JPS6227296B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shock absorber for a two-wheeled vehicle that prevents sinking during braking or starting.

The front fork of a motorcycle is used during sudden braking, etc.
The inertial force in the direction of the fork axis causes the fork to sink, which can impair steering stability, and a similar phenomenon occurs when the rear suspension unit sinks when starting.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydraulic shock absorber for a two-wheeled vehicle, etc., which has relatively high damping characteristics during braking to prevent sinking.

In order to achieve this object, in the present invention, an inner tube on the wheel side is slidably inserted into an outer tube connected to the vehicle body side, and a base plate fixed to the upper part of the outer tube is sandwiched between the inner tube and the hydraulic oil inside the outer tube. A plurality of damping valves are provided in parallel on the base plate to regulate the passage flow rate of hydraulic oil between the upper and lower oil chambers when expanding and contracting. A throttle valve is installed in the upstream or downstream passage of some of the damping valves, which opens and closes via a rod that is directly or indirectly linked to the brake, and releases excess oil from the oil chamber that contracts when the pressure side is activated to other oil chambers. The opening operation of some of the damping valves is restricted during braking.

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

In FIG. 1, 1 is an outer tube connected to the vehicle body side, 2 is an inner tube connected to the wheel side, 3 is a piston attached to the inner tube 2, and 4 is a bearing fixed to the outer tube 1.

Further, a base plate 5 is fixed in the middle of the outer tube 1, a spring guide tube 6 is connected to the base plate 5, and suspension springs 7 and 8 are interposed between the base plate 5 and the bottom surface of the inner tube 2. They are placed facing each other.

The base plate 5 has a first damping valve 9 and a second damping valve 9.
A damping valve 10 is installed.

These damping valves 9 and 10 apply a predetermined resistance to generate a compression-side damping force when excess oil in the oil chamber B, which contracts during pressure-side operation, flows out into the oil chamber A, which has an air chamber above. The first damping valve 9 has an annular leaf valve 9A.
A provides resistance to the flow from oil chamber B to A, but also has a check valve-like function that immediately opens fully to the flow from oil chamber A to B.

The second damping valve 10 is fitted into the center of the base plate 5, is housed inside a cylindrical body 11 that communicates with the oil chamber B via a passage 14A, and has a spring 13.
It is formed from a cylindrical valve 12 that is closed by the following steps.

Then, downstream of this damping valve 10 (however, oil chamber B
to the flow A), there is a communication passage 1 of the cylinder 11.
A throttle valve 15 is provided that closes 4B during control.

In this embodiment, the throttle valve 15 is connected directly to the brake;
It consists of a cap-shaped valve 17 connected to an operating rod 16 that moves upward during braking in an indirect manner, and is movable toward and away from an annular seat 18 fitted into the cylindrical body 11.

The operating rod 16 penetrates the upper end wall 1A of the outer tube 1 in an oil-tight manner, and a return spring 19 is interposed between the valve 17 and the seat 18.

In the above configuration, when the inner tube 2 moves in while compressing the suspension springs 7 and 8 during the pressure side operation, the base plate 5 and the piston 3
A part of the hydraulic oil in the oil chamber B between the piston 3 and the piston 3 flows into the expanding oil chamber C through a check valve formed in the piston 3, but the excess oil corresponding to the volume of entry into the inner tube 2 flows into the oil chamber C. 1. The oil flows into the oil chamber A while pushing open the second damping valves 9 and 10.

At this time, a compression damping force is generated based on the resistance provided by the damping valves 9 and 10.

In this case, in a region where the two damping valves 9 and 10 are both open, the damping force generated will necessarily be weaker than either one, resulting in, for example, the characteristics shown in FIG. 2. However, in the figure, is the damping characteristic of the first damping valve 9, and is the damping characteristic of the second damping valve 10, respectively, and is the composite characteristic.

Next, during braking, the operating rod 16 is pulled upward and the throttle valve 15 is brought into close contact with the valve seat 18 and closed.

Therefore, the communication passages 14A and 14B are connected to the damping valve 10.
Communication with oil chamber A will be cut off regardless of the situation.

Therefore, if operation on the pressure side occurs in this state, that is, sinking due to braking, the excess oil in the oil chamber B will flow to the oil chamber A only through the first damping valve 9.

