JPS61252928A - Air spring system using vibro-isolator rubber in combination - Google Patents

Abstract

PURPOSE:To improve the extent of vibro-isolating performance so better, by using a vibro-isolator rubber device combinedly for an air spring in a series manner, while reducing a horizontal direction spring constant so sharply enough, in case of a vibro-isolating system, bearing the above caption, available for various precision measuring instruments. CONSTITUTION:Supposing a surface plate 4, where an air spring 30 is locked, moves in a left direction, a metal device 40 on the air spring and a vibro- isolator rubber device 50 both rotate around each of turning centers 01 and 02 by horizontal directional force F and vertical directional force W, whereby shearing deformation and torsional deformation both are produced in this vibro- isolator rubber device 50. That is to say, both shearing and torsional deformations of the vibro-isolator rubber device 50 are added to the shearing deformation of a bellows 36 in series in addition, therefore spring action is made to be soft. Accordingly, with the vibro-isolator rubber device 50 combinedly used, a spring constant is remarkably reduced, thus the extent of vibro-isolating performance is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention improves the accuracy of various precision measuring instruments or manufacturing machines, such as holography sets and electron microscopes, by blocking or reducing minute vibrations transmitted to the precision instruments from the floor on which they are installed. It concerns an air spring system for maintenance.

[Etachi Katsuyoshi] Traditionally, it prevents vibrations from the surroundings, especially from the floor.

Air spring systems are used to maintain or improve the measurement accuracy of precision instruments or the processing accuracy of manufacturing machines. A conventional air spring system generally has a configuration schematically shown in FIG. 10. That is, the air spring system 1 has a vibration-proof pedestal (surface plate) 4 that supports the precision equipment 2, and the vibration-proof pedestal 4 is supported on the floor 8 by a plurality of air springs 6. Air spring 6.

A stopper 10 attached to the vibration isolating frame 4 and the stopper lO
A bellows 16 is attached to the bellows fixing fitting 12 to form an upper air chamber 14, and a lower fitting 2 is fixed to the bellows 16 to define an upper air chamber 18 inside and is installed on the floor 8.
0. The upper air chamber 14 and the upper air chamber 18 communicate with each other through a second stage orifice 24 formed on the upper surface of the lower metal fitting 20.

The upper air chamber 18 is communicated with an automatic pressure regulating valve 26 through a second stage orifice 24 provided in the stopper 20, and compressed air is supplied and exhausted.

Various types of automatic pressure regulating valves 26 are used, but in any case, the ON@OFF action of the automatic pressure regulating valve 26 ensures that the horizontal precision (leveling precision) of the equipment 2 on the vibration isolating pedestal 4 is accurate. maintained at 0 e.g. automatic pressure regulating valve 2
If the height dimension at position 6 can be adjusted from ±50 to ±100 m, and the support interval is 1000 mm (0,1
A levelness of ~012)/1ooo is achieved.

In the air spring system 1 having the configuration shown in FIG.
It is transformed into the state shown in Figure 2. Conventionally, the bellows 16 forming the upper air chamber 14 is made of a highly flexible material with a thickness of approximately 0.5 to 1 mm, such as a thin reinforcing cloth coated with rubber, and has a shear spring constant Ktz of the size. have. Generally, the shear spring constant Kt of an air spring is expressed by the following formula.

Kt=Kt, +Ktz Here, Kt is a spring constant based on the shear force F, that is, due to the difference in the contact length of the left and right bellows due to the displacement ε of the bellows shown in FIG. 11, and is expressed by a linear equation. It will be done.

K t I= F /ε=π2/ (8PDp) Thus, the shear spring constant Kk of the air spring expressed by the above formula
The value of cannot be below a certain limit, and the shear spring constant Kt cannot be reduced to the desired value. Therefore, as can be understood from the following equation, the horizontal natural frequency of the air spring vibration isolation system fnt does not become small.

fnt= (1/2π) ・t/M) Here, M
is the sprung mass.

Conventionally, a vibration transmissibility Tr expressed by the following equation has been employed as a factor for evaluating the vibration isolation effect of an air spring vibration isolation system.

Tr=11/(1-(f/fnt)2) lwhere,
f is the frequency of the vibration isolation target, and fnt is the natural frequency of the air spring vibration isolation system.

