JPS6343275B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a front fork of a motorcycle or the like.

In vehicles where the front wheels are supported by front forks, such as motorcycles, the center of gravity shifts during braking;
The front fork sinks due to inertial force, etc., and the front fork becomes nearly fully bent, especially during sudden braking, which is unfavorable in terms of steering stability.

Therefore, in order to prevent the front fork from sinking, various types of anti-dive mechanisms have been proposed and put into practical use.

On the other hand, the front fork may be equipped with a damping force adjustment mechanism that can arbitrarily adjust the damping force during normal driving, and in such cases, this damping force adjustment mechanism is installed separately from the anti-dive mechanism and is installed inside the front fork. It was incorporated.

Therefore, it is not only difficult to incorporate a damping force adjustment mechanism into this type of front fork, but also the internal structure of the front fork becomes complicated, and the damping force adjustment range is also limited.

In view of the above-mentioned problems regarding front forks, the present inventor has created the present invention to effectively solve the problems.

The object of the present invention is to provide a damping force adjustment mechanism which is arranged between the communication passages and has a piston having a plurality of orifices of different diameters around the piston which is rotated from the outside using an adjustment dial. By adding one or both of the damping force adjustment mechanisms that allow the set length of the spring that elastically contacts the provided valve body toward the oil hole side to be adjusted from the outside using a separate adjustment dial, These damping force adjustment mechanisms can be easily incorporated, simplifying the internal structure of the front fork, as well as providing a damping force adjustment function in addition to the anti-dive function, and further expanding the damping force adjustment range. The goal is to provide a front fork that can be used in a variety of ways.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a side view of the front part of a motorcycle equipped with a front fork having a mechanism according to the present invention, FIG. 2 is a longitudinal sectional side view of the lower part of the front fork, and FIG. 3 is a perspective view of the same.

In a motorcycle 1 shown in FIG. 1, an engine 3 is mounted on a body frame 2, and a fuel tank 4 is arranged above the engine 3.

A head pipe 5 is fixed to the front upper part of the vehicle body frame 2, and a top bridge 6 and a bottom bridge 7 are fixed to the upper and lower portions of a stem shaft (not shown in the figure), which is swingably inserted into the head pipe 5, respectively, as shown in the figure. has been done. An upper part of a front fork 8 is fixed in front of the head pipe 5 and between the bridges 6 and 7,
The front fork 8 extends downward while being inclined forward at a predetermined angle, and a front wheel 9 is rotatably supported at the lower part of the front fork 8. Note that 10 in the figure is a front fender.

On the other hand, a handle 1 is mounted on the top bridge 6.
1 is fixed, and a brake lever 12 is mounted near one grip portion 11a of the handle 11 as shown in the figure.
The brake lever 12 is connected to the front wheel brake mechanism via a brake wire 13.

Next, the lower structure of the front fork 8 is attached to the second
To explain based on the figure, 20 in the figure is an outer cylinder, and an inner cylinder 21 is fitted into the outer cylinder 20 from above so as to be vertically slidable. Further, the lower end of a seat pipe 22 whose upper end is open is fastened to the inner bottom of the outer cylinder 20 with a bolt 24 via a fixing member 23, and the seat pipe 22 is inserted into the outer cylinder 20 as shown in the figure.
are planted concentrically. This seat pipe 2
A plurality of oil passage holes 25 are bored in the lower side wall of the cylinder 2, and the enlarged diameter end portion 22a of the oil passage hole 25 is in sliding contact with the inner peripheral portion of the inner cylinder 21 as shown in the figure. The fixing member 23 is provided with a plurality of oil passage holes 26, and a check valve 27 is provided at the upper end thereof. A check valve 28 is provided at the inner periphery of the lower end of the inner cylinder 21.

In this way, the inside of the outer cylinder 20 is the inside of the sheet pipe, and the outside chamber
Divided into S ₁ , S ₂ and upper chamber S ₃ , each chamber S ₁ ,
Hydraulic oil is sealed in S ₂ and S ₃ .

On the other hand, a valve case 30 is bolted to the lower side of the outer periphery of the outer cylinder 20, and a horizontal hole 30a is formed through the case 30, and a vertical communication passage 30b is formed therein. and outer cylinder 2
Upper and lower oil passage holes 20a and 20b that open to the communication passage 30b are bored in the side wall of 0, and a valve seat 29 made of an elastic material and formed into a ring shape is provided on the outer periphery of the upper oil passage hole 20a. are fitted.

