JP2008240840A - Front fork - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To contribute to reduction of product cost while eternally easily ensuring exertion of damping action and suppression of bottom thrust. <P>SOLUTION: An outer periphery of a spring receiver 8 for engaging an upper end of a suspension spring 7 for urging a fork body built-in with a damper in an extension direction is slide-contacted with an inner periphery of a wheel side tube 2, and between an inner periphery of the vehicle body side tube 1 forming the fork body and an outer periphery of the wheel side tube 2 similarly forming the fork body, a clearance S made to a flow passage of an operation oil and having upper and lower ends shut-off from the outside is provided. An upper end side part in the wheel side tube 2 positioned in the vehicle body side tube 1 has a plurality of communication holes 2b for allowing communication of the inside of the wheel side tube 2 and the outside of the wheel side tube 2 with the above clearance S along an axial direction of the upper end side part when the fork body is in the longest extension state. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a front fork, and more particularly, to an improvement in a front fork that is a hydraulic shock absorber that is mounted on a front wheel side of a two-wheeled vehicle and absorbs road surface vibrations input to the front wheel while the front wheel is suspended.

  There have been various proposals for a front fork as a hydraulic shock absorber that is mounted on the front wheel side of a motorcycle and absorbs road surface vibrations that are input to the front wheel while suspending the front wheel. Document 1 discloses a proposal of a front fork that makes it possible to realize a damping action depending on the contraction position during contraction operation, and to prevent so-called bottom bumping at the time of maximum contraction.

  That is, the front fork disclosed in Patent Document 1 uses a cylinder body as an upper end side member in an axial center portion in a fore body in which a wheel side tube is inserted in a vehicle body side tube so as to be able to protrude and retract. On the other hand, it is assumed that an inverted type damper having the rod body that appears and disappears as a lower end side member is installed.

  In the front fork, the fork main body is energized in the extending direction while being accommodated in the fork main body, that is, a suspension spring for energizing the wheel side tube in the direction of projecting from the vehicle body side tube. In other words, the lower end is carried on the upper end of a spring receiver made of a cylindrical body arranged around the damper.

  By the way, the cylindrical body is erected on the shaft core portion of the wheel side tube, so that the upper end portion, which is a free end portion, is adjacent to the head portion of the cylinder body forming the damper.

  Further, in this front fork, the cylinder body has a plurality of communication holes in the vertical direction which is the axial direction of the cylinder body, and allows the outer periphery of the cylinder body to be connected to the cylinder body. It is assumed that the partition body slidably contacted with the inner periphery is slidably accommodated, and this partition body is held by the head portion.

  On the other hand, in this front fork, the lower end portion of the cylinder body is an oil lock case in an oil lock mechanism, and the partition body held by the head portion is inserted into the oil lock case. It is supposed to be an oil lock piece in the lock mechanism.

  Therefore, in the front fork disclosed in Patent Document 1, the damper is contracted in synchronization with the contraction operation of the fork main body. At this time, the partition body held by the head portion of the cylinder body is the cylindrical body. Will descend.

  In this front fork, the number of communication holes that allow communication between the inside of the cylinder and the outside of the cylinder gradually decreases as the partition wall descends inside the cylinder, and therefore, the hydraulic oil inside the cylinder is removed from the outside of the cylinder. The resistance when flowing out gradually increases.

  As a result, in this front fork, it becomes possible to embody the damping action depending on the contraction position of the fork body, and the damping action becomes so large that the contraction action becomes the latter half.

On the other hand, when the fork main body is contracted and reaches the most contracted state, the oil lock piece made of the partition body held by the head portion of the damper is inserted into the oil lock case made of the lower end portion of the cylinder. At this time, an oil lock phenomenon is generated in the oil lock case, so that further contraction of the fork main body can be prevented, and so-called bottom bumping of the front fork can be prevented.
JP 2005-257066 (abstract, paragraphs 0005, 0009, 0012, 0013, FIG. 1 in the specification)

  However, in the front fork proposed in the above-mentioned Patent Document 1, there is a possibility that it may be pointed out that there is a slight problem when it is realized, that is, when it is commercialized.

