JP2006307907A - Front fork - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elongation side damping force of proportional characteristic with a simple structure in a front fork. <P>SOLUTION: In the front fork 10, a first oil hole 51 facing a working oil chamber 31 even under a most extended condition of the front fork 10 is bored on a tube wall of an inner tube 12, and a second oil hole 52 facing an oil reservoir chamber 32 even under a most compressed condition of the front fork 10 is bored on the tube surface of the inner tube 12, and communication between the first oil hole 51 and the second oil hole 52 is maintained by an annular gap 53 between an outer tube 11 and the inner tube 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

As an inverted front fork, as described in Patent Document 1, a seat pipe fixed to a cap of an outer tube is slidably inserted into a vehicle body side outer tube, and a pipe guide provided on the inner tube is used as a pipe guide. There is a type in which a suspension spring is interposed between an annular spring holder and an inner tube that are slidably inserted and fixed to an insertion end of a seat pipe. In this front fork, an annular region between the inner tube and the seat pipe and a region located on the wheel side of the pipe guide is a hydraulic oil chamber, and an inner peripheral region of the inner tube that does not constitute the hydraulic oil chamber And the inner peripheral area of the seat pipe is a series of oil reservoir chambers, and the inner peripheral area of the outer tube and the inner peripheral area of the seat pipe are gas chambers that form a series at the upper part of the oil reservoir chamber, and the hydraulic oil chamber A damping force generating means for generating a damping force is provided by forming an orifice that discharges the oil to the oil reservoir chamber, and a check valve that allows the oil to flow from the oil reservoir chamber to the hydraulic oil chamber is provided on the annular spring receiver. Provided.
JP 59-149885

  In the front fork of Patent Document 1, in the extension stroke, the oil in the hydraulic oil chamber is discharged from the orifice provided in the seat pipe to the oil reservoir chamber, and the extension side damping force is obtained by the passage resistance exerted on the oil by the orifice.

  However, the extension side damping force obtained in the front fork of Patent Document 1 is based on the passage resistance of the orifice (hole) provided in the seat pipe, and is a damping force having a square characteristic. That is, if the orifice diameter is reduced in order to increase the damping force in the low speed region, the damping force in the high speed region becomes excessive accordingly. In the prior art, in order to obtain a damping force having a proportional characteristic, it is necessary to incorporate a damper cylinder unit having a disk-like damping valve, resulting in a complicated and heavy weight and high cost.

  An object of the present invention is to obtain an expansion-side damping force having a proportional characteristic with a simple configuration in a front fork.

  According to the first aspect of the present invention, the wheel side inner tube is slidably inserted into the vehicle body side outer tube, and the seat pipe fixed to the cap of the outer tube is slidably inserted into the pipe guide provided on the inner tube. The piston fixed to the insertion end of the pipe is slidably contacted with the inner periphery of the inner tube, and the region between the inner tube and the seat pipe that is sandwiched between the pipe guide and the piston is the hydraulic oil chamber, and the inner periphery of the inner tube The region that does not constitute the hydraulic oil chamber and the inner peripheral region of the seat pipe are a series of oil reservoir chambers, and the inner peripheral region of the outer tube and the inner peripheral region of the seat pipe are A series of gas chambers in the upper part is provided, and a damping force generating means for generating a damping force is provided by forming a passage for discharging the oil in the hydraulic oil chamber to the oil reservoir chamber. In the front fork provided with a check valve that allows oil to flow into the front fork, a first oil hole facing the hydraulic oil chamber is formed in the tube wall of the inner tube even when the front fork is fully extended, and the front fork Even in the most compressed state, the second oil hole facing the oil reservoir chamber is formed in the tube wall of the inner tube, and the first oil hole and the second oil hole are communicated by the annular gap between the outer tube and the inner tube. is there.

  According to a second aspect of the present invention, in addition to the first aspect of the invention, the passage resistance of the annular gap is made larger than the passage resistances of the first oil hole and the second oil hole.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the front fork is extended by changing the relative positions in the circumferential direction and / or the axial direction of the first oil hole and the second oil hole on the inner tube. In the stroke, the damping force generated when the hydraulic oil passes through the annular gap from the first oil hole and reaches the second oil hole can be adjusted.

(Claim 1)
(a) During the expansion stroke, the oil in the hydraulic oil chamber is discharged from the first oil hole of the inner tube through the long annular gap between the outer tube and the inner tube to the oil reservoir chamber from the second oil hole of the inner tube. Then, a damping force having a proportional characteristic based on the passage resistance exerted on the oil by the annular gap is generated. A damping force having a proportional characteristic can be obtained with an extremely simple configuration in which the first oil hole and the second oil hole are formed in the inner tube and an annular gap between the outer tube and the inner tube is used.

(Claim 2)
(b) By setting the passage resistance of the annular gap to be larger than the passage resistances of the first oil hole and the second oil hole, it is possible to reliably obtain a damping force having a proportional characteristic.

(Claim 3)
(c) By changing the relative positions in the circumferential direction and / or the axial direction of the first oil hole and the second oil hole on the inner tube, the damping force of the proportional characteristic can be easily adjusted.

  1 is a cross-sectional view showing a front fork, FIG. 2 is an enlarged cross-sectional view of the main part of FIG. 1, FIG. 3 is a cross-sectional view showing a piston and a check valve provided on a seat pipe, and FIG. FIG. 5 shows a piston, (A) is a sectional view, (B) is a plan view, FIG. 6 shows a check valve, (A) is a plan view, and (B) is a plan view of (A). It is sectional drawing which follows the BB line.

  As shown in FIGS. 1 and 2, an inverted front fork 10 such as a motorcycle is inverted by inserting a wheel-side inner tube 12 into a vehicle body-side outer tube 11 so as to be slidable between the tubes 11 and 12. A suspension spring 13 is interposed between the two.

  Bushings 14 and 15 that guide the sliding of the outer tube 11 and the inner tube 12 are provided at two positions on the inner periphery of the lower end (referring to the wheel side) of the outer tube 11 and the outer periphery of the upper end (referring to the vehicle body side) of the inner tube 12. Is inserted. An oil seal 16 and a dust seal 17 are fitted on the inner periphery of the lower end of the outer tube 11.

  The outer tube 11 is supported on the vehicle body side via an unillustrated upper or lower bracket, and the inner tube 12 is coupled to the axle via an axle bracket 18 that is screwed and fixed to the outer periphery of the lower end of the inner tube 12. The

  A cap 21 is screwed to the upper end of the outer tube 11, and a seat pipe 22 screwed and fixed to the cap 21 is slidably and liquid-tightly inserted into a guide ring 24 of a pipe guide 23 provided on the inner tube 12. To do. At this time, the inner tube 12 is screwed into and inserted into the collar 19 over a certain length range from the upper end side, and the pipe guide 23 is screwed into the inner periphery of the lower end of the collar 19.

  The piston 25 is fixed to the insertion end of the seat pipe 22 inserted in the pipe guide 23 provided in the inner tube 12, and the outer periphery of the large diameter portion of the piston 25 is in sliding contact with the inner periphery of the inner tube 12. As a result, the seat pipe 22 is centered with respect to the inner tube 12. The piston 25 is configured as shown in FIG. 5, and the upper small diameter portion is fitted to the inner periphery of the seat pipe 22, and the fitted state is fixed by the pins 27 inserted in the radial direction thereof. The 25A is a pin hole provided in the upper small diameter portion for the pin 27.

  Between the lower surface of the large-diameter portion of the piston 25 provided as described above on the seat pipe 22 fixed to the cap 21 of the outer tube 11 and the spring seat 28 provided on the bottom surface of the axle bracket 18 fixed to the inner tube 12, The aforementioned suspension spring 13 is interposed. The piston 25 includes a lower small diameter portion extending downward from a large diameter portion where the piston ring 26 is provided, and the suspension spring 13 is seated on the lower surface of the large diameter portion around the lower small diameter portion.

