JPS623558Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a shock absorber used in front forks of motorcycles, etc.

Conventionally, an inner tube as a fork pipe is slidably fitted inside an outer tube filled with oil, and a piston that slides into the inner tube is provided at the upper end of a cylinder planted on the bottom surface of the outer tube. , the upper end of the cylinder is open, and holes for generating damping force during expansion are provided on the side surfaces, and an oil hole is bored in the lower part of the cylinder to serve as an oil hole rod into which the lower end piston part of the inner tube fits. A cylindrical oil lock piece is fixed to the base end of the cylinder, and an oil hole communicating with the inside and outside of the cylinder is provided in the lower part of the oil lock piece,
A shock absorber is disclosed in Japanese Utility Model Publication No. 53-1707, etc., in which a cylindrical check valve is installed at a position facing this oil hole so that it can be opened and closed, and an annular gap is provided between the lower outer periphery of the cylinder and the inner periphery of the oil lock piece. Proposed.

This generates a damping force determined by the size of the damping force generating hole and the compression speed or expansion speed of the inner tube, and also by the oil lock action between the oil lock piece and the piston.
It is designed to reduce the mechanical compression impact of the inner tube.

However, when looking at the flow of oil when the inner tube moves from its most compressed state to its extension operation, the lack of oil in the oil lock chamber that occurs as the piston rises is due to the oil hole drilled from the cylinder to this cylinder. This is compensated for by supplying oil in the cylinder through an annular gap between the cylinder and oil lock piece, an oil hole in the oil lock piece, and a cylindrical check valve.

However, the oil hole drilled in the cylinder is drilled in a stepped part that creates an annular gap, and requires a sufficient opening area to supply oil to the oil lock chamber without resistance, resulting in a decrease in the strength of the cylinder. There is a problem. In particular, the cylinder must have sufficient strength since it receives an extension load at maximum extension, and it is not preferable to form large oil holes in the cylinder as described above.

The purpose of this invention is to provide a shock absorber suitable for use in front forks, etc., which has a simplified oil lock mechanism and improved cylinder strength and reliability.

In order to achieve this object, the structure of the present invention is characterized in that a gap is provided between the cylinder and the oil hole rod serving as the oil lock piece, and a check valve is interposed in the middle of this gap.

Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is a sectional view of the main part of the shock absorber of the present invention, and FIG. 2 is an enlarged sectional view showing the details of the main part. In the figure, reference numeral 1 denotes an outer tube, and the lower end of a cylinder 3 is screwed into and held by a bolt 2 attached to the bottom of the outer tube. Further, an oil hole rod 4 as an oil lock piece is fixed around the cylinder 3 at the bottom of the outer tube 1, and a gap 5 opening upward is formed between the oil hole rod 4 and the cylinder 3. has been done. Further, an oil hole 6 communicating with the inside of the outer tube 1 and the gap 5 is provided at the base of the oil hole rod 4. Reference numeral 7 designates a small diameter portion at the bottom of the cylinder 3. A check valve 8, which is an annular plate circumscribing the inner peripheral surface of the oil hole rod 4, is loosely fitted into the small diameter portion 7. , the gap 5 between the large diameter portion of the cylinder 3 and the oil hole rod 4 is always closed. 1
0 is an inner tube that slides into contact with the inner circumference of the outer tube 1. At the tip of this inner tube 10, an oil lock piston 12 having a conical through hole 11 that widens downward is attached. A check valve 13 that opens during the compression stroke is provided in the engine.
Further, 14 is an oil hole provided at the bottom of the cylinder 3.

In the shock absorber having such a structure, the check valve 1 is closed during the compression stroke of the inner tube 10.
3 opens, the oil in chamber B below the oil lock piston 12 moves to chamber A, and the check valve 8 is kept closed. Furthermore, when the oil lock piston 12 reaches the oil hole rod 4, the check valve 8 seals the gap 5. Therefore, the oil equivalent to the volume of the inner tube 10 that has entered the outer tube 1 enters the oil hole 14.
A part of the oil in the B chamber pushes open the valve 13 and flows out into the A chamber, and the flow resistance flowing through the notch in the valve 13 generates a damping force. That is, a damping force determined by the size of the notch in the valve 13 and the compression speed of the inner tube 10 is generated.

Furthermore, since the check valve 13 is closed during the extension stroke of the inner tube 10, the pressure inside the B chamber becomes negative. Until the oil lock piston 12 separates from the upper end of the oil hole rod 4, the oil lock chamber C becomes a negative pressure, and the gap 5 below the check valve 8 through the oil hole 6 also becomes a negative pressure. moves down against the spring 9. Therefore, the gap 5 is opened over its entire length, and the oil in the cylinder 3 passes through the oil hole 14, the gap 5, and the oil hole 6 to the oil lock chambers C and B.
It flows into the room.

In addition, in the compression stroke of the inner tube 10,
When the oil lock piston 12 descends to fit into the oil hole rod 4, the internal pressure in the oil lock chamber C increases, so the internal pressure in the gap 5 below the check valve 8 also increases, and the check valve 8 closes. Communication over the entire length of the gap 5 is cut off. Therefore, the oil in the oil lock chamber C is absorbed by the lock piston 1.
2 and the oil hole rod 4, the internal pressure of the oil lock chamber C rises as the amount of penetration of the oil lock piston 12 increases. 10 can be prevented from colliding with the bottom of the outer tube 1. In the extension operation, the valve 13 is closed, and the oil in the A chamber flows into the cylinder 3 through an orifice (not shown) bored in the upper part of the cylinder 3, and at this time, the action of the orifice generates a damping force during the extension.

As seen in this operating situation, the cylinder 3 itself has B in addition to the orifice for generating damping force.
Since the oil hole 14 for sucking and discharging oil corresponding to the volume change of the chamber into and out of the cylinder 3 is simply drilled, not only the reliability of the strength of the cylinder 3 is improved, but also the number of man-hours for machining it is significantly reduced. It is.

As explained in detail above, according to this invention, a gap is formed between the cylinder and the oil hole rod, and the cylinder is provided with an oil hole in the inner tube for sucking and discharging the oil corresponding to the volume change. By installing a check valve in the cylinder, there is sufficient passage, so there is no need to make the cylinder thinner.
The number of oil holes provided in the cylinder can also be reduced. This improves the reliability of cylinder strength, and
The number of man-hours required for machining the cylinder is also significantly reduced, and various effects such as the simplification of the entire oil lock mechanism can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main parts of an embodiment of the shock absorber of this invention, and FIG. 2 is an enlarged cross-sectional view of the main parts. 1... Outer tube, 3... Cylinder, 4
... Oil hole rod, 5 ... Gap, 6 ... Oil hole, 8 ... Check valve, 10 ... Inner tube, 12
...Oil lock piston, 13...Check valve, 14...Oil hole, A, B...Chamber, C...Oil lock chamber.

Claims (1)

[Scope of utility model registration request] An inner tube having an oil lock piston is slidably inserted into the outer tube,
In the shock absorber, the upper part of the cylinder that stands up from the center of the lower part of the outer tube slides into the inside of the inner tube, and an oil hole is provided at the bottom of the cylinder to form an oil lock chamber, and there is a gap between the cylinder and the oil hole. This gap is open to a chamber below the oil lock piston, and communicates with the inside of the cylinder through an oil hole drilled in the cylinder, and further communicates with the oil lock chamber through an oil hole formed in an oil hole rod,
A shock absorber has a check valve provided in the gap so that it can be opened and closed.