JP2006131119A - Motorcycle front fork - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a nose dive by increasing the pressure of a gas chamber at the time of a brake operation and to extend the operation after the brake operation in a front fork which suppresses an increase in the pressure of the gas chamber after the nose dive prevention and improves cushioning To ensure smoothness.
SOLUTION: In a front fork 10 of a motorcycle, a collar 60 is provided at an upper portion inside a vehicle body side tube 11, an inner gas chamber 61 is defined inside the collar 60, and an inner periphery of an intermediate portion of the collar 60 is provided. A valve seat 70 is provided, the inner gas chamber 61 is partitioned into an upper inner gas chamber 61A and a lower inner gas chamber 61B, and the valve seat 70 communicates with the upper and lower inner gas chambers 61A and 61B in conjunction with a brake operation. And a blow valve 90 that opens when the lower inner gas chamber 61 reaches a predetermined pressure with the open / close valve 70 closed, and the lower inner gas is disposed outside the collar 60. The outer gas chamber 62 communicating with the chamber 61B is partitioned.
[Selection] Figure 1

Description

  The present invention relates to a front fork of a motorcycle.

  In Patent Document 1, in the front fork of a motorcycle, the pressure of the air chamber is increased during brake operation to prevent nose dive, and the cushioning is improved by suppressing the pressure increase of the air chamber after the nose dive prevention. Are disclosed.

  That is, in the front fork of Patent Document 1, the solenoid that has obtained the brake signal retracts the iron core 49 upward, and the flow path 59 that connects the lower chamber B to the upper chamber C by the valve body 61 fixed to the iron core 49 is provided. It closes and raises the pressure in the lower chamber B to prevent nose diving. When the pressure in the lower chamber B exceeds a predetermined level, the auxiliary valve body 65 is opened and the pressure in the lower chamber B is blown into the upper chamber C. Thereby, the pressure in the lower chamber B is slightly weaker than before the auxiliary valve body 65 is opened, and as a result, the compression of the front fork 13 becomes smooth and the cushioning property can be secured.

Patent Document 1 states that “if the oil level of the hydraulic oil at the most compressed position of the front fork 13 is above the valve base 53, the air pressure in the chamber B increases more rapidly” (upper right on page 3). Column 3-5 lines).
JP 60-252085

  In the front fork of Patent Document 1, when the valve body 61 still closes the flow path 59 that communicates the lower chamber B with the upper chamber C at the initial stage of the extension operation after the brake operation, As a result of a part of the hydraulic oil that has entered the chamber C being left in the upper chamber C, the lower chamber B has a negative pressure corresponding thereto, and smooth extension operation is hindered.

  An object of the present invention is to prevent the nose dive by increasing the pressure of the gas chamber when the brake is operated, and to suppress the increase in the pressure of the gas chamber after preventing the nose dive and improve the cushioning property. This is to make the stretching operation smooth.

  The invention according to claim 1 is a motorcycle in which a vehicle body side tube and a wheel side tube are slidably inserted, and an oil chamber and a gas chamber above the oil chamber are provided inside the vehicle body side tube and the wheel side tube. In the front fork, a collar is provided at an upper portion inside the vehicle body side tube, an inner gas chamber is defined inside the collar, a valve seat is provided at an inner periphery of the middle portion of the collar, and the inner gas chamber is disposed at an upper portion. An on-off valve that is divided into an inner gas chamber and a lower inner gas chamber, closes communication between the upper and lower inner gas chambers in conjunction with a brake operation, and the lower inner gas chamber with the on-off valve closed. Is provided with a blow valve that opens when the pressure reaches a predetermined pressure, and an outer gas chamber communicating with the lower inner gas chamber is defined outside the collar.

  According to a second aspect of the present invention, in the first aspect of the invention, the collar is a spring collar that supports an upper end of a suspension spring interposed between the vehicle body side tube and the wheel side tube. It is.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a damper cylinder is attached to the wheel side tube, and a hollow rod provided with a piston that slides inside the damper cylinder is attached to the vehicle body side tube. The valve seat is provided between a hollow rod and the collar, an operation rod is provided in the hollow rod so as to be able to advance and retreat, and the open / close valve is supported by the operation rod.