  That is, in the above-described proposed front fork, a plurality of communication holes of the cylindrical body are closed by a partition body sliding in the cylindrical body, thereby enabling realization of a large damping action. The above-mentioned partition body is used as an oil lock piece in the oil lock mechanism and is fitted into a lower end portion of a cylinder that is also an oil lock case in the oil lock mechanism, thereby preventing bottom butt.

  Therefore, in the above-mentioned front fork, the bulkhead body has two functions, and as a result, precise dimensional management is required in the production of the parts, resulting in a reduction in the cost of the parts. It may be pointed out that it will hinder product cost reduction.

  On the other hand, in the above-mentioned front fork, since the partition body is configured to participate in both the damping action and the bottom bump prevention, for example, when a malfunction such as wear occurs in the partition body, the damping action It may be pointed out that the so-called risk is too great.

  The present invention was devised in view of such circumstances, and the object of the present invention is to make it easy to permanently guarantee the realization of a predetermined damping action and the prevention of bottom strike, and to reduce the product cost. The objective is to provide a front fork that can contribute to cost reduction and is optimal for improving its versatility.

  In order to achieve the above-described object, the structure of the front fork according to the present invention basically includes a shaft in an inverted fork main body in which the outer tube is a vehicle body side tube and the inner tube is a wheel side tube. The core has an inverted damper with the cylinder body serving as the upper end side member and the rod body serving as the lower end side member. A suspension spring comprising a coil spring in the fork body has a lower end at the lower end of the wheel side tube. The upper end of the fork main body is urged in the extending direction by being held on the inner bottom portion with a spring holder fixedly held on the outer periphery of the cylinder body forming the damper, and the inner bottom portion of the wheel side tube and this In the front fork having an oil lock mechanism between the cylinder body head portion facing the inner bottom portion, the outer periphery of the spring support is the inner periphery of the wheel side tube. When the fork main body is in the most extended state, it is slidably contacted and has a gap where the upper and lower ends are cut off from the outside while being the flow path of the hydraulic oil between the inner periphery of the vehicle body side tube and the outer periphery of the wheel side tube The upper end side portion of the wheel side tube positioned in the vehicle body side tube has a communication hole that allows communication between the inside of the wheel side tube and the above-mentioned gap outside the wheel side tube along the axial direction of the upper end side portion. Suppose you have more than one.

  Therefore, in the present invention, since the fork main body has a damper inside and an oil lock mechanism, a predetermined damping action is realized by the damper when the fork main body is contracted, and the oil lock A so-called bottom thrust when the fork main body contracts most is prevented by the mechanism.

  And in this invention, when the fork main body is in the most extended state, the upper end side portion of the wheel side tube positioned in the vehicle body side tube is in communication with the inside of the wheel side tube and the outside of the wheel side tube, And a plurality of communication holes that allow communication with a gap formed between the vehicle body side tube and the wheel side tube along the axial direction of the upper end side portion, and when the fork body is contracted, the wheel side Since the number of communication holes that allow communication between the gap and the wheel-side tube gradually decreases due to the lowering of the spring bearing that is in sliding contact with the inner periphery of the tube, the operation in the wheel-side tube is reduced as the fork body contracts. The resistance when oil flows out into the gap is gradually increased.

  As a result, in the present invention, it becomes possible to realize a damping action depending on the contraction position of the fork main body, and a damping action that is so large that the second half of the contraction action is expressed in the second half. Become.

  As a result, according to the present invention, it is possible to realize the damping action depending on the expansion / contraction position and to prevent bottom impact at the time of the most contraction, since the common part is not used, and the common part is used. There is an advantage that the so-called risk can be reduced.

  In addition, in the present invention, since the communication hole which is an element in realizing the position-dependent damping action is formed in the wheel side tube, another member for providing this communication hole is provided. There is no need, and this can enable a reduction in the number of components, a reduction in product weight and a reduction in product cost.

