JP2007146948A - Front fork - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front fork capable of obtaining elongation side damping force being substantially proportional characteristic by a simple configuration. <P>SOLUTION: This front fork 10 is constituted in such a way that a leaf valve 51 for opening and closing an orifice 34A of a seat pipe 22 is extended in the peripheral direction along the inner periphery of the seat pipe 22, is provided with springily restoring habit for closing the orifice 34A, and is elastically bent and deformed by oil pressure in a hydraulic fluid chamber 31 to open the orifice 34A. <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 expansion 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 expansion side damping force is obtained by the passage resistance exerted on the oil by the orifice.

  However, the extension side damping force that can be obtained in the front fork of Patent Document 1 is based on the passage resistance of an 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, which increases the complexity and weight and the cost.

  In the hydraulic shock absorber described in Japanese Utility Model Application Laid-Open No. 64-6445, a leaf valve that opens and closes a port (not an orifice) provided in the hollow cylinder is arranged along the inner periphery of the hollow cylinder, and the leaf valve is disposed on the inner periphery of the leaf valve. A valve stopper that regulates the deflection of the valve is provided. As the pressure increases, the leaf valve increases in deflection, increases the opening area, and the damping characteristic becomes a 2/3 power characteristic. Therefore, a member that regulates the deflection is required. Excessive deflection of the leaf valve not only increases the opening area of the flow path but also causes damage.

  An object of the present invention is to obtain an expansion-side damping force having a generally 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 The piston is provided with a damping force generating means that forms a series of gas chambers in the upper part and forms an orifice in the seat pipe that discharges the oil in the hydraulic oil chamber to the oil reservoir chamber to generate a damping force. In a front fork provided with a check valve that allows oil to flow from the oil reservoir into the hydraulic oil chamber, a leaf valve that opens and closes the orifice of the seat pipe extends in the circumferential direction along the inner circumference of the seat pipe. The leaf valve has a resilient restoring behavior of closing the orifice and is elastically deformed by the hydraulic pressure of the hydraulic oil chamber to open the orifice.

  According to a second aspect of the present invention, in the first aspect of the invention, a tubular valve body is fitted to the inner periphery of the seat pipe, and a leaf valve is formed by a cut formed in the valve body. .

(Claim 1)
(a) By providing a leaf valve along the inner circumference of the seat pipe to open and close the orifice of the seat pipe, the extension side damping force that the orifice exerts on the oil discharged from the hydraulic oil chamber to the oil reservoir chamber is insufficient. Is compensated by the damping force caused by the deflection reaction force of the lease valve. In the high speed range, the extension side damping force that is insufficient with only the leaf valve is compensated by the presence of the orifice. A desired damping characteristic can be obtained by a combination of the diameter and number of orifices, the plate thickness shape and the number of leaf valves, and the like.

  (b) Since the flow path of the oil discharged from the hydraulic oil chamber to the oil reservoir chamber is restricted by the orifice, the leaf valve is not excessively bent, and the leaf valve deflection regulating member is unnecessary.

(Claim 2)
(c) A cylindrical valve body is fitted to the inner periphery of the seat pipe, and a leaf valve is formed by a cut formed in the valve body. This simplifies the configuration of the leaf valve, attachment to the seat pipe, and the like.

  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 the seat pipe, and FIG. 5 is a cross-sectional view taken along the line VV in FIG. 3, FIG. 6 is a cross-sectional view showing the seat pipe, and FIGS. 7A to 7D are perspective views showing the leaf valves, FIG. Indicates a piston, (A) is a sectional view taken along line AA in (B), (B) is a plan view, FIG. 9 shows a check valve, (A) is a plan view, and (B) is ( FIG. 10 is a sectional view showing a piston and a check valve provided on the seat pipe of the first modification, and FIG. 11 is a reverse view of the seat pipe provided on the seat pipe of the second modification. FIG. 12 is a sectional view showing a piston and a check valve provided in the seat pipe of the third modification.

  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 slidably. 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 into the pipe guide 23 provided in the inner tube 12, and the piston ring 26 of the piston 25 is brought into 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. 8, and the upper small diameter portion is fitted to the inner periphery of the seat pipe 22 via a valve body 50 described later, and the single or plural positions in the circumferential direction of the seat pipe 22 are provided. Thus, the fitting state is fixed by the pins 27 inserted in the radial direction. 25A is a pin hole provided in the upper small diameter portion for the pin 27, and 25B is an annular groove provided in the large diameter portion for the piston ring 26.