(Claim 1)
(a) When the brake is operated, the load of the vehicle body moves forward, the front fork is compressed, and the air and hydraulic oil in the lower inner gas chamber try to flow into the upper inner gas chamber through the communication passage of the valve seat. However, the on-off valve closes the communication path of the valve seat and closes the communication between the upper and lower inner gas chambers. As a result, the pressure in the lower inner gas chamber rises to suppress the sinking of the front fork and prevent nose diving.

  (b) When the front fork is further compressed and the pressure in the lower inner gas chamber exceeds a predetermined level, the blow valve that has closed the blow passage of the valve seat opens, and the air and hydraulic oil in the lower inner gas chamber are removed from the upper inner gas chamber. To suppress the pressure rise in the lower inner gas chamber. This prevents the front fork from being locked, and the front fork is smoothly compressed to improve cushioning. At this time, the hydraulic oil in the lower inner gas chamber also enters the outer gas chamber.

  (c) When the front fork shifts to the extension operation, the lower inner gas chamber expands. At this time, when the on-off valve is still closed, the lower inner gas chamber becomes negative pressure, and the smooth extension operation of the front fork is hindered. However, in the present invention, the outer gas chamber communicates with the lower inner gas chamber, and the hydraulic oil that has entered the outer gas chamber at the time of compression returns to the lower gas chamber at the time of expansion. Thus, the negative pressure in the lower inner gas chamber can be avoided and the extension operation can be smoothly performed.

(Claim 2)
(d) The existing spring collar can be used as a partition member for the inner gas chamber and the outer gas chamber, and no special partition member is required, thereby reducing the cost.

(Claim 3)
(e) Since the operating rod for the on-off valve is provided in the hollow rod, the space in the hollow rod can be effectively used without sacrificing the volume of the inner gas chamber.

  1 is an overall sectional view showing a front fork, FIG. 2 is a lower sectional view of FIG. 1, FIG. 3 is an intermediate sectional view of FIG. 1, FIG. 4 is an upper sectional view of FIG. FIG. 6 is an enlarged view, FIG. 6 is an arrow view along line VI-VI in FIG. 5, and FIG. 7 is an arrow view along line VII-VII in FIG.

  A front fork 10 of a motorcycle is configured by inserting a vehicle body side tube 11 and a wheel side tube 12 in a fluid-tight manner so as to be slidable as shown in FIGS. A bush 13 is provided on the outer periphery of the lower end of the vehicle body side tube 11, and a bush 14 is provided on the inner periphery of the upper end side of the wheel side tube 12. An oil hole 11 </ b> A is provided on the lower end side of the vehicle body side tube 11 to communicate an oil reservoir chamber 28, which will be described later, between the vehicle body side tube 11 and the wheel side tube 12 in an annular gap sandwiched between the bushes 13 and 14.

  The vehicle body side tube 11 is provided with a cap 16 detachably and liquid-tightly at the opening 15 at the upper end, and the vehicle body side tube 11 is provided with a vehicle body side mounting portion. The wheel side tube 12 is integrally provided with a bottom bracket 18 at a lower end portion, and a wheel side mounting portion 19 is provided at the bottom bracket 18.

  The front fork 10 accommodates a damper cylinder 21 and a hollow rod 24 constituting the damper 20 inside the vehicle body side tube 11 and the wheel side tube 12. That is, as shown in FIG. 2, the front fork 10 has a damper cylinder 21 fixed inside the bottom bracket 18 erected inside the wheel side tube 12. A stopper piece 22A engaged with the inner periphery of the lower end of the damper cylinder 21 is pulled by a bottom piece 51 to which a center bolt 22 inserted into the bottom portion of the bottom bracket 18 is screwed. It is fixed to the bottom of the bottom bracket 18 with 37A interposed.

