JP4408208B2 - Spring stiffness variable air spring vibration isolation unit - Google Patents

Description

  The present invention relates to a general-purpose passive vibration isolation unit using an air spring, and more particularly to a spring stiffness variable air spring vibration isolation unit capable of easily adjusting spring rigidity.

  In order to increase the vibration isolation performance with the passive vibration isolation unit, it is necessary to set the spring rigidity against the load as soft as possible. However, when the center of gravity of the apparatus on the table fluctuates in the horizontal direction (for example, movement of a movable table on the apparatus), the apparatus may be greatly inclined.

  Normally, a passive vibration isolation unit for an air spring is equipped with a leveling valve (opens and closes the valve at the height of the table to supply and exhaust air to the pressure chamber of the air spring), keeping the height of the table constant, Designed to correct tilt. However, it may take several minutes for stable restoration after the height fluctuation occurs, and in order to restore it in a short time, it is necessary to keep the initial height fluctuation as small as possible. In order to suppress this, the spring rigidity must be large to some extent.

  As described above, since the vibration isolation performance and the inclination stability of the apparatus are in conflict, an appropriate setting of the spring rigidity is required if the inclination is allowed to fall within an allowable range without impairing the vibration isolation performance as much as possible. . However, in the conventional passive vibration isolation unit, the spring stiffness cannot be adjusted except for replacing the spring.

  Accordingly, it is an object of the present invention to obtain a passive vibration isolation unit that can easily adjust spring rigidity.

According to the first aspect of the present invention, there is provided a top plate for placing an object to be vibration-isolated; a volume cylinder having an upper end opened and having an axis line oriented vertically below the top plate; A vibration-isolating elastic diaphragm member having a lower peripheral edge fixed to the upper end of the upper plate and an upper peripheral edge fixed to the lower surface of the top plate ; a piston body located in the volume cylinder and coaxial with the volume cylinder ; An airtight member interposed between the cylinder and defining a vibration isolation pressure chamber closed between the piston body, the volume cylinder, the top plate, and the vibration isolation elastic diaphragm member; a control air pressure is supplied to the vibration isolation pressure chamber; And a movement adjusting mechanism for moving the piston body in the axial direction.
As the airtight member, a packing such as an O-ring or a rolling diaphragm can be used.

According to the second aspect of the present invention, there is provided a top plate for placing an object to be vibration-isolated; a volume cylinder having an upper end opened and having an axis line oriented vertically below the top plate; A vibration-isolating elastic diaphragm member having a lower peripheral edge fixed to the upper end of the upper plate and an upper peripheral edge fixed to the lower surface of the top plate ; a piston body located in the volume cylinder and coaxial with the volume cylinder ; above the piston body An airtight member that defines a closed anti-vibration pressure chamber together with the top plate, the anti-vibration elastic diaphragm member, and the volume cylinder, and that defines a variable volume pressure chamber together with the volume cylinder below the piston body; A throttle passage for communicating the pressure chamber and the variable volume pressure chamber; an air pressure supply means for supplying a control air pressure to the vibration isolation pressure chamber; and a movement adjusting mechanism for moving the piston body in the axial direction.

  The throttle passage can be constituted by an orifice formed in the piston body, or can be constituted by an external pipe line having a needle valve having a variable passage area.

  The hermetic member may be composed of a packing such as an O-ring, but is preferably interposed between the upper outer peripheral surface of the piston body and the inner peripheral surface of the volume cylinder, and the top plate, the vibration isolation elastic diaphragm A first rolling diaphragm defining a closed vibration isolation pressure chamber between the member, the volume cylinder and the piston body; interposed between a lower outer peripheral surface of the piston body and an inner peripheral surface of the volume cylinder, And a second rolling diaphragm defining a variable volume pressure chamber below the vibration isolation pressure chamber.

  In either of the first and second modes, the movement adjustment mechanism manually adjusts, for example, the adjustment rod fixed to the shaft portion of the piston body and guided to the outside of the volume cylinder, and the axial position of the adjustment rod. And a manual position adjusting mechanism.

  Alternatively, the movement adjustment mechanism can be configured by an adjustment rod that is fixed to the shaft portion of the piston body and is airtightly guided to the outside of the volume cylinder, and a linear actuator that moves the adjustment rod in the axial direction.

  ADVANTAGE OF THE INVENTION According to this invention, the passive type air spring vibration isolator unit which can change a spring rigidity easily is obtained.