  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

  An annular gap between the outer tube 11 and the inner tube 12 and a region sandwiched between the upper and lower bushes 14 and 15 is an oil reservoir chamber through a through hole 12A provided in the inner tube 12 (collar 19). 32, communicated with the gas chamber 33 and compensated for volume.

  In the front fork 10, damping force generating means 34 that communicates the hydraulic oil chamber 31 and the oil reservoir chamber 32 is provided in the seat pipe 22. 2 to 4, the damping force generating means 34 is composed of one or more (one in this embodiment) hole orifices 34 </ b> A formed in the seat pipe 22, and during the extension stroke of the front fork 10. A passage for discharging the oil in the hydraulic oil chamber 31 to the oil reservoir chamber 32 is formed, and an extension side damping force due to the passage resistance is generated.

  As shown in FIGS. 2, 3, and 5, the front fork 10 is provided with a check valve 35 that allows the piston 25 to allow the oil to flow from the oil reservoir chamber 32 to the hydraulic oil chamber 31 and prevent the backflow thereof. . 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. 8, 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 within the end surface of the large diameter portion. Are provided at a plurality of positions in the circumferential direction (four positions in this embodiment). As shown in FIG. 9, the check valve 35 has a generally disk shape and includes notched oil passages 42 that are notched in a circular 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 are made to be unmatched so that part of them does not overlap when the seat pipe 22 is viewed in the axial direction. 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 is closed by the piston 25. . 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 31 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.

  However, in the front fork 10, as shown in FIGS. 2 to 4, the leaf valve 51 that opens and closes the orifice 34 </ b> A of the seat pipe 22 extends in the circumferential direction along the inner periphery of the seat pipe 22 without a gap. Provide as follows. That is, as shown in FIGS. 4 and 6, the tubular valve body 50 is fitted on the inner periphery of the lower end portion of the seat pipe 22 over a certain range, and the upper small diameter portion of the piston 25 is disposed on the lower end side inner periphery of the valve body 50. In the state of fitting, the fitting state is fixed by the above-described pin 27 inserted in the radial direction thereof. In this embodiment, the seat pipe 22 is formed as an annular stepped portion obtained by cutting the inner circumference over a certain range of the lower end portion to a certain depth (the thickness of the valve body 20), and the valve body 50 is fitted and inserted into the annular stepped portion. The inner circumference of the valve body 50 other than the annular stepped portion 22 is flush with the inner circumference of the valve body 50.

  As shown in FIG. 7A, the valve body 50 has a U-shaped cut 50A in a certain range along the circumferential direction on the upper end side, and forms a tongue-like leaf valve 51 surrounded by the cut 50A. The leaf valve 51 is attached along the inner periphery of the seat pipe 22 so as to face the orifice 34A of the seat pipe 22 and its periphery, and has a resilient restoring behavior for closing the orifice 34A. As indicated by the dotted line, the hydraulic pressure of the hydraulic oil chamber 31 that is pressurized in the extension stroke is received from the orifice 34A to elastically deform and open the orifice 34A, and the extension side damping caused by the deflection reaction force of the leaf valve 51 occurs. Generate power. The leaf valve 51 bends and deforms starting from the base end portion 51A of the tongue piece, and is separated from the inner periphery (orifice 34A and its periphery) of the seat pipe 22.

  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 is extended, the piston 25 pressurizes the hydraulic oil chamber 31. As a result, the check valve 35 is closed, and the pressurized hydraulic pressure in the hydraulic oil chamber 31 is applied to the leaf valve 51 via the orifice 34A. The valve 51 is bent and deformed so as to push open, and the oil in the hydraulic oil chamber 31 is discharged to the oil reservoir chamber 32 through the orifice 34A opened thereby. As a result, the expansion-side damping force having a substantially proportional characteristic, which is obtained by adding the damping force of the square characteristic caused by the passage resistance of the orifice 34A and the damping force of the square characteristic caused by the deflection reaction force of the leaf valve 51, is obtained. Arise.

  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.