  As shown in FIG. 4, the front fork 10 has a mounting sleeve 23 screwed in a liquid-tight manner at the center of the cap 16, and a hollow rod 24 and a lock at the lower end of the mounting sleeve 23 inserted into the vehicle body side tube 11. The nut 23 </ b> A is screwed and the hollow rod 24 is fixedly supported to the vehicle body side tube 11. As shown in FIG. 3, the hollow rod 24 slidably passes through a rod guide 25 provided at the upper end portion of the damper cylinder 21 and is inserted into an oil chamber 27 inside the damper cylinder 21, and is provided at an insertion tip portion thereof. The piston bolt 24A is provided with a piston 26. The piston 26 is fixed by a nut 24B screwed onto the piston bolt 24A. 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 hollow rod side oil chamber 27A on the side where the hollow rod 24 is inserted and a piston side oil chamber 27B on the side where the hollow rod 24 is not inserted.

  In the front fork 10, the space around the damper cylinder 21 is an oil reservoir chamber (oil chamber) 28 inside the vehicle body side tube 11 and the wheel side tube 12, and the upper portion of the oil reservoir chamber 28 is a gas chamber (air chamber) 29. It is said. 1, 4, and 5, L indicates the oil level.

  The front fork 10 has a suspension spring 33 made of a coil spring interposed between upper and lower spring receivers 31 and 32 between the vehicle body side tube 11 side and the wheel side tube 12 side. The spring receiver 31 is backed up by a spring collar 34 supported by a cap 16 screwed to the vehicle body side tube 11, and the spring receiver 32 is provided on a support member 35 fixed to the tip of the damper cylinder 21.

  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 33 and the spring reaction force of the gas spring of the gas chamber 29.

  The damper 20 includes a piston valve device (extension-side damping force generation device) 40 and a bottom valve device (compression-side damping force generation device) 50. The damper 20 suppresses the expansion and contraction vibration of the vehicle body side tube 11 and the wheel side tube 12 due to the absorption of the impact force by the suspension spring 33 and the gas spring by the damping force generated by the piston valve device 40 and the bottom valve device 50.

Hereinafter, the damping mechanism of the front fork 10 will be described.
(Piston valve device 40)
In the piston valve device 40, a piston bolt 24A is mounted on the tip of the hollow rod 24, and a piston 26 and a valve stopper 42 are mounted by a nut 24B and a valve stopper 41 that are screwed to the piston bolt 24A. The piston 26 includes an expansion side valve 44A and includes an expansion side flow path 44 that allows the rod side oil chamber 27A and the piston side oil chamber 27B to communicate with each other, and a pressure side valve (check valve) 45A. And a pressure-side flow path 45 (not shown) that allows the piston-side oil chamber 27B to communicate with each other.

  In addition, the piston valve device 40 makes the bolt 24A hollow and is provided with an orifice passage 46 in the bolt 24A so that the rod-side oil chamber 27A and the piston-side oil chamber 27B are always in communication with each other through the orifice passage 46 of the bolt 24A. .

  Therefore, when the front fork 10 is compressed, the oil in the piston-side oil chamber 27B passes through the pressure-side flow path 45, opens the pressure-side valve 45A, and is guided to the rod-side oil chamber 27A.

  Further, when the front fork 10 is extended, when the relative speed between the damper cylinder 21 and the hollow rod 24 is low, the oil in the rod-side oil chamber 27A is guided to the piston-side oil chamber 27B through the orifice path 46, and the orifice in the meantime. An expansion side damping force is generated by the throttle resistance of the path 46.

  Further, when the relative speed when the front fork 10 is extended is medium to high, the oil in the rod side oil chamber 27A passes through the extension side flow path 44 and bends and deforms the extension side valve 44A and is guided to the piston side oil chamber 27B. A damping force on the extension side is generated.