A plunger 31 is slidably fitted into the horizontal hole 30a of the valve case 30, and a rod 32 is rotatably and slidably inserted into the plunger 31. A piston 34 having a U-shaped cross section and having a plurality of orifices 33 of different diameters on its outer periphery is provided at the right end of the rod 32 so as to rotate together with the rod 32 and to slide relative to the piston 34. The piston 34 is always resiliently biased toward the valve seat 29 by a return spring 35 stretched between the piston 34 and the plunger 31. On the other hand, the other end of the rod 32 is supported by a stay 36 fixed to the valve case 30, and
An adjustment dial 37 is fixed to a portion projecting outward from the stay 36. Note that balls 39, which are sprung by springs 38, are engaged with a plurality of grooves formed on the right end surface of the adjustment dial 37, so that the adjustment dial 37 has a click feeling when it is rotated. Granted.

Further, a nut member 40 having a thread cut on the outer periphery is slidably fitted on the outer periphery of the rod 32 between the valve case 30 and the stay 36, and the nut member 40 is fitted between the rod 32 and the stay 36. Its rotation is restricted by a plurality of provided pins 41. The inner diameter part of an adjustment dial 42 is screwed onto the outer periphery of this nut member 40 as shown in the figure.
A ring-shaped sliding member 43 is fixed to the left end face of the dial 42, while a ball 45, which is resiliently sprung by a spring 44, is engaged with the right end face of the ring-shaped sliding member 43. The dial 42 is prevented from moving in the axial direction and is only allowed to rotate.

By the way, as shown in FIG.
Laterally elongated holes 30a, 30a are bored in both sides of the plunger 31, and pins (not shown) protruding from both sides of the plunger 31 protrude from these elongated holes 30a, 30a. The bifurcated lower portions 50a, 50a of the link 50 are connected as shown.

The upper end of the link 50 is pivotally connected to the bracket 8a of the front fork 8, as shown in FIGS. are doing.

Next, the function of the front fork 8 described above will be explained with reference to FIGS. 4 to 8.
4 to 8 show the compression side damping force with respect to the operating speed (operating stroke), and in each figure, the horizontal axis is the operating speed and the vertical axis is the compression side damping force.

During normal running of the motorcycle 1, the front fork 8 operates according to the unevenness of the road surface and generates a desired damping force.

That is, if we now consider the compression stroke of the front fork 8, the oil corresponding to the intrusion volume due to the downward movement of the inner cylinder 21 will flow from the seat pipe outer chamber _S2 to the oil passage hole 20a.
The oil flows into the seat pipe inner chamber _S1 through the orifice 33-1 that opens in the communication passage 30b, that is, the orifice 33-1 located at the bottom, the communication passage 30b, and the oil passage holes 20b, 26, and 25, and finally flows into the upper part. Flows into chamber _S3 .

In this case, a predetermined damping force is generated due to flow resistance (energy loss) when the oil passes through the orifice 33-1. This generated damping force can be easily adjusted by turning the adjustment dial 37 and changing the orifice that opens to the communication path 30b.
Generally, the generated damping force increases as the orifice diameter decreases. This relationship is shown in FIG. 4, where the damping force increases in the order of curves A, B, C, and D as the orifice diameter decreases.

At this time, a hydraulic force is generated in the piston 34 against the spring 35 to try to separate the piston 34 from the valve seat 29 (a force directed to the left in the figure).
At low operating speeds, this force is transferred to the spring 35
is smaller than the set load of piston 34.
remains seated on the valve seat 29, and the damping force characteristics as shown in FIG. 4 are obtained.

Next, when the operating speed is high and the force based on the hydraulic pressure acting on the piston 34 increases beyond the set load of the spring 35, the piston 34 separates from the valve seat 29, and the piston 34 functions as a kind of blow-off valve. As shown in FIG. 5, each of the damping force curves A, B, C, and D saturates midway into a straight line A' indicating the damping force characteristic of the piston 34 as a blow-off valve.

The damping force generated when the piston 34 acts as a blow-off valve is easily adjusted by the set load of the spring 35, and generally, as the set load increases, the generated damping force also increases.

Incidentally, the set load of the spring 35 can be easily adjusted by turning the adjustment dial 42. That is, when the dial 42 is turned in either direction, the nut member 40 screwed into it moves in the axial direction, and the plunger 31 in contact with it is moved, for example, to the right in FIG. 2, and the set length of the spring 35 is adjusted. shorten and increase the set load of this. The damping force characteristics at each set load are shown in Figure 6, and as the set load increases, the generated damping force changes along the straight lines A', B',
It increases according to C′ and D′.

In a case like this embodiment, if the orifice diameter and the set load of the spring 35 are adjusted simultaneously using both adjustment dials 37 and 42, the seventh
The damping force characteristics shown in the figure can be obtained, a damping force of any desired magnitude can be easily obtained, and as is clear from the figure, the adjustment range of the damping force can be expanded.

By the way, when the brake lever 12 is actuated to apply braking, the brake drum 51 rotates counterclockwise in FIG. As a result, the plunger 31 is rotated by the piston 34.
, and the piston 34 becomes immovable. Therefore, the flow of oil flows through the orifice 33- of the piston 34.
As a result, a high damping force is obtained as shown in FIG. 8, which effectively prevents the front fork 8 from sinking, and effectively exhibits the so-called anti-dive function. If you turn the dial 37 to change the orifice diameter of the piston 34,
The degree of anti-dive can be changed.

If the wheel 9 receives a strong impact due to a large unevenness of the road surface while the above anti-dive function is operating, the force acting on the piston 34 based on the hydraulic pressure generated in the front fork 8 will be The piston 34 overcomes the pressure of the valve seat 29, and as a result, the
As shown in the figure, any further increase in damping force is prevented, each characteristic curve bends approximately horizontally, and the anti-dive function is released.

Since the anti-dive mechanism described above is also equipped with a damping force adjustment mechanism, there is no need to make any changes to the internal structure of the front fork other than these mechanisms, and therefore the structure of the front fork can be modified accordingly. It can be simplified.

As is clear from the above description, the present invention provides a damping force adjustment mechanism in which a piston, which is interposed between communication passages and has a plurality of orifices of different diameters around the piston, is rotated from the outside using an adjustment dial; Either or both of the damping force adjustment mechanisms can be adjusted from the outside using a separate adjustment dial to adjust the set length of the spring that elastically contacts the piston toward the oil hole side, which is installed in the communication path. Because it is attached to the mechanism, it is easy to incorporate the damping force adjustment mechanism.
The structure inside the front fork can be simplified, and the range of damping force adjustment can be expanded.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a side view of the front part of a motorcycle equipped with a front fork having functions according to the present invention, and FIG. 2 is a longitudinal cross-section of the lower part of the front fork. FIG. 3 is a side view, FIG. 3 is a perspective view of the same, and FIGS. 4 to 8 are damping force characteristic diagrams of the front fork. In addition, 8 in the drawing is the front fork, 20 is the outer cylinder,
21 is an inner cylinder, 22 is a seat pipe, 30 is a valve case, 31 is a plunger, 32 is a rod, 33
is a different diameter orifice, 34 is a piston, 35 is a return spring, 37 and 42 are adjustment dials, 4
0 is a nut member.

Claims (1)

[Scope of Claims] 1. An inner cylinder is slidably fitted into an outer cylinder, and an oil chamber formed within the inner cylinder and an oil chamber formed between the inner and outer cylinders are communicated through a communication passage. , a front fork of a motorcycle, etc., which generates a damping force by causing hydraulic oil to flow in and out between the two oil chambers through the communication passage, wherein the front fork is configured to adjust the damping force. A damping force adjustment mechanism and an anti-dive mechanism that restricts sliding between the inner cylinder and the outer cylinder during sudden braking, etc. are provided, and the damping force adjustment mechanism is fixed to the side of the outer cylinder, and has an anti-dive mechanism fixed to the side of the outer cylinder. A valve case having a horizontal hole and a portion of the communicating passage; a plunger slidably fitted into the horizontal hole of the valve case; and a plunger slidably and rotatably inserted into the plunger. a piston provided at an end of the rod so as to be slidable relative to the rod and having a plurality of orifices of different diameters; an adjustment dial that is operably fixed and that rotates the rod by the rotational operation so that one of the plurality of different diameter orifices selectively faces the communication path; and an adjustment dial that is arranged between the piston and the plunger. The anti-dive mechanism includes: a tensioned return spring; and an engaging portion provided on a brake device; the anti-dive mechanism is engaged with the engaging portion, and one end is connected to the plunger, and the anti-dive mechanism is configured to act in the event of sudden braking, etc. A front fork comprising: a link that presses the plunger against the piston. 2. The inner cylinder is slidably fitted into the outer cylinder, and the oil chamber formed in the inner cylinder and the oil chamber formed between the inner and outer cylinders are communicated through a communication passage. A front fork for a motorcycle, etc., which generates a damping force by causing hydraulic oil to flow in and out between the two oil chambers, the front fork having a damping force adjustment mechanism for adjusting the damping force; An anti-dive mechanism is provided to restrict sliding between the inner cylinder and the outer cylinder during sudden braking, etc., and the damping force adjustment mechanism is fixed to the side of the outer cylinder, and has a horizontal hole and the communication passage inside. a plunger slidably fitted into the horizontal hole of the valve case; and an adjustment rod slidably and rotatably inserted through the plunger. a piston provided at one end of the rod; a return spring stretched between the piston and the plunger and urging the piston to face the communication passage in the valve case; and a return spring provided on the outer periphery of the adjustment rod. an adjustment dial that is rotatably provided and that adjusts the elasticity of the return spring by sliding the plastic gear with respect to the adjustment rod through the rotary operation, and the anti-dive mechanism is provided in a brake device. A front fork comprising: an engaging portion; and a link that engages with the engaging portion, has one end connected to the plunger, and presses the plunger against the piston during sudden braking.