CN112292543A

CN112292543A - Front fork

Info

Publication number: CN112292543A
Application number: CN201980027394.0A
Authority: CN
Inventors: 坂胁俊彦
Original assignee: KYB Motorcycle Suspension Co Ltd
Current assignee: KYB Motorcycle Suspension Co Ltd
Priority date: 2018-06-29
Filing date: 2019-05-31
Publication date: 2021-01-29
Anticipated expiration: 2039-05-31
Also published as: JP2020003024A; CN112292543B; TW202010675A; TWI813707B; JP7051614B2; WO2020003891A1

Abstract

The invention provides a front fork capable of freely setting a compression side throttle hole and generating stable damping force. It is provided with: a piston section (20) which is provided on the inner tube (2) on the vehicle body side and which divides a space between the outer tube (1) on the wheel side and the cylinder (3) provided on the inner side thereof into an extension-side chamber (L1) and a lower chamber (O); a cover (4) which is fixed to the upper end of the cylinder (3) and separates a cylinder inner chamber (I) which forms a compression-side chamber (L2) together with the lower chamber (O) from a liquid storage chamber (R); an extension-side orifice (3d) that applies resistance to the flow of liquid from the extension-side chamber (L1) to the compression-side chamber (L2); a compression-side orifice (4f) for communicating the compression-side chamber (L2) and the reservoir chamber (R); an extension-side check valve (7) that allows liquid to flow from the liquid storage chamber (R) to the compression-side chamber (L2); and a compression-side check valve (6) that allows liquid to flow from the reservoir chamber (R) or the compression-side chamber (L2) to the extension-side chamber (L1).

Description

Front fork

Technical Field

The present invention relates to a front fork.

Background

Conventionally, a front fork used for suspending a front wheel of a saddle type vehicle is provided with a telescopic pipe member having an outer pipe and an inner pipe slidably inserted into the outer pipe. Further, as disclosed in, for example, JPH09-217780a, there is a so-called upright front fork in which an outer tube is provided on a wheel side and an inner tube is provided on a vehicle body side (for example, patent document 1).

In such a front fork of the upright type, a cylinder is provided inside the outer tube, a liquid chamber formed between the outer tube and the cylinder is partitioned from a liquid storage chamber formed from the inside of the cylinder to the upper side thereof, and a piston portion provided at the lower end of the inner tube divides the liquid chamber into an extension-side chamber and a compression-side chamber. Further, an extension-side orifice for communicating the extension-side chamber and the reservoir chamber, and a compression-side orifice for communicating the compression-side chamber and the reservoir chamber are formed in the cylinder.

According to the above configuration, when the front fork extends, the liquid in the extension side chamber moves to the liquid storage chamber after passing through the extension side orifice, and the extension side damping force is generated by applying resistance to the flow of the liquid. On the contrary, when the front fork contracts, the fluid in the compression-side chamber moves to the reservoir chamber after passing through the compression-side orifice, and a compression-side damping force is generated by applying resistance to this fluid flow.

Summary of The Invention

In the conventional front fork, the compression-side damping force is adjusted by changing the size of the compression-side orifice formed in the cylinder. When the compression-side damping force is to be increased, the compression-side orifice is only required to be decreased.

However, the compression-side orifice formed on the cylinder also serves as an extension-side suction passage to supply liquid from the reservoir chamber to the compression-side chamber during an extension stroke of the front fork. Therefore, if the compression-side orifice is reduced, there is a possibility that insufficient suction of the compression-side chamber may be caused in the extension stroke, and the compression-side chamber becomes a negative pressure. Further, if the compression-side chamber becomes negative pressure during the extension stroke, the rise of the compression-side damping force is delayed during the subsequent compression stroke, giving the occupant a feeling of discomfort such as the damping force disappears.

As such, in the conventional front fork, depending on the setting of the compression-side orifice, a stable compression-side damping force may not be generated, and the range in which the size of the compression-side orifice can be changed is limited. The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a front fork capable of freely setting a compression-side orifice and generating a stable damping force.

