Front fork

The present invention relates to a front fork, and more particularly to an improvement of the front fork that is set to increase the spring force during compression operation.

[0002] As is well known, the front fork functions to absorb road surface vibration and maintain a good ride quality in a motorcycle, but in general, in principle, as shown in FIG. It is configured as shown.

[0003] That is, when this front fork is set to be inverted, the upper end side of the inner tube 2 which is the axle side tube is inserted into the lower end side of the outer tube 1 which is the vehicle body side tube so as to be able to appear and disappear. At the same time, it is said that the inner tube 2 is urged in the extension direction so as to protrude from the inside of the outer tube 1 by the suspension spring 3 which is housed inside.

[0004] Further, this front fork has a so-called oil reservoir (not indicated) in the reservoir chamber R partitioned by the outer tube 1 and the inner tube 2, and the oil level O is defined above the oil reservoir. It is supposed to have an air chamber G to be used.

[0005] Further, the front fork has a damper (not shown) that enables the generation of a damping force that absorbs a predetermined energy when the inner tube 2 appears and decreases with respect to the outer tube 1, that is, during expansion and contraction operation. It is supposed to be held in the core.

[0006] By the way, the damper may be set to an arbitrary structure, but as shown in the figure, the damper has a cylindrical gap between the inner circumference and the inner circumference of the inner tube 2 and is formed on the shaft core portion of the inner tube 2. The cylinder 4 is erected in a fixed state, the rod 5 is vertically hung on the shaft core of the outer tube 1 and the base end side is inserted into the cylinder 4, and the rod 5 is slidably housed in the cylinder 4. The cylinder 4 is provided with a piston 6 connected to the base end of the rod 5 while partitioning the upper oil chamber R1 and the lower oil chamber R2.

[0007] The damper includes an extension side damping valve 6a in which the piston 6 allows the passage of oil between the upper oil chamber R1 and the lower oil chamber R2 to generate a predetermined damping force, and this extension. It has an extension side check valve 6b parallel to the side damping valve 6a.

[0008] Further, this damper sets the above-mentioned tubular gap formed between the inner tube 2 and the cylinder 4 in the reservoir chamber R, and is the bottom portion of the inner tube 2 and the lower end of the cylinder 4. A compression side damping valve 2b that allows oil to pass between the reservoir chamber R and the lower oil chamber R2 to generate a predetermined damping force in the base portion 2a that closes the cylinder, and a compression side check that is parallel to this compression side damping valve 2b. It has a valve 2c.

[0009] In the figure, the suspension spring 3 is arranged between the top of the damper and the inside of the upper end of the outer tube 1.

[0010] Therefore, in this front fork, the damper expands and contracts during the expansion and contraction operation in which the inner tube 2 appears and disappears with respect to the outer tube 1, and a predetermined damping force is generated. It becomes possible to absorb the road surface vibration input to the front fork.

[0011] When the front fork is compressed, an amount of oil corresponding to the volume integral of the rod 5 discharged from the damper flows into the reservoir chamber R, and the inner tube 2 is immersed in the outer tube 1. As a result, the oil level O in the reservoir chamber R rises, the air chamber G bordering the oil level O contracts, and the spring force rises, and the spring force of the air chamber G at this time increases. It acts to extend the front fork in cooperation with the suspension spring 3.

[0012] However, in the above-mentioned front fork, the spring force at the time of compression operation is increased according to the compression state of the front fork, that is, depending on the position. Since it is set, only the same increase in spring force can be expected even when the compression operation is performed at high speed.

[0013] That is, the case where the front fork is compressed at high speed is often the case where the nose dive phenomenon is exhibited in the motorcycle, and is represented by, for example, sudden braking.

[0014] Since it is natural that the nose dive phenomenon does not occur during this sudden braking or the like, the spring force should be greatly increased in order to maintain the vehicle body posture properly, but as described above. Since the conventional front fork is set to increase the spring force depending on the position, it is not possible to expect a large increase in the spring force during the compression operation at high speed.

[0015] It should be noted that it may be proposed to set the pressure in the air chamber G higher in advance in order to obtain a high spring force during the compression operation at high speed, but in this case, during the normal expansion / contraction operation. However, there is a problem that the spring force becomes high, which deteriorates the riding comfort in a motorcycle, and further, the durability of the seal tends to be lowered due to the so-called high internal pressure.

[0016] The present invention has been invented in view of the above circumstances, and its purpose is, of course, to enable absorption of road surface vibration during normal traveling of a motorcycle, as well as suddenly. It is possible to appropriately increase the spring force when compression operation is performed at high speed such as during braking, and to provide a front fork that is optimal for expecting an improvement in its versatility.

[Means for Solving the Problems] In order to achieve the above object, basically, the configuration of the front fork according to the present invention is internally formed during expansion / contraction operation between the vehicle body side tube and the axle side tube. In addition to enabling the damping action by the damper of the bicycle, it is set to increase the spring force by compressing the air chamber that is partitioned from the oil reservoir chamber at the boundary of the oil level in the reservoir chamber during compression operation. In the front fork, a squeezing means is arranged in the oil reservoir in the reservoir chamber, and a second air chamber that contracts due to an increase in oil pressure is arranged below the squeezing means.

[0018] In the above-mentioned basic configuration, more specifically, the second air chamber is partitioned on the outer circumference of the damper by fixing the upper and lower ends of the bellows, which is an elastic body, to the outer circumference of the damper. To do.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the illustrated embodiment, but even in the case of the front fork according to the embodiment of the present invention, basically, the above-mentioned invention is described. It has the same configuration as the front fork shown in Fig. 3.

[0020] Therefore, in FIGS. 1 and 2 showing the front fork according to this embodiment, where the same configuration is used, the same reference numerals are given in the respective drawings except when necessary. The detailed description thereof will be omitted, and the features of the present invention will be mainly described below.

That is, first, in the front fork according to the present invention, a damper (not shown) internally accommodated during expansion / contraction operation between the outer tube 1 which is the vehicle body side tube and the inner tube 2 which is the axle side tube. It is said that it is set to enable the damping action by.

[0022] Then, the damper discharges an amount of oil corresponding to the volume of the intruder of the rod 5 into the reservoir chamber R through the hole 4a (see FIG. 2) opened in the cylinder 4 during the compression operation, and during the extension operation. An amount of oil corresponding to the exit volume integral of the rod 5 is also set to be sucked from the reservoir chamber R through the above-mentioned hole 4a.

Next, in the front fork according to the present invention, the squeezing means 10 is arranged in the oil reservoir in the reservoir chamber R, and the second squeezing means 10 contracts below the squeezing means 10 due to an increase in oil pressure. It is said that air chamber A is distributed.

[0024] To explain a little, first, the second air chamber A is independent of the air chamber G (see FIG. 1) partitioned above the oil reservoir with the oil level O (see FIG. 1) as a boundary. On the other hand, it is arranged in the oil reservoir and is set to contract and increase the spring force when the oil pressure in the oil reservoir is increased.

That is, the second air chamber A has a pressure with the air chamber G when the oil above the squeezing means 10 flows downward through the squeezing means 10 due to the compression operation of the front fork at medium and low speeds. It is set to contract while balancing.

[0026] By the way, when the front fork is compressed at medium and low speeds, the flow velocity of the oil passing through the drawing means 10 is slowed down and no resistance is generated by the drawing means 10, but when the front fork is compressed at high speeds, , The flow velocity of the oil passing through the drawing means 10 also becomes high, and resistance by the drawing means 10 is generated.

[0027] Therefore, when the front fork is compressed at high speed, the second air chamber A contracts without pressure balance with the air chamber G.

[0028] By the way, in the illustrated embodiment, the second air chamber A is made of a bellows 21 which is an elastic body having a predetermined mechanical strength and abundant elasticity, and the upper and lower ends of the bellows 21. Is fixed on the outer circumference of the cylinder 4 constituting the damper under the use of the tightening band 22, and as a result, it is formed so as to surround the cylinder 4, that is, the outer circumference of the damper.

[0029] The second air chamber A is set to be smaller in volume than the air chamber G. For example, when the front fork is fully extended, the volume of the air chamber G becomes 1000 cc. Sometimes the volume of the second air chamber A becomes 60cc, and at this time, the pressure in the air chamber G and the second air chamber A is 1Kgf / cm.²It is supposed to be.

By the way, the cross-sectional area of the rod 5 constituting the damper is 1 cm.²The pressure receiving area on the inner tube 2 side, that is, the pressure receiving area determined by the diameter indicated by the symbol D in FIG. 1, is 10 cm excluding the cross-sectional area of the rod 5.²It is set to be.

Next, in the illustrated embodiment, the drawing means 10 has an inner tube 2 in which the outer circumference of the cylinder 7 continuously provided at the upper end of the cylinder 4 constituting the damper and the outer circumference of the cylinder 7 face each other. It is said that it is positioned between the inner circumference of the oil reservoir and is arranged so as to divide the oil reservoir into upper and lower parts.

[0032] Then, the drawing means 10 has a relief plate 11 which is formed in an annular shape and is arranged so-called horizontally and is adjacent to the lower end of the suspension spring 3, that is, is fixed by the suspension spring 3. It is said that the plate 11 is provided with an orifice 11a as a throttle.

[0033] By the way, in the illustrated embodiment, the relief plate 11 is interposed around the outer circumference of the tubular body 7 to lock the lower end of the suspension spring 3, and is substantially oil. It is said that it is mounted on the upper end of the support 12, which functions as a partition of the reservoir into upper and lower parts, so that it can be taken off and seated.

[0034] In the relief plate 11, the orifice 11a is opened toward the so-called inner peripheral end side so as to avoid obstruction by the lower end of the suspension spring 3.

[0035] Further, the support 12 has an opening 12a facing the above-mentioned orifice 11a, and the outer circumference is in sliding contact with the inner circumference of the inner tube 2 via a bearing 13 interposed therein. ..

[0036] By the way, regarding the above throttle, this throttle is placed between the outer circumference of the bearing 13 interposed on the outer circumference of the support 12 and the inner circumference of the inner tube 2 to which the throttle is in sliding contact, regardless of the orifice 11a. It may depend on the formed annular sliding gap (not indicated), and in this case, it is advantageous in that the trouble of opening the orifice 11a in the relief plate 11 can be saved.

[0037] In the illustrated embodiment, the above-mentioned cylinder 7 is an oil lock case constituting an oil lock structure that operates at the time of maximum compression of the front fork, and the cylinder 7 that is the oil lock case In many cases, the oil lock piece 8 held in a fixed state on the tip side, which is the upper end of the rod 5 constituting the damper, is fitted and inserted on the inner peripheral side so as to be able to appear and disappear (virtual diagram in FIG. 1). reference).

[0038] Therefore, in the drawing means 10 formed as described above, when the oil above the drawing means 10 flows below the drawing means 10 due to the compression operation of the front fork, the oil flows at medium and low speeds. Allows the oil to pass through the orifice 11a, whereas when the oil passes through the orifice 11a at high speed, it becomes throttle resistance and tends to block the passage of high speed oil.

[0039] In the case where the pressure accumulation is caused below the throttle means 10 due to the continuous compression operation of a large stroke in an extremely short time, the front fork extends regardless of the speed. When the load of the suspension spring 3 is reduced, such as when the suspension spring 3 is turned off, the relief plate 11 is lifted to release the accumulated pressure below the throttle means 10 above the throttle means 10.

[0040] At this time, as shown by the broken line in FIG. 1, if the required number of so-called vertical grooves 7a are formed on the outer circumference of the tubular body 7 to which the relief plate 11 is interposed, the relief plate 11 is lifted. The upper and lower sides thereof are communicated with each other through the vertical groove 7a, and the above-mentioned release of the accumulated pressure is quickly realized.

[0041] By the way, as described above, the tubular body 7 is an oil lock case constituting an oil lock structure, and when it functions as an oil lock structure, the inner peripheral side is an operating portion, so that it is on the outer circumference. Even if a so-called detour such as the vertical groove 7a is formed, it does not hinder the functioning of the oil lock structure.

[0042] In the front fork formed as described above, it is possible to generate a damping force by the damper during the expansion and contraction operation, while the front fork operates as follows depending on the speed during the compression operation. become.

That is, first, when the front fork is compressed at high speed, the speed at which the oil above the drawing means 10 flows below the drawing means 10 also increases, so that the drawing means 10 becomes a drawing resistance and the oil reservoir. The chamber is divided into upper and lower parts, so to speak, the air chamber G side and the second air chamber A side with the squeezing means 10 in between.

As a result, the second air chamber A has only the inflow of the oil discharged from the compression-operated damper into the reservoir chamber R, that is, the increase in the oil pressure in the oil reservoir portion below the squeezing means 10. It contracts only by itself and raises the spring force, and the spring force at this time becomes the rod reaction force in the damper.

[0045] On the other hand, the air chamber G is contracted only by the immersion of the inner tube 2 into the outer tube 1, that is, by the rise of the oil level O in the oil reservoir portion above the drawing means 10. The spring force is increased, and the spring force at this time becomes the tube reaction force in the front fork.

[0046] As a result, when the front fork is compressed at high speed, the rod reaction force and the tube reaction force described above become a combined reaction force, and the front fork moves in cooperation with the spring force of the suspension spring 3. It becomes a reaction force when the compression operation is performed.

By the way, the rod reaction force and the tube reaction force are as follows.

[0048] That is, when the front fork is compressed at high speed, the throttle resistance of the throttle means 10 is large and the air chamber G and the second air chamber A are separated, so that the volume of the air chamber G is changed from 1000 cc to 100 cc. Assuming that the volume of the second air chamber A is changed from 60cc to 30cc, the compression ratio in the air chamber G is 1000cc / 100cc = 10, and the compression ratio in the second air chamber A is 60cc. / 30cc = 2.

Therefore, the above tube reaction force is 10 cm.²× 10Kgf / cm²= 100Kgf, and the above rod reaction force is 1cm²× 2Kgf / cm²= 2Kgf, and the total 102Kgf becomes the reaction force that cooperates with the spring force of the suspension spring 3.

Next, when the front fork is compressed at medium and low speeds, the oil discharged from the compression-operated damper flows out to the oil reservoir in the reservoir chamber R, and the inner tube 2 is immersed in the outer tube 1. Then, the oil level O in the oil reservoir rises, and the air chamber G bordered by this oil level O contracts.

At this time, the speed at which the oil above the drawing means 10 flows below the drawing means 10 also slows down, and therefore the drawing resistance of the drawing means 10 is small, so that the pressure is balanced with the contraction of the air chamber G. The second air chamber A is also contracted.

[0052] Then, the reaction force, which is the spring force at this time, is as follows.

[0053] That is, when the front fork is compressed at a medium or low speed, the resistance of the drawing means 10 is small, so that the air chamber G and the second air chamber A contract due to pressure balance, and the compression at this time. The ratio is (1000cc + 60cc) / (100cc + 30cc) 8.2, so the reaction force at this time is (10cm).²+1 cm²) × 8.2Kgf / cm²= 90 2Kgf, and this reaction force becomes the reaction force that cooperates with the spring force of the suspension spring 3.

[0054] Therefore, when the front fork is compressed and operated at a high speed, a so-called high reaction force is generated as compared with the case where the front fork is compressed and operated at a medium and low speed.

[0055] As a result, when the motorcycle on which the front fork is mounted is normally running, it absorbs the road surface vibration to maintain a good riding comfort in the motorcycle, and at the same time, sudden braking operation or the like. When the nose dive phenomenon is caused by the above, the vehicle body posture can be properly maintained by the high spring force, so to speak.

[0056] In this front fork, it is a temporary situation that the spring force is increased in order to maintain the proper body posture of the motorcycle, and therefore, the so-called internal pressure is continuously increased. Since it is not invited, it does not cause deterioration of riding comfort, and there is no fear of reducing the durability of the seal.

[0057] In the above description, an example is obtained in which the second air chamber A is provided in a fixed state on the outer periphery of the damper, but in consideration of the function of the air chamber A, it is located below the throttle means 10. It may be arranged, and therefore, although not shown, it may be fixed to the inner circumference of the inner tube 2, and further, it is formed in an independent contractile bag shape as long as it does not interfere with the drawing means 10. It may be stored in a so-called floating state below the drawing means 10.

[0058] Further, in the drawing means 10, the relief plate 11 is so-called fixed by the suspension spring 3, but instead of this, although not shown, a separately distributed urging spring is used at a predetermined position. It may be fixed in.

[0059] It goes without saying that the diaphragm means 10 itself may be set in any other mode, although not shown, in place of the above-described embodiment.

[0060] Further, although the front fork is set to the inverted type as shown in the figure, the outer tube 1 is set to the axle side tube and the inner tube 2 is set to the vehicle body side tube. Even so, it goes without saying that the same effects as described above can be expected.

[Effect of the Invention] As described above, in the present invention, while it is possible to generate a damping force by the damper when the front fork expands and contracts, the front fork compresses at medium and low speeds. The spring force is lower than that of the case where the compression operation is performed at high speed. Therefore, when the motorcycle with the front fork mounted is normally running, it absorbs the road surface vibration and the ride comfort in the motorcycle. Can be maintained well.

[0062] In the present invention, when the front fork is compressed at high speed, the spring force is higher than that at medium and low speed, and therefore, it is automatically operated by sudden braking or the like. When a nose dive phenomenon is caused in a two-wheeled vehicle, it becomes possible to maintain an appropriate body posture.

[0063] Further, in the present invention, an elastic body in which a second air chamber arranged below the squeezing means fixes the upper and lower ends to the outer circumference of the damper and divides the air chamber between the upper and lower ends of the damper. When it is made of a barrel bellows, it is possible to simplify the configuration and exert a predetermined function, and it is possible to avoid unnecessarily complicated configuration in the front fork.

[0064] Further, in the present invention, the front fork is set to exert an oil lock function at its maximum compression, and the oil lock function is realized by immersing the oil lock piece in the oil lock case. If it is set to, the squeezing means can be arranged so as to be interposed around the outer circumference of the oil lock case, and when a similar tubular body or the like is separately arranged to provide the squeezing means. By comparison, it is possible to prevent an increase in the number of parts.

[0065] Further, in the present invention, the amount of oil corresponding to the volume of the rod discharged to the oil sump chamber is compensated in the second air chamber by the compression operation of the damper, so that when the front fork is compressed. It is possible to prevent the oil level from being disturbed by the flow of oil, and it is also possible to prevent aeration.

As a result, according to the present invention, it is possible not only to absorb the road surface vibration during normal running of the motorcycle, but also to appropriately increase the spring force when compressing at high speed such as during sudden braking. It is possible to supply the product at a low price, and it is most suitable for expecting an improvement in its versatility.

BRIEF DESCRIPTION OF THE DRAWINGS [FIG. 1] FIG. 1 is a partial vertical sectional view showing an intermediate portion of a front fork according to the present invention.

FIG. 2 is a partial vertical sectional view showing a lower end portion of the front fork according to the present invention.

FIG. 3 is a vertical cross-sectional view showing a front fork as a conventional example in principle.

[Code description] 1 Outer tube 2 Inner tube 2a Base 2b Pressure side damping valve 2c Pressure side check valve 3 Suspension spring 4 Cylinder that constitutes the damper 4a Hole 5 Rod that constitutes the damper 6 Piston that constitutes the damper 6a Extension side damping valve 6b Extension side check valve 7 Cylinder 7a Vertical groove 8 Oil lock piece 10 Squeezing means 11 Relief plate 11a Opening 12 Support 12a Opening 13 Bearing 21 Bellows 22 Tightening band A Second air chamber G Air chamber O Oil level R Reservoir chamber R1 Upper oil chamber R2 Lower oil chamber