JP5444087B2 - Front fork - Google Patents

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 absorbs road surface vibration that is input to a front wheel that is mounted on a front wheel side of a two-wheeled vehicle and is suspended at a lower end portion.

  There have been various proposals for a front fork as a hydraulic shock absorber that absorbs road vibration input to a front wheel that is mounted on the front wheel side of a motorcycle and is suspended at the lower end. Document 1 discloses a proposal in which a front fork slidably houses a piston body in a wheel side tube constituting a fork main body.

  That is, the front fork disclosed in Patent Document 1 has a fork main body in which a wheel side tube as a lower end side member is inserted into a vehicle body side tube as an upper end side member so as to be retractable and extendable. Has a piston body that is slidable in the wheel side tube, and a tip of a rod body that is suspended in the vehicle body side tube is connected to the piston body.

  At this time, the piston body defines a piston upper chamber above the piston body and a piston lower chamber below the piston body in the wheel side tube in which the working oil as the working fluid is accommodated. When the body moves up and down in the wheel side tube, it has damping means for allowing communication between the piston upper chamber and the piston lower chamber and realizing a predetermined damping action.

  In the front fork, the fork main body has a partition wall member formed in a bottomed cylindrical shape with a square U-shaped cross section inward from the opening end which is the upper end of the wheel side tube to the lower side. And the opening end part which is the upper end part of this partition member is integrally connected and suspended by the opening end part of the wheel side tube, and said rod body penetrates the bottom part of this partition member.

  Therefore, in the proposal disclosed in Patent Document 1, when the fork main body expands and contracts, that is, when the piston body moves up and down in the wheel side tube, the piston body has damping means. In this case, it is effective because the pressure receiving area is increased compared to the case where the piston body is housed in a so-called damper cylinder separately provided in the wheel side tube. It can be expected that the damping effect will be manifested.

Japanese Patent No. 4055843 (see claims, paragraphs 0011, 0012, FIGS. 1, 2, and 3 in the specification)

  However, in the proposal disclosed in Patent Document 1 described above, the piston body does not necessarily have a problem in that the pressure receiving area is increased to enable the expression of an effective damping action. There is a possibility that it is pointed out that there is a minor defect in use.

  That is, according to the proposal disclosed in Patent Document 1 described above, the wheel side tube is inserted into the vehicle body side tube through the upper and lower bearings that are spaced apart from each other. In the arrangement, a so-called cylindrical lubrication gap appears between the vehicle body side tube and the wheel side tube.

  Then, hydraulic oil from the piston upper chamber below the partition wall member flows into the lubrication gap as a lubricating oil through a communication hole formed in the wheel side tube, and between the vehicle body side tube and the wheel side tube. Although lubrication is ensured, there is a concern that the hydraulic oil mixed with air bubbles may remain in the gap portion above the communication hole in the lubrication gap.

  In other words, the upper end of the cylindrical lubrication gap is prevented from communicating with the outside above the bearing by the seal disposed on the outer periphery of the upper end of the partition wall member facing the inner periphery of the vehicle body side tube. Therefore, the gap portion above the communication hole becomes a dead-end gap like a so-called bag path, and the hydraulic oil flowing into the gap portion does not escape to the outside.

  When the hydraulic oil remaining in the gap portion above the communication hole includes bubbles, for example, the piston body has a period until the bubbles in the hydraulic oil are crushed by pressurization due to the contraction operation of the fork main body. In the damping means, the problem that the “sagging phenomenon of the damping action” occurs is caused.

  The present invention has been made in view of the above-described circumstances, and the object of the present invention is that hydraulic oil mixed with bubbles flows into a lubrication gap between the vehicle body side tube and the wheel side tube. An object of the present invention is to provide a front fork that can effectively prevent staying, can realize a damping action by a damping means as set, and is expected to be expected to improve its versatility.

In order to achieve the above-described object, the configuration of the front fork according to the present invention includes a vehicle body side tube, a fork main body including a wheel side tube that is inserted into and retracted into the vehicle body side tube, a vehicle body side tube, and a wheel side tube. A sliding gap formed between the cylinder, a bottomed cylindrical partition member that is positioned in the wheel side tube and defines an internal reservoir and an oil chamber in the wheel side tube, and slides in the wheel side tube A front fork comprising a piston body that is disposed so as to define the oil chamber into a piston upper chamber and a piston lower chamber, and a rod body that is connected to the piston body and penetrates the bottom of the partition member. In this case, a check valve is provided in the middle of the lubrication gap to separate the lubrication gap into an upper gap and a lower gap, and the reservoir is placed above the partition wall member and the wheel side tube. A communication hole that communicates with the upper gap is formed, a communication hole that communicates the piston upper chamber with the lower gap is formed in the wheel side tube, and the check valve allows hydraulic oil to flow only from the upper gap to the lower gap. It is characterized by being allowed.