According to the present embodiment, the following operational effects can be obtained.
(a) By providing the leaf valve 51 that opens and closes the orifice 34A of the seat pipe 22 along the inner periphery of the seat pipe 22, only the passage resistance exerted by the orifice 34A on the oil discharged from the hydraulic oil chamber 31 to the oil reservoir chamber 32 is obtained. Then, the insufficient extension side damping force is compensated by the damping force caused by the deflection reaction force of the lease valve. In the high speed range, the extension side damping force that is insufficient with only the leaf valve is compensated by the presence of the orifice 34A. A desired damping characteristic can be obtained by a combination of the diameter and number of the orifices 34A, the plate thickness shape and the number of the leaf valves 51, and the like.

  (b) Since the flow path of the oil discharged from the hydraulic oil chamber 31 to the oil reservoir chamber 32 is throttled by the orifice 34A, the leaf valve 51 is not excessively deflected, and the leaf valve deflection regulating member becomes unnecessary.

  (c) A tubular valve body 50 is fitted on the inner periphery of the seat pipe 22, and a leaf valve 51 is formed by a cut 50 </ b> A inserted in the valve body 50. This simplifies the configuration of the leaf valve 51, attachment to the seat pipe 22, and the like.

  FIG. 10 shows a main part of the front fork 10 of the first modification, and uses the valve body 60 shown in FIG. 7B. The valve body 60 in FIG. 7B has a U-shaped cut 60A provided in a certain range along the circumferential direction on the upper end side, and an upper end surface along the axial direction from the starting point on the U-shaped upper side of the U-shaped cut 60A. A straight cut 60B extending to the bottom, and a straight cut 60C extending from the starting point of the U-shaped lower side of the U-shaped cut 60A to the lower end surface along the axial direction, and surrounded by the U-shaped cut 60A A valve 61 is formed. The leaf valve 61 opens and closes the orifice 34A of the seat pipe 22 in the same manner as the leaf valve 51 of the above-described embodiment.

  FIG. 11 shows a main part of the front fork 10 of the second modification, and uses the valve body 70 shown in FIG. 7 (C). The valve body 70 in FIG. 7C is provided with a straight cut 70A extending from the upper end surface to the lower end surface along the axial direction, and forming a plate-like leaf valve 71 having the cut 70A as a leading end portion of the deflection. is there. The leaf valve 71 opens and closes the orifice 34A of the seat pipe 22 in the same manner as the leaf valve 51 of the above-described embodiment.

  FIG. 12 shows a main part of the front fork 10 of the third modification, and uses the valve body 80 shown in FIG. 7 (D). The valve body 80 in FIG. 7D is provided with a straight cut 80A extending from the upper end surface to the lower end surface along the direction oblique to the axial direction, and the plate-like leaf valve 81 having the cut 80A as the leading end portion of the deflection. Is formed. The leaf valve 81 opens and closes the orifice 34A of the seat pipe 22 in the same manner as the leaf valve 51 of the above-described embodiment.

  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. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a view taken along the line V-V in FIG. FIG. 6 is a sectional view showing the seat pipe. 7A to 7D are perspective views showing a leaf valve. FIG. 8 shows a piston, (A) is a sectional view taken along line AA of (B), and (B) is a plan view. 9A and 9B show a check valve, where FIG. 9A is a plan view and FIG. 9B is a cross-sectional view taken along line BB in FIG. FIG. 10 is a cross-sectional view showing a piston and a check valve provided in the seat pipe of the first modification. FIG. 11 is a cross-sectional view showing a seat pipe and a check valve provided in the seat pipe of the second modification. FIG. 12 is a sectional view showing a piston and a check valve provided in the seat pipe of the third modification.

Explanation of symbols

DESCRIPTION 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 34A Orifice 35 Check valves 50, 60, 70, 80 Valve body 50A, 60A, 70A, 80A Break 51, 61, 71, 81 Leaf valve

Claims (2)

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 an orifice in the seat pipe 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,
A leaf valve that opens and closes the orifice of the seat pipe extends in the circumferential direction along the inner circumference of the seat pipe, and the leaf valve has a resilient restoring behavior that closes the orifice and elastically deforms by the hydraulic pressure of the hydraulic oil chamber The front fork is characterized by opening the orifice.   The front fork according to claim 1, wherein a tubular valve body is fitted to the inner periphery of the seat pipe, and a leaf valve is formed by a cut formed in the valve body.

Images