As a result, the damping force generated is higher than when braking is not applied, and this itself prevents the front fork from sinking rapidly.

Of course, if the vehicle is pushed up from the road surface in this state, the damping valve 9 suppresses excessive subsidence, and a proper predetermined damping characteristic is obtained during control, although the damping valve 9 is a little stiff.

Note that when the braking is completed, the throttle valve 15 is fully opened by the return spring 19, resulting in normal damping characteristics.

Next, the embodiment shown in FIG. 3 will be explained. In this embodiment, the operating rod 16 is pushed in by braking, and therefore the valve 1 of the throttle valve 15'
7A is formed into an annular plate shape, and the second damping valve 1
It is designed to be crimped onto a valve seat 18A which also serves as a spring holder.

In this embodiment, the valve 17A that slides on the rod 16 is pressed by the spring 19A, so even if the throttle valve 15' is closed during braking, the oil chamber B will be damaged due to excessive upheaval from the road surface.
When the pressure suddenly increases, the valve 17A opens to allow excess oil to escape, further improving maneuverability during control.

The embodiment of FIG. 4 has a rod 16 for braking action.
This is a type in which the valve 17B is fixed to the rod 16 and the hole position between the valve seat 18B and the valve seat 18B is changed to increase or decrease the communication area.

Therefore, according to this embodiment, the rod 16 rotates in accordance with the braking force and reduces or completely closes the opening of the throttle valve 15'', so that the damping force is increased during sudden braking when the sinking becomes larger. It is possible to effectively suppress subsidence.

In principle, this mechanism is installed on the left and right shock absorbers (front forks), but it may be installed on only one side, or when the oil chambers of the left and right shock absorbers are connected to a tank, etc. Alternatively, a throttle valve 15 may be attached to the merging portion.

As explained above, according to the present invention, the damping force is relatively increased during braking, thereby producing the effect of suppressing sinking due to braking.

Furthermore, since a throttle valve or the like can be placed on the upper side of the suspension spring, the structure is simple and easy to operate. The present invention is based on a so-called inverted type front fork in which the inner tube is attached to the wheel side and the outer tube is attached to the vehicle body side. However, if an upright type front fork, which is opposite to this, is attached, the same as the present invention can be used. If an attempt is made to construct a subsidence suppressing means, an oil chamber or the like for controlling changes in the intrusion volume of the inner tube must be provided on the outside of the outer tube located below, resulting in an increase in the size of the device. In this regard, the present invention has an inverted configuration in which the outer tube is connected to the sprung side of the vehicle body as described above.
The oil chamber, the valve, etc. can be housed in the outer tube, which has the advantage of making the operation easier and downsizing.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the first embodiment of the present invention, FIG. 2 is a diagram of its operating characteristics, and FIGS.
FIG. 3 is a sectional view of a main part of an example. DESCRIPTION OF SYMBOLS 1... Outer tube, 2... Inner tube, 5... Base plate, 7, 8... Suspension spring, 9, 10... First and second damping valve, 11... Cylindrical body,
12...Valve, 14A, 14B...Communication path, 15...
Throttle valve, 16... rod, 17, 17A, 17B... valve, 18, 18A, 18B... valve seat.

Claims (1)

[Claims] 1. The inner tube on the wheel side is slidably inserted into the outer tube connected to the vehicle body side, and hydraulic oil is filled inside the outer tube with a base plate fixed to the upper part of the outer tube sandwiched therebetween. In addition to defining upper and lower oil chambers, a plurality of damping valves are provided in parallel on the base plate to regulate the passage flow rate of hydraulic oil between the upper and lower oil chambers when expanding and contracting, and some of the plurality of damping valves are damped. A damping valve that has a throttle valve that opens and closes via a rod that is directly or indirectly linked to the brake in the upstream or downstream passage of the valve, and releases excess oil from the oil chamber that contracts when the pressure side is operated to other oil chambers. A shock absorber characterized in that the opening operation of a part of the valve is limited during braking. 2. The shock absorber according to claim 1, wherein the rod is configured to be displaced upward or downward as the brake is applied to press the throttle valve against the valve seat. 3. The shock absorber according to claim 1, wherein the rod is configured to rotate with the brake operation and continuously change the valve opening degree of the throttle valve.