JPS607988Y2 - Front fork for motorcycles - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a front fork used in a motorcycle.

A telescopic type front fork consisting of a spring and a hydraulic damping force generating mechanism is used as a front wheel suspension system for motorcycles, and generally the left and right members are each provided with a damping force generating mechanism, but in this case, the setting of the left and right members is Variations in pressure may occur, and attempts to suppress this will make manufacturing complicated and increase costs.

Therefore, as a simple front fork for a motorcycle, one member is given the function of generating hydraulic damping force, and the other member is filled with a spring, a spring, gas and oil, or gas and oil, etc., to provide guide, return, and buffer functions. A front fork has been proposed in which the functions are separated between the two members, and since the hydraulic damping force is applied only to one side, variations can be narrowed and stable characteristics can be obtained.

By the way, a front fork of the above type in which the amount of movement of the hydraulic oil on the hydraulic damping side is controlled by the internal pressure in the gas chamber has been proposed, but in order to obtain a predetermined appropriate spring characteristic with such a front fork, it is difficult to If a gas chamber with a large space is required and the waist gas chamber is small, the gas pressure in the gas chamber will rise above a predetermined pressure during the compression process of the front fork, generating a large repulsive force.

The above-mentioned tendency is particularly noticeable in front forks for small two-wheeled vehicles due to their small inner diameters.To improve this, for example, in Utility Model Application No. 51-74953, the oil chamber is communicated from the hydraulic chamber on one side to the chamber on the other side. A system has been proposed in which a gas chamber is defined by a free piston-like member under the hydraulic chamber communication section on the other side. According to this, the volume of the gas chamber can be increased, and the above-mentioned problems can be solved.

However, such a structure has a hydraulic chamber communication section on the top and a gas chamber on the bottom, so it requires a sliding structure for the gas chamber, making the structure complicated.

The present invention was devised to improve the above-mentioned disadvantages of the functionally separated type front forks for motorcycles equipped with such a gas chamber. A hydraulic damping force generation mechanism is provided in the member, and a gas chamber is provided above the oil chamber of this member, and an oil chamber is provided below and a gas chamber is provided above this in the other member, and the gas chambers are communicated with each other. In this way, sufficient gas chamber volume is secured, appropriate spring characteristics are obtained, and the oil level in the member on the side of the hydraulic damping force generation mechanism is set at a high level and the oil level in the other member is set at a low level. To provide a front fork which prevents so-called air trapping by suppressing the mixing of oil into hydraulic oil.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The drawing shows a longitudinal front view of the front fork, and the front fork 100 consists of left and right members 1-51.

The member 1 on the right side of the figure is provided with a hydraulic damping force generation mechanism, and the member 51 on the left side is not provided with this.

The members 1 and 51 consist of a bottom case 2, 52 which is a lower outer cylinder member, and a fork pipe 3, 53 which is an inner cylinder upper member slidably fitted to the bottom case 2, 52. is connected to the vehicle body at its upper part through a bridge 101 so as to be able to rotate freely for steering, and the lower ends of the bottom cases 2 and 52 are provided with axle insertion holes 102 and 102, through which an axle 103 is inserted and a front wheel 104 is supported.

One member 1 mainly carries the damping force generation mechanism, and a seat pipe 5 is installed vertically at the bottom 2a in the bottom case 2 of the member 1 through bolts 4 to the middle part in the axial direction. An oil lock piece 6 is provided, an orifice 7 is provided above the oil lock piece 6, a piston portion 8 is provided at the upper end of the seat pipe 5, and a coil spring 10 is interposed between the upper end of the piston portion 8 and the plug body at the upper end of the fork pipe 3. A piston ring 11 is interposed between the outer diameter of the piston portion 8 and the inner diameter of the fork pipe 3.

Oil lock collar 1 on the inner diameter of the lower end of fork pipe 3
2 is fitted and attached, there is a clearance between the inner diameter of this and the outer diameter of the seat pipe, and orifices 13 that communicate with each other are provided in a part of the oil lock collar 12 and the upper part of the lower end of the fork pipe. A valve material orifice member 15 is provided at the top of the oil lock collar 12 via a holder 14, a rebound spring 16 is provided on the holder 14 so as to surround 5 circumferences of the seat pipe, and an orifice 17 is provided at the top of the seat pipe. It is being

A dust seal 18 is attached to the upper end of the bottom case 2, and an oil seal 19 for sealing between the dust seal and the fork pipe is attached to the inner step of the bottom case 2 by means of upper and lower stoppers 20, etc., and 21 in the figure is a side bush.

