oil lock chamber is caused to flow out from the gap between the oil hole 8 and the oil lock collar 32 to absorb the most compressed impact.

In the extending stroke, the oil lock collar comes out upward from the outer periphery of the oil hole ridge 8, but at this time, the inner periphery of the oil hole ridge 8 from the lower oil chamber 10 of the oil hole ridge 8 is prevented so that negative pressure is not generated in the oil lock chamber. The hydraulic oil is sucked into the oil lock chamber through a notch 8a formed in the upper part.

  Next, the configuration of the oil passage A and the check valve B shown in FIGS. 1 and 2 will be described. This is because the valve holder 11 is fixed to the inner periphery of the lower portion of the hollow rod 2 by caulking or the like. A check valve in which the two-stage annular grooves 12 and 13 formed on the outer periphery of the cylinder and the through hole 14 formed in the hollow rod 2 constitute an oil passage A, and the one large-diameter-side annular groove 12 has a notch. B is provided so as to be freely opened and closed.

  Therefore, in the pressure stroke, the inner tube 31 is lowered, the oil chamber 5 in the outer tube 1 is pressurized, and the check valve B is pushed up by the internal pressure of the oil chamber 5 as shown in FIG. The hydraulic oil in the oil chamber 5 flows out into the reservoir-side oil chamber 3 through the port 4 and generates a damping force.

In the extension stroke, as shown in FIG. 2, the inner tube 31 is raised to lower the internal pressure of the oil chamber 5, the check valve B is opened by the pressure of the reservoir-side oil chamber 3, and the hydraulic oil in the reservoir-side oil chamber 3 is discharged. The oil chamber 5 is sucked through the port 4 and the oil passage A, so that a sufficient amount of hydraulic oil can be sucked into the oil chamber 5.

  Next, the oil passage A and the check valve B1 shown in FIG. 3 will be described. This is because the valve seat 15 and the valve holder 16 are fixed to the inner periphery of the lower portion of the hollow rod 2 by caulking or the like. An oil passage A is formed by a chamber 17 between the valve seat 15 and the valve holder 16 and a through hole 18 formed in the hollow rod 2, and a valve body 19 in which the check valve B 1 is movably inserted into the valve holder 16. The valve body 19 is composed of a spring 20 that presses against the seat surface of the valve seat 15.

  The valve holder 16 is formed with a port 22 for communicating the chamber 17 with the lower chamber 21.

  For this reason, as shown in FIG. 3, the oil chamber 5 is pressurized during the pressure stroke, and the valve body 19 is pressed against the seat surface of the valve seat 15 to close the oil passage 4.

  Accordingly, the hydraulic oil in the oil chamber 5 flows out to the reservoir-side oil chamber 3 side through the port 4, and a compression side damping force is generated by the port 4.

  In the extension stroke, the internal pressure of the oil chamber 5 decreases, the check valve B1 is opened by the pressure of the reservoir-side oil chamber 3, and the hydraulic oil in the reservoir-side oil chamber 3 is sucked into the oil chamber 5 via the check valve B1 and the port 4. .

  Accordingly, supply of hydraulic oil from the port 4 and the oil passage A during the extension stroke prevents oil from being insufficiently sucked, and generation of negative pressure can be prevented.

It is a partially cutaway longitudinal sectional view of a front fork according to an embodiment of the present invention. It is a partial longitudinal cross-sectional view of FIG. 1 which shows the position of the check valve at the time of extension stroke. It is a partially cutaway longitudinal cross-sectional view of a front fork according to another embodiment. It is a partial longitudinal cross-sectional view of FIG. 3 which shows the position of the check valve at the time of extension stroke. It is a partially cutaway longitudinal sectional view of a conventional front fork.

Explanation of symbols

1 wheel side tube outer tube 2 hollow rod 3, 5 oil chamber 4 port 7 collar 8 oil hole 10 chamber 18 through hole
31 Inner tube that is the body side tube
32 Oil lock piece A Oil passage
B, B1 Check valve

Claims (2)

The vehicle body side tube is slidably inserted into the wheel side tube, the hollow rod rises in the center of the wheel side tube, the upper piston part of the hollow rod is in sliding contact with the inner periphery of the vehicle body side tube, and the oil in the hollow rod is The chamber communicates with the oil chamber in the wheel-side tube through a port formed in the hollow rod, and an oil hole erects upright on the outer side of the base end of the hollow rod. is provided, the hydraulic oil in the wheel side tube in about flows out to the oil chamber in the hollow rod through the port stroke to generate a damping force of the compression side, also, the oil lock collar the oil hole in the front fork for generating oil lock invade the outer periphery of the rod, it arranged to fix the valve holder into the lower inner circumference of the hollow rod, an annular groove formed in the outer circumference of the valve holder and the hollow Constitute an oil passage to bypass the port in the head to form the through hole, the front fork, characterized in that a check valve that opens in a closed extension stroke in about stroke provided openably in the annular groove. The vehicle body side tube is slidably inserted into the wheel side tube, the hollow rod rises in the center of the wheel side tube, the upper piston part of the hollow rod is in sliding contact with the inner periphery of the vehicle body side tube, and the oil in the hollow rod is The chamber communicates with the oil chamber in the wheel-side tube through a port formed in the hollow rod, and an oil hole erects upright on the outer side of the base end of the hollow rod. The hydraulic oil in the wheel side tube flows out to the oil chamber in the hollow rod through the port in the pressure stroke to generate a compression side damping force, and the oil lock collar is in the oil hole. In a front fork that enters the outer periphery of the rod and generates an oil lock, a valve seat and a valve holder are fixedly provided on the inner periphery of the lower portion of the hollow rod, and the valve seat and the valve chassis are fixed. The oil passage that bypasses the port is formed by the chamber between the valve and the valve holder and the through hole formed in the hollow rod, and a check valve that closes in the pressure stroke and opens in the extension stroke is provided in the middle of the oil passage, A front fork comprising a valve body in which the check valve is movably inserted into the valve holder, and a spring that presses the valve body against a seat surface of a valve seat .

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