  The front fork 10 loads hydraulic oil into the outer tube 11 and the inner tube 12. An annular region between the inner tube 12 and the seat pipe 22 and a region sandwiched between the pipe guide 23 and the piston 25 is referred to as a hydraulic oil chamber 31. A region that is at least the inner peripheral region on the lower end side of the inner tube 12 and does not constitute the hydraulic oil chamber 31 and an inner peripheral region on the lower end side of the seat pipe 22 are defined as a series of oil reservoir chambers 32. A gas chamber 33 that forms a series of an inner peripheral region on the upper end side of the outer tube 11 and an inner peripheral region on the upper end side of the seat pipe 22 at the upper portion of the oil reservoir chamber 32 through a through hole 22A provided in the seat pipe 22. And

  The front fork 10 is provided with damping force generating means 34 that allows the hydraulic oil chamber 31 and the oil reservoir chamber 32 to communicate with each other. As will be described in detail later, the damping force generating means 34 forms a passage for discharging the oil in the hydraulic oil chamber 31 to the oil reservoir chamber 32 during the extension stroke of the front fork 10, and the extension side damping caused by the passage resistance. Generate power.

  As shown in FIGS. 3 and 4, the front fork 10 is provided with a check valve 35 in the piston 25 that allows oil to flow from the oil reservoir chamber 32 to the hydraulic oil chamber 31 and prevents backflow. The check valve 35 has the same outer diameter as the piston 25 and can slide on the inner periphery of the inner tube 12. The check valve 35 is pressed in the hydraulic oil chamber 31 by valve pressing means 36 fixed to the seat pipe 22 side, and is placed in close contact with the upper end surface of the large diameter portion of the piston 25. The valve pressing means 36 is backed up by the valve stopper 37 and the valve stopper 37 that are sandwiched between the lower end surface of the seat pipe 22 and the step surface of the upper and lower diameter portions of the piston 25 to which the seat pipe 22 is fitted. The valve spring 38 presses the check valve 35.

  As shown in FIG. 5, the piston 25 penetrates from the upper end surface to the lower end surface of the large diameter portion, and includes a plurality of oil passages 41 that allow the hydraulic oil chamber 31 and the oil reservoir chamber 32 to communicate with each other on the outer periphery of the large diameter portion. Provided with a plurality of circumferential positions (four positions in this embodiment) cut out in an arc shape (when the piston 25 is provided with a piston ring on the outer periphery of the large diameter portion, an oil passage 41 is formed in the end surface of the large diameter portion of the piston 25. It is also possible to install and prepare). As shown in FIG. 6, the check valve 35 has a generally disc shape and includes notched oil passages 42 that are notched in an arc shape at a plurality of circumferential positions (four positions in this embodiment) on the outer periphery. An annular passage 43 is provided between the valve stopper 37 of the valve pressing means 36 and the inner tube 12 while being fixed to the seat pipe 22 side.

  In a state where the piston 25 is fixed to the seat pipe 22 and the check valve 35 is assembled at a predetermined position on the upper end surface of the large-diameter portion of the piston 25, the notch-like oil passage 42 of the check valve 35 and the oil passage of the piston 25 41 is a non-match so that part of the seat pipe 22 does not overlap in the axial direction of the seat pipe 22, and the outer peripheral portion of the check valve 35 not cut out of the cut-out oil passage 42 is the oil passage 41 of the piston 25. Completely block. In the present embodiment, the positioning hole 35A of the check valve 35 is slidably engaged with the non-rotating pin 39 press-fitted in the axial direction of the large diameter portion of the piston 25, and the positions of the oil passages 41 and 42 of both are slidably engaged. Are assembled and maintained in the mismatched state described above.