  FIG. 1 shows a first embodiment of a spring stiffness variable air spring vibration isolation unit 100 according to the present invention. This vibration isolation unit 100 has a bottomed volume cylinder 10 whose upper end is opened with its axis fixed to the floor surface S oriented in the vertical direction, and a lower peripheral edge is fixed to the upper end of the volume cylinder 10. It has a bellows (vibration isolation elastic diaphragm member) 30 whose peripheral edge is fixed to the lower surface of the top plate 20.

  A coaxial piston body 11 is located in the volume cylinder 10, and the adjustment screw rod 12 fixed to the shaft portion of the piston body 11 passes through a sliding hole 10 a provided in the bottom wall of the volume cylinder 10. Led outside. A lock nut 13 is screwed to the adjustment screw rod 12 outside the displacement cylinder 10.

  The volume cylinder 10 is divided into two upper and lower members, and a peripheral bead portion 41 of a rolling diaphragm (airtight member) 40 is sandwiched and fixed therebetween. The rolling diaphragm 40 has an annular folded portion 42 that is deformed in accordance with the pressure difference between the front and back along the inner peripheral surface of the volume cylinder 10 and the outer peripheral surface of the piston body 11, following the peripheral bead portion 41. 43 is airtightly fixed to the upper surface of the piston body 11. The rolling diaphragm 40 is not fixed except for the peripheral bead portion 41 and the central portion 43, and the position of the folded portion 42 changes with the movement of the piston body 11, and the axial movement length of the piston body 11 is increased. The pressure receiving area does not change regardless of the movement position of the piston body 11.

  The vibration damping pressure chamber 50 is formed by the top plate 20, the bellows 30, and the rolling diaphragm 40 (piston body 11). A control pressure supplied from a compressed air source 51 and regulated by a control circuit (pressure reducing valve) 52 is supplied to the vibration isolation pressure chamber 50. The chamber 14 in the volume cylinder 10 below the piston body 11 (rolling diaphragm 40) communicates with the atmosphere through the communication hole 15, and the vibration isolation pressure chamber 50 is constantly at a higher pressure than the atmosphere communication chamber 14. . Therefore, the annular folded portion 42 of the rolling diaphragm 40 is always convex downward.

  The vibration isolation pressure chamber 50 is also connected to an air tank 61 via an orifice (needle valve) 60. The air tank 61 is filled with air having the same pressure as that of the vibration isolation pressure chamber 50.

  Three or more of the above vibration isolation units 100 are used for one semiconductor manufacturing apparatus, precision equipment (an object of vibration isolation) such as an electron microscope. For example, three vibration isolation units 100 are arranged and used at each vertex of a planar virtual triangle. The position of the piston body 11 is adjusted so as to maximize the volume, and is locked at the adjusted position by the lock nut 13. In this state, the compressed air source 51 is connected to the vibration isolation pressure chamber 50, and the control air pressure is introduced into the vibration isolation pressure chamber 50 and the air tank 61 by the control circuit 52. The top plate 20 is supported by the bellows 30 in a floating state, and the introduction of the control air pressure into the vibration isolation pressure chamber 50 prevents propagation of floor vibrations, particularly vertical vibrations, to the vibration isolation object. Alternatively, a vibration isolation operation that is reduced is executed. In addition, the action of attenuating vibration is obtained by the movement of the air given resistance through the orifice 60 between the vibration isolation pressure chamber 50 and the air tank 61. The attenuation rate can be changed by adjusting the opening degree of the orifice 60.

  On the other hand, when it becomes necessary to change (adjust) the spring rigidity of the vibration isolation unit 100, such as changing the vibration isolation object placed on the top plate 20, the lock nut 13 is loosened and the adjustment screw rod 12 is interposed. Thus, the axial position of the piston body 11 is adjusted. Then, the volume of the vibration isolation pressure chamber 50 is changed while the rolling diaphragm 40 is deformed (while the position of the folded portion 42 is changed). Since the spring rigidity of the vibration isolation unit 100 varies depending on the volume of the vibration isolation pressure chamber 50, a vibration isolation system having a vibration isolation characteristic corresponding to the vibration isolation object can be easily obtained.