  Therefore, in the present invention, since the lubrication gap between the vehicle body side tube and the wheel side tube communicates with the wheel side tube via the lower communication hole formed above, the piston upper portion in the wheel side tube is provided. The hydraulic oil mixed with bubbles in the chamber does not flow into the lubrication gap, and therefore, there is no concern about the flow of hydraulic oil mixed with bubbles in the piston upper chamber into the lubrication gap.

  In addition, when hydraulic fluid that contains air bubbles flows into the gap between the lubrication gap and above the check valve, the hydraulic oil passes through the upper communication hole and is adjacent to the upper communication hole. Therefore, the hydraulic oil flowing into the reservoir does not stay in the lubrication gap through the communication hole formed in the opposite partition wall member.

  As a result, according to the present invention, it is possible to effectively prevent the hydraulic oil mixed with bubbles from flowing into the lubrication gap between the vehicle body side tube and the wheel side tube, and flow into the lubrication gap. Until the bubbles in the hydraulic oil are crushed by pressurization, the “damping action sabor” phenomenon in which the predetermined damping action is not realized is not expressed, and the damping action by the damping means can be realized as set.

It is a figure which shows in principle the front fork by one Embodiment of this invention. 1 is a front view of a semi-longitudinal vertical section showing a front fork according to a specific embodiment of the present invention. FIG. 3 is a longitudinal sectional view showing an enlarged main part of the front fork of FIG. 2, in which (A) shows an operating state during an extension side stroke, and (B) shows an operating state during a compression side stroke.

  Hereinafter, the present invention will be described based on the illustrated embodiment. A front fork according to the present invention is mounted on a front wheel side of a two-wheeled vehicle (not shown) and is suspended at a lower end portion (not shown). It functions as a hydraulic shock absorber that absorbs road vibrations input to the motor.

  Incidentally, although not shown, the front fork is mounted on the front wheel side of the two-wheeled vehicle, the upper end sides of the two left and right front forks are integrated in advance by a bridge mechanism, and each wheel side tube in the two front forks is integrated. 2 (see FIG. 1 and FIG. 2) is connected to a front wheel axle (not shown) and suspended so as to sandwich the front wheel.

  And although a bridge mechanism is not shown in figure, the upper bracket connected with the upper side part of the upper end part in the vehicle body side tube 1 (refer FIG.1 and FIG.2) which comprises a front fork, and the under connected with a lower side part. Each has a bracket, and the upper end portion of the vehicle body side tube 1 is inserted into the mounting holes formed at both ends, and is gripped integrally.

  Although not shown, this bridge mechanism has a single steering shaft that integrally connects the upper bracket and the under bracket at the center of the two, and this steering shaft constitutes the front end of the vehicle body in the motorcycle. The head pipe is turnably connected to the head pipe, whereby the front wheel can be steered in the left-right direction via the two front forks by operating the handle.

  By the way, the front fork according to the present invention is as shown in FIG. 1, and a wheel side tube 2 which is a lower end side member is inserted into a telescopic type so as to be able to appear and retract in a vehicle body side tube 1 which is an upper end side member. The fork main body has a fork body that can be expanded and contracted, and the fork main body is urged in the extending direction in which the wheel side tube 2 protrudes from the vehicle body side tube 1 by the urging force of the suspension spring S (see FIG. 2).

  And in this fork main body, the piston body 3 is slidably accommodated in the wheel side tube 2 that accommodates the working fluid as the working fluid, and the piston body 3 causes the piston body 3 to move inside the wheel side tube 2. The upper piston portion R1 is defined as an upper piston chamber R1 and the lower piston portion chamber R2 is located below the piston body 3, and the lower end portion of the rod body 4 suspended from the shaft core portion of the vehicle body side tube 1 in the figure. The leading end is connected to the piston body 3.

  Further, in the fork main body, the piston body 3 is provided with damping means for realizing a predetermined damping action by allowing the hydraulic oil to reciprocate when the piston upper chamber R1 and the piston lower chamber R2 communicate with each other. Have.

  By the way, this damping means includes an extension side damping valve 31 that realizes a predetermined extension side damping action when the piston upper chamber R1 communicates with the piston lower chamber R2, and the piston lower chamber R2 as shown in FIG. A pressure-side damping valve 32 that realizes a predetermined pressure-side damping action when communicating with the upper chamber R1.

