JP4898746B2 - 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 is mounted on the front wheel side of a two-wheeled vehicle and absorbs road surface vibrations that are input to the front wheel of the two-wheeled vehicle that is running.

  In a front fork that is a hydraulic shock absorber that is mounted on the front wheel side of a two-wheeled vehicle and absorbs road surface vibrations that are input to the front wheel of the traveling two-wheeled vehicle, the load at the time of compression operation is absorbed by the compression operation of the suspension spring ( For example, see Patent Document 1).

  As a measure for effectively absorbing the compression load by the suspension spring, although not explicitly disclosed in the patent literature, there is a measure to increase the spring constant in the middle of the compression operation of the suspension spring. Divide the pitch into two parts: increasing the pitch and decreasing the pitch.

  According to this measure, the suspension spring at the time of compression operation bends preferentially from the place where the winding pitch is large, so that the whole is bent, so that the first stage characteristic with a small spring constant can be obtained, and then the winding pitch. As a result, the entire structure bends even when it is small, so that it is possible to obtain a second stage characteristic that increases the spring constant.

As a result, in the first half normal operation region where the front fork compresses, it is possible to obtain a favorable ride comfort in a motorcycle, and when the front fork operates at the maximum compression due to sudden braking in the motorcycle, a large load is absorbed. It becomes possible, and the bottom butt in the front fork can be prevented.
JP2003-322191A (paragraphs 0006, 0007, 0010 to 0012 and 0014 in the specification, see FIG. 2)

  However, in the above proposal that bisects the winding pitch in one suspension spring into two parts, the basic one, it is possible to absorb different compressive loads in the first and second stages. There is a possibility that it is pointed out that there is a minor defect in the actual use.

  In other words, even if a single suspension spring has different winding pitches and obtains a two-stage spring characteristic, the wire diameter of the coil spring constituting the suspension spring is actually set to a wire diameter commensurate with the maximum compression load. The

  As a result, when viewed as a whole suspension spring, the coil spring has a large wire diameter, and therefore, the weight of the suspension spring itself tends to be increased to prevent the reduction of the overall weight of the front fork. It is inevitable that the material cost will increase by increasing the wire diameter as a whole, and it will not be possible to expect a reduction in the product cost of the front fork.

  Accordingly, the present invention has been developed in view of the above-described present situation, and the object of the present invention is to ensure the predetermined operation of the suspension spring, and to reduce the overall weight of the front fork. The present invention is to provide a front fork that is most suitable for the improvement of versatility by contributing to the reduction of product cost and the reduction of product cost.

  In order to achieve the above-described object, the structure of the front fork according to the present invention is basically a damper which has a damping action in the fork main body composed of the vehicle body side tube and the wheel side tube when the fork main body expands and contracts. And a fork for energizing the fork main body in the extension direction, the suspension spring has a double structure inside and outside and a long outside spring arranged inside and a inside outside. A short inner spring, and the outer spring is sandwiched between the cylinder body constituting the damper and the vehicle body side tube side or the wheel side tube side connecting the rod body constituting the damper. One end is fitted to a stopper fixed to the body, and is also slidably mounted on the rod body, while facing the head end of the cylinder body so as to be detachably seated. Ida in to fitting the other end and composed.

  Therefore, according to the present invention, in the front fork, first, since the suspension spring has an internal / external double structure consisting of the outer spring and the inner spring, the spring action is shared by the two springs. The length of the spring on each side can be made different, and the wire diameter and winding pitch can be made different accordingly.

  Therefore, while the suspension spring is made of one coil spring having the same wire diameter, the possibility of buckling in the spring on each side can be reduced as compared with the case of selecting a configuration in which the winding pitch is made large and small, By reducing one of the wire diameters, the overall weight of the suspension spring can be reduced, and the material cost of the suspension spring can be reduced.

  By the way, for suspension springs that are long and short inside and outside, the front spring that compresses when the outer spring increases the winding diameter while increasing the wire diameter, and the inner spring decreases the winding pitch while decreasing the wire diameter. In the fork, in the normal operation region, the first stage of small spring characteristics can be realized mainly by compression of the outer spring, and in the most compression operation region, mainly by compression of the inner spring, two steps of compression are achieved. A spring characteristic with large eyes can be realized.

