JPS6131564Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a damping force adjusting device for a hydraulic shock absorber in which the damping force is changed in accordance with changes in cylinder internal pressure due to changes in piston stroke position.

Hydraulic shock absorbers, which are generally vehicle suspension systems that utilize fluid pressure and have a spring action, have internal pressure that increases due to an increase in oil temperature due to temperature rise, or an increase in fluid pressure due to compression equivalent to the piston rod intrusion volume due to changes in piston stroke position. Spring repulsion force (spring constant)
becomes large, and the matching between this spring repulsion force and damping force becomes poor, often resulting in poor ride comfort and handling of vehicles such as trains, automobiles, and motorcycles.

Generally, as the cylinder internal pressure increases, the spring repulsive force increases accordingly, so it is ideal that the damping force also changes in response to this spring repulsive force.

Therefore, the purpose of this invention is to constantly improve ride comfort and handling by utilizing changes in the fluid pressure inside the cylinder as the piston stroke position changes, and by automatically increasing or decreasing the damping force according to that pressure. It is an object of the present invention to provide a damping force adjusting device for a hydraulic shock absorber suitable for use in a good suspension system or the like.

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

The hydraulic shock absorber 1 consists of a cylinder 2 and a piston rod 4 inserted into the cylinder 2 via a piston 3 so as to be freely retractable.The cylinder 2 is divided into two upper and lower oil chambers 5 and 6 by the piston 3. is,
Further, a gas chamber 8 is defined below the oil chamber 6 via a free piston 7.

The piston rod 4 is formed hollow and has a vertical passage 9 at the tip, an oil chamber 10 in the main body, and a lateral passage 11 serving as an orifice adjacent to the upper part of the passage 9, and the piston rod 4 is connected to the piston 3. In this state, the longitudinal passage 9 opens into the lower oil chamber 6 and the transverse passage 11 opens into the upper oil chamber 5.

When the gas chamber 8 is filled with gas pressure, the oil chamber in the piston rod is filled with oil, but the free piston 7 is abolished and the gas chamber 8 and the oil chamber 6 are integrated into one oil chamber. On the other hand, it is also possible to fill the upper part of the oil chamber 10 within the piston rod 4 and use it as a gas chamber.

Piston rod 4 has bearing 12 and seal 1
3 and protrudes to the outside, and its upper end is connected to a bracket on the vehicle body side of an automobile, etc., and an eye 14 is connected to the lower end of the cylinder 2, so that it is connected to the link shaft side through this eye 14. It's summery.

Reference numeral 15 denotes a gas filling valve, which is sealed when the eye 14 is fixed after gas filling.

The piston 3 has a passage 16 that communicates the oil chambers 5 and 6.
and an orifice 17 are provided, and a leaf valve 18 is provided at the upper end of the passage 16 so as to be openable and closable, thereby generating a damping force characteristic of a plate valve.

Next, a slide member 19 is slidably inserted into the longitudinal passage 9 of the piston rod 4, the inner end of a control rod 20 is splined to the slide member 19, and one end of the control rod 20 is connected to the piston rod. It is guided by a back-up spring 21 and an O-ring 22 that are interposed at the upper end of 4, and protrudes into the outside atmosphere so as to be able to move up and down, and its outer end is attached to a rotation stopper 23 held on the vehicle body side, for example. combined. That is, the slide member 19 and the control rod 20 can slide up and down, but are prevented from moving in the rotational direction.

As shown in FIG. 3, the slide member 19 has a passage formed by chamfers 24 and 25 in the vertical direction.
It opens directly to 1. Although such chamfers 24 and 25 may be used to directly connect the passages 9 and 11, it is also possible to form one or more passages vertically inside the slide member 19.

The inside of the piston rod 4 has oil holes 26 and 27 at the bottom.
A plate-shaped spring seat 28 having a shape formed thereon is held horizontally, and a spring 29 is interposed between the spring seat 28 and the slide member 19 to constantly urge the slide member 19 downward.

A set load is arbitrarily set when the spring 29 is at rest, and at this time, for example, as shown in FIG. It is convenient to cut it in half.

When the passage 11 is a single ordinary cylindrical hole, the slide member 19 slides on the opening end of the passage 11, and the passage 11 is moved by the vertical stroke amount of the slide member 19.
The opening area (orifice) of the damping force changes automatically, and the damping force changes accordingly.

There may be only one lateral passage 11 as shown in Fig. 2, or a passage 11a may be used in which two holes 30 and 31 are connected by a through hole 32 with a narrow opening area and a length corresponding to a dead zone as shown in Fig. 4. Or, as shown in FIG. 5, two holes 33 and 34 are provided separately, and this hole 3
A passage 11b with a dead zone 35 having a length between 3 and 34 can also be used.

Next, we will discuss the operation.

