JP2854874B2 - Inverted front fork - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a damping force generating means in an inverted front fork in which an outer tube is provided on a vehicle body side and an inner tube is provided on an axle side.

2. Description of the Related Art Japanese Patent Application Laid-Open No. 58-85777 discloses a front fork of a motorcycle in which an outer tube is provided on a vehicle body and an inner tube is provided on an axle.

This means that the inner tube 2 is slidably housed in the outer tube 1 as shown in FIG.
The piston 3 that slides on the inside of the
A bearing 5 is provided at the upper end of the inner tube 2 for sliding contact with the outside of the piston rod 4.

Inside the upper portions of the outer tube 1 and the piston rod 4, oil reservoirs 10 filled with gas are formed above the oil level, and communicate with each other via ports 11.

The piston rod 4 has an orifice 14 that connects the oil chamber 8 above the piston 3 in the inner tube 2 to the oil reservoir 10, the bearing 5 has a check valve (not shown) that opens when the pressure side is operated, and the piston 3 has Also provided are an orifice (not shown) and a check valve which opens when the pressure side is activated.

In the pressure side operation, the hydraulic oil in the oil chamber 9 below the piston 3 flows into the upper oil chamber 8 via a check valve provided in the piston 3, and the hydraulic oil corresponding to the intrusion volume of the piston rod 4 is Oil reservoir through the hollow part 4
Flow into 10. In the extension side operation, the hydraulic oil in the oil reservoir 10 returns to the oil chamber 9 through the hollow portion of the piston rod 4, and the hydraulic oil in the oil chamber 8 passes through the orifice 14 and the orifice formed in the piston 3. And flows into the oil chamber 9 while generating a damping force.

(Problems to be Solved by the Invention) However, in this front fork, the generation of damping force is limited during the extension side operation, and the front fork has a structure that cannot generate the damping force during the compression side operation.

In view of the above problems, an object of the present invention is to provide an inverted front fork that has a simple structure and can generate both an extension and a damping force.

(Means for Achieving the Object) According to the present invention, an inner tube supported by an axle below a vehicle body is slidably inserted into an outer tube supported by the vehicle body, and a piston sliding in contact with an inner periphery of the inner tube is hollow. Fixed to the outer tube base end through the piston rod of
A bearing is provided at the upper end of the inner tube for sliding contact with the outer periphery of the piston rod, a port is provided at the upper part of the piston rod to allow communication between the hollow portion of the piston rod and the inner side of the outer tube, and an oil reservoir and an inner portion are provided at the hollow portion of the piston rod and the inner side of the outer tube. In an inverted front fork having an upper oil chamber and a lower oil chamber inside an inner tube defined by a piston slidingly contacting the tube, an orifice 12 and an oil reservoir for communicating the lower oil chamber with the oil reservoir chamber. A check valve that allows only inflow of hydraulic oil from the chamber to the lower oil chamber is provided in the hollow portion of the piston rod, while an orifice 14 that communicates the upper oil chamber with the lower oil chamber is provided with a piston below the orifice 12. It was formed on the wall of the rod.

(Operation) Since the check valve is closed during the operation on the pressure side, the orifice 12 provided in the hollow portion of the piston rod has a greater throttling effect than the orifice 14 and resists the outflow of hydraulic oil from the oil chamber below to the oil reservoir. Generates damping force. Also, during the extension side operation, the check valve opens, so the orifice 12
Does not function, and the orifice 14 formed on the wall surface of the piston rod resists outflow of hydraulic oil from the upper oil chamber to the lower oil chamber to generate a damping force.

(Embodiment) FIGS. 1 to 3 show an embodiment of the present invention.

In FIG. 1, 1 is an outer tube supported on the vehicle body side, and 2 is an inner tube supported on the axle side.
The inner tube 2 is slidably inserted inside the outer tube 1, and a piston 3 slidably contacting the inside of the inner tube 2 is supported at the base end of the outer tube 1 via a hollow piston rod 4.