  Hereinafter, the present invention will be described based on the illustrated embodiment. A front fork according to the present invention is mounted on the front wheel side of a two-wheeled vehicle and absorbs road surface vibrations input to the front wheel while suspending the front wheel. A shaft in an inverted fork main body (not shown) in which an outer tube is a vehicle body side tube 1 and an inner tube is a wheel side tube 2 as shown in FIG. It is assumed that the core body has an inverted type damper (not shown) in which the cylinder body 3 is an upper end side member and the rod body 4 is a lower end side member.

  At this time, in the front fork, the inside of the fork body which is the outside of the damper is set as the reservoir chamber R, and the reservoir chamber R has an air chamber A with the oil level O as a boundary. The air chamber A expands and contracts when the fork main body expands and contracts to exert an air spring force.

  In this front fork, a gap S is formed between the inner circumference of the vehicle body side tube 1 and the outer circumference of the wheel side tube 2, and this gap S is the lower end of the vehicle body side tube 1. A bearing member 5 disposed on the inner circumference of the wheel-side tube 2 and slidably contacting the outer circumference of the wheel-side tube 2; and a bearing member 6 disposed on the inner circumference of the upper end portion of the wheel-side tube 2 and slidably contacting the inner circumference of the vehicle-body-side tube 1; It is said that it is cut off from the outside, that is, is so-called closed.

  Incidentally, in the fork body of the kind that has the vehicle body side tube 1 and the wheel side tube 2, it is normal that the gap S is formed, but in the present invention, as will be described later. In addition, the gap S is actively used as a flow path for hydraulic oil.

  In the front fork, the suspension spring 7 including a coil spring accommodated in the fork main body is a cylinder body in which the lower end is supported on the bottom portion 2a which is the inner bottom portion of the wheel side tube 2 and the upper end forms a damper. The fork main body is urged in the extending direction by being locked by a spring receiver 8 fixedly held on the outer periphery of 3.

  At this time, since the outer periphery of the spring receiver 8 is in sliding contact with the inner periphery of the wheel-side tube 2, the upper and lower side communication of the spring receiver 8 is cut off. ) And a damping valve 9 in the passage. The damping valve 9 has a check valve 10, that is, hydraulic oil from above the spring receiver 8 flows out below the spring receiver 8. The check valve 10 is allowed to be provided, but the check valve 10 for preventing the reverse flow is provided.

  Therefore, in this spring receiver 8, when the fork main body is contracted and thus the damper is contracted, the fork body is lowered in the wheel side tube 2 while sliding on the inner periphery of the wheel side tube 2. Therefore, the hydraulic oil in the wheel side tube 2 flows out to the reservoir chamber R through the damping valve 9, and at this time, a predetermined damping action by the damping valve 9 can be realized. It will be.

  The oil surface O is positioned above the spring receiver 8 when the fork main body is in the most extended state as shown in the figure. In short, the above-described damping of the spring receiver 8 is included. It is sufficient that the valve 9 and the check valve 10 are in an oil-immersed state during the contraction of the fork main body. Therefore, it is not always necessary to position the valve 9 and the check valve 10 above the spring receiver 8.

  Further, the front fork has an oil lock mechanism (not shown) between the bottom portion 2a of the wheel side tube 2 and the head portion 3a in the cylinder body 3 facing the bottom portion 2a. The oil lock mechanism includes an oil lock piece 11 that is held by the head portion 3 a of the cylinder body 3 and protrudes toward the bottom portion 2 a of the wheel side tube 2, and a bottom portion 2 a of the wheel side tube 2. The oil lock case 12 is arranged and opened toward the head portion 3 a of the cylinder body 3.

  Therefore, in this front fork, when the fork main body contracts most and the head portion 3a of the cylinder body 3 collides with the bottom portion 2a of the wheel side tube 2, the head portion 3a of the cylinder body 3 is obtained. The oil lock piece 11 held in the oil lock case 12 is fitted into the oil lock case 12 disposed in the bottom portion 2a of the wheel side tube 2, and at this time, an oil lock phenomenon is expressed in the oil lock case 12, Further contraction of the fork main body is prevented, and so-called bottom thrust in the front fork is prevented.