  At this time, the piston upper chamber R1 and the piston lower chamber R2 communicate with each other by bypassing one or both of the expansion side damping valve 31 and the pressure side damping valve 32 from the piston body 3 to the tip of the rod body 4. While having the bypass path 33 to accept | permit, it may have the adjustment valve 34 which act | operates to this bypass path 33 by external operation etc. and adjusts the flow volume of the hydraulic oil in this bypass path 33.

  Further, the fork main body has upper and lower bearings 11 and 12 that are spaced apart from each other between the vehicle body side tube 1 and the wheel side tube 2, and the upper and lower bearings 11 and 12 are separated from each other. The sliding which has the concentricity between the vehicle body side tube 1 and the wheel side tube 2 is ensured.

  In this fork main body, a so-called cylindrical lubrication gap A is defined between the vehicle body side tube 1 and the wheel side tube 2 by separating the upper and lower bearings 11 and 12, and at this time, An annular cross-sectional area A2 in the lubrication gap A and a circular cross-sectional area A1 in the rod body 4 are set such that A2 ≧ A1.

  Incidentally, a seal member 13 is disposed on the inner periphery of the opening end portion, which is the lower end portion in FIG. 1, of the vehicle body side tube 1. The distribution of the seal member 13 makes the inside of the fork main body a sealed space. It is possible to accommodate a predetermined amount of working oil as a working fluid in the space and to define a gas chamber G with the oil level O as a boundary above the working oil.

  The gas chamber G is filled with an inert gas under an arbitrary pressure. Alternatively, the gas chamber G may be an air chamber and the atmosphere may be sealed under an arbitrary pressure. Regardless of the air pressure chamber, the internal pressure enclosed through the valves (not shown) disposed on the cap member 14 (see FIG. 2) that closes the upper end opening of the vehicle body side tube 1 is increased or decreased. You may get it.

  In addition, the upper bearing 11 described above is held on the inner periphery on the upper end side of the vehicle body side tube 1 and is in sliding contact with the outer periphery of the wheel side tube 2, but instead of this, for example, FIG. As shown, it may be held on the outer periphery of the upper end of the wheel side tube 2 and slidably contact the inner periphery of the vehicle body side tube 1.

  By the way, in this fork body, the wheel side tube 2 has a partition wall member 5 formed in the shape of a bottomed cylinder with a square U-shaped cross section inside the upper end side portion. The piston upper chamber R1 is defined, and the reservoir R, that is, the reservoir R having the gas chamber G that contains the hydraulic oil and borders the oil level O of the hydraulic oil is defined above the partition member 5. To do.

  That is, the partition wall member 5 is disposed in such a manner that the opening end portion that is the upper end portion is integrally connected to the opening end portion that is the upper end portion of the wheel side tube 2, and so to be suspended inside the wheel side tube 2. Is done.

  The partition member 5 is squeezed while allowing the rod body 4 to pass through the bottom (not shown) under the bush 51 (see FIG. 2) and allowing the piston upper chamber R1 to communicate with the reservoir R. It has the diaphragm means 52 which exhibits an effect.

  At this time, the throttle means 52 may be formed between the bush 51 and the rod body 4, and in this case, it is not necessary to provide the throttle means at the bottom of the partition wall member 5. This is advantageous in reducing the number of points and simplifying the configuration at the bottom of the partition wall member 5.

  Incidentally, the throttle means 52 is necessary when the cross-sectional area A2 of the lubrication gap is larger than the cross-sectional area A1 of the rod body 4, but the cross-sectional area A2 of the lubrication gap is equal to the cross-sectional area A1 of the rod body 4. May be omitted.

  Further, the partition member 5 is formed in a cylindrical shape, so that the reservoir R, which is the inner side of the partition member 5, is connected to the outer side of the partition member 5 through a communication hole 5 a formed in a main body (not shown). In other words, as shown in the figure, the above-described lubrication gap A is communicated also through the communication hole 2a formed in the wheel side tube 2 so as to face and face the communication hole 5a.

  On the other hand, the above-mentioned lubrication gap A is shown in the figure, and the piston upper chamber is connected via a lower communication hole 2b separately formed in the wheel side tube 2 so as to be positioned below the upper communication hole 2a. Communicate with R1.

The lubrication gap A is positioned between the upper and lower communication holes 2a and 2b while being held on the outer periphery of the wheel-side tube 2 so as to face the lubrication gap A, and the lubrication gap A is defined as the upper gap A3. And a check valve C that is separated from the lower gap A4 .