(Bottom valve device 50)
The bottom valve device 50 has a housing bolt 52 attached to the tip of a bottom piece 51 attached to the wheel side tube 12 together with the damper cylinder 21 and the oil lock piece 37 by the center bolt 22 as described above, and is screwed to the bolt 52. The pressure side valve 56A, the valve housing 53, and the valve stoppers 54A and 54B are held by the nut 52A. The valve stoppers 54 </ b> A and 54 </ b> B hold the extension side valve 57 </ b> A and the spring 57 </ b> B between the valve housing 53. The valve housing 53 is in liquid-tight contact with an intermediate portion of the damper cylinder 21, and forms a bottom valve chamber 55 below the piston-side oil chamber 27B. The valve housing 53 includes a pressure-side flow path 56 that enables communication between the piston-side oil chamber 27B provided in the pressure-side valve 56A and the bottom valve chamber 55, and an expansion-side valve 57A, and includes the piston-side oil chamber 27B and the bottom valve chamber 55. And an extension side flow channel 57 (not shown). The bottom valve chamber 55 can communicate with an oil reservoir chamber 28 provided outside the damper cylinder 21 by an oil passage 58 provided on the wall surface of the damper cylinder 21.

  Further, the bottom valve device 50 makes the bolt 52 hollow and is provided with an orifice passage 59 in the bolt 52 so that the piston-side oil chamber 27B and the bottom valve chamber 55 are always in communication with each other by the hollow passage of the bolt 52 and the orifice passage 59. ing.

  Therefore, when the relative speed between the damper cylinder 21 and the hollow rod 24 is low when the front fork 10 is compressed, the oil corresponding to the volume of the hollow rod 24 that has entered the damper cylinder 21 flows from the piston-side oil chamber 27B to the orifice passage 59. Then, the oil is discharged to the oil reservoir chamber 28 through the bottom valve chamber 55 and the oil passage 58 on the wall surface of the damper cylinder 21. In addition, when the front fork 10 is compressed and the relative speed between the damper cylinder 21 and the hollow rod 24 is medium to high, the oil corresponding to the volume of the hollow rod 24 that has entered the damper cylinder 21 is compressed from the piston-side oil chamber 27B to the pressure side. The oil is discharged into the oil reservoir 28 through the flow path 56, the bottom valve chamber 55, and the oil passage 58 on the wall surface of the damper cylinder 21. At this time, the oil passing from the piston-side oil chamber 27B through the pressure-side flow path 56 bends and deforms the pressure-side valve 56A and is guided to the bottom valve chamber 55 to generate a pressure-side damping force.

  When the front fork 10 is extended, the oil corresponding to the retraction volume of the hollow rod 24 retreating from the damper cylinder 21 is recirculated from the oil reservoir chamber 28 to the piston-side oil chamber 27B through the bottom valve chamber 55 and the expansion-side flow passage 57. The

Accordingly, the front fork 10 performs a damping action as follows.
(When compressed)
When the front fork 10 is compressed, in the bottom valve device 50, a compression side damping force is generated by the oil flowing through the orifice path 59 of the bottom piece 51 or the pressure side valve 56 </ b> A of the valve housing 53, and the piston valve device 40 generates almost no damping force.

(When stretched)
When the front fork 10 is extended, in the piston valve device 40, the expansion side damping force is generated by the oil flowing through the orifice path 46 of the piston 26 or the expansion side valve 44A, and the bottom valve device 50 generates almost no damping force.

The damping force on the compression side and the extension side suppresses the stretching vibration of the front fork 10.
When the front fork 10 is compressed most, the check valve 36A of the oil lock collar 36 provided at the lower end of the vehicle body side tube 11 is fitted to the outer periphery of the oil lock piece 37 erected on the bottom of the wheel side tube 12. Then, an oil lock oil chamber is defined between the wheel side tube 12 and the oil lock piece 37 to restrict the maximum compression stroke.

  Further, when the front fork 10 is most extended, the rebound spring 39 backed up and supported by the spring receiver 38 locked to the outer peripheral portion of the upper end of the damper cylinder 21 is compressed by the upper end washer of the oil lock collar 36 to restrict the maximum extension stroke. .