  In the oil lock mechanism described above, the check valve 12a, that is, hydraulic oil outside the oil lock case 12 flows into the oil lock case 12 through the bottom portion 2a into the bottom portion 2a of the wheel side tube 2. However, the check valve 12a is provided to prevent the reverse flow.

  By the way, the damper disposed in the shaft core portion of the fork main body, as shown in the figure, is a rod body in which the cylinder body 3 is vertically suspended from the shaft core portion of the vehicle body side tube 1 and is inserted into the cylinder body 3 so as to be able to protrude and retract. 4 is erected on the shaft core portion of the wheel side tube 2.

  The damper is slidably accommodated in the cylinder body 3, and the rod side oil chamber (not shown) and the piston side oil chamber R1 are defined in the cylinder body 3 while defining the rod. The piston body 13 held at the upper end of the body 4 allows the flow of the hydraulic oil from the piston side oil chamber R1 to the rod side oil chamber, that is, the check valve 13b parallel to the damping valve 13a and the damping valve 13a. Is provided with a check valve 13b for preventing the reverse flow.

  Further, in this damper, a so-called base valve portion 14 is fixed inside a barrel portion (not shown) which is an upper end side portion in the drawing of the cylinder body 3. A portion 14 is a damping valve 14a and a check valve 14b parallel to the damping valve 14a, that is, an upper side of the base valve portion 14 in the figure, and a piston from a chamber R2 that can communicate with the reservoir chamber R described above. A check valve 14b that allows the flow of hydraulic oil toward the side oil chamber R1 but prevents the reverse flow is provided.

  Further, in this damper, it is assumed that the above-described chamber R2 has a free piston 15, and this free piston 15 is provided with an urging spring 15a disposed on the rear side which is the upper side in the drawing. It is assumed that it is energized in the forward direction, which is the downward direction in the figure by the spring force, and retracts so as to rise in the figure by the hydraulic action on the pressure receiving surface (not shown) which is the lower face in the figure. When the amount increases, the open communicating hole 3b is opened in the cylinder body 3, and hydraulic fluid from the container chamber R2 is allowed to flow out toward the reservoir chamber R through the communicating hole 3b.

  Therefore, in the damper formed as described above, the piston body 13 is slid in the cylinder body 3 during the expansion and contraction operation of the fork main body, and the damping valve 13a and the base valve section 14 arranged on the piston body 13 are located. A predetermined damping action is realized by the damping valve 14a in FIG.

  When the amount of hydraulic oil in the cylinder body 3 increases for some reason such as an increase in the oil temperature of the hydraulic oil, the free piston 15 moves backward to open the communication hole 3b formed in the cylinder body 3. In other words, so-called surplus hydraulic oil is allowed to flow out into the reservoir chamber R.

  On the other hand, in the front fork formed as described above, the outer periphery of the spring receiver 8 is in sliding contact with the inner periphery of the wheel side tube 2 as described above. 2 has a plurality of communication holes 2b on the upper end side (not shown).

  That is, as shown in the drawing, the upper end side portion of the wheel side tube 2 positioned in the vehicle body side tube 1 when the fork main body is in the most extended state includes the inside of the wheel side tube 2 and the outside of the wheel side tube 2. A plurality of communication holes 2b that allow communication with the above-described gap S are provided along the axial direction that is the vertical direction in the drawing of the upper end side portion.

  Therefore, in the front fork, as described above, when the fork main body contracts, the hydraulic oil in the wheel side tube 2 causes the damping valve 9 of the spring receiver 8 to be caused by the lowering of the spring receiver 8. However, when the dampening valve 9 is in resistance, the hydraulic oil in the wheel side tube 2 flows through the communication hole 2b to the wheel. It flows out into the clearance S outside the side tube 2.

  At this time, as the spring receiver 8 is lowered, the number of the communication holes 2b communicating the inside of the wheel side tube 2 and the gap S is reduced. The resistance when the hydraulic oil flows out into the gap S gradually increases.

  As a result, in the present invention, it becomes possible to realize a damping action depending on the contraction position of the fork main body, and a damping action that is so large that the second half of the contraction action is expressed in the second half. Become.