The front fork for solving the above problems is provided with: a piston portion that is provided on the inner tube on the vehicle body side and that divides a space between the outer tube on the wheel side and the cylinder provided inside thereof into an extension-side chamber and a lower chamber; a cover fixed to an upper end of the cylinder and separating an inner chamber of the cylinder, which forms a compression-side chamber together with the lower chamber, from the liquid storage chamber; an extension-side damping element that applies resistance to a flow of liquid from the extension-side chamber to the compression-side chamber; a compression-side orifice for communicating the compression-side chamber with the reservoir chamber; an extension-side check valve that allows fluid to flow from the reservoir chamber to the compression-side chamber; and a compression-side check valve that allows fluid to flow from the reservoir chamber or the compression-side chamber to the extension-side chamber.

Drawings

Fig. 1 is a side view showing a simplified state of attachment of a front fork according to an embodiment of the present invention.

Fig. 2 is a longitudinal sectional view of a front fork according to an embodiment of the present invention.

Fig. 3 is a longitudinal sectional view showing a part of fig. 2 in an enlarged manner.

Fig. 4 is an enlarged plan view of a cover of a front fork according to an embodiment of the present invention.

Fig. 5 is a longitudinal sectional view showing a modification of the front fork according to the embodiment of the present invention, and showing a modified portion thereof in an enlarged manner.

Detailed Description

A front fork according to an embodiment of the present invention will be described below with reference to the drawings. The same reference numerals are used throughout the several drawings to designate the same or corresponding components. Further, the up and down when the front fork is mounted in the vehicle is simply referred to as "upper" and "lower" unless otherwise specified.

As shown in fig. 1, a front fork F according to an embodiment of the present invention is a suspension device for suspending a front wheel W in a saddle-type vehicle V. The saddle-ride type vehicle is a generic term for a type of vehicle that rides in a saddle-riding posture, and includes a motorcycle, a scooter, a bicycle, and the like. The front fork according to the present invention can be mounted on any saddle type vehicle.

Next, a specific structure of the front fork F according to an embodiment of the present invention will be described. The front fork F includes a telescopic pipe member T having an outer pipe 1 and an inner pipe 2. Further, the front fork F is upright, and the inner tube 2 is slidably inserted from the upper opening of the outer tube 1.

The wheel-side bracket BW is integrally provided on the outer tube 1, and the outer tube 1 is connected to the axle of the front wheel W via the wheel-side bracket BW. On the other hand, the inner tube 2 is connected to the vehicle body B via a bracket BB on the vehicle side connected to the upper end portion thereof.

In this way, the front fork F is attached between the vehicle body B and the axle of the front wheel W with the outer tube 1 disposed toward the front wheel (wheel) W and the inner tube 2 disposed toward the vehicle body B. When the front wheel W vibrates vertically while the saddle-ride type vehicle V is traveling on an uneven road surface, the inner tube 2 is inserted into and removed from the outer tube 1, and the front fork F expands and contracts.

Next, the upper end opening of the inner tube 2 is closed with a cap (not shown). On the other hand, as shown in fig. 2, the outer tube 1 has a bottomed cylindrical shape, and the lower opening of the outer tube 1 is closed by a bottom portion 1a thereof. Further, the space between the overlapping portions of the outer pipe 1 and the inner pipe 2 is blocked by the oil seal 10 and the dust seal 11. As such, the interior of the tube member T is a closed space, and the liquid and gas are enclosed in this tube member T.

Further, the cylinder 3 is coupled to the bottom 1a of the outer pipe 1 by a bolt 30. The cylinder 3 includes a cylindrical portion 3a and an annular valve body portion 3b extending radially outward from a tip end of the cylindrical portion 3 a. The cylindrical portion 3a is erected in the axial direction at the center of the outer tube 1, and the valve body portion 3b is inserted into the inner tube 2 so as to be movable in the axial direction. Further, a cap 4 for closing the upper end of the cylinder 3 is stacked on the upper end of the valve body 3 b.

Thus, in the pipe member T, a reservoir chamber R is formed on the inner peripheral side of the inner pipe 2 and on the upper side of the valve body 3b and the cover 4, an in-cylinder chamber I is formed on the inner peripheral side of the cylinder 3 and on the lower side of the cover 4, and a cylindrical gap (not shown) is formed between the cylinder 3 and the outer pipe 1. Then, the cylindrical gap and the cylinder inner chamber I are filled with a liquid such as hydraulic oil. On the other hand, the same liquid as the above-described liquid is stored in the liquid storage chamber R, and a gas such as air is sealed above the liquid surface.

