JPS6256833B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a shock absorber for a motorcycle,
In particular, this invention relates to a front fork designed to prevent the front fork from sinking during braking.

For example, when braking a motorcycle while driving, the rider's weight is applied to the handlebars, creating inertia and adding an extremely large load to the handlebars. Therefore, the front fork is compressed to the maximum, resulting in poor steering performance, and not only the riding comfort but also the stability is significantly impaired, which is dangerous.

Therefore, in order to prevent the handle from sinking during braking, the hydraulic pressure at the time of pushing is conventionally controlled by a valve mechanism, but this requires the use of a complex mechanism and a large number of parts. Ta.

The present invention aims to fundamentally solve these conventional problems and provide a mechanism that is simple and works reliably. An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a partially longitudinal side view showing one embodiment of the front fork of the present invention. As shown in the figure, attach the lower part of the fork pipe 1 whose upper end is attached to the handlebar of the motorcycle to the bottom case 2.
The bottom case 2 is filled with oil, and the upper end of the seat pipe 3 installed on the bottom of the fork pipe 1 is slidably fitted inside the fork pipe 1. A vehicle body suspension spring 4 is stretched between the upper end of the fork pipe 3 and the upper end of the fork pipe 1. The bottom case 2 has a mounting hole (not shown) formed at its lower end into which a front wheel shaft is fitted, and an oil seal 5 is provided at its upper end. Further, a check valve 6 is provided at the lower end of the fork pipe 1, and an orifice 7 is formed at the upper part of the seat pipe 3. Further, a cylindrical oil lock piece 9 fitted with an O-ring 8 is attached to the lower part of the seat pipe 3, and oil holes 10 and 11 are provided in the lower part of the seat pipe 3 and the piece 9, respectively. An oil passage consisting of oil passages 12, 13, and 14 is formed, and a flexible membrane 15 filled with magnetic fluid is inserted into the oil passage 14. Note that the membrane body 15 is inserted into the mesh case 16 above and below so that it does not pop out. On the other hand, an electromagnet 17 is installed between the oil passages 14 so that oil normally flows through the oil passages 12, 14, and 13. When controlling the oil, an external power source is connected to the brake and the electromagnet 17 is excited. A magnetic field is created by passing a current through the coil, and a second
As shown in the figure, the magnetic fluid within the flexible film body 15 is expanded by magnetic force, closing the oil passage 14 and stopping the operation. However, if the operation remains stopped forever, the handlebar position remains high and the center of gravity is high, making the car body unstable.
4 is opened and activated to lower the center of gravity and stabilize the vehicle body.

Next, its operation will be described.

In the above-mentioned front fork, the oil passages 12, 14, 13, 1 are normally located on the outside of the seat pipe 3.
2, 11, and 10 to the inside thereof. Therefore, when the fork pipe 1 moves downward due to the unevenness of the road surface, the check valve 6 rises, and the oil at the bottom of the pipe 1 moves into the fork pipe 1 through the groove formed on the upper surface of the valve 6, and the It flows into the pipe 1 through the oil passage and the inside of the sheet pipe 3, so that the fork pipe 1 is easily lowered by a relatively small damping force. Next, when the pipe 1 starts to rise due to the force of the spring 4, the check valve 6 closes as shown in the figure, so that the oil between the lower part of the fork pipe 1 and the seat pipe 3 passes through the orifice 7 to the seat. The oil is ejected into the pipe, generating a large damping force, and the valve 18 rises, so oil is supplied to the lower part of the fork pipe 1 through the oil hole 10.
Furthermore, when braking is applied while driving in the state shown in the figure, current is passed from the external power source to the excitation coil of the electromagnet 17 in conjunction with the braking mechanism, so that the flexible membrane 15 is expanded and the oil passage 14 is closed. It will be done. Therefore, when the fork pipe 1 moves downward due to the load applied to the handle due to the inertia of the rider, the oil in the lower part of the pipe moves to the upper part only through the groove on the upper surface of the check valve 6.
Further, the oil corresponding to the volume of the fork pipe 1 that has penetrated into the oil is ejected into the interior of the sheet pipe 3 through the orifice 7. Because of this, a large damping force is generated and prevents the fork pipe 1 from descending.
The steering wheel is prevented from sinking and stable steering performance can be maintained. In addition, if an RC circuit is connected in parallel to the excitation coil of the electromagnet 17, R, C
It is also possible to operate the electromagnet 17 with a time constant.

As described above in detail, the front fork of the present invention has the excellent effect of preventing the steering wheel from sinking when braking is applied with an extremely simple structure.

[Brief explanation of the drawing]

FIG. 1 is a partially longitudinal side view showing an embodiment of the front fork of the present invention, and FIG. 2 is a diagram illustrating its operation. 1...fork pipe, 2...bottom case, 3...
Seat pipe, 6... Check valve, 10, 11... Oil hole,
12, 13, 14...Oil passage, 15...Flexible film body enclosing magnetic fluid, 17...Electromagnet.

Claims (1)

[Claims] 1. The lower part of the fork pipe attached to the handlebar is slidably fitted inside the bottom case tied to the front wheel, and the upper end of the sheet pipe planted on the bottom of the bottom case is slid inside the fork pipe. In addition to being freely fitted and filled with oil, the bottom case is provided with an oil passage that connects the inside and outside of the sheet pipe, and a flexible membrane body containing magnetic fluid is provided in the oil passage. An electromagnet is provided to surround the membrane body, and a current is passed through the excitation coil of the electromagnet in conjunction with braking to expand the magnetic fluid in the membrane body and close the oil passage. A front fork for a motorcycle featuring