When the piston is extended, the piston 3 and the piston rod 4 rise, and at this time the oil chamber 5 is compressed and the internal hydraulic oil is discharged into the lower oil chamber 6 via the piston-side passage 17, and a portion of the oil is discharged into the lower oil chamber 6 through the passage 17 on the piston side. The oil is introduced into the lower oil chamber 6 through the vertical passage 9 formed by the chamfers 24 and 25, and at this time, damping force is generated in the passage 11 due to the opening area regulated by the slide member 19.

Similarly, in piston compression operation, the piston 3 descends, compressing the lower oil chamber 6 and discharging the oil into the passage 1.
6, 17 to the upper oil chamber, and a portion is supplied to the upper oil chamber via the passage 11 with the chamfered passages 24, 25 and the passage 11.
A damping force corresponding to the opening area of 1 is generated.

Next, we will discuss how the damping force automatically changes according to changes in internal pressure.

As shown in the figure, when the protruding repulsive force corresponding to the cross-sectional area of the control rod 20 multiplied by the internal pressure, which is the difference between atmospheric pressure and the spring 29, is balanced, the opening area of the passage 11 is divided into two. The slide member 19 is stopped at the first position.

When the internal pressure changes due to temperature changes or displacement of the piston rod, for example due to compression of the amount equivalent to the piston entry volume, or when the internal pressure of the oil chambers 5 and 6 changes due to external vehicle height adjustment, the balance between the spring 29 and the internal pressure is lost. The slide member 19 slides upward or downward to change the opening area of the passage 11 and change the damping force.

That is, not only when the internal pressure increases due to a rise in temperature, but also when the piston rod is compressed or when the gas pressure in the gas chamber 8 increases due to vehicle height adjustment, the internal pressure of the cylinder 2 increases, and this internal pressure causes the control rod 2 to increase.
The repulsive force against the spring 29 of 0 increases, and the slide member 9 connects with the control rod 20.
rises against the spring 29, thereby reducing the opening area of the passage 11, which is an orifice, and thereby increasing the damping force generated.

On the other hand, as the internal pressure of the oil chamber 6 decreases and the protruding repulsive force becomes smaller, the slide member 19 descends due to the reaction force of the spring 29, and the area of the passage 11 serving as the orifice is increased, so that the damping force generated decreases.

This relationship is shown in the graphs of Fig. 6 and Fig. 7, which show the characteristics of repulsive force and damping force. When the force (internal pressure) increases, or when the internal pressure increases due to temperature rise or vehicle height adjustment, the repulsive force increases from characteristic a to characteristic b, and at this time, as shown in Figure 7, the repulsive force attenuates at characteristic a. The force characteristic is shown by a characteristic curve a, and when the characteristic changes to b, the damping force characteristic becomes b, and in the embodiment shown in Fig. 1, the damping force characteristic changes steplessly due to changes in internal pressure. .

Note that the passages 11a and 11b serving as orifices are
When dead zones 32 and 35 are provided as shown in FIGS. It becomes zero. That is, for example, in Fig. 6, the repulsive force (internal pressure) difference △F
In the range of , the change in passage area is small in the case of FIG. 4 and zero in the case of FIG.

Therefore, by providing such dead zones 32 and 35, there is no need to improve the accuracy of the set positions of the control rod 20 and the slide member 19.
Within this range, relatively rough machining is possible, making manufacturing easy.

As described above, in the present invention, the damping force automatically changes as the repulsion force (spring constant) changes due to changes in internal pressure, and optimal ride comfort and handling stability can always be obtained.

[Brief explanation of the drawing]

The attached drawings relate to one embodiment of the present invention and are
2 is a partially enlarged sectional view of FIG. 1, FIG. 3 is a cross-sectional plan view of the slide member, and FIGS. 4 and 5 are orifices according to other embodiments. FIG. 6 is a graph showing repulsion force characteristics, and FIG. 7 is a graph showing damping force characteristics. 2... Cylinder, 3... Piston, 4... Piston rod, 5, 6... Oil chamber, 9... Vertical passage, 11, 11a, 11b... Orifice, 19
...Slide member, 20...Control rod, 29...Spring, 30, 31, 33, 3
4...hole, 32, 35...dead zone.

Claims (1)

[Claims for Utility Model Registration] (1) A piston rod is inserted into and out of the cylinder via a piston, and two oil chambers (upper and lower) are defined within the cylinder by the piston. In a hydraulic shock absorber equipped with a vertical passage and a horizontal orifice that communicate the chambers, one end of the control rod, which is slidably inserted into the piston rod, protrudes into the atmosphere, and a passage is formed at the inner end. A slide member is attached and slidably fitted into the vertical passage, and a spring is interposed on the end surface of the slide part on the control rod side to urge the orifice in the direction of opening. A damping force adjustment device for a hydraulic shock absorber that is balanced with the internal pressure of an oil chamber, and a slide member moves up and down in response to changes in internal pressure to change the opening area of an orifice. (2) The damping force adjusting device for a hydraulic shock absorber according to claim (1) of the utility model registration, wherein the slide member is prevented from rotating via a control rod. (3) The orifice consists of multiple holes and a dead zone provided between these holes.
A damping force adjustment device for the hydraulic shock absorber described in (1).