In addition, the check valve C allows the hydraulic oil from above the upper gap A3 to pass below the lower gap A4 in the lubrication gap A, but vice versa. As long as it passes through, it may be arbitrarily configured.

  In particular, in the illustrated check valve C, since this is disposed in the lubrication gap A between the vehicle body side tube 1 and the wheel side tube 2, for example, as in the proposal disclosed in Patent Document 1, The number of parts can be reduced as compared with the case where the rod member is disposed around the bottom of the partition member.

  Further, the check valve C is always positioned below the oil level O appearing inward of the partition member 5 and below the upper communication hole 2a. Therefore, it is possible to prevent the hydraulic oil mixed in from flowing into the lubrication gap A.

  Incidentally, although the hole diameters of the communication holes 2a and 2b are not shown in the drawing, it is not limited to a minute hole diameter. In particular, an upper communication hole facing the communication hole 5a formed in the partition wall member 5 is used. As for 2a, it is assumed that the diameter is set so as not to cause flow path resistance. This improves the flowability of the hydraulic oil that is difficult to pass through the communication hole having a minute hole diameter because air bubbles are mixed therein.

  Therefore, as shown in the figure, the reservoir R, which is the inner side of the partition wall member 5, passes through the communication hole 5a, the upper communication hole 2a, the lubrication gap A, the check valve C, the lubrication gap A, and the lower communication hole 2b. It communicates with the piston upper chamber R1.

  As a result, when the hydraulic oil from the piston upper chamber R1 mixes bubbles, first, the hydraulic oil mixed with the bubbles flows into the reservoir R through the throttle means 52 and mixes the bubbles. The oil is prevented from flowing into the lubrication gap A.

  In the lubrication gap A, since the check valve C is arranged at a position above the communication hole 2b that communicates the lubrication gap A with the piston upper chamber R1, the gap portion above the check valve C is provided. Therefore, the hydraulic oil mixed with bubbles does not flow into the lubricating gap A, and the hydraulic fluid mixed with bubbles does not flow into the lubrication gap A from this point.

  If the hydraulic oil mixed with the bubbles flows into the gap portion above the check valve C, the upper communication hole 2a is formed to have a large diameter, and the upper communication hole 2a. Since the communication hole 5a which is adjacent to and is formed to have a large diameter, the working oil mixed with bubbles flows into the reservoir R without stagnation and does not stop in the lubrication gap A.

  With regard to this point, in the proposal disclosed in the above-mentioned Patent Document 1, a communication hole that allows communication between the piston upper chamber and the lubrication gap, that is, the upper communication hole formed in the wheel side tube has a minute passage. Since the hydraulic oil mixed with bubbles enters the lubrication gap, as described above, the lubrication gap may become a dead end mode, as described above. The inflow of hydraulic oil mixed with bubbles into the lubrication gap cannot be avoided, and the bubbles cannot be expelled from the flowing hydraulic oil.

  As a result, in the proposal disclosed in Patent Document 1 described above, until the air bubbles in the hydraulic oil are crushed by the pressurization by the contraction operation of the fork main body, As described above, it causes a problem that the “sag phenomenon of action” is manifested.

  On the other hand, in the present invention, the opportunity for the hydraulic oil to be mixed with bubbles into the gap portion above the check valve C in the lubrication gap A is greatly reduced. Does not easily flow into the gap.

  Therefore, the front fork formed as described above operates as follows when the fork main body extends and retracts with respect to the vehicle body side tube 1 and the wheel side tube 2 extends and retracts.

  First, at the time of a contraction operation of the fork main body in which the wheel side tube 2 is immersed in the vehicle body side tube 1, the piston body 3 descends in the wheel side tube 2 and the piston lower chamber R2 becomes narrow.

  As a result, the hydraulic oil in the piston lower chamber R2 flows into the piston upper chamber R1 via the pressure side damping valve 32, and the hydraulic oil passes through the pressure side damping valve 32, thereby realizing a predetermined pressure side damping action. The

  At this time, when the cross-sectional area A2 in the lubrication gap A between the vehicle body side tube 1 and the wheel side tube 2 is equal to the cross-sectional area A1 in the rod body 4, there is no excess or deficiency in the amount of hydraulic oil in the piston upper chamber R1. .

  On the other hand, when the cross-sectional area A2 in the lubrication gap A is larger than the cross-sectional area A1 in the rod body 4, the amount of hydraulic oil is insufficient in the lubrication gap A communicating with the piston upper chamber R1, and this shortage is the reservoir R The lower lubrication gap A is replenished via the communication hole 5a, the communication hole 2a, the upper lubrication gap A, and the check valve C.