  In the front fork 10, when the check valve 35 is placed on the end face of the piston 25, the notched oil passage 42 of the check valve 35 does not match the oil passage 41 of the piston 25, and the piston 25 Closed by Since the oil passage 41 of the piston 25 is completely closed by the check valve 35 having the same outer diameter as the piston 25, the piston 25 is integrally provided with the check valve 35 in this manner, so that the hydraulic oil chamber 31 is provided. And the oil reservoir 32 can be partitioned. When the oil in the oil reservoir 32 pushes the check valve 35 from the end face of the piston 25 through the oil passage 41 of the piston 25 in the compression stroke of the front fork 10, the oil in the oil reservoir 32 is changed to the oil in the piston 25. After passing through the passage 41, it flows from the inner tube 12 side outer peripheral oil passage 42 of the check valve 35 into the hydraulic oil chamber through the inner tube 12 side annular passage 43 of the valve pressing means 36. Thereby, the compression side damping force resulting from the passage resistance of the oil passages 41 and 42 is generated. At this time, the oil flow path from the inner tube side outer peripheral oil passage 42 of the check valve 35 to the inner tube side annular passage 43 of the valve pressing means 36 is a simple straight line along the inner periphery of the inner tube 12. It becomes a simple flow path. For this reason, bubbles are not easily generated in oil flowing through a simple flow path, and the damping force is not destabilized, and the fluctuation of the damping force due to temperature is also difficult to occur.

  Therefore, the front fork 10 absorbs the impact force that the vehicle receives from the road surface by the suspension spring 13 and the gas spring of the gas chamber 33, and the outer tube 11 and the inner tube accompanying the absorption of the impact force by the suspension spring 13 and the gas spring. The expansion and contraction vibration of the tube 12 is suppressed by the following damping force.

(When compressed)
When the front fork 10 is compressed, the outer tube 11 and the seat pipe 22 sink into the inner tube 12, the hydraulic oil chamber 31 is expanded, and the hydraulic oil chamber 31 becomes negative pressure. As described above, the check valve 35 is pushed open, and the hydraulic oil chamber passes through the oil passage 41 of the piston 25, the notched oil passage 42 of the check valve 35, and the annular passage 43 between the inner tube 12 and the valve stopper 37. The pressure side damping force caused by the passage resistance of the oil passages 41 and 42 is generated.

(When stretched)
When the front fork 10 extends, the piston 25 pressurizes the hydraulic oil chamber 31. As a result, the check valve 35 is closed, and the oil in the hydraulic oil chamber 31 flows between the outer tube 11 and the inner tube 12 described later of the damping force generating means 34. The oil is discharged into the oil reservoir 32 through the annular gap 53, and an extension side damping force due to the passage resistance of the annular gap 53 is generated.

  During maximum compression of the front fork 10, the bump rubber 101 provided on the lower end surface of the cap 21 of the outer tube 11 abuts against the upper end surface of the inner tube 12 (collar 19) to perform buffering at the time of maximum compression.

  When the front fork 10 is extended to the maximum, the rebound spring 102 supported by the spring receiver 102A locked to the outer periphery of the lower end of the seat pipe 22 is provided on the lower end surface of the pipe guide 23 provided on the inner tube 12 (collar 19). Collide and buffer at maximum extension.

  However, in the front fork 10, the damping force generating means 34 that communicates the hydraulic oil chamber 31 and the oil reservoir chamber 32 to generate the extension side damping force is configured as follows.

  As shown in FIG. 2, the front fork 10 has a first oil hole 51 facing the hydraulic oil chamber 31, even when the outer tube 11 and the inner tube 12 are in the most extended state. ) And the second oil hole 52 facing the oil reservoir chamber 32 is drilled in the tube wall of the inner tube 12 (the tube wall below the piston 25) even when the outer tube 11 and the inner tube 12 are in the most compressed state. The first oil hole 51 and the second oil hole 52 are communicated with each other through the annular gap 53 between the outer tube 11 and the inner tube 12.

  The passage resistance of the annular gap 53 that communicates the first oil hole 51 and the second oil hole 52 is set to be larger than the passage resistances of the first oil hole 51 and the second oil hole 52. The above-described passage resistance of the annular gap 53 is determined by the size of the gap between the outer tube 11 and the inner tube 12, the distance passing through the annular gap 53 between the first oil hole 51 and the second oil hole 52, and the like.

