JPS6137884Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic shock absorber in which the area of a fluid communication passage is increased or decreased through a damper valve to adjust the generated damping force.

Hydraulic shock absorbers are known in which a damping force is obtained by flow loss when a liquid such as hydraulic oil sealed inside flows, thereby effectively mitigating external shocks.

In such a conventional shock absorber, since the area of the flow path through which the liquid flows remains unchanged, its damping force characteristic becomes a smooth curve A, as shown in FIG. 6, for example.
The damping force increases smoothly in proportion to the actuation speed.

By the way, when a shock absorber is applied to a vehicle, for example, if the damping force is kept high, the handling stability of the vehicle will generally increase, but ride comfort will decrease, so the damping force must be kept below a certain value. For example, when sudden braking is applied to a vehicle, the vehicle body may sink forward due to inertia, or the shock absorber may bottom out due to large road surface irregularities, impairing steering stability and ride comfort. Undesirable.

The present inventor has devised the present invention in view of the above-mentioned problems with such a buffer, and to effectively solve the problems.

The object of the present invention is to slidably fit a damper valve equipped with orifices and a check valve that closes these orifices, and to connect this to a diaphragm that operates by differential pressure, and to operate the damper valve in a predetermined manner. sliding the damper valve at a speed (operating stroke) or higher to increase or decrease the flow area of the liquid;
Therefore, it is an object of the present invention to provide a hydraulic shock absorber which can achieve stable and smooth operation by adjusting the damping force.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional side view of a shock absorber according to the present invention, and FIG. 2 is an enlarged sectional view taken along the line 2-2 in FIG.

In Fig. 1, reference numeral 1 denotes a hollow cylindrical outer case that is open at the top;
Inside, a small-diameter inner case 2, which is also open at the top, is fixed at its lower end with a lock bolt 3 and a lock nut 4 screwed into the lock nut 4, and is planted concentrically with respect to the outer case 1. And these outer case 1 and inner case 2
As shown in the figure, an inner tube 5 is fitted in between so as to be vertically slidable. That is, inner tube 5
The outer circumference of this 5 is in sliding contact with the inner circumference of the outer case 1, and the inner circumference of this 5 is in sliding contact with the upper end of the inner case 2, and a ring-shaped inner tube seal is fixedly attached to the lower circumference of this 5. 6 is in sliding contact with the outer periphery of the inner case 2. A dust seal 7 and an oil seal 8 are provided at the upper end of the outer case 1, and a seal ring 9 is provided at the upper end of the inner case 2. 2 are airtightly sealed.

Thus, outer case 1 and inner case 2
A first working fluid chamber _S1 is formed between them, a second working fluid chamber _S2 is formed in the inner case 2, and a gas chamber _S3 is formed in the upper part of the inner tube 5. Hydraulic oil is filled in the liquid chambers S ₁ and S ₂ , and air is filled in the gas chamber S ₃ .

An oil lock orifice 10 is provided in the upper part of the inner case 2, and a damper orifice 11 in two stages, upper and lower, and an oil lock off orifice 12 are provided in the lower part of the inner case 2, respectively.
The first hydraulic fluid chamber S ₁ and the second hydraulic fluid chamber S ₂ communicate with each other via these orifices 10, 11, . . . , 12. As shown in the figure, a cushion spring 1 is installed inside the inner tube 2, that is, inside the gas chamber _S3 .
3 is mounted, and a seal 6 of the first hydraulic fluid chamber _S1 is installed.
Upper and lower hydraulic fluid chambers divided into upper and lower sections _S1U ,
A stopper spring 14 is provided in the upper hydraulic fluid chamber _S1U of _S1L . Further, numeral 15 in the figure is a gas valve.

On the other hand, a dish-shaped bottom cap 16 is tightened and fixed to the lower end surface of the outer case 1 with screws 17. is divided into upper and lower chambers S ₄ and S ₅ by a diaphragm 18 made of a flexible membrane fixed by the bottom cap 16. The upper chamber _S4 is connected to the second hydraulic fluid chamber through a through hole 3a penetrating the center of the lock bolt 3.
It forms a pressure chamber that communicates with S ₂ , while the lower chamber
S ₅ forms a spring chamber inside which accommodates a spring 19 that springs the diaphragm 18 upward, and this spring chamber S ₅ communicates with the atmosphere through an air orifice 16 a bored in the center of the bottom cap 16. are doing.

By the way, as shown in the figure, a damper valve 20 is fitted into the inner case 2 so as to be able to slide vertically, and this valve 20 is connected to a rod 21 that extends downward through the through hole 3a of the lock bolt 3.
It is connected to the center portion of the diaphragm 18 via. The second hydraulic fluid chamber S ₂ is thus divided into upper and lower hydraulic fluid chambers S _2U and S _2L by the damper valve 20.