  Next, during the extension operation of the fork main body in which the wheel side tube 2 protrudes from the vehicle body side tube 1, the piston body 3 rises in the wheel side tube 2 and the piston upper chamber R1 becomes narrow.

  At this time, the hydraulic oil in the piston upper chamber R1 flows into the piston lower chamber R2 via the expansion side damping valve 31, and the hydraulic oil passes through the expansion side damping valve 31, thereby causing a predetermined expansion side damping action. Embodied.

  At this time, if the cross-sectional area A2 in the lubrication gap A between the vehicle body side tube 1 and the wheel side tube 2 is larger than the cross-sectional area A1 in the rod body 4, an excess in the hydraulic oil amount in the piston upper chamber R1. This surplus oil flows out to the reservoir R through the throttle 52.

  And the piston upper chamber R1, that is, the piston lower chamber R2, is pressurized by the resistance at that time, and the negative pressure in the piston lower chamber R2 can be prevented, and the generation of bubbles in the hydraulic oil due to the negative pressure is prevented. it can.

  Even if the fork main body is contracted, the hydraulic oil is distributed to the partition member 5 as described above even if there is hydraulic oil that mixes bubbles in the piston upper chamber R1 during the expansion operation. Since priority is given to flowing out to the reservoir R through the throttle means, it is difficult to flow into the lubrication gap A.

  As described above, if the hydraulic oil mixed with the bubbles flows into the gap portion above the check valve C in the lubrication gap, the upper communication hole 2a is formed to have a large diameter. At the same time, the opposing communication hole 5a adjacent to the upper communication hole 2a is also formed with a large diameter, so that the hydraulic oil mixed with bubbles flows into the reservoir R without stagnation and does not flow into the lubrication gap A.

  As described above, in the present invention, the hydraulic oil mixed with bubbles can be effectively prevented from flowing into the lubrication gap A between the vehicle body side tube 1 and the wheel side tube 2 and attenuated. The damping action by the means can be embodied as set.

  FIG. 2 shows a front fork according to a specific embodiment of the present invention, which will be described below. However, it is shown in the figure, and the configuration is the same as that shown in FIG. In the drawings, the same reference numerals are used in the drawings, and the detailed description is omitted unless necessary.

  First, even in the front fork shown in FIG. 2, an inverted type that has a vehicle body side tube 1 as an upper end side member and a wheel side tube 2 as a lower end side member and can be expanded and contracted under the distribution of the suspension spring S. It has a set fork body.

  As shown in the figure, the vehicle body side tube 1 is held on the inner periphery of the opening end portion which is the lower end portion in the figure and is slidably contacted with the outer periphery of the wheel side tube 2 and the seal member 13 (see FIG. 1), that is, an oil seal 13a and a dust seal 13b.

  On the other hand, for the bearing disposed between the outer periphery of the opening end portion serving as the upper end portion in the drawing of the wheel side tube 2 and the inner periphery of the upper end side portion in the drawing of the vehicle body side tube 1, As shown in the figure, the bearing 21 held on the outer periphery of the upper end portion of the wheel side tube 2 is in sliding contact with the inner periphery of the vehicle body side tube 1, so that the slidability between the vehicle body side tube 1 and the wheel side tube 2 is achieved. Is guaranteed.

  Therefore, in the fork main body, a lubricating gap A that is cylindrical is defined between the vehicle body side tube 1 and the wheel side tube 2 by separating the upper bearing 21 and the lower bearing 12 from each other.

  The upper bearing 21 may be the bearing 11 held on the inner periphery of the vehicle body side tube 1 as in the case shown in FIG. 1, but instead of the bearing 11, as shown in the figure. When the bearing 21 is held at the upper end of the wheel side tube 2, the fitting length when the fork main body is contracted can be increased according to the contraction stroke, which is advantageous in improving the rigidity.

  The suspension spring S is accommodated in the lower end side of the fork main body, that is, in the illustrated case, in the lower end side of the wheel side tube 2. At this time, the lower end of the suspension spring S is the figure of the wheel side tube 2. The upper end of the suspension spring S is locked to a spring receiver S1 adjacent to a piston body 3 to be described later.

  Incidentally, the spring receiver S1 is formed in the form of a free piston without a seal and is movably accommodated in the wheel side tube 2, and is formed into a disk shape in the piston body 3 by the urging force of the suspension spring S. Locked to the stopper 35.

  Moreover, although it is an air tank T, when this is accommodated in the lower end side of the wheel side tube 2, the amount of hydraulic oil accommodated inside the wheel side tube 2 can be reduced by this volume, Contributes to a reduction in overall weight.

  In addition, a bottom member 22 that closes a lower end opening of the wheel side tube 2 is integrally connected to a bottom end portion of the wheel side tube 2, and the bottom member 22 connects an axle of a front wheel in a two-wheeled vehicle and is illustrated in the figure. However, it has a caliper portion that holds a brake mechanism and the like.

  The fork body also includes a piston body 3 that is slidable in the wheel side tube 2, and the piston body 3 is provided at the tip of a rod body 4 that is suspended in the vehicle body side tube 1. Connect the parts.

  At this time, the rod body 4 is integrally connected to the cap member 14 whose upper end portion serving as the base end portion closes the upper end opening of the vehicle body side tube 1 under the intervention of the lock nut 41. The through hole of the part has an outer control rod made of a pipe and an inner control rod made of a rod inserted through the axial core part of the outer control rod.

  And the base end used as the upper end of an outer side control rod and an inner side control rod is located in said cap member 14, and contact | abuts to the lower end of each adjuster distribute | arranged to this cap member 14, respectively.

  The lower end of the outer control rod is in contact with the adjusting means 32a adjacent to the compression side damping valve 32, and the lower end of the inner control rod is disposed in a bypass path 33 (see FIG. 1) that bypasses the extension side damping valve 31. The adjusting valve 34 (see FIG. 1) is in contact with the rear end of the needle valve body.

  Therefore, in the fork main body shown in the drawing, for example, by rotating the one adjuster, for example, the outer control rod is moved forward and backward, and the damping action realized by the compression side damping valve 32 is adjusted by the adjustment means 32a. Can do.

  In the fork main body shown in the figure, the inner control rod is advanced and retracted by rotating the other adjuster, and the damping action realized by the extension side damping valve 31 is achieved by the operation of the adjustment valve 34 formed of a needle valve body. High and low can be adjusted.

  Next, even in this fork main body, the wheel side tube 2 has the partition member 5 inward, and also has a cylindrical lubricating gap A defined between the upper and lower bearings 21 and 11 that are spaced apart. The check valve C is disposed in the lubrication gap A.

  First, the partition wall member 5 has a communication hole 5a in the vicinity of the bottom portion, which is the lower end portion of the cylindrically formed main body, and the partition wall member 5 outside the partition wall 5 is located inside the partition wall member 5 through the communication hole 5a. Communication, that is, communication with the annular groove 5b formed in the outer peripheral portion so as to face the communication hole 2a formed in the wheel-side tube 2 and opening in the lubrication gap A is enabled.

  The partition member 5 has a seal ring 53 on the outer periphery of the bottom portion below the annular groove 5b, and although not shown, the aperture means of the seal ring 53 has the aperture means 52 described above. (See FIG. 1).

  Incidentally, the joint gap of the seal ring 53 functions as a throttle means when the cross-sectional area A2 of the lubricating gap is larger than the cross-sectional area A1 of the rod body 4 as described above.

  Therefore, the seal ring 53 may be configured to have a perforation while being endlessly formed to constitute the throttle means. However, in view of the actual formation of the perforations, for example, it is easy to reduce the hole diameter to 1 mm or less. Therefore, the hole diameter may be 1 mm or more, and an effective squeezing effect may not be obtained.

  On the other hand, when the abutment gap forms a throttle, the size of the abutment gap is easy to set, and therefore the abutment gap is advantageous in that it can select a preferable squeeze effect as compared to perforation.

  Further, in the partition member 5, the hole diameter of the communication hole 5a is not limited to the minute hole diameter as described above, and the upper communication hole 2a facing the communication hole 5a is not limited to the minute hole diameter. The hole diameter is also set to a large diameter that does not cause flow path resistance. This improves the flowability of the hydraulic oil that is difficult to pass through the communication hole having a small hole diameter because air bubbles are mixed therein.

  On the other hand, the lubrication gap A has a check valve C that is positioned between the upper and lower communication holes 2a and 2b while being held on the outer periphery of the wheel side tube 2 so as to face the lubrication gap A.

  The check valve C allows the hydraulic oil from above in the lubrication gap A to pass downward, but prevents the hydraulic oil from passing downward from the opposite direction.

  In addition, the check valve C is always positioned below the oil level O appearing inward of the partition wall member 5 and below the upper communication hole 2a. It is possible to prevent the hydraulic oil mixed with bubbles from flowing into the inside, or to make it easier for the bubbles in the flowing hydraulic oil to flow out of the lubrication gap A.