  Next, FIG. 2 shows another embodiment of the spring stiffness variable air spring vibration isolation unit 100A according to the present invention. In this embodiment, the piston body 11 is provided with a lower second rolling diaphragm (airtight member) 40 ′ in addition to the upper rolling diaphragm 40 (first rolling diaphragm) below the piston body 11. It differs from the first embodiment in that a variable volume pressure chamber 50 'is formed and an orifice (throttle passage) 11a is provided in the piston body 11. Similar to the rolling diaphragm 40, the rolling diaphragm 40 ′ is connected to the peripheral bead portion 41 ′ sandwiched and supported between the divided volume cylinders 10, the inner peripheral surface of the volume cylinder 10, and the outer peripheral surface of the piston body 11. And an annular folded portion 42 ′ that deforms according to the pressure difference between the front and back sides, and a central portion 43 ′ is airtightly fixed to the lower surface of the piston body 11.

  The variable volume pressure chamber 50 ′ is formed by the volume cylinder 10 and the rolling diaphragm 40 ′ (piston body 11). The orifice 11a of the piston body 11 communicates the vibration isolation pressure chamber 50 and the variable volume pressure chamber 50 '. As in the first embodiment, the vibration isolation pressure chamber 50 is supplied with a control pressure supplied from the compressed air source 51 and regulated by a control circuit (leveling valve or pressure reducing valve) 52. Since the vibration isolation pressure chamber 50 and the variable volume pressure chamber 50 ′ are in communication with each other, the inside of the variable volume pressure chamber 50 ′ is a positive pressure, and the annular folded portion 42 ′ of the rolling diaphragm 40 ′ is always convex upward. ing. The chamber surrounded by the two rolling diaphragms 40, 40 'is communicated with the atmosphere. The sliding hole 10a of the displacement cylinder 10 is provided with an O-ring 16 that holds the sliding portion (variable displacement pressure chamber 50 ') of the adjusting screw rod 12 in an airtight manner.

  According to this embodiment, the vibration isolation operation in a state where the position of the piston body 11 is fixed by the lock nut 13 is basically the same as that of the first embodiment. In this embodiment, the air is slightly passed between the vibration isolation pressure chamber 50 and the variable volume pressure chamber 50 ′ via the orifice 11a along with the vibration isolation operation (with supply / exhaust of compressed air to the vibration isolation pressure chamber 50). Distribution of. Since the air flow through the orifice 11a is given resistance in the same manner as the air flow through the orifice 60 between the vibration isolation pressure chamber 50 and the air tank 61, the vibration is damped. To do.

  On the other hand, when it is necessary to change (adjust) the spring rigidity of the vibration isolation unit 100A, such as changing the vibration isolation object placed on the top plate 20, the lock nut 13 is loosened and the adjustment screw rod 12 is interposed. Thus, the axial position of the piston body 11 is adjusted. Then, the volume of the vibration isolation pressure chamber 50 (variable volume pressure chamber 50 ′) is changed while the rolling diaphragms 40, 40 ′ are deformed (while the positions of the folding portions 42, 42 ′ are changed). Since the spring rigidity of the vibration isolation unit 100A varies depending on the volume of the vibration isolation pressure chamber 50, a vibration isolation system having a vibration isolation characteristic according to the vibration isolation object can be easily obtained.

  3 and 4 show an embodiment in which a linear actuator 18 is used instead of the manual position adjusting mechanism (lock nut 13) of the piston body 11 in the embodiment of FIGS. Both of the linear actuators 18 have a function of linearly moving the adjustment rod 12 ′ (no screw is formed) of the piston body 11 in accordance with an input signal, such as an electric mechanism, a pneumatic mechanism, a hydraulic mechanism, etc. Any mechanism can be used.

  Further, FIG. 5 shows that, in the embodiment of FIG. 2 (FIG. 4), instead of forming the orifice 11a in the piston body 11, the vibration isolation pressure chamber 50 and the variable volume pressure chamber 50 ′ are replaced with a needle having a variable flow area. It is an embodiment connected via an external pipe line having a valve 60. According to this embodiment, the attenuation rate can be made variable by the opening degree of the needle valve 60.

The bellows 30 shown in the above embodiment is an example of a vibration isolation elastic diaphragm member, and the shape thereof has a degree of freedom. Further, the rolling diaphragm can be replaced with a packing such as an O-ring.

1 is a longitudinal sectional view showing a first embodiment of a spring stiffness variable air spring vibration isolation unit according to the present invention. It is a longitudinal section showing the second embodiment. It is a longitudinal section showing the third embodiment. It is a longitudinal section showing the fourth embodiment. It is a longitudinal section showing the fifth embodiment.