  In the front fork 10, the hydraulic oil is first discharged during the extension stroke of the front fork 10 by changing the relative positions of the first oil hole 51 and the second oil hole 52 in the circumferential direction and / or the axial direction on the inner tube 12. The damping force generated when the first oil hole 51 passes through the annular gap 53 and reaches the second oil hole 52 can be adjusted.

According to the present embodiment, the following operational effects can be obtained.
(a) In the extension stroke, the oil in the hydraulic oil chamber 31 passes through the first oil hole 51 of the inner tube 12, passes through the long annular gap 53 between the outer tube 11 and the inner tube 12, and then reaches the second oil of the inner tube 12. It is discharged from the hole 52 to the oil reservoir chamber 32 and generates a damping force having a proportional characteristic based on the passage resistance exerted on the oil by the annular gap 53. A damping force having a proportional characteristic can be obtained with an extremely simple configuration in which the first oil hole 51 and the second oil hole 52 are formed in the inner tube 12 and the annular gap 53 between the outer tube 11 and the inner tube 12 is used. .

  (b) By setting the passage resistance of the annular gap 53 to be larger than the passage resistances of the first oil hole 51 and the second oil hole 52, it is possible to reliably obtain a damping force having a proportional characteristic.

  (c) By changing the relative positions of the first oil hole 51 and the second oil hole 52 in the circumferential direction and / or the axial direction on the inner tube 12, the damping force of the proportional characteristic can be easily adjusted.

  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 a front fork. FIG. 2 is an enlarged cross-sectional view of the main part of FIG. FIG. 3 is a sectional view showing a piston and a check valve provided in the seat pipe. FIG. 4 is a plan view showing a check valve mounted on a piston. FIG. 5 shows a piston, (A) is a sectional view, and (B) is a plan view. 6A and 6B show a check valve, in which FIG. 6A is a plan view and FIG. 6B is a cross-sectional view taken along line BB in FIG.

Explanation of symbols

10 Front fork 11 Outer tube 12 Inner tube 21 Cap 22 Seat pipe 23 Pipe guide 25 Piston 31 Hydraulic oil chamber 32 Oil reservoir chamber 33 Gas chamber 34 Damping force generating means 35 Check valve 51 First oil hole 52 Second oil hole 53 Annular gap

Claims (3)

Insert the wheel side inner tube slidably into the vehicle body side outer tube,
Insert the seat pipe fixed to the outer tube cap slidably into the pipe guide provided on the inner tube,
The piston fixed to the insertion end of the seat pipe is in sliding contact with the inner periphery of the inner tube,
An annular region between the inner tube and the seat pipe and a region sandwiched between the pipe guide and the piston is a hydraulic oil chamber,
The inner peripheral area of the inner tube, which does not constitute the hydraulic oil chamber, and the inner peripheral area of the seat pipe are a series of oil reservoirs,
The inner peripheral region of the outer tube and the inner peripheral region of the seat pipe are a gas chamber that forms a series at the upper part of the oil reservoir chamber,
A damping force generating means for generating a damping force by forming a passage for discharging the oil in the hydraulic oil chamber to the oil reservoir;
In the front fork in which the piston is provided with a check valve that allows inflow of oil from the oil reservoir chamber to the hydraulic oil chamber,
The first oil hole facing the hydraulic oil chamber is drilled in the tube wall of the inner tube even when the front fork is fully extended, and the second oil hole facing the oil reservoir chamber is formed in the inner tube even when the front fork is fully compressed. Drilled in the tube wall,
A front fork characterized in that a first oil hole and a second oil hole are communicated by an annular gap between an outer tube and an inner tube.   The front fork according to claim 1, wherein passage resistance of the annular gap is larger than passage resistances of the first oil hole and the second oil hole.   By changing the relative positions of the first oil hole and the second oil hole in the circumferential direction and / or the axial direction on the inner tube, hydraulic oil passes through the annular gap from the first oil hole during the extension stroke of the front fork. The front fork according to claim 1 or 2, wherein the damping force generated when reaching the two oil holes can be adjusted.

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