  Hereinafter, the present invention will be described based on the illustrated embodiment. As described above, the front fork according to the present invention is mounted on the front wheel side of the two-wheeled vehicle and is input to the front wheel of the traveling two-wheeled vehicle. It functions as a hydraulic shock absorber that absorbs vibration.

  That is, as shown in FIG. 1, the front fork includes a damper that has a damping action when the fork main body extends and contracts in a fork main body including a vehicle body side tube 1 and a wheel side tube 2, and the fork main body extends in the extending direction. And a suspension spring for energizing.

  Although the fork main body is not shown, the upper end side is coupled to the handle side of the two-wheeled vehicle and the lower end portion suspends the front wheel, thus enabling the front wheel to turn by steering the handle.

  The fork main body shown in the figure is set to an inverted type in which the upper end side of the wheel side tube 2 made of a small-diameter inner tube is inserted into the lower end side of the vehicle body side tube 1 made of a large-diameter outer tube so as to be retractable. However, from the realization of the present invention, contrary to the above, the vehicle body side tube 1 may be set to an upright type in which the small diameter inner tube and the wheel side tube 2 are large diameter outer tubes. .

  The fork main body shown in the figure has bearings 1a and 1b arranged with a vertical interval between the vehicle body side tube 1 and the wheel side tube 2, and the upper and lower bearings 1a. , 1b through the communication hole 2a opened in the wheel side tube 2 to ensure that the hydraulic oil enters between the tubes 1 and 2 on both sides.

  In addition, the damper shown in the figure is set to be an upright type in which the rod body 4 as the upper end side member is connected to the cylinder body 3 as the lower end side member so as to be able to protrude and retract. On the contrary, the cylinder body 3 may be set to an inverted type in which the upper end side member is used and the rod body 4 is used as the lower end side member.

  In this damper, the expansion / contraction operation is performed in synchronization with the expansion / contraction operation of the fork main body, and a predetermined attenuation action is performed in the cylinder body 3 by the attenuation portion of the housing, and the front fork functions as a hydraulic shock absorber.

  As for the damping part in the cylinder body 3, the piston body 5 that is slidably accommodated in the cylinder body 3 while being held at the tip of the rod body 4 inserted into the cylinder body 3, and the cylinder body 3 It is provided in the base valve part provided in the bottom end part.

  In the above-described damper, the cylinder body 3 is erected on the shaft core portion of the wheel side tube 2, and at this time, the wheel is set such that the lower end portion of the cylinder body 3 closes the lower end opening of the wheel side tube 2. Although not shown in detail in a state of being seated on the bottom member 21 connected to the side tube 2, it is coupled to the wheel side tube 2 by tightening a tightening bolt that penetrates the shaft core portion of the bottom member 21.

  The rod body 4 is screwed to the shaft core portion of the cap member 11 whose upper end portion closes the upper end opening of the vehicle body side tube 1 with the lock nut 12 interposed therebetween.

  The upper end of the wheel-side tube 2 is brought into contact with the lower end of the cap member 11 when the fork main body is in the most compressed state, and so-called bottom-out in the fork main body is prevented.

  The suspension spring urges the fork main body in the extending direction. If it has been conventional, for example, as disclosed in Patent Document 1 described above, the suspension spring is composed of a single coil spring. The inner spring S2 is formed of a long coil spring having a long structure and a long coil spring having a long side and a long side, and an inner spring S2 having a short coil spring disposed on the inner side and having a short side. And two coil springs.

  As described above, when the suspension spring is not composed of one coil spring but is composed of two coil springs that are inside and outside, the spring action when the suspension spring is composed of one coil spring is shared by the two coil springs. Accordingly, the length of each coil spring can be shortened or the wire diameter can be made different accordingly.

  Therefore, compared with the case where the suspension spring is composed of a single coil spring and the configuration in which the winding pitch is large or small is selected, the suspension spring can reduce the possibility of buckling in each coil spring. For example, the overall weight of the suspension spring can be reduced by setting the wire diameter of the inner spring S2 smaller than the wire diameter of the outer spring S1 to reduce the weight.

  As described above, the suspension spring according to the present invention includes the outer spring S1 and the inner spring S2, each of which is disposed in the fork main body as follows.