The cylindrical gap between the outer pipe 1 and the cylinder 3 is divided into an upper extension side chamber L1 and a lower chamber O by a piston portion 20 provided at the lower end portion of the inner pipe 2. The lower chamber O communicates with the cylinder inner chamber I through a communication hole 3c formed in the lower end portion of the cylinder 3, and constitutes a compression-side chamber L2 together with the cylinder inner chamber I. In other words, the lower chamber O and the cylinder inner chamber I can function as a connected chamber (compression side chamber L2), and the liquid can freely reciprocate between the lower chamber O and the cylinder inner chamber I after passing through the communication hole 3c of the cylinder 3.

Further, an extension-side orifice 3d is formed in the cylinder 3 at an upper portion of the cylindrical portion 3a, and the extension-side chamber L1 and the cylinder inner chamber I communicate with each other through the extension-side orifice 3 d. When the front fork F extends, the fluid flows through the extension-side orifice 3d from the extension-side chamber L1 to the cylinder inner chamber I, and resistance is applied to this flow.

Next, as shown in fig. 3, an annular valve housing gap 20a is formed on the inner periphery of the piston portion 20. An annular valve 5 which is in sliding contact with the outer periphery of the cylindrical portion 3a of the cylinder 3 is inserted into this valve housing gap 20a movably in the axial direction. In the piston portion 20, a portion opposed to the lower end of the valve 5 is a seating surface 20b, and the valve 5 is seated on or separated from this seating surface 20 b.

Further, when the front fork F contracts, the valve 5 is separated from the valve seat surface 20b, and the liquid is allowed to flow from the lower chamber O to the extension side chamber L1 after passing through the outer peripheral side of the valve 5. On the other hand, when the front fork F extends, the valve 5 is seated on the seat surface 20b, and the liquid flows from the extension-side chamber L1 to the lower chamber O after passing through the sliding gap between the valve 5 and the cylinder 3 without passing through the outer peripheral side of the valve 5. Since the sliding gap is a very narrow gap, resistance is applied to the flow of the liquid flowing from the extension side chamber L1 to the lower chamber O.

As described above, the lower chamber O and the cylinder inner chamber I communicate with each other, and they become a part of the compression-side chamber L2. That is, the extension side orifice 3d and the valve 5 both function as an extension side damping element that applies resistance to the flow of liquid from the extension side chamber L1 to the compression side chamber L2 when the front fork F extends. Further, the valve 5 also functions as a compression-side check valve that opens when the front fork F contracts and allows liquid to flow from the compression-side chamber L2 to the extension-side chamber L1.

Further, an extension spring 21 is laminated on the upper side of the piston portion 20. When the front fork F is maximally extended, the extension spring 21 is compressed between the piston portion 20 and the valve body portion 3b, thereby absorbing the impact at the time of maximum extension. The tension spring 21 shown in fig. 2 is a coil spring, but may be a spring other than a coil spring. Further, instead of the tension spring 21, a cushion rubber or the like may be provided, and the cushion rubber may be used to cushion the impact when the front fork F is maximally extended.

Next, an annular valve accommodating groove 3e is formed on the outer periphery of the valve body portion 3b formed at the upper end portion of the cylinder 3. Further, an annular compression-side check valve 6 which is in sliding contact with the inner periphery of the inner tube 2 is inserted axially movably inside this valve receiving groove 3 e. Further, a portion of the wall surface of the valve housing groove 3e that faces the upper end of the compression-side check valve 6 is a seat surface 3f, and the compression-side check valve 6 is seated on or separated from this seat surface 3 f.

When the front fork F contracts, the compression-side check valve 6 separates from the valve seat surface 3F, and allows the fluid to flow from the reservoir chamber R to the expansion-side chamber L1 after passing through the inner peripheral side of the compression-side check valve 6. On the contrary, when the front fork F extends, the compression-side check valve 6 is seated on the seat surface 3F, and communication between the reservoir chamber R and the extension-side chamber L1 is blocked.