However, the front fork 10 has a nose dive prevention structure as follows.
The front fork 10 is provided with a collar 60 (consisting of divided bodies 60A and 60B) in the upper part of the vehicle body side tube 11, and as shown in FIGS. 4 and 5, an inner gas chamber 61 is defined inside the collar 60, The valve seat 70 is provided on the inner periphery of the middle portion of the collar 60 (between the split body 60A and the split body 60B), the inner gas chamber 61 is connected to the upper inner gas chamber 61A closer to the cap 16 than the valve seat 70, and the valve A lower inner gas chamber 61B closer to the rod guide 25 than the sheet 70 is partitioned. Further, the front fork 10 defines an outer gas chamber 62 outside the collar 60, and the inner gas chamber 61 and the outer gas chamber 62 communicate with each other through a communication hole 63 provided in the divided body 60B. The inner gas chamber 61 (upper inner gas chamber 61A, lower inner gas chamber 61B) and the outer gas chamber 62 form a gas chamber 29. The collar 60 (divided bodies 60A, 60B) constitutes a spring collar 34.

  As shown in FIGS. 6 and 7, the valve seat 70 includes a communication passage 71 and a blow passage 72 that connect the upper and lower inner gas chambers 61 </ b> A and 61 </ b> B, and an open / close valve that opens and closes the communication passage 71 and the blow passage 72, respectively. 80 and a blow valve 90 are provided. The on-off valve 80 closes the communication path 71 in conjunction with the brake operation of the motorcycle. The blow valve 90 opens the blow passage 72 when the lower inner gas chamber 61B reaches a predetermined pressure with the on-off valve 80 closed.

  The valve seat 70 is provided in an annular space between the hollow rod 24 and the collar 60 (divided bodies 60A and 60B). The valve seat 70 includes an O-ring 73 in an inner circumferential annular groove fitted to the hollow rod 24, and the lower end of the divided body 60A. An outer peripheral flange 70A is sandwiched between the upper end portion of the divided body 60B and an O-ring 74 in an outer circumferential annular groove fitted to the divided body 60A.

  The on-off valve 80 is mechanically opened and closed by a solenoid that is actuated by a brake signal and a flexible cable that is interlocked with a brake operation. In this embodiment, the operating rod 81 is inserted into the hollow rod 24 so as to be able to advance and retreat, and a connecting pin 82 connected to the insertion end of the operating rod 81 is provided through the elongated hole 24A provided in the hollow rod 24 along the axial direction. The both ends of the connecting pin 82 are engaged with the lower end groove of the on-off valve 80 fitted to the outer periphery of the hollow rod 24. A solenoid or a flexible cable is connected to the external projecting end of the operation rod 81. The on-off valve 80 is set at an open position by a compression spring 83 interposed between the lower surface of the valve seat 70 and is hollowed against the compression spring 83 by the upward movement of the operation rod 81 connected to a solenoid or a cable. The rod 24 is slidably guided on the outer periphery of the rod 24 and smoothly moves upward to close the communication path 71. The seat surface that closes the communication passage 71 of the on-off valve 80 is coated with rubber or the like to improve the sealing performance with the communication passage 71.

  The blow valve 90 is set at a closed position by a compression spring 93 backed up by a spring receiver 92 locked to the outer periphery of the hollow rod 24 by a stopper ring 91, and resists the compression spring 93 by a predetermined pressure in the lower inner gas chamber 61B. Then, it is slidably guided on the outer periphery of the hollow rod 24 and smoothly moves upward to open the blow passage 72. The seat surface that closes the blow passage 72 of the blow valve 90 is coated with rubber or the like to improve the sealing performance with the blow passage 72.

According to the present embodiment, the following operational effects can be obtained.
(a) When the brake is operated, the load of the vehicle body moves forward, the front fork 10 is compressed, and the air and hydraulic oil in the lower inner gas chamber 61B pass through the communication passage 71 of the valve seat 70 to the upper inner gas chamber 61A. Try to flow in. However, the on-off valve 80 closes the communication passage 71 of the valve seat 70 and closes the communication between the upper and lower inner gas chambers 61A and 61B. As a result, the pressure in the lower inner gas chamber 61B rises to prevent the front fork 10 from sinking and prevent nose diving.