  First, the outer spring S1 is configured such that the fork main body is an inverted type and the damper is an upright type, so that the cylinder body 3 and the rod body 4 connected to the cylinder body 3 so as to be able to project and retract are connected. It is clamped between the tube 1 side.

  More specifically, the base end which is the lower end in the drawing of the outer spring S1 is carried by the head end which is the upper end of the cylinder body 3, and the tip which is the upper end in the drawing is locked to the lower end of the cylindrical spacer 6. The upper end of the cylindrical spacer 6 is locked to the lower end of the cap member 11 described above.

  Therefore, the outer spring S1 is compressed in synchronization with the movement of the rod body 4 when the fork main body is compressed and the rod body 4 is immersed in the cylinder body 3, and the reaction force at that time is reflected as the reflection. Thus, the rod body 4 is urged in the extending direction to project from the cylinder body 3.

  Although shown in the figure, the cylindrical spacer 6 is directly locked to the upper cap member 11 so that the upper end position does not move. Instead, although not shown, the cylindrical spacer 6 moves to the cap member 11. Therefore, the moving means moves the upper end position of the cylindrical spacer 6 up and down, thereby changing the spring force of the outer spring S1, so that the height position of the handle in the two-wheeled vehicle, that is, the position of the vehicle body is changed. The height position may be changeable.

  Further, the lower end, which is the base end of the outer spring S1, is supported on the inner bottom of the bottom member 21 in the wheel side tube 2, although not shown, instead of being supported on the head end, which is the upper end of the cylinder body 3 described above. It is also good.

  The cylindrical spacer 6 is set so long that its lower end is positioned near the head end of the cylinder body 3, and the suspension spring is formed between the cylindrical spacer 6 and the inner bottom of the bottom member 21 in the wheel side tube 2. It may be sandwiched between them.

  Next, as shown in FIG. 2, the inner pulling S <b> 2 is fitted to the stopper 7 which is interposed in the rod body 4 constituting the damper and fixed by the fitting of the snap ring 71, and the rod is similarly rod-like. The lower end, which is the other end, is fitted to the slider 8 that is slidably interposed in the body 4 and that is slidably opposed to the head end of the cylinder body 3 that also constitutes the damper.

  The stopper 7 is formed in an annular shape and is fixed to the outer periphery of the rod body 4 to prevent the upper end of the inner spring S2 from rising from the set position. When the slider 8 described later is seated on the head end of the cylinder body 3, Allow compression of the inner spring S2.

  Therefore, the stopper 7 is fixed by caulking to a snap ring 71 fitted on the outer periphery of the rod body 4, and the snap ring 71 is fitted into an annular groove 4 a formed on the outer periphery of the rod body 4 and is made immovable. ing.

  Therefore, the stopper 7 suspends the inner spring S2, so that the inner spring S2 is prevented from playing with the slider 8 below, and noise generation is avoided.

  On the other hand, the slider 8 has a cylindrical portion 8a through which the rod body 4 is inserted and a flange portion 8b that engages the other end of the inner spring S2, and is fitted to the lower end of the inner spring S2 as described above. Thus, when the inner spring S2 moves away from the head end of the cylinder body 3 due to the movement of the rod body 4, it is also separated from the head end of the cylinder body 3.

  The slider 8 allows the rod body 4 to slide after the flange portion 8b is seated on the head end of the cylinder body 3, so that the cylindrical portion 8a has a lateral hole 8c that allows communication between the inside and the outside. And the slidability of the rod body 4 with respect to the cylinder part 8a is ensured.

  Further, when the rod body 4 repeatedly moves in and out of the cylinder body 3, the slider 8 repeats the seating of the flange portion 8b with respect to the head end of the cylinder body 3, but the flange portion 8b separates from the head end. In order to prevent generation of noise at the time, the flange portion 8b has a radiation groove 8d facing the head end of the cylinder body 3.

  In the present invention, the following relationship is established between the outer spring S1 and the inner spring S2 formed as described above.

  That is, first, the wire diameter of the outer spring S1 is set larger than the wire diameter of the inner spring S2, and conversely, the wire diameter of the inner spring S2 is made smaller than that of the outer spring S1.

  As a result, it is possible to reduce the overall weight of the suspension spring as compared with the case where the wire diameter is the same even when the pitch is different in the conventional case of a single suspension spring.

  Next, the winding pitch in the outer spring S1 is set larger than the winding pitch in the inner spring S2, and conversely, the winding pitch in the inner spring S2 is made smaller than that in the outer spring S1.

  As a result, it is possible to reduce the cost of parts compared to the case where the pitch of the conventional suspension spring is different, and the setting of the side springs S1 and S2 can be easily changed.

  Note that the winding directions between the outer spring S1 and the inner spring S2 formed as described above are reversed, and the occurrence of biting between the two is avoided.

  Incidentally, in each of the side springs S1 and S2 that are long and short inside and outside, the outer spring S1 exerts a spring force that urges the fork main body in the extension direction from the beginning, while the inner spring S2 is set by the fork main body. Since the spring force that urges the fork body in the extension direction after compressing the stroke is exerted, the first half of the compression stroke depends on the spring force of the outer spring S1, and the spring force of the inner spring S2 is also added in the second half of the compression stroke. Depends on the spring force.

  By the way, in the present invention, the maximum pressure interposed in the rod body 4 is between the stopper 7 for fitting one end of the inner spring S2 and the slider 8 for fitting the other end of the inner spring S2. A spring S is arranged.

  In this way, the most pressure spring S is disposed between the stopper 7 and the slider 8, so that the most pressure spring S or an alternative to this is disposed in another location. This is advantageous in that the so-called rod stroke is not reduced.

  Incidentally, the most pressure spring S compresses the fork body when it is in the most compressed state to alleviate the impact. Therefore, at the normal time, the upper end is separated from the stopper 7 as shown in FIG. The lower end is seated on the slider 8.

  Therefore, in the front fork formed as described above, the suspension spring has an inner and outer double structure consisting of the outer spring S1 and the inner spring S2. The springs S1 and S2 can be shared, and accordingly, the lengths of the side springs S1 and S2 can be shortened or the wire diameters can be made different.

  Therefore, the possibility of buckling in the springs S1 and S2 on each side can be reduced as compared with the case where the suspension spring is made of one coil spring having the same wire diameter and the winding pitch is made larger or smaller. At the same time, the setting of the springs S1 and S2 on each side can be easily changed. On the other hand, by reducing the wire diameter of either one, the overall weight of the suspension spring can be reduced and the material cost of the suspension spring can be reduced. Can be reduced.

  The above description does not mention whether the motorcycle is a bicycle or a motorcycle, but it goes without saying that any of them is suitable for the realization of the present invention.

FIG. 2 is a front view of a half-crown cross section showing the front fork according to the present invention. It is a partial half-sectional view which expands and shows the principal part of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body side tube 2 Wheel side tube 3 Cylinder 4 Rod body 5 Piston body 6 Cylindrical spacer 7 Stopper 8 Slider 8a Cylinder part 8b Flange part S Maximum pressure spring S1 Outer spring S2 Inner spring

Claims (5)

In a front fork comprising a fork body composed of a vehicle body side tube and a wheel side tube and a damper that dampens when the fork body is extended and retracted and a suspension spring that urges the fork body in the extending direction. The suspension spring has a double outer structure and has a long outer spring disposed on the outside and a short inner spring disposed on the inner side, and the outer spring constitutes a damper and a cylinder body and a damper. It is sandwiched between the vehicle body side tube side or the wheel side tube side to which the rod body is connected, and an inner spring is fitted to one end of the stopper fixed to the rod body, and is also slidably mounted on the rod body. A front fork characterized in that the other end is fitted to a slider facing the head end of the cylinder body so as to be separable. The front fork according to claim 1, wherein a wire diameter of the outer spring is set larger than a wire diameter of the inner spring. The front fork according to claim 2, wherein a winding pitch of the outer spring is set larger than a winding pitch of the inner spring. The front fork according to claim 3, wherein a most pressure spring interposed in the rod body is arranged between a stopper for fitting one end of the inner spring and a slider for fitting the other end of the inner spring. The slider has a cylinder portion through which the rod body is inserted and a flange portion that engages the other end of the inner spring. The cylinder portion has a lateral hole that allows communication between the inside and the outside, and the flange portion is connected to the head end of the cylinder body. The front fork according to claim 4, wherein the front forks have opposed radial grooves.

Images