Explanation of symbols

10 displacement cylinder 10a sliding hole 11 piston body 11a orifice 12 adjusting screw rod 13 lock nut (manual position adjusting mechanism)
14 Atmospheric communication chamber 16 O-ring 18 Linear actuator 19 Control circuit 20 Top plate 30 Bellows 40 40 'Rolling diaphragm (airtight member)
41 41 ′ Peripheral bead portion 42 42 ′ Ring-back portion 43 43 ′ Center portion 50 Anti-vibration pressure chamber 50 ′ Variable volume pressure chamber 51 Compressed air source 52 Control circuit 60 Orifice (needle valve)
100 100A Vibration isolation unit

Claims (9)

A top plate on which the object to be isolated is placed;
A volume cylinder with the upper end open and positioned below the top plate with the axis line in the vertical direction ;
A vibration isolation elastic diaphragm member having a lower peripheral edge fixed to the upper end of the volume cylinder and an upper peripheral edge fixed to the lower surface of the top plate ;
A piston body coaxial with the volume cylinder, located in the volume cylinder;
An airtight member that is interposed between the piston body and the volume cylinder and defines a vibration isolation pressure chamber that is closed between the piston body, the volume cylinder, the top plate, and the vibration isolation elastic diaphragm member;
Air pressure supply means for supplying control air pressure to the vibration isolation pressure chamber; and a movement adjusting mechanism for moving the piston body in the axial direction;
A spring stiffness variable air spring vibration isolation unit characterized by comprising: 2. The spring stiffness variable air spring vibration isolation unit according to claim 1, wherein the movement adjustment mechanism includes an adjustment rod fixed to the shaft portion of the piston body and guided to the outside of the volume cylinder, and an axial position of the adjustment rod is manually adjusted. A spring stiffness variable air spring vibration isolation unit that is configured with a manual position adjustment mechanism that adjusts with. 2. The spring stiffness variable air spring vibration isolation unit according to claim 1, wherein the movement adjusting mechanism includes an adjustment rod fixed to the shaft portion of the piston body and guided to the outside of the volume cylinder, and moves the adjustment rod in the axial direction. A spring stiffness variable air spring vibration isolation unit composed of a linear actuator. A top plate on which the object to be isolated is placed;
A volume cylinder with the upper end open and positioned below the top plate with the axis line in the vertical direction ;
A vibration isolation elastic diaphragm member having a lower peripheral edge fixed to the upper end of the volume cylinder and an upper peripheral edge fixed to the lower surface of the top plate ;
A piston body coaxial with the volume cylinder, located in the volume cylinder;
An airtight pressure chamber is defined above the piston body together with the top plate, the vibration isolation elastic diaphragm member and the volume cylinder, and a variable volume pressure chamber is defined below the piston body together with the volume cylinder. Element;
A throttle passage communicating the vibration isolation pressure chamber and the variable volume pressure chamber;
Air pressure supply means for supplying control air pressure to the vibration isolation pressure chamber; and a movement adjusting mechanism for moving the piston body in the axial direction;
A spring stiffness variable air spring vibration isolation unit characterized by comprising: 5. The spring stiffness variable air spring vibration isolation unit according to claim 4, wherein the throttle passage is an orifice formed in the piston body. 5. The spring stiffness variable air spring vibration isolation unit according to claim 4, wherein the throttle passage is an external pipe having a needle valve with a variable passage area. The spring stiffness variable air spring vibration isolation unit according to any one of claims 4 to 6, wherein the airtight member is interposed between an upper outer peripheral surface of the piston body and an inner peripheral surface of the volume cylinder, and A first rolling diaphragm defining a vibration isolation pressure chamber closed between the plate, the vibration isolation elastic diaphragm member, the volume cylinder and the piston body; and a lower outer peripheral surface of the piston body and an inner peripheral surface of the volume cylinder A spring stiffness variable air spring vibration isolation unit comprising: a second rolling diaphragm which is interposed between the second rolling diaphragm and defines a variable volume pressure chamber below the vibration isolation pressure chamber. 8. The spring stiffness variable air spring vibration isolation unit according to claim 4, wherein the movement adjustment mechanism includes an adjustment rod fixed to the shaft portion of the piston body and guided to the outside of the volume cylinder, and the adjustment rod. A spring stiffness variable air spring vibration isolation unit composed of a manual position adjustment mechanism that manually adjusts the axial position of the rod. The spring stiffness variable air spring vibration isolation unit according to any one of claims 4 to 7, wherein the movement adjustment mechanism is an adjustment rod fixed to the shaft portion of the piston body and airtightly guided to the outside of the volume cylinder. A spring stiffness variable air spring vibration isolation unit comprising a linear actuator for moving the adjustment rod in the axial direction.