JPH054589Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Field of Application] The present invention relates to a pendulum-type vibration isolator, and particularly to a pendulum-type vibration isolator with improved vibration isolation performance in the horizontal direction. [Prior Art] Conventionally, vibration isolators and vibration isolators include those using coil springs, vibration isolating rubber, air springs, and the like. The characteristics of each are shown in Table 1 below, and all of these are known as vibration isolators with good characteristics also in the horizontal direction.

【table】

[Table] Furthermore, pendulum-type vibration isolators and vibration isolators have traditionally been used as devices that maintain good stability and have good horizontal vibration isolation and vibration isolation characteristics.
As shown in the figure, there is a suspension shaft 2 which is a pendulum with anti-vibration rubber 8 attached to it (Utility Model 59-
(See No. 17342). [Problems to be solved by the invention] By the way, in such conventional vibration isolating and vibration isolating devices, those using coil springs, vibration isolating rubber, and air springs are capable of vertical vibration isolating and vibration isolating at the same time. In many cases, it also functions as a vibration damper, and if only the characteristics in the horizontal direction are focused on, there is a problem that the stability of the vibration isolator and vibration isolator may be lacking and buckling may occur. In addition, in the pendulum-type vibration isolator and vibration isolator, the natural frequency in the horizontal direction is as clear from the following equation (1):
The longer the pendulum length l (FIG. 6) is, the more the vibration is reduced, but if the pendulum is not long enough, there is a problem that the horizontal vibration isolation and vibration damping characteristics are not improved much. g = gravity connection l = pendulum length EI = bending rigidity of the shaft m = mass added to the shaft Furthermore, in the case of using a hanging shaft and vibration isolating rubber, the spring constant ratio of the vibration isolating rubber (KV /KM)
is about 10 to 1, and when a horizontal force is applied, the vibration isolating rubber 8 moves into a state 8' as shown in FIG.
The width of movement of the center point was small, ε, and there were difficulties in maintaining stability against large loads. The present invention was devised in view of the above-mentioned difficulties, and aims to provide a pendulum-type vibration isolator that has particularly excellent vibration isolation performance in the horizontal direction even when the length of the pendulum is insufficient. [Means for Solving the Problems] In the present invention, the outer cylinder is suspended and supported within the outer cylinder by an elongated hanging shaft swingably suspended from the upper end of the outer cylinder, and is equipped with an air spring. In a pendulum-type vibration isolator consisting of an inner cylinder, a suspension shaft protrudes through the upper end of the outer cylinder, and a laminated rubber-like elastic body with extremely high horizontal elasticity placed on the upper end of the outer cylinder and a suspension It is characterized by being pivotally connected in series with the shaft to reduce the natural frequency in the horizontal direction. [Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings. As shown in Fig. 1, the pendulum type vibration isolator according to the present invention consists of an outer cylinder 1 and an inner cylinder 3 which is suspended and supported by a suspension shaft 2 which is swingably suspended from the upper end 1a of the outer cylinder. . An air spring 3a is attached to the upper part of the inner cylinder 3. Furthermore, as shown in FIG.
are installed in series on the lifting shaft 2, and the lifting shaft 2
Its upper end is pivotally connected to the laminated rubber-like elastic body 4. Both the hanging shaft 2 and the laminated rubber-like elastic body 4 are made of members that are hard in the load application direction (vertical direction) and very soft in the horizontal direction. For example, the hanging shaft 2 is made of copper material with a large slenderness ratio, non-ferrous metal,
The laminated rubber-like elastic body 4 is a hollow body, as shown in FIG. It is made up of alternating layers of substances. Such a laminated rubber-like elastic body 4 can achieve a spring constant ratio of 50:1 or more, whereas the spring constant ratio (KV/KH) of commercially available anti-vibration rubber is about 10:1. . Therefore, as shown in FIG.
The horizontal movement will be from state 4a to state 4a' in the figure, and the width of movement of the center point is ε', which is large enough to maintain stability, so even if the diameter is the same, it is possible to support a large load. can. [Function] In the above configuration, vibration isolation in the horizontal direction,
Vibration isolation is achieved by two springs, the suspension shaft 2 and the laminated rubber-like elastic body 4, which are very soft in the horizontal direction and very hard in the vertical direction. As shown in FIG. 4, the fulcrum of the pendulum moves upward by a length of Δl by the amount that the laminated rubber-like elastic body 4 is bent in the horizontal direction.
Since the length l of the pendulum can be made longer than its actual length, it is possible to lower the natural frequency in the horizontal direction. Furthermore, since the Young's modulus of the suspension shaft 2 and the laminated rubber-like elastic body 4 are greatly different, the sound transmission loss is large.
It becomes possible to block high frequency vibrations propagated from the outer cylinder 1 to the inner cylinder 3 or from the inner cylinder 3 to the outer cylinder 1. Furthermore, high viscosity oil, gel 7
(Fig. 1) makes it possible to apply appropriate damping. Furthermore, if vibration isolation in the vertical direction is required, vertical vibration isolation can be easily achieved by using vibration isolating rubber, coil springs, rubber pads, etc. in combination. Figure 5 is a graph comparing the horizontal vibration transmissibility of the pendulum-type vibration isolator of the present invention with the vibration transmissibility of other pendulum-type vibration isolators. , it is clear that the vibration isolation effect range is stable, and the performance can be further improved by using damping oil or the like. [Effects of the invention] As is clear from the above, according to the pendulum type vibration isolator of the invention, even if the length of the suspension shaft is short, the laminated rubber-like elastic body can be arranged in series on it. By doing so, the same effect as using a long suspension shaft is produced, and a horizontal vibration isolation effect with good characteristics can be obtained. In addition, since the hanging shaft and the laminated rubber-like elastic body are combined with members having greatly different sound transmission losses, high-frequency vibrations propagated from the outer cylinder to the inner cylinder or from the inner cylinder to the outer cylinder can also be isolated. Furthermore, in recent years, vibration isolators and anti-vibration devices are often integrated with or built into machines, and are required to provide better performance than ever with smaller devices. , can be realized according to the present invention.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of one embodiment of the present invention, Fig. 2 is a partial view thereof, Fig. 3 is an explanatory diagram of a laminated rubber-like elastic body, and Fig. 4 is an explanatory diagram of the operation of an embodiment of the present invention. , FIG. 5 is a graph showing the relationship between horizontal vibration transmissibility and frequency, FIG. 6 is a cross-sectional view of a conventional example, and FIG. 7 is an explanatory diagram of a conventional vibration-proof rubber. DESCRIPTION OF SYMBOLS 1... Outer cylinder, 1a... Upper end of outer cylinder, 2... Hanging shaft, 3... Inner cylinder, 3a... Air spring, 4... Laminated rubber-like elastic body, 5... Rubber, 6... Thin metal plate.

Claims (1)

[Scope of utility model registration request] A pendulum-type vibration isolator comprising an outer cylinder and an inner cylinder that is provided with an air spring and is suspended and supported within the outer cylinder by an elongated suspension shaft that is swingably suspended from the upper end of the outer cylinder, A pendulum-type vibration isolator characterized in that the upper end of the hanging shaft protrudes from the upper end of the outer cylinder and is pivotally connected to a laminated rubber-like elastic body mounted on the upper end of the outer cylinder.