JPH0517461Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a shock absorber, and is applied to a vibration system having excitation input or self-vibration in a frequency range that includes a specific frequency vibration range (e.g. natural frequency = resonance point). This is useful when applied to vibration isolators.

[Conventional technology]

For example, a shock absorber applied to a vibration system that receives excitation input in a region including the natural frequency should generate damping force only near the natural frequency of the vibration system and not in other regions. is desirable.

As seen in, for example, Japanese Utility Model Application Publications No. 50-123784 and No. 60-116437, such a shock absorber has a compression side chamber and a compression side chamber in a cylinder partitioned by a piston having a throttle hole. It is known that this can be achieved by installing a pair of gas chambers in series.

[Problem that the invention attempts to solve]

However, such a shock absorber has a problem when it is applied to a monocylindrical shock absorber, which is likely to be subject to restrictions in terms of installation dimensions (basic length).

In other words, if a pair of gas chambers are provided outside the cylinder and an external tank type is used, as in the latter Japanese Utility Model Application No. 60-116437, even though the installation dimensions can be cleared, such an external tank is easily damaged. Therefore, it is particularly inappropriate as a shock absorber for vehicles.

On the other hand, this type of monocylindrical shock absorber is generally equipped with a gas chamber for compensating for the piston rod intrusion volume at the end of the pressure side chamber. It is conceivable to build in a gas chamber in the same way, but if you do this, the basic length of the shock absorber will become longer by the amount of the gas chamber in the expansion side chamber, so there is a problem that it will not be possible to install it. .

Therefore, the purpose of this invention was to eliminate the need for an external tank type, which is susceptible to damage, and to create a single cylinder type shock, which originally had a gas chamber for compensating for the intrusion volume of the piston rod at the end of the pressure side chamber inside the cylinder. Without increasing the basic length compared to absorbers,
It is an object of the present invention to provide a shock absorber of this type that can generate a large damping force only in a specific frequency vibration range.

[Means for solving problems]

The above object, according to this invention, includes a cylinder, a piston that divides the inside of the cylinder into a growth side chamber and a compression side chamber and has a throttle hole that communicates these two chambers with each other, and a bearing case at one end of the cylinder from the piston. It is equipped with a piston rod that penetrates and extends to the outside, and a pair of gas chambers provided in the expansion side chamber and the compression side chamber in the cylinder, each gas chamber being configured by sealing gas in an elastic bag made of rubber or the like. , and for the compression side chamber, it is connected to the end of the cylinder through a partition member having an oil passage hole, and for the expansion side chamber, it is connected to the inside of the bearing case through a partition member also having an oil passage hole. This can be achieved by means of shock absorbers provided in each case.

[Effect]

That is, by the above means, the pair of gas chambers connected to the expansion side chamber and the compression side chamber are both located within the cylinder, so that the risk of being damaged by external impact is extremely reduced.

In addition, since the gas chamber connected to the expansion side chamber is housed in a bearing case that does not obstruct the piston stalk, the single-cylinder type, which originally had a gas chamber for compensating for the piston rod's intrusion volume at the end of the compression side chamber in the cylinder, The basic length is not longer than that of a shock absorber, and therefore there are no restrictions on its installation.

〔Example〕

This invention will be explained below based on the illustrated embodiments.

In Figure 1, 2 is a cylinder, and piston 1
A compression side chamber 3 partitioned by a cap 4 is sealed, and the other expansion side chamber 5 is sealed under a bearing of a piston rod 7 by a bearing case 6.

An oil passage hole 8 is provided at the end of the pressure side chamber 3.
A gas chamber 11 is arranged under the partition wall 9 which has been opened, and is constructed by sealing gas in a bag body 10 made of an elastic material such as rubber.

Furthermore, a gas chamber 12 consisting of a bag body 10 is disposed within the bearing case 6 with a partition wall 9 having an oil passage hole 8 similarly arranged at the end of the expansion side chamber 5. The compression side chamber 3 and the expansion side chamber 5 are filled with hydraulic oil.