Further, as shown in fig. 3 and 4, the cover 4 stacked on the upper side of the valve body 3b includes: an annular valve seat portion 4 a; an annular leg portion 4b projecting downward from a lower end outer peripheral portion of the valve seat portion 4 a; an annular boss portion 4c projecting upward from an upper end inner peripheral portion of the valve seat portion 4 a; and a plurality of branch portions 4d that protrude upward from the valve seat portion 4a and radially extend from the boss portion 4c toward the outer peripheral side of the cover 4. Fig. 3 shows a cross section of the cover 4 along the line X-X in fig. 4.

In this way, the suspension spring S formed of a coil spring is fitted to the outer periphery of the plurality of branch portions 4d extending radially. The cap 4 is pressed against the valve body 3b by the suspension spring S, and is fixed so that the tip of the leg portion 4b does not separate from the valve body 3 b.

Therefore, the lower end of the suspension spring S is always supported by the cylinder 3 through the cover 4. On the other hand, the upper end of the suspension spring S is supported by a cap (not shown) for closing the upper end of the inner tube 2. That is, it can be said that the suspension spring S in the present embodiment is interposed between the cylinder 3 and the inner tube 2.

Also, when the inner tube 2 enters the outer tube 1 so that the front fork F contracts, the amount of compression of the suspension spring S increases, and the spring force of the suspension spring S against the compression increases. As a result, the suspension spring S exerts an elastic force corresponding to the amount of compression thereof, and urges the front fork F in the extending direction so as to elastically support the vehicle body B.

Further, a port 4e is formed in the cover 4, which is open on the outer peripheral side of the boss portion 4c, that is, between the

adjacent branch portions

4d and 4d, and on the inner side of the leg portion 4b, and communicates the reservoir chamber R and the cylinder inner chamber I, and an extension side check valve 7 which is seated on or separated from the lower side of the seat portion 4a to open and close the port 4e is laminated on the cover 4.

Also, when the front fork F is extended, the extension-side check valve 7 moves away from the valve seat portion 4a to open the port 4e, and allows the liquid to flow from the reservoir chamber R to the cylinder inner chamber I after flowing through this port 4 e. On the contrary, when the front fork F contracts, the extension-side check valve 7 is seated on the seat portion 4a and maintains a state of closing the port 4 e.

Further, one or more holes penetrating the leg portion 4b in the radial direction are formed in the leg portion 4b of the cover 4, and the compression-side orifice 4f is formed by the holes. Further, the outer diameter of the cap 4 is smaller than the inner diameter of the inner tube 2, and an annular gap is formed between the cap 4 and the inner tube 2.

Therefore, the opening of the compression-side orifice 4f is not blocked by the inner tube 2, and the reservoir chamber R and the cylinder inner chamber I communicate via the compression-side orifice 4 f. And also. When the front fork F contracts, the fluid flows from the cylinder inner chamber I to the reservoir chamber R through the compression-side orifice 4F, and resistance is applied to this flow.

Next, the operation of the front fork F according to an embodiment of the present invention will be described.

When the inner tube 2 is withdrawn from the outer tube 1 and the front fork F is elongated, the inner tube 2 is withdrawn from the cylindrical gap between the outer tube 1 and the cylinder 3, and the piston portion 20 moves upward in this gap to contract the elongation side chamber L1 and expand the lower chamber O.

When the front fork F extends, the liquid in the reduced extension-side chamber L1 moves into the cylinder inner chamber I through the extension-side orifice 3d, and moves into the enlarged lower chamber O through the sliding gap between the valve 5 and the cylinder 3. At this time, the liquid in the cylinder inner chamber I flows into this lower chamber O through the communication hole 3c, and the extension-side check valve 7 opens to supply the liquid from the reservoir chamber R into the cylinder inner chamber I.

In the extension stroke of the front fork F, resistance is applied to the flow of the liquid flowing from the extension side chamber L1 to the cylinder inner chamber I and the lower chamber O (compression side chamber L2) through the extension side orifice 3d and the valve 5. Therefore, when the front fork F is extended, the pressure in the extension side chamber L1 rises, and an extension side damping force for obstructing the extension action of the front fork F is generated.

In contrast, when the inner tube 2 enters the outer tube 1 and the front fork F contracts, the inner tube 2 enters a cylindrical gap between the outer tube 1 and the cylinder 3, and the piston portion 20 moves downward in this gap to contract the lower chamber O and expand the extension side chamber L1.