Bottom case 2 and fork pipe 3 in member 1 above
Hydraulic oil 22 is sealed inside and filled to the vicinity of the upper part of the hydraulic oil fork pipe 3 to ensure a sufficient amount of oil, and gas is sealed above this to form a gas chamber 23.

As is known, the hydraulic damping force is controlled by the relative sliding of the fork pipe 3 and the bottom case 2 in the axial direction to obtain a predetermined hydraulic damping force by controlling the flow rate of the orifice.

The other member 51 is filled with hydraulic oil 72 from the lower part to the middle part of the bottom case 52, and gas is sealed thereon to form a gas chamber 73. The gas chamber 73 is long in the axial direction and has a sufficient volume. The upper end of the pipe 53 is closed with a plug 59.

A seat pipe 55 similar to the one described above is installed on the bottom center of the bottom case 52, and an oil lock piece 56 is installed at the lower end of the seat pipe 55.
An oil lock collar 62 provided at the lower end of the fork pipe 53 surrounds the seat pipe 55.

A coil spring 60 is interposed between the upper end of the piston portion 58 at the upper end of the seat pipe 55 and the plug body 59, and the liquid level 72a of the hydraulic oil 72 is at a low level, and the liquid level 22a of the hydraulic oil 22 on the damping force mechanism side is at a low level. It's high enough.

In the drawing, 71 is a guide bushing, 68 is a dust seal, 6
9 is an oil seal.

The member on this side does not have a damping force generating mechanism, and performs a damping motion by the spring action of the spring 57 and hydraulic oil or gas pressure, or by the spring action of the hydraulic oil or gas pressure.

The plug body 9, 59 has a passage 24 opening into the gas chamber 23.73.
．． 74, one side 24 is a blind hole and the other side is provided with a gas filling valve 75, such passage 24.74 is connected to the communication pipe 1.
05, and therefore the gas chambers 23 and 73 of the left and right members 1 and 51 communicate with each other through the communication pipe 105,
The volume of the gas chamber is the sum of 23.73.

By the way, for the function of the member 1 on the side having the hydraulic damping force generation mechanism, the member is sufficiently filled with hydraulic oil up to the upper part to ensure its function, and the oil level 22a is capable of generating hydraulic damping force even during the extension stroke of the member. Ensure that there is sufficient distance between the
On the other hand, in the other members, the oil level 72a fills up to the middle of the bottom case 52, and is filled with gas from the valve 75 to form gas chambers 23, 73 communicating with each other on the oil levels 22a and 72a.

The hydraulic oil 22 of member 1 satisfies the maximum permissible 8 in which the oil level 22a does not interfere with the passage 24 even at the top dead center in the compression stroke, and the total amount of the hydraulic oil 22.72 is equal to the internal gas pressure during the compression stroke of each member. The compression ratio is determined by the diameter and stroke of the inner and outer cylinders, and the remaining amount to ensure this compression ratio is put into the member 52 on the other side.

Therefore, the oil level 22a is at a high level as described above, while the oil level 7
2a is at a low level, and between these gas chambers are formed that communicate with each other and have different volumes.Since the oil level 22a is high while forming gas chambers with sufficient capacity, the oil level 22a is high due to violent axial expansion and contraction. Even if bubbles are generated, the bubbles do not reach the vicinity of the orifice, which is the lower part where the hydraulic damping force is generated, and it is possible to prevent the bubbles from entering the orifice and causing so-called air entrapment.

As is clear from the above, according to the present invention, in a gas-liquid type shock absorbing front fork, it is possible to prevent air trapping while ensuring sufficient gas chamber volume, and to achieve the above with a simple structure. A front fork for a motorcycle that can be used in combination with gas and liquid can be obtained at a low cost.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing an embodiment of the present invention. In the drawing, 100 is the front fork, 1.51 is the telescopic member, 5, 6, 7, 8° 12. 13, 1
4 and 15 are the damping force generation mechanism, 22.72 is the oil chamber, 22a
t72a is an oil level, 23°73 is a gas chamber, and 105 is a communication pipe.

Claims (1)

[Scope of utility model registration request] In a front fork consisting of a pair of left and right telescopic members, one member has a lower oil chamber and an upper gas chamber equipped with a hydraulic damping force generation function, and the other member has a lower oil chamber and an upper gas chamber. The upper gas chambers of each member are connected to each other by a communication pipe, and the oil level of the member equipped with a hydraulic damping force generation mechanism is set at a high level, while the oil level of the other member is set at a low level. Front fork for motorcycles.