  In view of the above, the communication hole 2b has a distance, a number, and a size so that the two-wheeled vehicle on which the front fork of the present invention is mounted is on-road type or off-road type. You can select any setting you want.

  Incidentally, the hydraulic oil that has flowed out of the wheel-side tube 2 into the gap S through the communication hole 2b has become useless in the wheel-side tube 2, that is, communication that has become unnecessary from the viewpoint of a position-dependent damping action. It flows into the upper part of the spring receiver 8 through the hole 2b.

  By the way, even in the place disclosed in Patent Document 1 described above, since the plurality of communication holes are gradually closed according to the contraction operation of the fork main body, in realizing the position-dependent damping action, It can be said that there is basically no difference.

  However, as disclosed in the above-described Patent Document 1, a cylinder body in which a plurality of communication holes serving as elements for realizing a position-dependent damping action is a spring support, that is, a wheel-side tube. According to the present invention, since the plurality of communication holes 2b, which are elements for embodying the damping action, are formed in the wheel-side tube 2, according to this invention. There is no need to prepare, and this can reduce the number of components, thereby reducing the product weight and reducing the product cost.

  In addition, in the present invention, since the hydraulic oil in the wheel side tube 2 is based on the resistance when flowing out of the wheel side tube 2 through the communication hole 2a, the above-mentioned patent document Compared to the resistance when flowing out to the outside through a communication hole formed in the cylinder inside the wheel side tube 2 as in the proposal disclosed in FIG. It can be said that there is an advantage that generation of a large resistance can be expected as the value of increases.

  Further, since the spring receiver 8 in the present invention is not used as an oil lock piece forming an oil lock mechanism as proposed in the above-mentioned Patent Document 1, even if the spring receiver 8 is worn out. The oil lock mechanism does not affect the operation, and conversely, even if wear occurs on the oil lock piece in the oil lock mechanism, the function of the spring receiver 8 is not affected. Compared to the proposal disclosed in Patent Document 1 described above, there is an advantage that so-called risk is reduced.

  FIG. 2 shows a specific example of the spring receiver 8. The spring receiver 8 will be described below. First, the spring receiver 8 is formed in a downward funnel shape. The small diameter portion 8a, which is the upper end portion in the figure, is fixedly held on the outer periphery of the cylinder body 3.

  At this time, the spring receiver 8 is raised by the spring force when the upper end of the lower suspension spring 7 is brought into contact therewith. Therefore, in the drawing, the spring receiver 8 is attached to the outer periphery of the cylinder body 3. Further, the amount of rise is restricted by the stop ring 16, that is, it is held fixed.

  And this spring receiver 8 makes the outer periphery of the large diameter part 8b which is a lower end part in a figure slidably contact with the inner periphery of the wheel side tube 2, that is, in the figure, under the distribution of the bush member 17, the wheel side The inner periphery of the tube 2 is slidably contacted.

  In addition, the spring receiver 8 has a check valve 18 that prevents communication between the upper side and the lower side when it is raised on the inner periphery of the large-diameter portion 8b. It is assumed that the check valve 18 has an orifice 18a as a damping portion that performs a damping action when hydraulic fluid passes.

  Incidentally, the check valve 18 is formed in a ring seat shape interposed on the outer periphery of the cylinder body 3, and is formed on the inner periphery of the large-diameter portion 8 b with the stop ring 19 mounted on the outer periphery of the cylinder body 3. It is assumed that it is accommodated in the annular expanded diameter portion 8c so as to be movable up and down.

  The check valve 18 has a passage 18b having a notch in the outer peripheral portion that is in sliding contact with the inner periphery of the annular bulging portion 8c, as shown in the figure. When the check valve 18 rises in the annular bulge portion 8c, it is assumed that the check valve 18 is closed by a wall portion (not shown) of the annular bulge portion 8c. When it descends within 8c, it is supposed to be opened.

  Incidentally, the above-described orifice 18a as the attenuating portion is formed in the shape of a notch groove on the inner peripheral side portion of the check valve 18 as shown in the figure, but as long as it functions as a so-called orifice, Instead of this, although not shown, it is of course possible to form the check valve 18 so as to penetrate the so-called thickness.

  It should be noted that the spring sheet member 20 is attached to the lower end portion of the large-diameter portion 8b, and the upper end of the suspension spring 7 is not in direct contact with the lower end of the large-diameter portion 8b.

  Further, the spring receiver 8 has a communication hole 8d between the small diameter portion 8a and the large diameter portion 8b so that the communication between the upper and lower sides with the spring receiver 8 interposed therebetween is facilitated.

  Therefore, in the spring receiver 8, as in the spring receiver 8 shown in FIG. 1 described above, when the damper is contracted, the cylinder body 3 is integrated with the cylinder body 3 to move down. Therefore, the check valve 18 is maintained in the ascending state illustrated by the annular bulged portion 8c by the hydraulic action from below, and as a result, the lower working oil is supplied to the wheel side tube when descending at a high speed where the orifice 18a does not function. 2 flows out into the clearance S of the wheel-side tube 2 through the communication hole 2a formed in FIG.

  In the spring receiver 8, when the damper is extended, the cylinder body 3 is united with the cylinder body 3 to rise in the wheel side tube 2. Therefore, the check valve 18 is moved by the hydraulic action from above. As a result, the check valve 18 opens and the upper hydraulic oil flows into the wheel side tube 2.

It is a longitudinal cross-sectional view which shows the place where the front fork by this invention exists in the most extended state. It is a fragmentary longitudinal cross-section which shows the state by which the spring receiver which latches the upper end of a suspension spring was hold | maintained on the outer periphery of the cylinder body which forms a damper.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body side tube 2 Wheel side tube 2a Bottom part which is inner bottom part 2b Communication hole 3 Cylinder body 3a Head part 4 Rod body 5,6 Bearing member 7 Suspension spring 8 Spring receiver 8a Small diameter part 8b Large diameter part 11 Oil lock piece 12 Oil Lock case S Clearance

Claims (4)

Inverted in which the cylinder body is an upper end side member and the rod body is a lower end side member in an axial fork main body in an inverted fork body in which the outer tube is a vehicle body side tube and the inner tube is a wheel side tube A suspension spring consisting of a coil spring that is housed in the fork body, while holding the lower end on the inner bottom of the wheel side tube, the upper end is fixedly held on the outer periphery of the cylinder body forming the damper. The fork main body is energized in the extending direction by being engaged with the spring receiver, and an oil lock mechanism is provided between the inner bottom portion of the wheel side tube and the head portion of the cylinder body facing the inner bottom portion. In the front fork, the outer periphery of the spring receiver is slidably contacted with the inner periphery of the wheel side tube, and the hydraulic oil passage is not formed between the inner periphery of the vehicle body side tube and the outer periphery of the wheel side tube. The upper and lower ends of the wheel side tube that are positioned in the vehicle body side tube when the fork main body is in the fully extended state have the upper and lower ends cut off from the outside. A front fork comprising a plurality of communication holes which allow communication with the gaps along the axial direction of the upper end side portion. The bearing member that the wheel side tube has on the outer periphery of the upper end portion is brought into sliding contact with the inner periphery of the vehicle body side tube, and the bearing member that the vehicle body side tube has on the inner periphery of the lower end portion is made to slide in contact with the outer periphery of the wheel side tube. The front fork according to claim 1. While the spring support is formed in a downward funnel shape and the small diameter portion that is the upper end portion is fixedly held on the outer periphery of the cylinder body, the outer periphery of the large diameter portion that is the lower end portion is slidably contacted with the inner periphery of the wheel side tube. A check valve for preventing communication between the upper side and the lower side of the large-diameter portion when it is lifted is provided on the inner periphery of the large-diameter portion. The front fork according to 1. The oil lock mechanism has an oil lock piece that is held by the head portion of the cylinder body and protrudes toward the inner bottom portion of the wheel side tube, and is arranged at the inner bottom portion of the wheel side tube and opens toward the cylinder body head portion. The front fork according to claim 1, comprising an oil lock case.

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