A bearing 5 is provided at the upper end of the inner tube 2 for sliding contact with the outer periphery of the piston rod 4. The piston 3 is interposed between the main spring 6 interposed between the inner tube 2 and the bottom and the bearing 5. Sub spring 7
Thereby, it is elastically supported inside the inner tube 2.

The inner side of the inner tube 2 is defined by a piston 3 into an upper oil chamber 8 and a lower oil chamber 9. Further, an oil reservoir 10 in which gas is sealed is formed above the oil level above the hollow portions of the outer tube 1 and the piston rod 4. The inside and outside of the piston rod 4 communicate with each other via a port 11 formed on the top of the piston rod 4.

The lower end of the hollow portion of the piston rod 4 opens toward the oil chamber 9, and an orifice 12 that connects the oil chamber 9 and the oil reservoir 10 and a check valve 13 that opens only at the time of extension side operation are provided inside the hollow portion. .

Further, an orifice 14 communicating with the oil chambers 8 and 9 is formed on the wall surface of the piston rod 4 below these.

 Next, the operation will be described.

At the time of the compression side operation, as the piston 3 slides down inside the inner tube 2, the hydraulic oil in the oil chamber 9 that contracts as shown in FIG. 2 flows into the oil chamber 9 that expands through the orifice 14. At the same time, the hydraulic oil corresponding to the intrusion volume of the piston rod 4 flows out into the oil reservoir 10 while generating a compression-side damping force via the orifice 12.

Also, at the time of extension operation, as shown in FIG.
Hydraulic oil that has flowed out to the oil chamber 9 that expands through the check valve 13 returns to the oil chamber 9 without resistance, and the hydraulic oil in the oil chamber 8 that shrinks flows through the orifice 14 into the oil chamber 9 while generating damping force. Inflow.

In this way, by generating a damping force when operating in either the compression side or the extension side, shocks and vibrations applied to the front wheels are efficiently attenuated, and comfortable traveling becomes possible.

(Effects of the Invention) As described above, the present invention provides the orifice 12 that connects the lower oil chamber and the oil reservoir and the check valve that allows only the flow of hydraulic oil from the oil reservoir to the oil chamber. On the other hand, the orifice 14 communicating with the upper oil chamber and the lower oil chamber is formed on the wall surface of the piston rod below the orifice 12, so that the orifice 12 in the hollow part operates on the extension side during the pressure side operation. In some cases, the orifices on the piston rod wall surfaces respectively generate damping force, so that a damping force can be obtained in both directions of expansion and contraction with a simple structure, and the cushioning characteristics of the inverted front fork can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an essential part of an inverted type front fork showing an embodiment of the present invention, and FIGS. 2 and 3 are sectional views further enlarging the essential part of FIG. FIG. 4 is a longitudinal sectional view of an inverted front fork showing a conventional example. 1 ... outer tube, 2 ... inner tube, 3 ...
Piston, 4 ... Piston rod, 8 ... Upper oil chamber,
9: Lower oil chamber, 10: Oil chamber, 12: Orifice 1
2, 14 ... Orifice 14.

Claims (1)

(57) [Claims] An inner tube supported by an axle below the vehicle body is slidably inserted into an outer tube supported by the vehicle body, and a piston that slides in contact with the inner periphery of the inner tube is inserted through a hollow piston rod into the outer tube. Fixed to the base end,
A bearing is provided at the upper end of the inner tube for sliding contact with the outer periphery of the piston rod, a port is provided at the upper part of the piston rod to allow communication between the hollow portion of the piston rod and the inner side of the outer tube, and an oil reservoir and an inner portion are provided at the hollow portion of the piston rod and the inner side of the outer tube. In an inverted front fork having an upper oil chamber and a lower oil chamber inside an inner tube defined by a piston slidingly contacting the tube, an orifice 12 and an oil reservoir for communicating the lower oil chamber with the oil reservoir chamber. A check valve that allows only inflow of hydraulic oil from the chamber to the lower oil chamber is provided in the hollow portion of the piston rod, while an orifice 14 that communicates the upper oil chamber with the lower oil chamber is provided with a piston below the orifice 12. An inverted front fork characterized by being formed on the wall of a rod.