On the other hand, the piston 1 is provided with a throttle hole 13 that communicates the compression side chamber 3 and the expansion side chamber 5.

In the embodiment with such a configuration, during low frequency operation when this is assembled as a vibration isolator for a vibration system, the reciprocating movement of the piston 1 due to vibration causes the hydraulic oil in the compression side chamber 3 and the expansion side chamber 5 to be moves between the two chambers through the throttle hole 13 of the piston 1.

Due to the flow resistance of the hydraulic oil passing through the throttle hole 13 at this time, the differential pressure acting on both the compression side and the expansion side of the piston 1 becomes a damping force.

At this time, the volume change of the cylinder 2 that occurs as the piston rod 7 enters or exits the cylinder 2 is the compression or expansion of the gas chambers 11 and 12 disposed in the pressure side chamber 3 and the bearing case 7, respectively. The resulting rise in pressure within the cylinder 2 appears as a spring reaction force.

Therefore, during extremely low frequency operation, the pressure acting on both sides of the piston 1 is almost equal, so as shown in the reaction force characteristic diagram in Fig. 2, almost no damping force is generated, and the spring The reaction force is the pressure inside the cylinder 2 multiplied by the cross-sectional area of the piston rod 7.

On the other hand, when the operating frequency of piston 1 increases,
Accordingly, the damping force and the spring force both increase as shown in FIG. At the same time, the spring force gradually increases as the frequency increases.

Furthermore, when the operating frequency of the piston 1 increases and reaches a high frequency operating range, the flow resistance of the hydraulic oil passing through the throttle hole 13 increases, so the hydraulic oil in the compression side chamber 3 and the expansion side chamber 5 mainly flows into the respective gas chambers. 11
and 12.

Therefore, the differential pressure between the two sides of the piston 1 due to the hydraulic oil passing through the throttle hole 13 becomes smaller. In other words, vibration absorption is performed by the gas damper while the throttle hole 13 is closed. The damping force becomes smaller again. On the other hand, gas chamber 11
Or the pressure difference for compressing 12 becomes larger and the spring force becomes even higher.

Thus, by appropriately selecting the volumes and sealing pressures of the gas chambers 11 and 12 and the diameter of the throttle hole 13 of the piston 1, frequency selectivity can be imparted to the damping force generated by the shock absorber according to this embodiment.

[Effect of idea]

As described above, according to this invention, the gas chamber that communicates with the expansion side chamber is provided inside the bearing case for the piston rod guide, thereby eliminating the need for an external tank type that is prone to damage. A shock absorber that generates a large damping force only in a specific frequency vibration range without increasing the basic length compared to a monocylindrical shock absorber that has a gas chamber at the pressure side end of the cylinder to compensate for the intrusion volume. It becomes possible to configure.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view showing an embodiment of the shock absorber according to this invention, and FIG. 2 is a diagram showing the operating characteristics of the same shock absorber. 1... Piston, 2... Cylinder, 3... Compression side chamber, 5... Rebound side chamber, 6... Bearing case, 7
... Piston rod, 8 ... Oil passage hole, 9 ... Partition wall, 10 ... Bag body, 11, 12 ... Gas chamber, 13
...Aperture hole.

Claims (1)

[Scope of utility model registration request] a cylinder, a piston that divides the inside of the cylinder into a growth side chamber and a compression side chamber and has a throttle hole that communicates these two chambers with each other; a piston rod that extends from the piston to the outside through a bearing case at one end of the cylinder; Equipped with a pair of gas chambers respectively provided in the expansion side chamber and the compression side chamber in the cylinder,
Each gas chamber is configured by sealing gas in an elastic bag made of rubber or the like, and for the compression side chamber, it is connected to the end of the cylinder through a partition member having an oil passage hole, and to the expansion side chamber. In this case, a monocylindrical shock absorber is provided within a bearing case via a partition member having an oil passage hole.