JPS6111551Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a shock absorber using a viscous liquid fluid, and in particular, in order to reduce the pressure increase caused by the temperature expansion of the viscous liquid fluid filled in a closed container, gases such as air are enclosed together. The present invention relates to a shock absorber having a structure suitable for use in various cases.

A shock absorber using a viscous liquid fluid such as silicone oil is used, for example, in a pulse motor to prevent vibrations caused by rotation.

1 and 2 are a plan view and a sectional view showing such a conventional shock absorbing device. In the figure, 1 is a rotating body made of a material with a high density (g/cm ³ ) such as metal (for example, a hollow cylinder), and 2 is a rotating body made of a material with a high density (g/cm 3 ) such as metal, and 2 is a rotating body made of a material with a high density (g/cm 3 ) such as a metal. an airtight container that surrounds the rotating body 1 with a gap of several tens of micrometers to several hundred micrometers and accommodates the rotating body 1 in a rotatable state;
3 is a viscous liquid fluid such as silicone oil filled in the small gap between the rotating body 1 and the closed container 2, and 4 is air sealed in the small gap.

The airtight container 2 is fixed to a rotating body such as a pulse motor, and thereby acts to suppress the generation of vibrations when the pulse motor or the like rotates. That is, when the rotational speed of the pulse motor is about to change rapidly, initially there is no or very small speed difference between the closed container 2 and the rotating body 1, and therefore the viscosity coefficient and speed gradient of the viscous liquid fluid 3 change. The mechanical bonding force between the closed container 2 and the rotating body 1 based on the shear stress given by the product of is small. Therefore, the rotation of the closed container 2 precedes for a while,
Thereafter, the mechanical coupling force between the closed container 2 and the rotating body 1 increases in proportion to the speed difference, and the effective inertial mass increases, so that the rotational speed of the closed container gradually changes. Therefore, the time during which the rotational speed of the closed container undergoes a sudden change is short, and fluctuations in the rotational speed are also reduced. In particular, when vibration occurs, a large damping effect will be exerted.

The above is the basic structure and function of the shock absorber, but in practical use, the viscous liquid fluid 3 filled in the closed container 2 is Since the thermal expansion is larger than that of (solid), as the temperature rises, the airtight container 2
This increases the internal pressure of the sealed container 2 and applies a steady stress (if the temperature fluctuation is periodic, a stress that changes periodically) to the closed container 2, which increases its fatigue and shortens its life. Therefore, in order to solve this problem, conventionally a sealed container 2 is used as shown in the figure.
Air (a fluid with a smaller bulk elastic modulus than liquid) is often sealed in the airtight container 2 to reduce the pressure rise inside the closed container 2.

However, because it is necessary to reduce the gap between the closed container 2 and the rotary body 1, the area occupied by the sealed air becomes relatively large, and the position of the sealed air sometimes moves to be close to the rotation axis of the container. In addition, since the area occupied by the air changes greatly depending on the temperature, the vibration damping rate based on the viscous liquid fluid 3 is not constant and fluctuates greatly.

The object of the present invention is to eliminate the above-mentioned drawbacks and to provide a shock absorbing device that can always maintain a constant cross-sectional area on which a viscous liquid acts.

The purpose of this invention is to provide a rotating body, a closed container that surrounds the rotating body through a small gap and accommodates it in a rotatable state, and a small gap between the rotating body and the closed container that is filled with air. In a shock absorbing device for preventing vibration of a rotary drive shaft connected to a closed container, a small hole that does not penetrate through both or one of the rotating body and the closed container is provided. This is achieved by filling the small hole with gas, and an embodiment thereof will be described in detail below with reference to the drawings.

FIGS. 3 and 4 are a plan view and a sectional view illustrating a rotating body of a shock absorber improved based on the present invention. The closed container and viscous liquid fluid (not shown) are the same as the conventional one, and the difference lies in the rotating body shown.

That is, the rotating body 10 according to the present invention has a plurality of small holes 5 having a diameter of, for example, about 0.1 to 0.5 mm and a predetermined depth or more depending on the diameter, and air, etc. It is designed to enclose the following gas.

Therefore, the sealed gas does not occupy a large cross-sectional area in the gap between the rotating body 10 and the closed container, and the pressure increase in the closed container due to thermal expansion can be suppressed. As a result, the area of action of the viscous liquid fluid can be maximized, and there is no movement of the enclosed gas or change in the occupied area in the gap, so various drawbacks seen in the past can be avoided. .

Furthermore, the decrease in the moment of inertia of the rotating body 10 due to the formation of the small holes 5 is further reduced, processing is facilitated, and the action of the viscous liquid fluid is reduced when a portion of the sealed gas overflows from the small holes 5. In order to reduce the amount, it is preferable to adopt a structure as shown in FIGS. 5 and 6.

5 and 6 are a plan view and a sectional view showing another embodiment of the present invention, and this embodiment has a plurality of small holes 5 in the axial direction of the rotating body 10 and near the axis. 5, and has a structure in which gas is sealed in these small holes.

Rotating body 10 in proportion to the distance from the rotating body
Since the shear stress increases due to the viscosity acting between the rotor and the closed container, the reduction in the shear stress is smaller when the sealed gas overflows from the small hole 5 near the rotating body, and the inertia of the rotor increases. Regarding the moment, it can be said that the decrease due to the formation of the small hole 5 is smaller in the portion closer to the rotation axis.

In addition, in the above two embodiments, the small hole 5
Both have a structure that does not penetrate the rotating body 10,
In addition, in order to prevent the gas in this small hole 5 from being replaced by the viscous liquid fluid and expelled, the diameter and depth are set according to the viscosity (temperature change range) of the viscous liquid fluid. When injecting viscous liquid fluid into the gas hole 5, the gas can be left in the small hole 5 and sealed without any special means, and the gas can be sealed even if the pressure at the opening of the small hole increases. The entire gas does not move and can be held in a fixed position. If a small hole is used as a through hole, a pressure difference may occur between one opening and the other.
There is an inconvenience that the sealed gas may somehow escape from the small hole. Note that a small hole can also be provided on the side of the airtight container if necessary.

As described above, according to the present invention, it is possible to provide a shock absorber with a simple structure that can always perform constant vibration damping.

[Brief explanation of the drawing]

1 and 2 are a plan view and a sectional view showing a conventional shock absorber, FIGS. 3 and 4 are a plan view and a sectional view illustrating a rotating body improved based on the present invention, and FIGS. FIG. 6 is a plan view and a sectional view showing another embodiment of the present invention. 2... Airtight container, 1, 10... Rotating body, 3...
Viscous liquid fluid, 5...Characteristic small hole.

Claims (1)

[Scope of utility model registration request] It is composed of a rotating body, a closed container that surrounds the rotating body through a small gap and accommodates it in a rotatable state, and a viscous liquid fluid that fills the small gap between the rotating body and the closed container. In a shock absorbing device for preventing vibration of a rotary drive shaft connected to a sealed container, a small hole that does not penetrate through both or one of the rotating body and the sealed container is provided, and gas is sealed in the small hole. A shock absorbing device using a viscous liquid fluid characterized by: