JPH06670Y2 - Damping force adjusting device for hydraulic shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a damping force adjusting device for a hydraulic shock absorber that is interposed between a vehicle body and an axle of a vehicle to damp vibrations from a road surface.

[Conventional technology]

An example of this type of conventional hydraulic shock absorber is,
The one disclosed in Japanese Patent Publication No. 164838 is known.

In this hydraulic shock absorber, a piston rod is movably inserted into a cylinder via a piston, and the piston divides two upper and lower oil chambers in the cylinder, and the two oil chambers are provided in a port provided in the piston and a piston rod. The extension side leaf valve is openably and closably provided at the lower mouth end of the port, and the needle valve interlocking with the push rod is movably provided during the bypass.

The needle valve is moved via the push rod to adjust the opening area of the bypass, that is, the orifice, and a damping force is generated by the combination of the leaf valve and the orifice during the extension operation.

That is, as shown in FIG. 4, for example, the characteristics a and b are obtained by the degree of restriction of the needle valve of the orifice, and the characteristic A is obtained by the leaf valve. The characteristics obtained by combining the two are A + a and A + b.

[Problems to be solved by the invention]

In the above conventional hydraulic shock absorber, if the orifice is adjusted, the characteristics change over the entire range of the piston speed from the low speed region to the high speed region.
There is a problem that it is not possible to meet the demand for changing the damping force only in the high speed range or the demand for changing the damping force in the extremely low speed range.

Further, since the damping force is adjusted by adjusting the orifice with a needle valve, the expansion side damping force is adjusted as desired, but the orifice is effective even when the compression side is operated, and the compression side damping force also changes. .

Therefore, an object of the present invention is to provide a damping force adjusting device for a hydraulic shock absorber capable of changing the damping force only in the medium / high speed range and not opening the valve during compression so as not to change the damping force. That is.

[Means for solving problems]

In order to achieve the above-mentioned object, the structure of the present invention is such that a piston rod is movably inserted into a cylinder via a piston, and the piston defines two upper and lower oil chambers in the cylinder.
The piston and piston rod are each provided with a port that connects two oil chambers and a bypass, a leaf valve that can be opened and closed at the mouth end of the piston port, and a valve that adjusts the opening area in the middle of the piston rod bypass. In the hydraulic shock absorber, the valve is configured with a movable poppet valve provided in the bypass and a spring attached to the poppet valve in the closing direction, and the poppet valve is provided with the pressure oil in the lower oil chamber at the back. A pilot passage for guiding is formed, and further, a push rod that directly opposes the poppet valve at an arbitrary interval and restricts the position of the port valve is provided movably in the piston rod, and a back portion of the poppet valve for the above interval is provided. It is characterized by allowing directional movement.

[Action]

During the extension operation, a damping force is generated by the leaf valve in the low speed range, and when the pressure in the oil chamber reaches a predetermined pressure, the poppet valve opens against the spring, and the damping force according to the opening area of the bypass at that time. Occurs, the pressure in the lower oil chamber rises during compression operation, but the pressure oil at that time is guided to the back of the poppet valve via the pilot passage to urge the poppet valve in the closing direction, and the damping force by the orifice is Does not occur. The interval changes according to the position of the push rod, the opening area of the poppet valve is adjusted according to the interval, and the damping force changes in the middle and high speed ranges.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

1 and 2 show a hydraulic shock absorber according to an embodiment of the present invention.

A piston rod 3 is movably inserted into a cylinder 1 via a piston 2, and the piston 2 defines two upper and lower oil chambers 4 and 5 in the cylinder 1.

An extension port 6 that connects the two oil chambers 4 and 5 to the piston 2.
An expansion side leaf valve 8 as an expansion valve is openably and closably provided at the lower mouth end of the expansion port 6, and a pressure side leaf valve 9 is openably and closably provided at the upper end mouth end of the pressure port 7. ing.

At the time of extension, the oil in the upper oil chamber 4 opens the extension side leaf valve 8 from the extension port 6 and flows out to the lower oil chamber 5, and the extension side leaf valve 8 causes the damping force of the characteristic A ′ shown in the graph of FIG. Generate.

At the lower part of the piston rod 3, there are provided passages 10 and 11 as bypasses that connect the upper and lower oil chambers 4 and 5, and a cylindrical sheet 12 is provided in the middle of the passage 11.

The piston rod 3 has a hole 13 facing the passage 11 in series.
Below the hole 13, a poppet valve 14 facing the seat 12 is vertically movably inserted. Normally, the poppet 14 is biased in a closing direction by a spring 15 provided on the back portion of the seat 12 to open the seat 12. The ends are closed.

The upper end of the spring 15 is supported by the spring seat 16.

A vertically movable push rod 17 is inserted into the hole 13 and the lower end of the push rod 17 faces the poppet valve 14 at an arbitrary interval and is above the poppet valve 14 by this interval. Allows movement in the back direction. The push rod 17 is vertically operated from the outside and is used as a position regulating member for the poppet valve 14.

A pilot passage 18 is formed in the center of the poppet valve 14, and the pilot passage 18 connects the passage 11 to the poppet valve 1
4 to the back oil chamber 19 and when the internal pressure of the lower oil chamber 5 rises, this pressure is guided to the oil chamber 19 and presses the poppet valve 14 in the closing direction in cooperation with the spring 15.

During the extension operation, the internal pressure of the upper oil chamber 4 rises, and a part of the oil pushes the poppet valve 14 from the passage 10 against the spring 15 and opens it through the orifice formed between the poppet valve 14 and the seat 12. Out into the passage 11 and the lower oil chamber 5, and a damping force is generated by the orifice.

The size of the orifice is determined by the lift amount of the poppet valve 14, and this lift amount is determined by the position of the push rod 17.

Therefore, depending on the position of the push rod 17, when the lift amount is small, the orifice is also small, and the damping force at this time is shown by the characteristic a'in FIG. The characteristics of the combined damping force with the valve 8 are A '+ a' and A '+ b'.

In the low speed region of the piston 2, the poppet valve 14 is pushed by the spring 15 and does not open. Therefore, the damping force of the characteristic A'is generated only by the leaf valve 8, and the internal pressure of the upper oil chamber 4 is increased in the middle and high speed regions. Overcame Spring 15,
Oil also flows from the orifice regulated by the poppet valve 14, and the characteristic at that time becomes A '+ a' or A '+ b'.
Therefore, the damping force in the low speed range is constant, but in the middle / high speed range, the damping force changes by the operation of the push rod 17. During the compression operation, the piston 2 descends and the internal pressure of the lower oil chamber 5 rises, and this pressure is guided to the oil chamber 19 via the pilot passage 18 and further urges the poppet valve 14 in the closing direction. Therefore, the oil in the lower oil chamber 5 flows out only from the pressure side leaf valve 9.

The compression side damping force is generated by the pressure oil leaf valve 9 and the base valve below the cylinder 1, and at that time, the damping force is generated by the poppet valve 1.
Since 4 does not open, it is not affected by the orifice of this poppet 14.

In FIG. 3, a graph d shows the spring characteristic of the spring 15. If the push rod 17 is formed of a thermal expansion member such as aluminum, it is possible to correct the lack of damping force due to the decrease in the viscosity of the hydraulic oil.

[Effect of the Invention] According to the present invention, the following effects are obtained.

In the low speed range of the piston, the poppet valve is closed, only the leaf valve opens, and in the high speed range, the poppet valve opens, and the damping force of the orifice characteristic according to the opening of the poppet valve is generated. The damping force can be adjusted with. At this time, an interval is provided between the push rod and the poppet, and this interval can be adjusted by moving the push rod.Therefore, by moving the push rod to adjust the size of the interval, the poppet valve can be moved by the interval. And the opening can be adjusted easily.

During the compression operation, the poppet valve closes freely, and the damping force of the orifice characteristic is not generated, so there is no change in the compression side damping force.

The push rod directly faces the poppet, and the spring and push rod are independent. Therefore, even if the push rod is moved, the spring load of the spring does not change.

[Brief description of drawings]

1 is a partially cutaway vertical front view of a hydraulic shock absorber according to an embodiment of the present invention, FIG. 2 is a partially enlarged sectional view of FIG. 1, and FIG.
FIG. 4 is a graph showing damping force characteristics, and FIG. 4 is a graph showing damping force characteristics of a conventional hydraulic shock absorber. 1 ... Cylinder, 2 ... Piston, 3 ... Piston rod,
4, 5 ... Oil chamber, 6, 7 ... Port, 8 ... Leaf valve, 1
0, 11 ... Bypass, 14 ... Poppet valve, 15 ... Spring, 17 ... Push rod, 18 ... Pilot passage.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography SHO 58-149640 (JP, U) ACTUAL 59-63246 (JP, U) ACT 62-66895 (JP, U)

Claims (2)

[Scope of utility model registration request] 1. A piston rod is movably inserted into a cylinder via a piston, the piston defines two upper and lower oil chambers in the cylinder, and the piston and the piston rod have a port for communicating the two oil chambers with each other. In a hydraulic shock absorber in which bypasses are provided, a leaf valve is freely opened and closed at the mouth end of the piston port, and a valve for adjusting the opening area is provided in the middle of the bypass of the piston rod, the valve is provided in the bypass. A movable poppet valve and a spring attached to the poppet valve in the closing direction,
The poppet valve has a pilot passage that guides the pressure oil in the lower oil chamber to the back, and a push rod that directly opposes the poppet valve at an arbitrary interval and restricts the position of the port valve is formed in the piston rod. A damping force adjusting device for a hydraulic shock absorber, wherein the damping force adjusting device is provided so as to be movable, and allows the poppet valve to move in the back direction by the distance. 2. The damping force adjusting device for a hydraulic shock absorber according to claim 1, wherein the push rod is made of a thermal expansion material such as aluminum.