In the damper valve 20, 22 is a dish-shaped valve body with an open top, and the bottom wall 22a of this is provided with a plurality of valve bodies (8 in the illustrated example) as shown in FIG.
orifices 23... are provided, and some of these orifices 23... (four in the illustrated example) are made of flexible metal plates formed into a cross shape as shown in the figure. The stop valve 24 is closed when not in operation, and the remaining orifices 23-2 are always open to communicate the upper hydraulic fluid chamber _S2U and the lower hydraulic fluid chamber _S2L . The check valve 24 is provided on the upper surface of the bottom wall 22a of the valve body 22, and allows hydraulic fluid to flow from the lower hydraulic fluid chamber _2L to the upper hydraulic fluid chamber _S2U .

Thus, when this shock absorber is used for a vehicle, for example, the upper end of the inner tube 5 is connected to the vehicle body side, while the lower end of the outer case 1 is connected to the wheel side via the bracket 1a, and both 1 and 5 are connected to each other. It expands and contracts to create the desired cushioning effect.

Next, the operation of this shock absorber will be explained.

First, to describe the compression process of the device, for convenience's sake, the outer case 1 is immovable.
In contrast, the inner tube 5 is assumed to move downward as shown in FIGS. 3a and 3b.

At the initial stage of compression as shown in FIG. 3a, as the inner tube 5 moves downward, the hydraulic fluid in the first hydraulic fluid chamber _S1 is compressed and the pressure increases, and as shown by the arrows in the figure, the orifice 11..., 12 into the lower chamber _S2L of the second hydraulic fluid chamber _S2 , this hydraulic fluid further opens the check valve 24 of the damper valve 20, passes through the orifice 23, and flows into the upper chamber _S2U. do. The hydraulic fluid that has flowed into the upper chamber _S2U is placed in the upper chamber S1U of the first hydraulic fluid chamber _S1 , whose volume increases with the downward movement of the inner tube 5 through _an orifice 10.
It flows in as shown by the arrow in the figure.

In this way, a damping force is generated due to flow resistance, ie, energy loss, which occurs when the hydraulic oil passes through each orifice, and external shocks are effectively absorbed and alleviated.

Therefore, as shown in Fig. 2b, the inner tube 5
As the compression stroke of the inner tube 5 progresses, hydraulic oil equivalent to the volume that has entered the first hydraulic fluid chamber _S1 of the inner tube 5 flows into the gas chamber _S3 , and its level rises as shown in the figure. However, as a result, the volume occupied by the air decreases, the air is compressed by that much, and its pressure increases. This air pressure propagates to the pressure chamber _S4 via the hydraulic oil, acts on the upper surface of the diaphragm 18, and pushes the diaphragm 18 downward against the elastic force of the spring 19. The damper valve 20 moves downward together with the downward movement of the diaphragm 18, and the main body 22 of this 20 gradually closes the damper orifices 11 as shown in the figure as the air pressure increases, and restrict the flow of hydraulic fluid. If orifice 11... is completely blocked,
The flow of hydraulic fluid from the first hydraulic fluid chamber _S1 to the second hydraulic fluid chamber _S2 is achieved only through the oil lock orifice 12, and therefore the flow of hydraulic fluid is significantly restricted, and its flow resistance rapidly increases. , the damping force generated is the sixth
It changes along curve B in the figure. In this manner, the damping force increases significantly at a high stroke of the inner tube 5, so that the so-called bottoming out phenomenon of the device is effectively prevented, and stable and smooth operation of the device is guaranteed.

Fig. 6 shows the damping force characteristics of the device, the horizontal axis shows the stroke, the vertical axis shows the damping force, and the point K in the figure shows the damping force characteristics of the device.
is the oil lock starting point, ie, the point at which the system begins to reach the condition of FIG. 3b. Furthermore, in the state shown in FIG. 2b, _the hydraulic fluid passes through the damper valve 20 and still flows from the lower chamber _S2L to the upper chamber _S2U of the second hydraulic fluid chamber S2. Flow resistance (pressure loss) when passing through
A pressure difference of 1.25 mm acts on the valve 20, and the force based on this pressure pressure always pushes the valve 20 upward, but in this case, the check valve 24 is in an open state and the orifice 23-1...
(See Fig. 2) is fully open, so the differential pressure is small, and therefore the upward pressing force acting on the valve 20 is also small. can be sufficiently overcome to move the valve 20 downward. Also, in this case, since the orifices 23 of the damper valve 20 are in an open state, the air pressure in the gas chamber S ₃ is propagated to the pressure chamber S ₄ without any problem.

The above is the operation of the device during the compression stroke.Next, the operation during the extension stroke will be described.