  (b) When the front fork 10 is further compressed and the pressure in the lower inner gas chamber 61B becomes equal to or higher than a predetermined value, the blow valve 90 that has closed the blow passage 72 of the valve seat 70 is opened, and the air and the operation in the lower inner gas chamber 61B Oil is blown into the upper inner gas chamber 61A to suppress the pressure increase in the lower inner gas chamber 61B. As a result, the front fork 10 is prevented from being locked, and the front fork 10 is smoothly compressed to improve cushioning. At this time, the hydraulic oil in the lower inner gas chamber 61 </ b> B also enters the outer gas chamber 62.

  (c) When the front fork 10 shifts to the extension operation, the lower inner gas chamber 61B expands. At this time, when the on-off valve 80 is still closed, the lower inner gas chamber 61B becomes negative pressure, and the smooth extension operation of the front fork 10 is hindered. However, in the present invention, the outer gas chamber 62 communicates with the lower inner gas chamber 61B, and the hydraulic oil that has entered the outer gas chamber 62 during compression returns to the lower gas chamber during expansion. In the initial stage, the negative pressure in the lower inner gas chamber 61B can be avoided, and the extension operation can be performed smoothly.

  (d) The existing spring collar 34 can be used as a partition member for the inner gas chamber 61 and the outer gas chamber 62, and the cost can be reduced because no special partition member is required.

  (e) Since the operation rod 81 of the on-off valve 80 is provided in the hollow rod 24, the space in the hollow rod can be effectively used without sacrificing the volume of the inner gas chamber 61.

  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 an overall cross-sectional view showing a front fork. FIG. 2 is a lower cross-sectional view of FIG. 3 is a cross-sectional view of the middle part of FIG. FIG. 4 is a top sectional view of FIG. FIG. 5 is an enlarged view of a main part of FIG. FIG. 6 is a view taken along the line VI-VI in FIG. FIG. 7 is a view taken along the line VII-VII in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Front fork 11 Car body side tube 12 Wheel side tube 21 Damper cylinder 24 Hollow rod 26 Piston 28 Oil reservoir (oil chamber)
29 Gas chamber 33 Suspension spring 34 Spring collar 60 Collar 61 Inner gas chamber 61A Upper inner gas chamber 61B Lower inner gas chamber 62 Outer gas chamber 70 Valve seat 71 Communication passage 72 Blow passage 80 On-off valve 81 Operation rod 90 Blow valve

Claims (3)

Insert the body side tube and wheel side tube slidably,
In the front fork of a motorcycle provided with an oil chamber and a gas chamber above the oil chamber inside the vehicle body side tube and the wheel side tube,
A collar is provided in the upper part of the vehicle body side tube, and an inner gas chamber is defined inside the collar,
A valve seat is provided on the inner periphery of the middle portion of the collar, and the inner gas chamber is divided into an upper inner gas chamber and a lower inner gas chamber,
An on-off valve that closes the communication between the upper and lower inner gas chambers in conjunction with the brake operation, and opens when the lower inner gas chamber reaches a predetermined pressure with the on-off valve closed. A blow valve,
A front fork for a motorcycle, wherein an outer gas chamber communicating with the lower inner gas chamber is defined outside the collar.   2. The front fork of a motorcycle according to claim 1, wherein the collar is a spring collar that supports an upper end of a suspension spring interposed between the vehicle body side tube and the wheel side tube. A damper cylinder is attached to the wheel side tube, and a hollow rod provided with a piston that slides inside the damper cylinder is attached to the vehicle body side tube,
The valve seat is provided between the hollow rod and the collar,
The front fork of a motorcycle according to claim 1 or 2, wherein an operating rod is provided in the hollow rod so as to be movable back and forth, and the open / close valve is supported by the operating rod.

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