JPH042822B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of an inverted front fork that supports a front wheel of a two-wheeled vehicle.

(Prior Art) A front fork that supports the front wheel of a two-wheeled vehicle generally consists of an outer tube and an inner tube that are configured to slide freely against each other, and a suspension spring is interposed between these tubes to damp vibrations. Many contain hydraulic oil. There are two types of front forks: an upright type with the outer tube attached to the axle side and an inner tube attached to the vehicle body, and an inverted type with the outer tube attached to the vehicle body side and the inner tube attached to the axle side. The inverted type has the advantage that the portion away from the axle has high rigidity, so the distribution of bending stress acting on the front fork against the lateral load that occurs depending on the inclination angle of the front fork is more favorable than that of the upright type. It is equipped with

(Problem to be solved by the invention) However, in an inverted front fork, the small-diameter inner tube enters and exits from the bottom of the large-diameter outer tube, so the hydraulic oil sealed inside is likely to leak from these gaps. Due to this problem, it has not been widely used despite its structural advantages.

The present invention aims to solve the above-mentioned problems.
The purpose of the present invention is to provide an inverted front fork with improved sealing ability of the outer tube.

(Means for Solving the Problems) The present invention has a damper cylinder connected to the axle side that is slidably inserted from below inside an outer tube disposed on the vehicle body side, and air and actuated inside the outer tube. A groove-shaped groove that forms an air spring chamber filled with oil and defines a space of a predetermined volume along the circumferential direction between the outer circumference of the upper end of the damper cylinder inserted into the outer tube and the inner circumferential surface of the outer tube. The outer tube forms an oil reservoir, and is provided with a sealing member that slides in parallel to the inner circumference of the outer tube directly below the oil reservoir.

(Function) The air spring chamber expands and contracts violently due to the sliding between the outer tube and the damper cylinder, and the internal hydraulic oil is scattered into the outer tube, but these droplets adhering to the inner circumferential surface of the outer tube eventually move downward on the inner circumferential surface. and collects in a groove-shaped oil reservoir formed on the outer circumference of the upper end of the damper cylinder. Therefore, the seal member directly below does not need to directly receive oil droplets running down the outer tube, and the burden on the seal member is reduced. Further, since the surface of the sealing member is always covered with an oil film by the hydraulic oil supplied little by little from this oil reservoir, the sealing ability is also enhanced.

(Example) FIG. 1 shows an embodiment of the present invention.

Reference numeral 1 designates an outer tube held on the vehicle body side, into which a damper cylinder 2 is slidably inserted from the lower end. The damper cylinder 2 has its lower end locked to the axle via the bottom member 3, and the base end of the piston rod 4 protruding from the damper cylinder 2 passes through the outer tube 1 and is attached to the upper end of the outer tube 1 via the cushion rubber 5. . Further, a piston 6 is provided at the tip inserted into the damper cylinder 2. The inside of the damper cylinder 2 is defined vertically by a plug 7 fixed in the middle, and the area below the plug 7 is further defined into an inside and an outside by an inner cylinder 8 which stands up from the bottom. The piston rod 4 is slidably and oil-tightly supported by the plug 7, and the piston 6 that slides into the inner cylinder 8 defines the interior of the inner cylinder 8 into an upper oil chamber A and a lower oil chamber B. do.
Further, an oil reservoir chamber C is provided outside the inner cylinder 7, and a retractable air bag 9 filled with air is provided in the oil reservoir chamber C. On the other hand, the damper cylinder 2 above the plug 7 opens into the outer tube 1 and communicates with the air spring chamber D formed inside the outer tube 1. is included. Further, a suspension spring 10 is interposed between the plug 7 and the upper end of the outer tube 1 through the air spring chamber D.

Outer tube 1 is installed at the top of damper cylinder 2.
A bearing 11 slidingly contacts the inner circumference of the outer tube 1.
A bearing 14 that slides on the outer periphery of the damper cylinder 2 is provided at the tip of the damper cylinder 2, and these bearings 11 and 14 support the outer tube 1 and the damper cylinder 2 so that they can freely slide relative to each other. At the upper end of the damper cylinder 2, an annular groove-shaped oil reservoir 13 having a predetermined volume is formed in the circumferential direction facing the inner periphery of the outer tube 1. Further, a sealing member 12 that is in sliding contact with the outer tube 1 is attached to the damper cylinder 2 directly below and parallel to the oil reservoir 13 .

The piston 6 is equipped with a valve 15 and a needle valve 1 that generate damping force on the rebound side by passing oil from oil chamber A to B.
6, and a check valve 17 that allows hydraulic oil to flow from oil chamber B to oil chamber A without resistance. Additionally, a needle valve 18 and a relief valve 19 that generate a compression side damping force by passing oil from the oil chamber B to the oil reservoir chamber C, and a check valve 20 that allows the hydraulic oil in the oil reservoir chamber C to flow back to the oil chamber B without resistance. 21 is provided at the bottom of the damper cylinder 2. Furthermore, a lock piece 22 is provided at the bottom of the inner cylinder 8 to prevent the piston 6 from bottoming out when the piston 6 enters the deepest part. This lock piece 22 is supported by a return spring 23 opposite to the piston 6, and when the piston 6 pushes down the lock piece 22, an outflow port 24 formed in the lock piece 22 closes and locks the hydraulic oil from flowing out from the oil chamber B.

Next, the action will be explained.

When the front fork moves from the balanced position to the pressure side while bending the suspension spring 10 due to braking or uneven ground, the piston 6 penetrates deep into the damper cylinder 2, and the hydraulic oil in the oil chamber B closes the valve 16. However, since the hydraulic oil corresponding to the intrusion volume of the piston rod 4 cannot be accommodated in the inner cylinder 8, it flows into the oil sump chamber C while generating a pressure-side damping force from the needle valve 18. Note that the increase in the amount of oil in the oil reservoir chamber C is due to the internal air bag 9.
It is absorbed by the contraction of. Further, as the piston 6 enters, the suspension spring 10 is bent, and the air in the air spring chamber D is compressed. These repulsive forces act in the direction of separating the outer tube 1 and the damper cylinder 2 and counter the contraction of the front fork, but this spring load is arbitrarily set in advance by the amount of adjustment oil sealed in the upper part of the damper cylinder 2. It is possible. As the piston 6 penetrates deeper, it eventually comes into contact with the lock piece 22, and the lock piece 22, which is pushed down against the return spring 23, closes the outflow port 24. Therefore, the hydraulic oil in the oil chamber B has nowhere to escape, and the piston 6 is prevented from entering further.

When the front fork shifts to the rebound side, the piston 6 moves upward in the inner cylinder 8, and the hydraulic oil in the oil chamber A passes through the valve 15 and the needle valve 17 to generate a rebound damping force and flows into the oil chamber B. inflow,
The hydraulic oil stored in the oil reservoir chamber C flows back to the oil chamber B from the check valves 20 and 21 without resistance.

In the above expansion and contraction operation, the hydraulic oil that generates the damping force only circulates through the oil chambers A and B and the oil reservoir chamber C below the plug 7 of the damper cylinder 2, and even during violent operation or the front fork may be disassembled. There is no risk of this hydraulic fluid leaking outside even in the event of an accident.

On the other hand, inside the outer tube 1, when the air spring chamber D expands and contracts violently with the operation of the front fork, the adjustment oil inside scatters, and some oil droplets run down the inner circumferential surface of the outer tube 1, or fall into the damper cylinder. Outer tube 1 by sliding 2
and reaches the gap between damper cylinder 2. However, since these oil droplets flow into the oil reservoir 13 formed at the upper end of the damper cylinder 2 and accumulate therein, the adjustment oil rarely reaches the sealing member 12 directly.
Therefore, leakage of the adjustment oil is prevented without placing a large burden on the seal member 12 that seals the outer tube 1. On the other hand, since the adjustment oil accumulated in the oil reservoir 13 is gradually supplied to the seal member 12, the surface of the seal member 12 is always covered with an oil film, so the seal member 12 is in close contact with the outer tube 1, and the outer tube 1 and the damper are In addition to maintaining good lubrication of the cylinder 2, the sealed air is also difficult to escape to the outside.

(Effects of the Invention) As described above, in the present invention, a groove-shaped oil reservoir is formed on the outer periphery at the upper end of the damper cylinder that is slidably inserted into the outer tube from below, and a seal is formed in parallel directly below the oil reservoir. Since the member is provided, even if the hydraulic oil scattered inside the outer tube reaches between the outer tube and the damper cylinder, the hydraulic oil is less likely to flow into the oil reservoir and reach the sealing member. Therefore, leakage of hydraulic oil can be efficiently prevented without placing a large burden on the seal member. In addition, since an oil film is formed on the surface of the seal member by the hydraulic oil supplied little by little from the oil reservoir to the seal member, the sliding resistance between the outer tube and the damper cylinder is reduced, and the adhesion of the seal member is improved. This makes it difficult for the enclosed air to escape to the outside.

Therefore, according to the present invention, the sealing ability of the outer tube is improved with a simple configuration, and the slidability of the front fork is also improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a front fork showing an embodiment of the present invention. 1... Outer tube, 2... Damper cylinder, 12... Seal member, 13... Oil reservoir, D...
...Air spring chamber.

Claims (1)

[Claims] 1 A damper cylinder connected to the axle side is slidably inserted from below inside an outer tube arranged on the vehicle body side, and an air spring chamber filled with air and hydraulic oil is formed inside the outer tube. A groove-shaped oil reservoir defining a space of a predetermined volume along the circumferential direction is formed between the upper end outer circumference of the damper cylinder inserted inside and the inner circumference of the outer tube, and a groove-shaped oil reservoir is formed in parallel directly below. An inverted front fork characterized by being equipped with a sealing member that slides into contact with the inner circumference of the outer tube.