Figure 4a shows the inner tube 5 below the specified speed.
is moving upward relative to the outer case 1. In this case, as the inner tube 5 moves upward, the hydraulic pressure in the upper chamber _S1U of the first hydraulic fluid chamber _S1 increases, and this chamber S The hydraulic fluid in _1U passes through the orifice 10 as shown by the arrow in the figure and enters the second hydraulic fluid chamber _S2.
into the upper chamber _S2U . The hydraulic oil in this upper chamber _S2U is further supplied to the normally open orifice 2 of the damper valve 20.
Pass through 3-2... (see Figure 2) and enter the lower chamber S _2L.
The fluid then flows through the orifices 11..., 12 and flows into the lower chamber _S1L of the first working fluid chamber _S1 whose volume increases with the upward movement of the inner tube 5. At this time, the check valve 24 of the damper valve 20 is in a fully closed state as shown in the figure.

In this way, a damping force is generated by the flow resistance generated when the hydraulic oil passes through each orifice, and as in the compression stroke, this damping force effectively absorbs and alleviates external shocks.

In this case, the operating speed of the inner tube 5 is low, and therefore the flow speed of the hydraulic oil is small.
The flow resistance (pressure loss) of the hydraulic oil passing through the orifices 23 of the damper valve 20 is small, and the downward pressing force based on the pressure difference acting on the upper surface of the damper valve 20 does not push down the valve 20 against the elastic force of the spring 19, so the valve 20 remains stationary, and the orifices 11, 12
is in the fully open position.

On the other hand, the operating speed of the inner tube 5 increases, and the flow resistance of the hydraulic oil passing through the orifice 23-2 (see Fig. 2) increases, and as a result, the downward force acting on the upper surface of the damper valve 20 increases. When the pressing force increases and this pressing force exceeds the elastic force of the spring 19, the damper valve 20 moves downward as shown in FIG. 22 is orifice 1
1... Gradually occlude. This orifice 11...
The flow of hydraulic oil is restricted due to the blockage, and the damping force generated due to increased flow resistance increases according to curve B in FIG. Even when the orifice 11 is completely closed, a small amount of water is generated from the lower chamber _S2L of the second working fluid chamber _S2 through the orifice 12, and the device becomes completely rigid (oil lock state). can be avoided.

When the extension stroke of the inner tube 5 increases and the seal 6 of the inner tube 5 reaches a state where the orifice 10 is completely closed as shown in FIG. 5, the upper chamber _S1U of the first working fluid chamber S1 _becomes A completely sealed state is achieved, and the device becomes completely rigid (oil-locked state), and further upward movement of the inner tube 5 is prevented, and the device avoids the so-called bottoming out phenomenon. In this case, the hydraulic oil level in the gas chamber _S3 decreases as the inner tube 5 rises (see FIG. 5).

In this way, stable and smooth operation of the device is guaranteed during the extension stroke as well as during the compression stroke.

In the above embodiments, each chamber inside the device is filled with air and oil as the working fluid, but any other combination of gas and liquid may be used as the working fluid.

As is clear from the above description, according to the present invention, a damper valve equipped with orifices and a check valve for closing these orifices is slidably fitted inside, and this is connected to a diaphragm operated by differential pressure. Connected and specified operating speed (operating stroke)
As described above, since the damper valve is slid to increase or decrease the liquid flow path area, the required damping force characteristics can be obtained, and stable and smooth operation of the device can be realized.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a longitudinal sectional side view of a shock absorber according to the invention, Fig. 2 is an enlarged sectional view taken along line 2-2 in Fig. 1, and Fig. 3 Figures 4a, b and 5 are explanatory diagrams of the operation of the device during the compression stroke, Figures 4a and 5 are explanatory diagrams of the operation of the device during the extension stroke, and Figure 6 is a comparison of the damping force characteristics of this device with those of a conventional device. FIG. In the drawing, 1 is an outer case, 2 is an inner case, 5 is an inner tube, 10, 11, 1
2 and 23 are orifices, 18 are diaphragms, 1
9 is a spring, 20 is a damper valve, 24 is a check valve, S ₁ is a first hydraulic fluid chamber, S ₂ is a second hydraulic fluid chamber, S ₃ is a pressure chamber, and S ₄ is a spring chamber.

Claims (1)

[Scope of utility model registration request] An inner case, which is also open at the top, is installed in the lower part of the outer case, which is open at the top, and an inner tube is slidably fitted between the outer case and the inner case. In a hydraulic shock absorber comprising a working fluid chamber, a second working fluid chamber in an inner case, and a gas chamber in an upper part of an inner tube, the second working fluid chamber is partitioned by a diaphragm in the lower part of the outer case; A pressure chamber that communicates with the liquid chamber and a spring chamber that is open to the atmosphere and houses a spring that elastically supports the diaphragm are formed therein, and the first working liquid chamber is provided in the upper and lower parts of the inner case. and a second hydraulic fluid chamber are provided, respectively, and the second hydraulic fluid chamber is divided into upper and lower sections within the inner case,
In addition, a damper valve comprising an orifice that communicates between these divided chambers and a check valve that closes a part of these orifices is slidably fitted, and the valve is connected to the diaphragm. Hydraulic shock absorber.