Although it is preferable that the vibration transmissibility Tr is small, as can be seen from the above, the conventional air spring vibration isolation system has the drawback that fnt cannot be made small and the vibration isolation performance in the horizontal direction cannot be improved. Ta.

For example, when the effective cross-sectional area Ae = 45 Cm2, the natural frequency fnt could not be lower than 2.5 Hz. In view of vibration damping performance, it is desirable to lower the natural frequency fnt to about 1.5 Hz.

Therefore, it is an object of the present invention to significantly reduce the spring constant in the horizontal direction, that is, to soften the spring action in the horizontal direction, thereby reducing the natural frequency, especially in the horizontal direction. An object of the present invention is to provide an air spring system with significantly improved anti-vibration performance.

- The above objects of divination are achieved by the present invention. To summarize, the present invention provides an air spring characterized by comprising: an air spring having an air chamber maintained at a predetermined pressure; and vibration-proofing rubber means connected to the air spring in series with the air spring. According to one embodiment of the invention, the anti-vibration rubber means are arranged between the air spring and the surface plate, and according to another embodiment, the anti-vibration rubber means are arranged between the floor and the air spring. placed between.

According to a preferred embodiment of the invention, the anti-vibration rubber means:
It is constructed by sandwiching a vibration isolating rubber between a vibration isolating rubber lower metal fitting and a vibration isolating rubber upper metal fitting, and the vibration isolating rubber lower metal fitting and the vibration isolating rubber upper metal fitting are flat or semispherical.

Next, the air spring system according to the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows an embodiment of the air spring system according to the present invention partially enlarged. In this embodiment, which includes an air spring 30 and a vibration isolating rubber means 50, the surface plate 4 is directly supported by the vibration isolating rubber means 50, and the vibration isolating rubber means 50 is supported by the air spring 30. be done.

In the embodiment shown in FIG. 1, the air spring 30 has a hollow space inside and an air spring lower metal fitting 32 having an open upper end.

A bellows 36 that is disposed at the upper open end of the lower air spring fitting 32 and cooperates with the lower air spring fitting 32 to define an air chamber 34; and a bellows that fixes the bellows 36 to the upper end of the lower air spring fitting 32. It has a presser metal fitting 38. The air chamber 34 is filled with compressed air and maintained at a pressure P.

An air spring lower metal fitting 40 is fixed to the bellows 36,
A vibration-proof rubber means 50 is connected.

The vibration isolating rubber means 50 is constructed by sandwiching a vibration isolating rubber 52 between a flat plate-shaped vibration isolating rubber lower metal fitting 54 and a vibration isolating rubber upper metal fitting 56, and the vibration isolating rubber lower metal fitting 54 is connected to the air spring by a connecting shaft 58. It is fixedly connected to the lower metal fitting 40, and the vibration-proof rubber upper metal fitting 56 is directly attached to the surface plate 4.

Next, the operation of the air spring system la configured as described above will be explained.

As shown in FIG. 2, relative horizontal movement occurs between the air spring 30 and the surface plate 4 due to vibration, and in FIG. 2, the air spring 3o is fixed and the surface plate 4 is moved to the left. Then, the air spring lower fitting 40 and the vibration isolating rubber means 5o are
rotates around rotation centers 01 and 02, and the anti-vibration rubber means 5
0, shear deformation and torsional deformation occur. Of course, before a relative horizontal movement occurs between the air spring 30 and the surface plate 4 due to vibration, the horizontal force F is not generated and the vertical force (of the air spring) is not generated, as shown in FIG. The rotation centers 01 and o2 of the air-spring lower metal fitting 4o and the vibration-isolating rubber means 50 are located on the line of action of the support load) W, and the vibration-isolating rubber means 50 is not subjected to shearing deformation or torsional deformation.

Now, the anti-vibration rubber means 50. That is, assuming that the vibration isolating rubber 52 is a round vibration isolating rubber, the spring constant Kr in the horizontal direction of the vibration isolating rubber means 5°, that is, in the shear direction, and the torsional spring constant of torsional deformation due to the action of the vertical force W are 0. is expressed by the following formula.

Kr=F/δr (1) Kθ=Kc-d2/16 (2) Where, F: Horizontal force δr: Shearing deformation KC: Compression spring constant of the vibration-proof rubber d: Diameter of the vibration-proof rubber Therefore, The overall spring constant Kk of the air spring system la according to the present invention is expressed by the following equation.

K t = 1 / [(1/ K b ) + (1
/Kr) +(J12 (1+AeP/KrJ
l)/ (Ko-AeP sentence))]
(3) Here, Kb: Horizontal spring constant of the bellows alone θ: Torsional spring constant of the anti-vibration rubber Ae: Air spring effective pressure area P: Air spring pressure (P = W / A e ) See: Center of rotation As can be understood from the above equation (3), the overall spring constant Kt is smaller than the spring constant Kb of the bellows alone.1 The air spring system according to the present invention has only an air spring.
In other words, compared to a conventional air spring system in which only shear deformation occurs in the bellows, shear deformation and torsional deformation of the anti-vibration rubber are added in series to the shear deformation of the bellows, resulting in a softer spring action. .

FIG. 3 is a graph showing the relationship between the horizontal spring constant Kb of the bellows alone and the spring constant Kk (actually measured values and calculated values) of the air spring system according to the present invention that uses a large vibration-proof rubber means. It will be seen that the spring constant is significantly reduced by the combined use of the vibrating rubber means.

As is clear from Fig. 3, in the air spring system of the present invention, the spring constant Kt decreases as the pressure increases, but this is because the moment due to the air spring support load W (= A e P) As can be seen from the figure, this is because the vibration isolating rubber means 50 acts in the direction of overturning, that is, one rotation.

Also, from the above formula (3), the distance statement between the rotation centers 01.02,
That is, if the length of the connecting shaft 58 is increased, the spring constant Kt
becomes smaller. Therefore, the spring constant Kt can be finely adjusted by preparing connecting shafts 58 of various lengths or by changing the length of the connecting shafts using spacers (not shown). However, in order to prevent buckling of the anti-vibration rubber means 50, the twisting force of the anti-vibration rubber (Kθ)
must satisfy Kθ>WZ, therefore, the connecting shaft 5
There is also a limit to the length of 8. For example, if the torsional spring constant of the anti-vibration rubber is θ of 3000 kg am/rad and the supporting load W is 350 kg, connect the parts so that the length is 8.5 cm or less. The length of shaft 58 should be set.

FIG. 4 shows another embodiment of the air spring system according to the present invention. The air spring system lb of this embodiment has the same structure as the air spring system la of FIG. The air spring system 1b of this embodiment differs from the air spring system la in that the surface plate 4 is directly supported by an air spring 30, and the air spring 30 is supported by a vibration isolating rubber means 50. The air spring system 1a also functions in the same manner as described in connection with the air spring system 1a, and has similar effects.

Further, the structure of the air spring 30 used in each of the above embodiments is not limited, and may be structured as shown in FIG. 5, for example. That is, the air spring 30a of the air spring system 1c of this embodiment is similar to the air spring 6 of the conventional structure explained in connection with FIG.
A lower air chamber 42 is provided below the air chamber 34 and is communicated with the first stage orifice 22. The lower air chamber 42 is communicated with the automatic pressure regulating valve 26 through the second stage orifice 24, and It is also possible to have a structure in which compressed air is supplied to and exhausted from the chamber.

FIG. 6 shows another embodiment of the air spring system according to the present invention. The air spring system 1d of this embodiment has the same configuration as the air spring system 1a shown in FIG. The rubber means 50 differ in their specific construction.

To explain in more detail, the vibration isolating rubber means 50 is the vibration isolating rubber 5.
2 is sandwiched between an anti-vibration rubber lower metal fitting 54 and an anti-vibration rubber upper metal fitting 56, and the anti-vibration rubber lower metal fitting 54 has a connecting shaft 58. It is fixedly connected to the main metal fitting 40 of the vibration isolating rubber upper metal fitting 56.
is the same as the above embodiment in that it is directly attached to the surface plate 4, but the vibration isolating rubber lower metal fitting 54 and the vibration isolating rubber upper metal fitting 5 are
6 has a different structure. That is, in this embodiment, the vibration-isolating rubber lower metal fitting 54 is a hemisphere with a convex surface of radius R1, and the vibration-isolating rubber upper metal fitting 56 is a hemisphere with a concave surface of radius R2 (>R1). be done. The vibration isolating rubber 52 is interposed between the convex lower metal fitting 54 and the concave upper metal fitting 56, and is preferably vulcanized and bonded to the surfaces of the lower metal fitting 54 and the main metal fitting 56.