  By the way, as for the check valve C, as shown in FIG. 3, the body portion C1 formed in an annular shape has its outer periphery slidably contacted with the inner periphery of the vehicle body side tube 1 and the body portion C1 and the vehicle body side tube. 1 has a notch passage C2 that allows the hydraulic oil to pass therethrough while preventing the hydraulic oil from passing between the main body C1 and the wheel. The passage of hydraulic oil between the side tubes 2 is allowed.

  In the check valve C, the main body C1 is housed in a floating manner in an annular groove 2c, which is a seat portion formed on the outer periphery of the wheel side tube 2, and is also positioned in the annular groove 2c. In other words, it has a pair of stoppers 23 and 24 on the wheel side tube 2 side that are spaced apart from each other on the upper and lower sides of the main body C1.

  Incidentally, the stoppers 23 and 24 regulate the movement of the check valve C interposed on the outer periphery of the wheel side tube 2. In view of its function, the stoppers 23 and 24 are replaced with the above. Good to be part of.

  Therefore, in the check valve C, as shown in FIG. 3A, when the lower side of the check valve C is on the high pressure side, the main body C1 is raised and is in close contact with the upper stopper 23. A so-called flow path is closed, and hydraulic oil below the check valve C is prevented from flowing out above the check valve C.

  In the check valve C, as shown in FIG. 3B, when the upper side of the check valve C is on the high pressure side, the main body C1 is lowered and comes into contact with the lower stopper 24. When the main body C1 has the notch passage C2 at the lower end, the so-called flow path is maintained in an open state, and hydraulic oil above the check valve C is allowed to flow below the check valve C. .

  Since the fork main body shown in FIG. 2 is formed as described above, when the hydraulic oil from the piston upper chamber R1 mixes bubbles, the hydraulic oil mixed with the bubbles is first sealed as a throttle means. The hydraulic oil that flows out into the reservoir R through the joint gap in the ring 52 and mixes the bubbles is prevented from flowing into the lubrication gap A.

  If the hydraulic oil mixed with the air bubbles flows into the gap above the check valve C, the upper communication hole 2a is formed to have a large diameter, and the upper communication hole 2a has a so-called large diameter. Since the adjacent communication holes 5a that are adjacent to each other are also formed with a large diameter, the hydraulic oil mixed with the bubbles flows into the reservoir R without stagnation and does not flow into the lubrication gap A.

  That is, the hydraulic oil from the piston upper chamber R1 below the bottom of the partition member 5 does not flow into the lubrication gap A via the lower communication hole 2b. Therefore, basically, the piston upper chamber R1. It is not feared that the hydraulic oil mixed with bubbles from the oil flows into the lubrication gap A.

  Bubbles mixed in the hydraulic oil flowing out to the reservoir R side through the joint gap in the seal ring 53 also flow into the annular groove 5b and also flow out into the reservoir R through the communication hole 5a.

  Therefore, even when the hydraulic oil in the piston upper chamber R1 or the piston lower chamber R2 below the bottom of the partition member 5 contains bubbles, the lubrication gap is limited as long as the hydraulic oil passes through the joint gap in the seal ring 53. Instead of flowing into A, it flows out preferentially to the reservoir R inside the partition member 5.

  Therefore, the fork main body formed as described above is basically the same as the fork main body shown in FIG. 1 when the wheel side tube 2 extends and retracts with respect to the vehicle body side tube 1. Operate.

  As a result, even in the front fork shown in FIG. 2, it is possible to effectively prevent the hydraulic oil mixed with bubbles from flowing into the lubrication gap A between the vehicle body side tube 1 and the wheel side tube 2. Thus, the damping action by the damping means can be embodied as set.

  In the above description, the present invention is embodied as a front fork that is a hydraulic shock absorber mounted on the front wheel side of the two-wheeled vehicle. It may be embodied in a shock absorber that is a hydraulic shock absorber disposed in each part.

  In order to effectively prevent the hydraulic oil mixed with bubbles from flowing into the lubrication gap between the vehicle body side tube and the wheel side tube so that the damping action by the damping means can be realized as set. Turn to.

DESCRIPTION OF SYMBOLS 1 Car body side tube 2 Wheel side tube 2a, 2b, 5a Communication hole 2c, 5b Annular groove 3 Piston body 4 Rod body 5 Partition member 11, 12, 21 Bearing 13 Seal member 13a Oil seal 13b Dust seal 14 Cap member 22 Bottom member 23 , 24 Stopper 31 Extension side damping valve 32 Pressure side damping valve 33 Bypass path 34 Adjusting valve 51 Bushing 52 Throttle means 53 Seal ring A Lubrication gap A1 Lubrication gap cross section A2 Rod body cross section
A3 Upper gap
A4 Lower gap C Check valve C1 Main body C2 Notch passage O Oil level R Reservoir R1 Piston upper chamber R2 Piston lower chamber S Suspension spring T Air tank

Claims (13)

A fork body composed of a vehicle body side tube and a wheel side tube inserted in the vehicle body side tube so as to be able to appear and retract, a lubrication gap formed between the vehicle body side tube and the wheel side tube, and a wheel side tube positioned in the wheel side tube A bottomed cylindrical partition wall member that defines an internal reservoir and an oil chamber in the wheel side tube, and a slidable housing in the wheel side tube so that the oil chamber is divided into a piston upper chamber and a piston lower chamber. A front fork comprising a piston body that is defined in the drawing and a rod body that is connected to the piston body and penetrates the bottom of the partition wall member, and a check valve is provided in the middle of the lubrication gap to raise the lubrication gap upward. A communication hole is formed in the gap member and the lower gap, and a communication hole for communicating the reservoir with the upper gap is formed in the partition wall member and the wheel side tube, respectively, Front fork the piston upper chamber to form a communication hole communicating with the lower gap, characterized in that the check valve is allowed to flow into the viewing hydraulic oil to lower the gap from above the gap.
The front fork according to claim 1, wherein the fork body is extendable by inserting a wheel side tube into the vehicle body side tube so as to be retractable through upper and lower bearings in which the fork main body is spaced apart.
The fork body is energized in the extension direction by the energizing force of the suspension spring that is accommodated inward, and the lower end of the suspension spring is carried on the air tank of the accommodation in the bottom end side of the wheel side tube. The front fork according to claim 1 or claim 2 formed.
The fork body is urged in the extending direction by the urging force of a suspension spring accommodated inward, and the upper end of the suspension spring is locked to the piston body. The front fork according to claim 3.
Between the upper and lower bearings in which the lubrication gap is spaced between the vehicle body side tube and the wheel side tube to ensure slidability between the vehicle body side tube and the wheel side tube. The front fork according to claim 1, claim 2, claim 3 or claim 4, which is defined by claim 1.
An extension side damping valve in which the damping means allows the upper chamber of the piston to communicate with the lower chamber of the piston, and a compression side damping valve that allows the lower chamber of the piston to communicate with the upper chamber of the piston. The front fork according to claim 1, claim 2, claim 3, claim 4 or claim 5.
7. The front according to claim 1, wherein the cross-sectional area in the lubricating gap is set equal to or larger than the cross-sectional area of the rod body. fork.
The upper end portion of the partition member is integrally connected to and suspended from the upper end portion of the wheel side tube, and is suspended. The front fork according to claim 7.
The first, second, third, and third claim, wherein the partition member has a throttle means for allowing the piston upper chamber to communicate with the reservoir at the bottom facing the piston upper chamber. A front fork according to claim 4, claim 5, claim 6, claim 7 or claim 8.
The said diaphragm | throttle means consists of the joint clearance gap in the seal ring which is interposed in the outer periphery of the bottom part in the said partition member, and slides the outer periphery on the inner periphery of the said wheel side tube. , Claim 4, Claim 5, Claim 6, Claim 7, Claim 8 or Claim 9.
2. The check valve is disposed in the lubrication gap while being held on the outer periphery of the wheel-side tube, and is always positioned below the oil surface that appears inward of the partition member. , Claim 2, claim 3, claim 4, claim 5, claim 7, claim 8, claim 9 or claim 10.
The check valve is located in the lubrication gap, and the upper communication hole formed in the wheel side tube that communicates the lubrication gap with the reservoir side, and the lubrication gap communicates with the piston upper chamber. 2. A wheel-side tube formed between a lower communication hole and a lower communication hole, which allows communication below the check valve above the check valve but prevents communication opposite thereto. , Claim 2, Claim 3, Claim 4, Claim 5, Claim 7, Claim 8, Claim 9, Claim 10, or Claim 11.
While the check valve is formed in an annular shape, the check valve is accommodated in the lubrication gap, and the annularly formed main body slides the outer periphery on the inner periphery of the vehicle body side tube, while the inner periphery is the outer periphery of the wheel side tube. The check valve has a notch passage at the lower end and rises when the pressure below the check valve is increased to prevent communication above the check valve below the check valve. The upper part of the valve is lowered when the pressure is increased, and the check valve above the check valve is allowed to communicate with the lower part of the check valve. The front fork according to claim 6, claim 7, claim 8, claim 9, claim 10, claim 11, or claim 12.

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