JPH0137352Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a front fork of a two-wheeled vehicle or the like.

Inner and outer cylinders are slidably fitted, a sheet pipe is installed in the inner bottom of the outer cylinder with an oil hole drilled in its peripheral wall, and an oil hole is drilled in the peripheral wall of the inner periphery of the sheet pipe. In the case of a front fork of the type in which a hollow bolt made of It is most desirable that the oil hole and the oil hole of the hollow bolt are located opposite each other.

However, since the hollow bolt is screwed onto the inner periphery of the seat pipe as described above, it is extremely rare for the oil holes provided on both sides to be located exactly opposite each other, and usually both oil holes are offset by a certain angle. It will be located at This relationship is shown in FIG. That is, in FIGS. 4a to 4g, four oil holes 104e are bored in the peripheral wall of the sheet pipe 104 at equal angle pitches (90° pitch), and four oil holes 104e are also formed in the hollow bolt 105.
Both holes 1 when drilling 05a... with equal angle pitch
04e..., 105a..., and the figure a shows the case where the deviation angle is 0, that is, both oil holes 1
04e..., 105a... are positioned completely opposite each other, and hereafter b, c, d, e, f, g are deviation angles = 15°, 30°, 45°, 60°, 75°, 90, respectively. The case of ゜ is shown.

Here, in the case shown in FIG. 4a, the opening ratio of each oil hole 105a provided in the hollow bolt 105 to the oil hole 104e provided in the seat pipe 104 is assumed to be 100%, and this is added for all oil holes 105a... In case of lever, the opening ratio is 400% (100×4)
If defined, the aperture ratios in each case of b to g are 360%, 224%, 180%, 224%, and 360%, respectively, as shown in the figure.
%, 400%, and this value shows the highest value of 400% for a and g, and the lowest value of 180% for d.

As a result of the above, the maximum value of the opening ratio is 400% and the minimum value
The width from 180% is 220% (=400% - 180%),
Therefore, there will be very large variations in performance between each front fork.

The present invention was developed to effectively eliminate such inconveniences, and its purpose is to prevent the opening of the oil hole due to the misalignment between the oil hole provided in the seat pipe and the oil hole provided in the hollow bolt. An object of the present invention is to provide a front fork for a two-wheeled vehicle or the like with small variations in performance by preventing a decrease in the ratio.

In order to achieve such an object, the present invention has an inner and an outer cylinder fitted together in a slidable manner, a sheet pipe formed by drilling an oil hole in the peripheral wall at the inner bottom of the outer cylinder, and In a front fork of a two-wheeled vehicle, etc., in which a hollow bolt with oil holes drilled in the peripheral wall thereof is screwed on the inner periphery, the oil holes in at least one of the seat pipe and the hollow bolt are bored at unequal pitches. is its characteristic.

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

FIG. 1 is a half-cut sectional view of a front fork according to the present invention, FIG. 2 is an enlarged cutaway side view of the front fork portion, and FIGS. 3 a to 3 g are sectional views taken along the line 3-3 in FIG.

In the front fork 1 shown in FIG. 1, 2 is an outer cylinder, and an inner cylinder 3 is inserted into and fitted into the outer cylinder 2 so as to be vertically slidable. Further, a seat pipe 4 is installed in the inner bottom of the outer cylinder 2, and the upper end piston portion 4a of the seat pipe 4 is in sliding contact with the inner circumference of the inner cylinder 3.

Oil holes 4b..., 4 are provided in the peripheral wall of the sheet pipe 4.
c..., 4d..., 4e... are bored respectively, and a hollow bolt 5 is screwed into the lower inner periphery of the seat pipe 4, and a hollow bolt 5 is screwed into the inner periphery of the hollow bolt 5 between the hollow bolt 5 and the hollow bolt 5. The center bolt 6 is screwed with a gap ΔS ₁ formed therebetween.

While the oil holes 4e of the seat pipe 4 are drilled at equal angle pitches (90° pitch) as shown in Fig. 3, the oil holes of the hollow bolts 5 located at the same height as these oil holes 4e... The holes 5a are bored at unequal pitches as shown in the figure.

By the way, a check valve 8, which is biased by a spring 7 in a direction to close the gap _ΔS1 , is in contact with the upper end surface of the hollow bolt 5.

An oil lock piece 9 is provided on the lower outer periphery of the seat pipe 4, and a gap ΔS ₂ is formed between the upper inner periphery of the oil lock piece 9 and the outer periphery of the seat pipe 4, as shown.

On the other hand, the upper end of the inner cylinder 3 is connected to the fork bolt 1.
0, and a free valve 1 is provided on the inner periphery of the lower part of the inner cylinder 3 and is in sliding contact with the outer periphery of the seat pipe 4.
1 is fitted. A spring 12 is stretched between the fork bolt 10 in the inner cylinder 3 and the upper end surface of the seat pipe 4 as shown in the figure.

Further, an oil seal 13 is fitted on the upper inner periphery of the outer cylinder 2, and the oil seal 13 is fitted in sliding contact with the outer periphery of the inner cylinder 3, and a dust seal 14, whose lip portion is also in sliding contact with the outer periphery of the inner cylinder 3, is fitted on the upper end of the outer cylinder 2. crowned. Furthermore, the outer circumferential sliding portion of the inner cylinder 3 is covered with a telescopic, bellows-shaped dust boot 15 installed between the inner cylinder 3 and the outer cylinder 2.

The interior of the front fork 1 is divided into seat pipe inner/outer chambers S ₁ , S ₂ and upper chamber S ₃ , and each chamber S ₁ , S ₂ , S ₃ is filled with hydraulic oil. In particular, the upper part of the upper chamber _S3 is occupied by gas.

Next, the function of the front fork 1 will be explained.

When the inner cylinder 3 moves downward with respect to the outer cylinder 2 during the compression stroke, the volume of the seat pipe outer chamber S ₂ decreases, and a portion of the hydraulic oil corresponding to this volume reduction flows into the oil hole of the seat pipe 4. Inner seat pipe through 4d...
The remaining hydraulic oil flows into _the gap ΔS ₂ and oil hole 4.
It flows into the gap ΔS ₁ through e..., 5a..., and its pressure pushes the check valve 8 upwardly open against the elastic force of the spring 7, thereby opening the check valve 8.
It flows into the sheet pipe interior chamber _S1 through the sheet pipe.

This hydraulic oil then flows through the oil holes 4d..., 4e..., 5a.
..., a necessary damping force is generated in the front fork 1 during this compression stroke due to flow resistance when passing through the check valve 8 and the like.

By the way, as mentioned above, the hollow bolt 5 has an oil hole 5.
Since the holes a... were drilled at unequal angle pitches, one of the oil holes 5a... 5a-1 was opposite to one 4e-1 of the oil holes 4e of the seat pipe 4 as shown in Fig. 3a. , that is, from the state of deviation angle = 0° to b to g in the same figure.
When the opening ratio of the oil holes 5a is calculated using the same calculation method as described above for the deviation angles of 15°, 30°, 45°, 60°, 75°, and 90°, it is 291% as shown in the figure. 336%,
336%, 291%, 247%, 247%, 291%. According to this result, the width between the maximum value of 336% and the minimum value of 247% is 89% (=336% - 247%), which is significantly reduced from the conventional value of 220%.

Therefore, it is possible to prevent a decrease in the opening ratio of the oil holes 5a due to misalignment between the oil holes 4e provided in the seat pipe 4 and the oil holes 5a provided in the hollow bolt 5, and thereby the front fork 1 It is possible to suppress variations in performance, that is, damping force, to a small level.

Next, when the inner cylinder 3 moves upward with respect to the outer cylinder 2 during the extension stroke, pressure is generated in the seat pipe outer chamber _S4 , and due to flow resistance when the hydraulic oil passes through the oil holes 4b and 4c, the required amount is A damping force is generated.

In addition, above has been particularly described an example in which the oil holes 5a of the hollow bolt 5 are drilled at unequal angle pitches.
Oil hole 4e of seat pipe 4... or both 5a...,
4e... may be drilled at unequal angle pitches. However, if both 5a..., 4e... are formed into unequal pitches of exactly the same shape, the result may be the same as when the same shape of equiangular pitches is formed, so both 5a...
..., 4e... with unequal angular pitches, it is necessary to use unequal angular pitches such that the corresponding oil holes 5a, 4e have different deviation angles.

As is clear from the above explanation, according to the present invention, the oil holes in at least one of the sheet pipe and the hollow bolt are bored at unequal pitches, making it possible to prevent a decrease in the opening ratio due to misalignment of both oil holes. , it is possible to minimize variations in front fork performance.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a half-cut sectional view of a front fork according to the present invention;
Figure 2 is an enlarged cutaway side view of the lower part of the front fork, Figures 3a to 3g are sectional views taken along the line 3-3 in Figure 2, and Figures 4a to 4g are similar views to Figure 3 of the conventional example. be. In the drawing, 1 is the front fork, 2 is the outer cylinder, and 3 is the front fork.
is the inner cylinder, 4 is the seat pipe, 4a is the tip piston part, 4b, 4c, 4d, 4e are the oil holes, 5 is the hollow bolt, 5a is the oil hole, 6 is the center bolt, S ₁ , S ₂
are the inner and outer chambers of the sheet pipe, S ₃ is the upper chamber, ΔS ₁ ,
ΔS ₂ is the gap.

Claims (1)

[Scope of utility model registration request] The inner and outer cylinders are slidably fitted together, a sheet pipe with an oil hole drilled in the peripheral wall is installed in the inner bottom of the outer cylinder, and a sheet pipe is installed in the inner periphery of the sheet pipe with an oil hole drilled in the peripheral wall. In a front fork of a two-wheeled vehicle, etc., in which a hollow bolt is screwed, the oil hole is bored at an unequal pitch in at least one of the seat pipe and the hollow bolt. A front fork for a two-wheeled vehicle, etc., characterized in that the angle of deviation of the opposing oil holes is different for each pair of opposing oil holes.