In the embodiment shown in FIG. 6, the connecting shaft 5B has threaded shafts 58a at both ends.
, 58b are provided and are screwed and attached to the vibration-isolating rubber lower metal fitting 54 and the air spring main metal fitting 40, respectively. Also, a spacer S is arranged between the connecting shaft 58 and the vibration-isolating rubber lower metal fitting 54. and the length of the connecting shaft 58, that is, the rotation center Of, 0
It is configured such that the distance statement between the two can be changed.

Next, the operation of the air spring system ld configured as described above will be explained.

As shown in FIG. 7, the vibration caused a relative horizontal movement between the air spring 30 and the surface plate 4, and in FIG. 7, the air spring 30 was fixed and the surface plate 4 moved to the left. Then, due to the horizontal force F and the vertical force (air spring support load) W, the air spring main metal fitting 40 and the anti-pregnancy rubber means 5
0 rotates around the rotation centers O1 and 02, and the vibration isolating rubber means 50 undergoes torsional deformation. Of course, before relative horizontal movement occurs between the air spring 30 and the surface plate 4 due to lifting,
As illustrated in FIG. 1, no horizontal force F is generated;
The rotation centers 01 and 02 of the air sprung metal fitting 40 and the anti-vibration rubber means 50 are located on the line of action of the vertical force (load supported by the air spring) W, and no torsional deformation occurs in the anti-vibration rubber means 50. .

The overall spring constant Kt of the air spring system ld in this embodiment is expressed by the following equation.

Kt=1/[1/Kb+Jl'/(KO-Ae・Pi)
1 (4) Here, Kb: Horizontal spring constant of the bellows alone 0: Torsional spring constant of the anti-vibration rubber Ae: Air spring effective pressure receiving area P: Air spring pressure (P = W / A e )! L Distance between two rotation centers Of and 02 As can be understood from the above equation (4), the overall spring constant Kt is smaller than the spring constant Kb of the bellows alone, and the air spring system ld according to the present invention has only an air spring. Compared to a conventional air spring system in which only the shear deformation of the bellows occurs, the torsional deformation of the anti-vibration rubber is added in series to the shear deformation of the bellows, resulting in a softer spring action. .

FIG. 8 is a graph showing the relationship between the horizontal spring constant Kb of the bellows alone and the spring constant Kt (actually measured values and calculated values) of the air spring system according to the present invention that uses hemispherical anti-vibration rubber means. It will be seen that the spring constant is significantly reduced by using the anti-vibration rubber means.

As is clear from FIG. 8, in the air spring system of the present invention, the spring constant Kt decreases as the pressure increases, but this is because the moment due to the air spring support load W (= A e P) As can be seen from the figure, this is because the vibration isolating rubber means 50 acts in the direction of overturning, that is, rotation.

Further, as understood from the above equation (4), the spring constant Kk of the air spring system 1d decreases in inverse proportion to the square of the distance between the rotation centers 01.02. Therefore, by adjusting the length of the connecting shaft 58 using the spacer S, the spring constant Kt can be finely adjusted.

However, in order to prevent buckling of the anti-vibration rubber means 50, it is necessary to satisfy the torsional spring constant (KO) of the anti-vibration rubber>W, and therefore there is a limit to the length of the connecting shaft 58, e.g. Torsional spring constant KO of anti-vibration rubber is 2000kg
* cm/rad, and if the supported load W is 350 kg, the length of the connecting shaft 58 should be set so that Jl is 5°7 cm or less.

Furthermore, unlike the embodiment shown in FIG. 1, the air spring system ld of this embodiment has a large spring constant in the compression direction and the horizontal direction, but a torsional spring constant around the center of one rotation 01 (and even 02). It has the characteristic of being small. In other words, the spring action in the vertical direction is stiff and therefore the permissible supporting load of the air spring system ld is large. Also, the constant s1 on the spring
When a horizontal force is applied to 4, the vibration isolating rubber 52 does not deflect purely in the horizontal direction, but due to torsional deformation of the vibration isolating rubber 52, it can easily deflect in the horizontal direction as well. Provides a soft spring action in the horizontal direction.