When the front fork F contracts, the valve 5 and the compression-side check valve 6 open, and the liquid in the contracted lower chamber O and the liquid in the liquid reservoir chamber R flow into the expanded expansion-side chamber L1. Further, when the front fork F contracts, at least the volume amount of the liquid of the inner tube 2 that has entered remains in the cylindrical clearance between the outer tube 1 and the cylinder 3, and this remaining amount of liquid moves from the lower chamber O into the cylinder inner chamber I through the communication hole 3c, and is discharged from the cylinder inner chamber I into the reservoir chamber R through the compression-side orifice 4F.

In the contraction stroke of the front fork F, the compression-side orifice 4F applies resistance to the flow of the liquid flowing from the cylinder inner chamber I (compression-side chamber L2) to the reservoir chamber R. Therefore, when the front fork F contracts, the pressure in the compression-side chamber L2 rises, and a compression-side damping force for obstructing the contraction action of the front fork F is generated.

In the present embodiment, the cylinder inner chamber I located inside the cylinder 3 is a part of the compression-side chamber L2, and the pressure in the cylinder inner chamber I increases during the contraction stroke of the front fork F. Therefore, in the contraction stroke, the liquid is supplied from the cylinder inner chamber I to the enlarged expansion side chamber L1 after passing through the expansion side orifice 3 d. Therefore, in the subsequent extension stroke, the pressure in the extension side chamber L1 is easily raised, and the generation responsiveness of the extension side damping force is improved.

Further, in the present embodiment, the compression-side orifice 4f is formed laterally in the radial direction of the cap 4, and the opening of the compression-side orifice 4f is opposed to the inner peripheral surface of the inner tube 2. Therefore, the liquid flowing from the cylinder inner chamber I to the reservoir R is not ejected toward the liquid surface of the reservoir R. Therefore, the liquid in the reservoir chamber R is hardly foamed.

When the liquid in the liquid reservoir chamber R is foamed, when the liquid is sucked from the liquid reservoir chamber R into the extension side chamber L1 or the compression side chamber L2 in the contraction stroke of the front fork F, the bubbles in the liquid reservoir chamber R are sucked together with the liquid, which also becomes a cause of a decrease in the generation responsiveness of the damping force. However, as described above, if the liquid in the reservoir chamber R can be suppressed from foaming, it is possible to suppress a decrease in the responsiveness of the generation of the damping force due to the mixing of the air bubbles.

The operation and effect of the front fork F according to the embodiment of the present invention will be described below.

The front fork F in the present embodiment includes: an outer tube 1 on the front wheel (wheel) W side; an inner tube 2 on the vehicle B side, which is slidably inserted into the outer tube 1; a cylinder 3 disposed in the outer tube 1 and having an upper end movably inserted into the inner tube 2; and a piston portion 20 that is provided on the inner tube 2 and divides a space between the outer tube 1 and the cylinder 3 into an extension-side chamber L1 and a lower chamber O.

The front fork F in the present embodiment includes a cover 4 fixed to the upper end of the cylinder 3, and the cover 4 separates the reservoir R on the upper side of the cylinder 3 from the cylinder inner chamber I inside the cylinder 3. The cylinder inner chamber I constitutes a compression-side chamber L2 together with the lower chamber O on the outer peripheral side of the cylinder 3.

Further, the front fork F in the present embodiment includes: an extension-side orifice (extension-side damping element) 3d and a valve (extension-side damping element) 5 that apply resistance to the flow of liquid from the extension-side chamber L1 to the compression-side chamber L2; a compression-side orifice 4f that applies resistance to the flow of liquid from the compression-side chamber L2 to the reservoir chamber R; an extension-side check valve 7 that allows fluid to flow from the reservoir chamber R to the compression-side chamber L2; a valve (compression-side check valve) 5 that allows liquid to flow from the reservoir chamber R or the compression-side chamber L2 to the expansion-side chamber L1 and a compression-side check valve 6.

According to the above structure, even if the compression-side orifice 4F is reduced in order to adjust the compression-side damping force, liquid can be supplied from the reservoir chamber R to the compression-side chamber L2 through the extension-side check valve 7 during the extension stroke of the front fork F. Therefore, even if the compression-side orifice 4f is reduced, the compression-side chamber L2 does not become negative pressure in the extension stroke, and the compression-side damping force can be quickly increased in the subsequent compression stroke.

That is, according to the above configuration, a stable damping force can be generated immediately after the switching from the extension stroke to the compression stroke regardless of the setting of the compression-side orifice 4 f. Therefore, in the front fork F according to the present embodiment, the compression-side orifice 4F can be freely set, and a stable damping force can be generated.

Further, for example, when a compression-side damping force is generated using an open-close type valve and the valve is biased in a closing direction by a suspension spring, the generated compression-side damping force changes in accordance with the stroke position of the front fork (the position of the piston portion). Further, the damping force characteristic on the compression side also varies depending on the specification of the suspension spring. Further, when the valve seat surface of this valve is large, the pressure in the compression-side chamber may sharply decrease with the open valve of the valve as a boundary, and the damping force may also sharply change.

On the other hand, according to the above configuration, since the compression-side damping force can be generated using the compression-side orifice 4F, a stable damping force can be generated over the entire stroke region of the front fork F. Further, since the flow passage area of the compression side orifice 4f is changed to adjust the compression side damping force, the change can be easily performed, and therefore, according to the above configuration, the compression side damping force can be easily adjusted.

The front fork F in the present embodiment includes an extension-side orifice 3d formed in the cylinder 3 and a valve 5 attached to the piston portion 20 as an extension-side damping element that applies resistance to the flow of liquid outward from the extension-side chamber L1. However, one of the expansion-side orifice 3d and the valve 5 may be omitted, and the structure of the expansion-side damping element may be appropriately changed.

Further, in the present embodiment, the compression-side check valve 6 attached to the valve body 3b of the cylinder 3 and the valve 5 attached to the piston portion 20 are provided as the compression-side check valve for sucking the liquid into the expansion-side chamber L1. However, one of the compression-side check valve 6 and the valve 5 may be omitted, and the structure of the compression-side check valve may be appropriately changed.

In the present embodiment, the compression-side orifice 4f is open toward the inner peripheral surface of the inner tube 2. Therefore, in the contraction stroke of the front fork F, the liquid flowing from the cylinder inner chamber I to the reservoir R is not ejected toward the liquid surface of the reservoir R, and foaming of the liquid in the reservoir R can be suppressed. Therefore, the air bubbles can be suppressed from being mixed into the expansion side chamber L1 and the compression side chamber L2, and the reduction in the generation responsiveness of the damping force due to the air bubbles can also be suppressed.

However, the opening direction of the compression-side orifice 4f is not limited to the above-described direction, and may be appropriately changed. In the present embodiment, the compression-side orifice 4f is formed by a hole formed in the cover 4, but the configuration and arrangement of the compression-side orifice 4f may be appropriately changed. For example, a radial slit may be formed at the lower end of the leg portion 4b, which is the opposing portion between the cap 4 and the cylinder 3, or at the upper end of the valve body portion 3b, and a compression-side orifice may be formed by this slit.

Moreover, such a change is possible regardless of the structures of the extension-side damping element and the compression-side check valve.

In the present embodiment, the cover 4 is stacked on the upper end of the cylinder 3 and is pressed and fixed to the cylinder 3 by a suspension spring (coil spring) S for elastically supporting the vehicle body B. In this way, in the present embodiment, the cover 4 and the cylinder 3 are formed separately, and the cover 4 can be fixed to the cylinder 3 by the urging force of the suspension spring S.

According to the above structure, after the cylinder 3 is fixed to the inside of the outer tube 1 by the bolts 30 and the liquid is injected into the cylinder 3, the cover 4 can be fixed to the cylinder 3 by the suspension spring S. Therefore, in the assembling process of the front fork F, since the liquid can be injected without closing the cylinder 3 with the cap 4, the liquid injection work can be performed quickly.

Further, in the present embodiment, the suspension spring (coil spring) S is fitted to the cover 4. According to this configuration, as described above, when the cap 4 is fixed to the cylinder 3 by the suspension spring S after the liquid is injected into the cylinder 3, the cap 4 can be prevented from being displaced from the cylinder 3. Therefore, according to the above configuration, the assembling work of the front fork F can be easily performed.

Further, in the present embodiment, the cover 4 includes: an annular valve seat portion 4 a; an annular leg portion 4b projecting downward from a lower end outer peripheral portion of the valve seat portion 4 a; an annular boss portion 4c projecting upward from an upper end inner peripheral portion of the valve seat portion 4 a; and a plurality of branch portions 4d that protrude upward from the valve seat portion 4a and radially extend from the boss portion 4c toward the outer peripheral side of the cover 4.

Further, ports 4e for communicating the reservoir chamber R and the cylinder inner chamber I are formed in the cover 4, and are opened on the outer peripheral side of the boss portion 4c, i.e., between the

adjacent branch portions

4d and 4d, and on the inner side of the leg portion 4b, respectively. The expansion-side check valve 7 is seated on or separated from the lower side of the seat portion 4a so as to open and close the port 4e, and a suspension spring (coil spring) S is fitted so as to integrally surround the outer periphery of the plurality of branch portions 4 d.

According to the above configuration, since the port 4e is opened on the inner peripheral side of the suspension spring (coil spring) S, even if the suspension spring (coil spring) S is fitted to the cover 4, the port 4e can be prevented from being blocked by the suspension spring S. Further, since the port 4e can be disposed on the outer peripheral side of the cover 4, the flow path area of the port 4e is easily increased, and the suction shortage of the compression-side chamber L2 caused in the extension stroke of the front fork F can be reliably prevented.

However, the structure of the cover 4 is not limited to the above-described structure, and may be appropriately changed. For example, although four branch portions 4d and four ports 4e are formed in the present embodiment, the number of branch portions 4d and ports 4e may be freely changed. Further, the state in which the cover 4 is fixed to the cylinder 3 means a state in which the cover 4 is not separated from the cylinder 3 during the expansion and contraction operation of the front fork F, and the configuration in which this state is formed can be appropriately changed.

Specifically, as shown in fig. 5, the cover 4 may be screwed and fixed to the cylinder 3. In addition, when the cap 4 is fixed to the cylinder 3 without using the biasing force of the suspension spring S, the configuration and arrangement of the suspension spring S can be changed. For example, the suspension spring S may be a spring other than a coil spring, such as an air spring or the like. Further, a suspension spring S may be installed between the lower end of the inner tube 2 and the bottom 1a of the outer tube 1.

Moreover, these modifications are possible regardless of the configuration of the expansion-side damping element, the compression-side check valve, and the compression-side orifice.

While the preferred embodiments of the present invention have been illustrated in detail, modifications, variations and changes may be made without departing from the scope of the claims.

The present application claims priority based on patent application 2018-123915 filed from the sun to the franchise on 29.6.2018, the entire content of which is incorporated by reference in the present specification.

Claims

1. A front fork is provided with a front fork body,

it is provided with:

an outer tube on a wheel side;

an inner tube on a vehicle body side slidably inserted into the outer tube;

a cylinder disposed inside the outer pipe and having an upper end movably inserted into the inner pipe;

a piston portion provided on the inner pipe and dividing a space between the outer pipe and the cylinder into an extension-side chamber and a lower chamber;

a cover fixed to an upper end of the cylinder and separating a liquid storage chamber formed on an upper side of the cylinder from an inner chamber of the cylinder formed inside the cylinder and constituting a compression-side chamber together with the lower chamber;

an extension-side damping element that applies resistance to a flow of liquid from the extension-side chamber to the compression-side chamber;

a compression-side orifice for communicating the compression-side chamber with the reservoir chamber;

an extension-side check valve that allows fluid to flow from the reservoir chamber to the compression-side chamber;

and a compression-side check valve that allows fluid to flow from the reservoir chamber or the compression-side chamber to the extension-side chamber.

2. The front fork as set forth in claim 1,

wherein the content of the first and second substances,

the compression-side orifice opens toward the inner peripheral surface of the inner tube.

3. The front fork of claim 1

Wherein the content of the first and second substances,

the cover is stacked on the upper end of the cylinder and is pressed and fixed on the cylinder by a coil spring for elastically supporting the vehicle body.

4. The front fork as set forth in claim 3,

wherein the content of the first and second substances,

fitting the coil spring to the lid.