JPS6257554B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a front fork that suspends a front wheel of a two-wheeled vehicle or the like, and particularly to a front fork whose damping force automatically increases as the inertial force of the front fork increases.

In the case of conventional so-called telescopic front forks, an oil hole is drilled on the outer periphery of the seat pipe.
Oil in the oil chamber whose volume decreases as the front fork expands and contracts flows out through the oil hole, and at this time, oil flow resistance acts as a so-called damping force. Therefore, the faster the inner cylinder penetrates into the outer cylinder, the more
The resistance is also increased to prevent the phenomenon of bottoming out between the inner cylinder and the outer cylinder. However, this type of means is not necessarily effective when the downward inertial force exerted on the inner cylinder becomes extremely large, such as during braking.
Therefore, various improvements were needed in terms of handling stability and shock absorption during braking.

As a means to solve the above problem, there is a so-called front fork with an anti-nose dive device, which has an oil passage connecting the oil chambers inside and outside the seat pipe on the side of the outer cylinder, and is equipped with a device that closes the oil passage during braking. This type of device is an effective means of solving the above problems, and has been put into practical use in many car models in recent years, but it has become complicated and requires further improvement in terms of cost, weight, assembly man-hours, etc. It has been demanded.

The present invention solves these problems of conventional devices by providing a flow path in the fork bolt that airtightly closes the upper end of the inner cylinder, and installing a free piston in an oil chamber filled in the inner cylinder and a separate tank. In a front fork of a two-wheeled vehicle, etc., which connects an oil chamber divided by an oil chamber with an oil chamber of a gas chamber, an inertia valve is disposed in the flow passage to slide and close the flow passage in response to a downward inertia force exerted on the inner cylinder. This is how it was done. An embodiment of the present invention will be described in detail below with reference to the drawings.

The figure is a longitudinal cross-sectional view of the main parts of a front fork according to an embodiment of the present invention, in which the lower part of an inner cylinder 1 to which a handle is attached and which suspends the front part of the vehicle body is slidably fitted into an outer cylinder as is well known. A suspension spring 2 is stretched between them, and the inner cylinder 1 is filled with oil 3.
Therefore, the inside of the inner cylinder 1 becomes an oil chamber. The upper end of this inner chamber 1 is sealed with a fork bolt 4, and a flow passage 5 is provided in this bolt 4, and an oil chamber A in the inner cylinder 1 and an oil chamber B are connected to the free piston 6a via this flow passage 5. and an oil chamber B of a separate tank 6 divided into a gas chamber C are communicated by a flexible pipe 7. Note 8
is a fork bolt cap screwed onto fork bolt 4. Further, the other pipe 7 of the tank 6 is connected to the other inner cylinder of the front fork. A cylindrical inertia valve 9 is slidably disposed in the flow path 5 of the fork bolt 4 via a valve spring 10, and when the downward inertia force received by the inner cylinder 1 exceeds a certain value, the spring 10 The spring pressure is adjusted so that the inertia valve 9 closes the flow passage 5 against the pressure.

In such a configuration, the vehicle body is suspended by suspension springs 2 and air springs made of gas sealed in the oil chamber A in the inner cylinder 1, the oil chamber B of the tank 6, and the gas chamber C, and the inner cylinder 1 is the overall structure of the suspension springs 2. Extends and contracts according to the spring characteristics. However, when the brakes are applied while driving, the inner cylinder 1 sinks, and when the sinking inertia becomes larger than a certain value, the inertia valve 9 is moved by the valve spring 1.
It is compressed against 0 and becomes the same state as above,
Since the flow path 5 is closed, the oil chamber A in the inner cylinder and the oil chamber B in the tank 6 are separated. Therefore, when the inner cylinder 1 descends, the oil pressure in the oil chamber A rapidly increases to prevent the inner cylinder 1 from descending. Therefore, the steering wheel is prevented from sinking due to the inertia of the passenger, and stable maneuverability can be maintained. If the front wheel rides on a protrusion on the road surface in this state, the inner cylinder 1 will also rise significantly, and the inertia valve 9 will operate to open the flow passage 5.
Therefore, the front fork easily compresses or expands to cushion the impact from the road surface.

As described above, the present invention provides a flow passage at the upper end of the front fork, and communicates the oil in the tank, which partitions the oil chamber and the gas chamber, with the oil filled in the cylinder by means of a separately placed free piston. By simply installing a simple inertia valve in the flow path, it is possible to prevent the steering wheel from sinking during braking and maintain stable maneuverability, while also maintaining a buffering effect against road impacts. .

[Brief explanation of the drawing]

The figure is a longitudinal sectional view of essential parts showing an embodiment of the front fork of the present invention. DESCRIPTION OF SYMBOLS 1...Inner cylinder, 2...Suspension spring, 3...Oil, 4...Fork bolt, 5...Flow path, 6...Tank, 6a...Free piston, 7...Pipe, 8...Fork bolt cap, 9...Inertia valve, 10... Valve spring, A, B...oil chamber, C...gas chamber.

Claims (1)

[Claims] 1 The inner cylinder and the outer cylinder are slidably fitted, the upper end of the inner cylinder is hermetically closed with a fork bolt, and a flow path is provided in the fork bolt, and the oil filled in the inner cylinder is passed through the flow path. In the front fork of a motorcycle, etc., which connects the chamber and the oil chamber in a separate tank divided into an oil chamber and a gas chamber by a free piston, a sliding valve pressed by a valve spring into the flow passage in the fork bolt. A front fork for a two-wheeled vehicle, etc., characterized in that a freely movable cylindrical inertia valve is disposed, and the inertia valve closes the flow passage when the downward inertia force received by the inner cylinder exceeds a certain value.