FIG. 9 shows eight embodiments of an air spring system l showing a modified embodiment of the air spring system according to the present invention shown in FIG. 6.
e has substantially the same structure as the air spring system la shown in FIG. The air spring system LE of this embodiment, which differs from the air spring system LD in that it is carried by means 50, also operates in the same manner as described in connection with the air spring system LD, and has similar effects. .

Furthermore, the structure of the air spring 30 used in each of the embodiments illustrated in FIGS. 6 and 9 is not limited to that shown in the drawings, and for example, the structure described in connection with FIG. It is also possible to use an air spring. Furthermore,
In the embodiment of FIG. 6, in the above description, the vibration isolating rubber means 50
, the vibration-proof rubber lower metal fitting 54 is a hemisphere with a convex surface with a radius R1, and the vibration-proof rubber upper metal fitting 56 has a radius R2 (>R1
), but conversely, the lower anti-vibration rubber fitting 54 is made into a hemisphere with a concave surface of radius R2, and the upper anti-vibration rubber fitting 56 is made of a convex surface with radius R1 (<R2). Alternatively, in the embodiment shown in FIG. 9, the shapes of the main metal fitting and the lower metal fitting can be reversed.

As described above, the air spring system according to the present invention uses the vibration isolating rubber means in series with the air spring, thereby significantly reducing the spring constant of the vibration isolating device, especially in the horizontal direction. thereby of the air spring system.

In particular, it has the effect of reducing the natural frequency in the horizontal direction and reducing the vibration transmissibility, that is, significantly improving the vibration damping performance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of an air spring system according to the present invention. FIG. 2 is a cross-sectional view illustrating the operation of the air spring system of FIG. FIG. 3 is a graph showing the relationship between the horizontal spring constant Kb of the bellows alone and the spring constant Kt (actually measured and calculated values) of the air spring system of FIG. 4 is a cross-sectional view of a modified embodiment of the air spring system of FIG. 1; FIG. FIG. 5 is a cross-sectional view of yet another alternative embodiment of the air spring system of FIG. FIG. 6 is a sectional view showing another embodiment of the air spring system according to the present invention. FIG. 7 is a cross-sectional view illustrating the operation of the air spring system of FIG. 6. FIG. 8 is a graph showing the relationship between the horizontal spring constant Kb of the bellows alone and the spring constant Kt (actually measured values and calculated values) of the air spring system of FIG. 9 is a cross-sectional view of a modified embodiment of the air spring system of FIG. 6; FIG. FIG. 1θ is a cross-sectional view of a conventional air spring system. FIGS. 11 and 12 are partial cross-sectional views illustrating how the air spring system of FIG. 10 operates. 4: Vibration-isolating frame (surface plate) 30: Air spring 32: Air spring lower bracket 34: Air chamber 36: Bellows 40: Air spring main bracket 50: Vibration-isolating rubber means 52: Vibration-isolating rubber 54: Vibration-isolating rubber lower bracket 56: Vibration-isolating rubber upper metal fitting 58 two-connection axis alignment ^ pressure Kshi. m2 to 90,000 Kg/Cm2 Figure 11

Claims (1)

[Claims] 1) an air spring having an air chamber maintained at a predetermined pressure;
an air spring system comprising: anti-vibration rubber means connected in series to the air spring; 2) The air spring system according to claim 1, wherein the vibration isolating rubber means is disposed above the air spring and supported by the air spring. 3) The air spring system according to claim 1, wherein the air spring is disposed above a vibration isolating rubber means and supported by the vibration isolating rubber means. 4) The anti-vibration rubber means is constructed by sandwiching the anti-vibration rubber between a lower anti-vibration rubber fitting and an upper anti-vibration rubber fitting.
The air spring system according to item 3 or item 3. 5) The air spring system according to claim 4, wherein the vibration-proof rubber lower metal fitting and the vibration-proof rubber upper metal fitting have a flat plate shape. 6) The lower anti-vibration rubber fitting is a convex hemisphere and the upper anti-vibration rubber fitting is a concave hemisphere, or the lower anti-vibration rubber fitting is a concave hemisphere and the upper anti-vibration rubber fitting is a convex hemisphere. An air spring system according to claim 4, comprising: